NASASpaceFlight.com Forum
SpaceX Vehicles and Missions => SpaceX Reusability => Topic started by: Kabloona on 07/22/2014 09:15 pm
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SpaceX has announced that F9 flights 14 & 15 will attempt "solid surface" landings. Where will that "solid surface" be? (These will be Cape launches).
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SpaceX has announced that F9 flights 14 & 15 will attempt "solid surface" landings. Where will that "solid surface" be? (These will be Cape launches).
Do we know the payloads? That will help.
- Ed Kyle
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Now shown as Orbcomm and CRS-5.
And Ed, you pointed out in another thread the mention of landing on a "floating launch pad," so that does open the door to the notion of a barge landing attempt with the barge anchored near shore. Which might be easier for SpaceX to get approval for at this point than an attempted landing on Cape terra firma.
Edit: corrected "Cape" per Jim. ;)
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Orbcomm OG2 and TurkmenSat 1 according to Wikipedia.
Orbcomm OG2 and CRS-5 according to SpaceX's manifest.
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Orbcomm OG2 and TurkmenSat 1 according to Wikipedia.
Orbcomm OG2 and CRS-5 according to SpaceX's manifest.
I think the Wikipedia editor that interprets the statement that way is wrong - TurkmenSat 1 weighs 4.5 tonnes and goes GTO so it would definitely require high performance, definitely not a candidate for the landing attempt flights. I have make the changes at Wikipedia so that it would fit with SpaceX's manifest as well as the press release wording. ;)
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Wikipedia more likely correct, I would think, since TurkmenSat probably a low-energy mission that should leave plenty of margin for boostback.
Nope, TurkmenSat is a 4.5 tonne comsat going to geostationary - far from being a low-energy mission. In fact Turkmenistan originally asks the Chinese to launch it (on their most powerful rocket right now - the Long March 3B - would have happened next month if the plan was followed), until ITAR revisions caught up with satellite producer Thales Alenia Space and it can't be launched by the Chinese! ::)
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Thanks, GalacticPenguin, mistaken assumption deleted. ;)
So, where will they attempt landing? On Cape terra firma, or on a barge?
Edit: corrected to "Cape" per Jim ;)
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FYI, they are not landing nor do they launch from KSC. The launch and landing sites are on the Cape. KSC=/ Cape
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Are there any disused oil platforms with helipads in a location that could be used?
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FYI, they are not landing nor do they launch from KSC. The launch and landing sites are on the Cape. KSC=/ Cape
Duly noted. Now, since we have your attention, where will they try to land?
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FYI, they are not landing nor do they launch from KSC. The launch and landing sites are on the Cape. KSC=/ Cape
Duly noted. Now, since we have your attention, where will they try to land?
Speculation on this forum has been that the following two areas are contenders for early landing attempts. (see image)
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Speculation on this forum has been that the following two areas are contenders for early landing attempts. (see image)
Think it more likely at location B IMO. Is that LC-46?
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If they options, would it depend on launch trajectories? Sometimes SpaceX heads to the equator, sometimes they head northeasterly. I would think the shortest distance is the best option all else equal.
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FYI, they are not landing nor do they launch from KSC. The launch and landing sites are on the Cape. KSC=/ Cape
Duly noted. Now, since we have your attention, where will they try to land?
LC-13 was mentioned
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FYI, they are not landing nor do they launch from KSC. The launch and landing sites are on the Cape. KSC=/ Cape
Duly noted. Now, since we have your attention, where will they try to land?
LC-13 was mentioned
I seem to recall that the master plan map showed a planned circular landing pad north of the LC-39 complex. I think that's the area that Lars_J marked "A" on his map above. Has work started on that pad yet?
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It will be a long time before anything launches or lands northo of LC39. It's a swamp, a protected national park swamp.
There is plenty of developed land at CCAFS that hasn't been used in decades. Easy access to roads back to SpaceX facilities.
I was watching a YouTube montage last night of launch failures. It is curious to me that we've become so nervous of a nearly empty returning stage, with a flight termination system when back in the glory days fully loaded vehicles use to put on all kinds of fireworks.
I wish we could just grow a pair and go for it. Worst case range safety blows it up.
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I was just rereading the statement released by SpaceX with the video and was struck by this sentance.
At this point, we are highly confident of being able to land successfully on a floating launch pad or back at the launch site and refly the rocket with no required refurbishment.
Assuming they fly the core back and land somewhere at the Cape and it's now already there needing "no required refurbishment".........
They wouldn't be planning to.......
Naaahhhhh.....
Would they?
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Would you care to spell out what you are thinking?
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I have simply observed that SpaceX likes to move much faster with their testing than others generally do.
They don't skip steps, but they move fast.
Perhaps, if they get a core to return to the Cape, they will leave it there and relaunch it.
I doubt they could do it with a paying payload, but I could see Elon loading a dummy paylod and launching it just to show he could.
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I have simply observed that SpaceX likes to move much faster with their testing than others generally do.
They don't skip steps, but they move fast.
Perhaps, if they get a core to return to the Cape, they will leave it there and relaunch it.
I doubt they could do it with a paying payload, but I could see Elon loading a dummy paylod and launching it just to show he could.
EM is on record as saying they'll land a core on land this year and relaunch a used core next year... so yah, that's what's happening.
Note: I suspect the returned core(s) will undergo re-testing at McGregor until they're sure of launch integrity
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The overall process of landing on a floating platform seems harder than on land. A floating crane would have to be used since having one on the landing platform will be an obstruction. Also, how will they secure the vehicle after landing if they plan to transport the platform and vehicle at the same time back to dock for post-flight assessment?
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How many times do we have to go over this? Perhaps SpaceX may try a one or two-time barge landing to work out bugs before RTLS, but the idea of just landing on a barge and taking off again is ludicrous. How do you re-fuel? How do you connect the necessary umbilicals? How do you move the rocket around on the barge? Is this whole thing automated? How many personnel and how many tons of equipment have to be taken out into the ocean and kept safe and ready to do their jobs? If you fly it off, you've now flown twice. If you try and bring it back on the barge, you're going to have to somehow take hold of it and lay it down before towing the barge. Look at what SpaceX goes through with the crane and gear in Texas with F9R-Dev1. Now try it on a floating barge. I seriously doubt that any owner of a float-on/float off ship is going to let their vessel be a target, so are you going to buy, crew and operate it by yourself? For the umpteenth time: it doesn't make sense to aim for this as a routine event.
Edit: this is in reply to posts on several threads scattered about the SpaceX section since the video was released today, such as this one:
http://forum.nasaspaceflight.com/index.php?topic=35248.0
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I remember on my honeymoon cruise in the Caribbean (many, many years ago) making a stop at the cruise line's "private island" - basically a sandbar a couple hours sailing out - so we didn't have to start the cruise with 3 days at sea.
I wonder if there are any similar small bits of land poking up offshore from, say, Jacksonville FL?
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There is plenty of developed land at CCAFS that hasn't been used in decades. Easy access to roads back to SpaceX facilities.
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You do realize that developed CCAFS land qualified for EPA Super-fund status?
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I was watching a YouTube montage last night of launch failures. It is curious to me that we've become so nervous of a nearly empty returning stage, with a flight termination system when back in the glory days fully loaded vehicles use to put on all kinds of fireworks.
I wish we could just grow a pair and go for it. Worst case range safety blows it up.
Times have changed, like it or hate it. Just think back to the glorious days of motor racing. The fact that a couple of drivers perished over one season of racing was considered normal, nowadays it's kind of unthinkable.
Zoe
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There is plenty of developed land at CCAFS that hasn't been used in decades. Easy access to roads back to SpaceX facilities.
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You do realize that developed CCAFS land qualified for EPA Super-fund status?
Yes I do, I use to watch people go to the monitoring wells to take readings. They used a lot of things during the cold war that wouldn't be allowed today. As well the amount of activity at the cape, especially long Missile Row was at a much higher rate than not even SpaceX has in their wildest projections.
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Before we speculate too much on landing sites at the Cape, lets look again at the SpaceX news article:
At this point, we are highly confident of being able to land successfully on a floating launch pad or back at the launch site and refly the rocket with no required refurbishment.
We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success.
(emphasis mine)
So I'm thinking more about what the "floating launch pad" will be. I'm not sure a barge fits that description.
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Just think back to the glorious days of motor racing. The fact that a couple of drivers perished over one season of racing was considered normal, nowadays it's kind of unthinkable.
At the Isle of Man TT, racers still die frequently. 2 died just this year.
Many people still die climbing Mount Everest or hang gliding.
Dangerous activities are still allowed, as long as the risk is well understood.
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Times have changed, like it or hate it. Just think back to the glorious days of motor racing. The fact that a couple of drivers perished over one season of racing was considered normal, nowadays it's kind of unthinkable.
Zoe
I appreciate the comparison as I am a fan of racing, especially Formula 1. But it's not equal comparison, the returning stage will be unmanned and nearly empty of consumables. It will be a big aluminum/lithium tank.
CCAFS was constituted as a test facility. SpaceX is testing, seems pretty open and shut. That is, once SpaceX has proven they can make a precise landing.
If that isn't enough to make a case maybe those powers that be at CCAFS (Federal) and Space Florida (State) they learn from their loss to Boca Chica to work with SpaceX. If not maybe they'll have a lot more time and room on their hands in the future.
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Times have changed, like it or hate it. Just think back to the glorious days of motor racing. The fact that a couple of drivers perished over one season of racing was considered normal, nowadays it's kind of unthinkable.
Zoe
I appreciate the comparison as I am a fan of racing, especially Formula 1. But it's not equal comparison, the returning stage will be unmanned and nearly empty of consumables. It will be a big aluminum/lithium tank.
Of course the comparison is a bit like apples and oranges, however the point I wanted to make still stands, that things that were acceütable in the past are often considered unacceptable today. Be it because of risk, of environmental issues, noise, whatever.
My guess is that in the US it is still more relaxed than in Europe, but the fact alone that there used to be a rocket testing facility once at a certain place, does not automatically mean that there won't be resitance today to re-open it as such again.
Zoe
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From the horse's mouth. I thought this would be a good jumping point and what we would possibly see from them in the next few launches, and was surprised I didn't see it referenced:
"At this point, we are highly confident of being able to land successfully on a floating launch pad or back at the launch site and refly the rocket with no required refurbishment. . . "
"Flights 14 and 15 will attempt to land on a solid surface"
http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage
I would also like to mention the interesting fact that if you Google "floating launch pad" the first result is the wikipedia article for Sea Launch. Decent rental?
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While a floating barge anchored well off-shore sounds best from a safety point of view I can't help thinking that SpaceX might want a landing place where they can just scrap it clean with a bulldozer if something goes ka-boom!
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I would also like to mention the interesting fact that if you Google "floating launch pad" the first result is the wikipedia article for Sea Launch. Decent rental?
Their platform is in the Pacific, off the west coast. I can't see that huge thing going through the Panama Canal, so I can't see any practical way of getting it to the east coast.
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Some sort of large barge/semi-mobile platform. You'd need something long and wide to soak up sea movements and maintain a stable surface. I can't see CCAFS allowing a landing attempt on the skid strip or NASA allowing it on the shuttle strip at KSC at this time.
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I've seen platforms that have stabiliser outriggers that lower to horizontal when the structure is anchored on station. I'm not sure for what they're normally used or how common they are.
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If it's stability you're after (and this application clearly demands it), the obvious solution would be a SWATH (http://en.wikipedia.org/wiki/Small_waterplane_area_twin_hull) ship"
A Small Waterplane Area Twin Hull, better known by the acronym SWATH, is a twin-hull ship design that minimizes hull cross section area at the sea's surface. Minimizing the ship's volume near the surface area of the sea, where wave energy is located, maximizes a vessel's stability, even in high seas and at high speeds. The bulk of the displacement necessary to keep the ship afloat is located beneath the waves, where it is less affected by wave action. Wave excitation drops exponentially as depth increases (Deeply submerged submarines are normally not affected by wave action at all). Placing the majority of a ship's displacement under the waves is similar in concept to creating a ship that rides atop twin submarines.
(http://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/SWATH_waterline.svg/300px-SWATH_waterline.svg.png)
However, I could not find an existing SWATH ship with a flat deck suitable for Falcon first stage landings, they are all passenger, military, or research vessels. A custom-built SWATH floating landing pad would be very stable, but much too expensive for the few times it would be used by SpaceX.
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I think that SpaceX does not know yet where they will land. That is why they say "or". My guess is that it will depend on permissions. I do hope that they are allowed to land on land somewhere, everything else is an unnecessary distraction and extra cost. Cant make progress without taking (well calculated) risks.
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I think that SpaceX does not know yet where they will land. That is why they say "or". My guess is that it will depend on permissions. I do hope that they are allowed to land on land somewhere, everything else is an unnecessary distraction and extra cost. Cant make progress without taking (well calculated) risks.
As long as NASA has their finger on the FTS button, they should be covered for anomalies.
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If it's stability you're after (and this application clearly demands it), the obvious solution would be a SWATH (http://en.wikipedia.org/wiki/Small_waterplane_area_twin_hull) ship"
A Small Waterplane Area Twin Hull, better known by the acronym SWATH, is a twin-hull ship design that minimizes hull cross section area at the sea's surface. Minimizing the ship's volume near the surface area of the sea, where wave energy is located, maximizes a vessel's stability, even in high seas and at high speeds. The bulk of the displacement necessary to keep the ship afloat is located beneath the waves, where it is less affected by wave action. Wave excitation drops exponentially as depth increases (Deeply submerged submarines are normally not affected by wave action at all). Placing the majority of a ship's displacement under the waves is similar in concept to creating a ship that rides atop twin submarines.
(http://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/SWATH_waterline.svg/300px-SWATH_waterline.svg.png)
However, I could not find an existing SWATH ship with a flat deck suitable for Falcon first stage landings, they are all passenger, military, or research vessels. A custom-built SWATH floating landing pad would be very stable, but much too expensive for the few times it would be used by SpaceX.
SWATH WOULD be a good idea, if most of the SWATH type ships didn't keep having structural issues. Seems most SWATH designs try to act like a tuning fork once they are up to speed, causing premature structural fatigue.
This doesn't mean they can't resolve the issue, (I learned about this problem about 10 years ago, so they've likely come up with a solution by now) but it may be an issue when talking about the vibrations that would be set up by a landing stage.
If they DO go for a floating platform, I think it'd be better if it were cast concrete like one of the old Mulberry structures used in WWII, or be an elevated platform with a hole in the middle for the exhaust flame to go through, like an oil platform. The Mulberry structure would likely be able to handle the exhaust without too much trouble, and they oil platform could be used for both landings and launches, so long as aretractable gantry could be rigged.
A launch gantry similar to what the Russians use might be a good idea for sealaunches, as it would keep a rocket more stable by holding it up about halfway up the stack. (Don't know if a Falcon 9 first stage has the strength to be set up like that though).
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How many times do we have to go over this? Perhaps SpaceX may try a one or two-time barge landing to work out bugs before RTLS, but the idea of just landing on a barge and taking off again is ludicrous. How do you re-fuel? How do you connect the necessary umbilicals? How do you move the rocket around on the barge? Is this whole thing automated? How many personnel and how many tons of equipment have to be taken out into the ocean and kept safe and ready to do their jobs? If you fly it off, you've now flown twice. If you try and bring it back on the barge, you're going to have to somehow take hold of it and lay it down before towing the barge. Look at what SpaceX goes through with the crane and gear in Texas with F9R-Dev1. Now try it on a floating barge. I seriously doubt that any owner of a float-on/float off ship is going to let their vessel be a target, so are you going to buy, crew and operate it by yourself? For the umpteenth time: it doesn't make sense to aim for this as a routine event.
It will start to make sense when SpaceX routinely performs multiple launches per month. In this case, they will have a significant number of heavy payloads where they can't RTLS, and must either fly in expendable mode, or spend money buying a used oil rig and land the stage on it.
This is not unthinkable. It makes economic sense.
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If it's stability you're after (and this application clearly demands it), the obvious solution would be a SWATH (http://en.wikipedia.org/wiki/Small_waterplane_area_twin_hull) ship"
A Small Waterplane Area Twin Hull, better known by the acronym SWATH, is a twin-hull ship design that minimizes hull cross section area at the sea's surface. Minimizing the ship's volume near the surface area of the sea, where wave energy is located, maximizes a vessel's stability, even in high seas and at high speeds. The bulk of the displacement necessary to keep the ship afloat is located beneath the waves, where it is less affected by wave action. Wave excitation drops exponentially as depth increases (Deeply submerged submarines are normally not affected by wave action at all). Placing the majority of a ship's displacement under the waves is similar in concept to creating a ship that rides atop twin submarines.
(http://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/SWATH_waterline.svg/300px-SWATH_waterline.svg.png)
However, I could not find an existing SWATH ship with a flat deck suitable for Falcon first stage landings, they are all passenger, military, or research vessels. A custom-built SWATH floating landing pad would be very stable, but much too expensive for the few times it would be used by SpaceX.
Sea Launch uses old oil rig. They ballast it heavily for launch. It is stable enough for Zenit to stand vertical for hours - it must be stable enough for F9 to land.
Also, oil rigs can have a large top surface area, after you remove all unnecessary drilling equipment.
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This oil rig idea is growing on me. As long as the rig isn't too close to any others and there is no projection of others wanting to be built in that vicinity.
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Personally I'm more worried about the stability of the vehicle after it's touched down. What do you do with it? Tie it down and tow the whole rig back to shore?
Edit: is it just me or are there now several threads talking about the sea platform thing? This is getting confusing.
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Personally I'm more worried about the stability of the vehicle after it's touched down. What do you do with it? Tie it down and tow the whole rig back to shore?
Edit: is it just me or are there now several threads talking about the sea platform thing? This is getting confusing.
well, what the heck do they do with
F9r? so far no reports of it tipping over after touchdown on land, my guess is that the job is up to very brave padrats.
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There are several threads talking about this because it was rather a revelation (or typo, take your pick) ... if we could consolidate that would be great. I'm loth to just merge them together but that's a possibility.
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Yes Lar, please make a single large hard surfaced pad for this thread ;)
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I reference this article because it's a good overview, gives a hat tip to this site and includes a youtube video of the Shuttle SRB on board cams after separation.
There's parts where one can see the other booster. It's similar to how FH booster stages will look after separation. The SRBs, with no control authority, settled down to slowly rotating positions a few hundred meters apart. FH boosters will have active control immediately after separation and won't be tumbling. It's easy to see how they could come down in tight formation. And quite possibly land together a football field apart.
http://www.extremetech.com/extreme/186764-falcon-9-performs-another-perfect-soft-landing-spacex-now-confident-it-can-land-back-at-the-launch-pad-video
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I reference this article because it's a good overview, gives a hat tip to this site and includes a youtube video of the Shuttle SRB on board cams after separation.
There's parts where one can see the other booster. It's similar to how FH booster stages will look after separation. The SRBs, with no control authority, settled down to slowly rotating positions a few hundred meters apart. FH boosters will have active control immediately after separation and won't be tumbling. It's easy to see how they could come down in tight formation. And quite possibly land together a football field apart.
http://www.extremetech.com/extreme/186764-falcon-9-performs-another-perfect-soft-landing-spacex-now-confident-it-can-land-back-at-the-launch-pad-video
That video of the SRBs reentering is amazing! I also think that the FH boosters will be able to fly in formation on RTLS. What an incredible sight that will be.
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Could SpaceX be trying to buy the Ocean Odyssey platform from Sea Launch? Given UKR-RUS tensions, the future of Zenit-3SL must be very much in doubt.
Related:
http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html (http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html)
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Questions: 1) Does "solid surface" imply land based or merely some stable surface at sea? 2) If land/water based, what are the assets required for a safe and successful landing (e.g. pad, safeing, access, etc.)
We're going about this the wrong way. If SpaceX is able to adhere to their aggressive schedule (fingers crossed) then the flights in question are going to be going up within 5 to 6 months. ISTM that this rules out any possible landing surface that is not able to be prepped and ready within that time period. Any site that needs large scale construction/demolition work is therefore unlikely. If they are to be landing on solid surfaces at sea, any specialized equipment (e.g. stabilized barges or drilling platforms and floating cranes) will have to be acquired very soon and crewed up amazingly fast. Not to mention, you'd think they would want to practice some before the big dance right? Has there been any indication that this work has already been happening?
Based on a second reading of SpaceX's statement, my inference from the wording is that they are talking about an ocean-based pad of some kind. But based on the logistical requirements coupled with the time constraint I think it's got to be on land. Cool any way you slice it though.
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Could SpaceX be trying to buy the Ocean Odyssey platform from Sea Launch? Given UKR-RUS tensions, the future of Zenit-3SL must be very much in doubt.
Related:
http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html (http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html)
Currently in the pacific. Not sure it even fits in the panama canal.
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They may just refuel on that barge for a return flight to the launch site, and still save literally tons of fuel (or increase the payload) on each flight relative to the fuel required for a direct RTLS from space.
If you have long enough umbilicals on what I'd call a landing/refuelling barge, a remotely controlled robotic arm "à la Canadarm" could potentially help connect them to the launcher using a crane, without moving the rocket or requiring a local teams.
In addition, even in the first few reusability tests, flying twice every time they launch to space should be no big deal, since SpaceX has repeatedly stated they want to achieve complete reusability for more than 10 times; and in terms of costs they always said that fuel is about 0.3% of the launcher; so they can launch, reenter and land on the barge, and then relaunch towards the original launch site, as many times as they wish until the system breaks, and still spend next to nothing compared to a single F9 launch (30 relaunch attempts < 10% of the cost an additional launcher - what I'd call a flight test program on a shoestring budget).
So is a barge-based reusable launch system doable? I'd say yes.
How many times do we have to go over this? Perhaps SpaceX may try a one or two-time barge landing to work out bugs before RTLS, but the idea of just landing on a barge and taking off again is ludicrous. How do you re-fuel? How do you connect the necessary umbilicals? How do you move the rocket around on the barge? Is this whole thing automated? How many personnel and how many tons of equipment have to be taken out into the ocean and kept safe and ready to do their jobs? If you fly it off, you've now flown twice. If you try and bring it back on the barge, you're going to have to somehow take hold of it and lay it down before towing the barge. Look at what SpaceX goes through with the crane and gear in Texas with F9R-Dev1. Now try it on a floating barge. I seriously doubt that any owner of a float-on/float off ship is going to let their vessel be a target, so are you going to buy, crew and operate it by yourself? For the umpteenth time: it doesn't make sense to aim for this as a routine event.
Edit: this is in reply to posts on several threads scattered about the SpaceX section since the video was released today, such as this one:
http://forum.nasaspaceflight.com/index.php?topic=35248.0
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They may just refuel on that barge for a return flight to the launch site, and still save literally tons of fuel (or increase the payload) on each flight relative to the fuel required for a direct RTLS from space.
If you have long enough umbilicals on what I'd call a landing/refuelling barge, a remotely controlled robotic arm "à la Canadarm" could potentially help connect them to the launcher using a crane, without moving the rocket or requiring a local teams.
In addition, even in the first few reusability tests, flying twice every time they launch to space should be no big deal, since SpaceX has repeatedly stated they want to achieve complete reusability for more than 10 times; and in terms of costs they always said that fuel is about 0.3% of the launcher; so they can launch, reenter and land on the barge, and then relaunch towards the original launch site, as many times as they wish until the system breaks, and still spend next to nothing compared to a single F9 launch (30 relaunch attempts < 10% of the cost an additional launcher - what I'd call a flight test program on a shoestring budget).
So is a barge-based reusable launch system doable? I'd say yes.
How many times do we have to go over this? Perhaps SpaceX may try a one or two-time barge landing to work out bugs before RTLS, but the idea of just landing on a barge and taking off again is ludicrous. How do you re-fuel? How do you connect the necessary umbilicals? How do you move the rocket around on the barge? Is this whole thing automated? How many personnel and how many tons of equipment have to be taken out into the ocean and kept safe and ready to do their jobs? If you fly it off, you've now flown twice. If you try and bring it back on the barge, you're going to have to somehow take hold of it and lay it down before towing the barge. Look at what SpaceX goes through with the crane and gear in Texas with F9R-Dev1. Now try it on a floating barge. I seriously doubt that any owner of a float-on/float off ship is going to let their vessel be a target, so are you going to buy, crew and operate it by yourself? For the umpteenth time: it doesn't make sense to aim for this as a routine event.
Edit: this is in reply to posts on several threads scattered about the SpaceX section since the video was released today, such as this one:
http://forum.nasaspaceflight.com/index.php?topic=35248.0
Methinks that most of your comment does not apply to F9 Flights 14 & 15, but could apply to floating platform launches generally. But that is OT for this thread, about landings on only these two near-term missions.
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Yes, please continue general discussion of floating pads here:
http://forum.nasaspaceflight.com/index.php?topic=35248.0
Meanwhile, on this thread's topic question, the most credible answer we have so far is from Jim, who says that "LC-13 has been mentioned." FWIW.
http://www.wired4space.com/launch-sites/cape-canaveral-afs/slc-13-launch-pad-13-at-cape-canaveral-afs
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Dunno, but it seems to me that LC-12 is a little clearer, with somewhat less to be demolished. Right now, the best clear space at LC-13 is the parking lot. There's still stuff above ground to be demolished in LC-13's launch area.
Or so it seems looking through the lens of Google Earth...
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Dunno, but it seems to me that LC-12 is a little clearer, with somewhat less to be demolished. Right now, the best clear space at LC-13 is the parking lot. There's still stuff above ground to be demolished in LC-13's launch area.
Or so it seems looking through the lens of Google Earth...
So maybe they land in the parking lot. Easy road access for cranes to come in, rotate the stage, and drop it on a trailer.
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Good conversation and info. I like the idea of a floating platform (barge) for the two noted flights for proof-of-concept and demonstrating safety, then making LC-13 the permanent "stage recovery pad" forward going. The overhead (including securing the stage on the platform)/associated costs of a floating platform defeats the purpose.
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Could SpaceX be trying to buy the Ocean Odyssey platform from Sea Launch? Given UKR-RUS tensions, the future of Zenit-3SL must be very much in doubt.
Related:
http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html (http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html)
Currently in the pacific. Not sure it even fits in the panama canal.
It doesn't, but there are other (longer) routes from the West coast to the East coast. Ocean Odyssey has spent much of its operating life in the Atlantic.
https://www.youtube.com/watch?v=TVY8LoM47xI
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Could SpaceX be trying to buy the Ocean Odyssey platform from Sea Launch? Given UKR-RUS tensions, the future of Zenit-3SL must be very much in doubt.
Related:
http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html (http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html)
Currently in the pacific. Not sure it even fits in the panama canal.
The canal is only 110 feet across, give or take.
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Could SpaceX be trying to buy the Ocean Odyssey platform from Sea Launch? Given UKR-RUS tensions, the future of Zenit-3SL must be very much in doubt.
Related:
http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html (http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html)
Currently in the pacific. Not sure it even fits in the panama canal.
The canal is only 110 feet across, give or take.
Wikipedia says Odyssey is 220ft wide. Little too big for Panama.
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Wikipedia says Odyssey is 220ft wide. Little too big for Panama.
http://www.icebergfinder.com/
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Could SpaceX be trying to buy the Ocean Odyssey platform from Sea Launch? Given UKR-RUS tensions, the future of Zenit-3SL must be very much in doubt.
Related:
http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html (http://www.themoscowtimes.com/business/article/sea-launch-denies-plans-to-shelve-launch-platform/502579.html)
yes. They would have to wait until the new locks open.
Currently in the pacific. Not sure it even fits in the panama canal.
The canal is only 110 feet across, give or take.
Wikipedia says Odyssey is 220ft wide. Little too big for Panama.
new locks would be 180 feet wide.
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Wikipedia says Odyssey is 220ft wide. Little too big for Panama.
http://www.icebergfinder.com/
The site tagline:
"90% of them are under water. Find the rest here."
Hilarious!
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Yep, landing on an iceberg is more likely than landing these flights on Odyssey! :)
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Confirmation that the "solid surface" landings of flights 14 & 15 will be on an unnamed barge. And second-hand word from Gwynne Shotwell that CRS-4 may also attempt barge landing.
http://www.nasaspaceflight.com/2014/07/spacex-roadmap-rocket-business-revolution/
Tweet from @Rand_Simberg:
@FLspacereport Talked to Gwynne yesterday and she confirmed that they're working permission on flyback, but next landing will be on a barge.
5:19pm - 27 Jul 14
Next guessing game: which barge will it be? Lease or buy used?
http://www.graybarge.com/abs-ocean-class-barges
http://www.oceanmarine.com/catalog.cfm?Deck&category_current_sub=24
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Confirmation that the "solid surface" landings of flights 14 & 15 will be on an unnamed barge. And second-hand word from Gwynne Shotwell that CRS-4 may also attempt barge landing.
http://www.nasaspaceflight.com/2014/07/spacex-roadmap-rocket-business-revolution/
Tweet from @Rand_Simberg:
@FLspacereport Talked to Gwynne yesterday and she confirmed that they're working permission on flyback, but next landing will be on a barge.
5:19pm - 27 Jul 14
Next guessing game: which barge will it be? Lease or buy used?
http://www.graybarge.com/abs-ocean-class-barges
http://www.oceanmarine.com/catalog.cfm?Deck&category_current_sub=24
What are the dimensions of the current pad used by F9R?
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What are the dimensions of the current pad used by F9R?
This image is from Google Earth. The yellow line along the bottom edge of the pad measures out at around 154 ft. You do the math, I don't have a pencil handy at the moment. :)
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The Gray barge link above shows one barge 100' wide and two 72' wide. I'd want a 100 foot width barge for maximum margin, but given the accuracy of the F9R landings, landing on a narrower barge might be possible.
Sea breeze and wave motion will probably add some error, though.
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I have simply observed that SpaceX likes to move much faster with their testing than others generally do.
They don't skip steps, but they move fast.
Perhaps, if they get a core to return to the Cape, they will leave it there and relaunch it.
I doubt they could do it with a paying payload, but I could see Elon loading a dummy paylod and launching it just to show he could.
EM is on record as saying they'll land a core on land this year and relaunch a used core next year... so yah, that's what's happening.
Note: I suspect the returned core(s) will undergo re-testing at McGregor until they're sure of launch integrity
McGregor's going to be the best place to land it for that reason.
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Nothing is going to land at McGregor for many years. And the first "on land" landing that Elon mentioned will almost certainly be at the Cape.
Let's stay on topic, which is where the next few flights will land.
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...and with that in mind, I expect the barge to be parked closely off-shore of CCAFS to replicate as closely as possible the land landing RTLS that will be executed forward-going. Added bonus is that people making decisions to permit such activity will actually see the stages return, and there's nothing like watching something to gain confidence in the capability...
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Agreed, and the Southeast Shoal would be a good place to anchor the barge in 20 feet or so of water. It's within the restricted area and not far from LC-13, the next target.
http://www.charts.noaa.gov/OnLineViewer/11484.shtml
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If you are going to move that close to the coast, then why bother landing on a barge in the first place?
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If you are going to move that close to the coast, then why bother landing on a barge in the first place?
Instead of a few hundred yards of safety zone, you have a couple of miles.
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If you are going to move that close to the coast, then why bother landing on a barge in the first place?
Instead of a few hundred yards of safety zone, you have a couple of miles.
Uhm, there is plenty of empty, unused space at the cape... each launch pad is at least 700 yards from the next one and a lot of them are not in use. It would be easy to find a landing spot with a 2 mile safety zone around it.
LC39A, close to the shore would be a good spot. LC39A is leased by SpaceX anyway.
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If you are going to move that close to the coast, then why bother landing on a barge in the first place?
Because they don't yet have permission to land on Cape property. Gwynne has said they're still working on it. And I doubt they'll get it until they demonstrate a successful near-shore barge landing.
A big piece of that is demonstrating the accuracy of boost-back navigation, which has not yet been done, and which FAA/Cape officials probably want to see before allowing a landing attempt on terra firma.
And as for where the barge gets placed for the next few launches, it would be much easier to have the barge just off shore as opposed to hundreds of miles out. That far out it would be extremely difficult, if not impossible, to anchor the barge, and you can't have tugboats there holding it in position. Not to mention the difficulty of towing a barge that size hundreds of miles out and back, and the difficulty of stabilizing the upright stage on the barge for the inbound trip, especially if weather turns bad.
A barge just off shore in relatively shallow water will be much easier to tow into position, anchor, and retrieve.
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If you are going to move that close to the coast, then why bother landing on a barge in the first place?
Because they don't yet have permission to land on Cape property. Gwynne has said they're still working on it. And I doubt they'll get it until they demonstrate a successful near-shore barge landing.
A big piece of that is demonstrating the accuracy of boost-back navigation, which has not yet been done, and which FAA/Cape officials probably want to see before allowing a landing attempt on terra firma.
And as for where the barge gets placed for the next few launches, it would be much easier to have the barge just off shore as opposed to hundreds of miles out. That far out it would be extremely difficult, if not impossible, to anchor the barge, and you can't have tugboats there holding it in position. Not to mention the difficulty of towing a barge that size hundreds of miles out and back, and the difficulty of stabilizing the upright stage on the barge for the inbound trip, especially if weather turns bad.
A barge just off shore in relatively shallow water will be much easier to tow into position, anchor, and retrieve.
I think that the barge would have to be further away from the shore of the cape than 2 miles to satisfy that. Otherwise, there is NO, absolutely NO reason to land on a barge ( am actually think that there is none whatsoever, but I can see why a government official might think otherwise).
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I think that the barge would have to be further away from the shore of the cape than 2 miles to satisfy that.
To satisfy what? And where does the "2 miles" reference come from? Not sure what you are referring to.
Otherwise, there is NO, absolutely NO reason to land on a barge ( am actually think that there is none whatsoever, but I can see why a government official might think otherwise).
Apparently you were not consulted. ;)
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I think that the barge would have to be further away from the shore of the cape than 2 miles to satisfy that.
To satisfy what? And where does the "2 miles" reference come from? Not sure what you are referring to.
It was in response to a post by user rpapo.
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Let's get back on topic.
There WILL be barge landings as an interim step before terra firma landings, so opinions as to whether or not barge landings should be necessary are moot.
The only question now is where the barge(s) will be located. I see several factors that point towards a just-offshore location for the barge, possibly in the Southeast Shoal area as I mentioned earlier.
Any other ideas? And if you believe the barge will be far downrange (no boostback), please elaborate on how the barge will be "anchored" and how the stage will be stabilized on the barge for the return trip to the Cape. Maybe possible, but sure a lot more difficult.
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Let's get back on topic.
There WILL be barge landings as an interim step before terra firma landings, so opinions as to whether or not barge landings should be necessary are moot.
The only question now is where the barge(s) will be located. I see several factors that point towards a just-offshore location for the barge, possibly in the Southeast Shoal area as I mentioned earlier.
Any other ideas? And if you believe the barge will be far downrange (no boostback), please elaborate on how the barge will be "anchored" and how the stage will be stabilized on the barge for the return trip to the Cape. Maybe possible, but sure a lot more difficult.
It is clear that there will be barge landings, no one doubts that anymore.
Maybe the first one will be further downrange and the second one will be closer to shore. Putting the barge downrange could enable them to prepare for potential downrange landing with heavier payloads (which might or might not be happening) and would still enable them to demonstrate precision landing.
I doubt that either landing will be much closer to the shore than 5 miles. Otherwise, there is very little safety gained from landing on a barge versus just landing at a remote part of the cape.
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Where is limited by range safety - assume a gimbal locks and a stage cartwheels. Or related issues.
Calculate a probability locus of such and its debris field. Two sigma outside of that will be closest approach to range/other.
Also, given tracking radar coverage, inbound assets managing the range will have to monitor, so plot the intersection of these two and you have where you can land.
From that, you probably can figure out the parameter of what you can land on.
And, from the safety requirements, what will be needed to handle/translate/transport the landed stage.
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5 miles or so offshore looks feasible as water depth is 50-60 feet, and the barge wouldn't be too difficult to anchor at that depth, though it would still take quite some time to retrieve.
The "restricted area" marked on charts off the Cape looks to extend about 3 miles or so offshore. So they could presumably anchor the barge anywhere within that area without having to issue a NOTAM to exclude other vessels. And it sure would be convenient for land-based videography if the barge were within visual range.
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We won't know until we know, of course Kabloona. But your solid logic and clarity as you've outlined in this scenario make a good case for this approach.
SpaceX has made it clear that they can land downrange. The next step is to start returning to launch place. Since there hasn't been a successful test yet to return to launch site, an anchored barge located off shore would provide a safe-er alternative to returning to the launch site, but still prove to FAA and NASA that the hardware and software are up to the task. Fingers crossed it goes as planned.
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And as for where the barge gets placed for the next few launches, it would be much easier to have the barge just off shore as opposed to hundreds of miles out.
Agreed. One good reason for doing that would be to allow use of range tracking assets (radar and cameras) to follow the returning stage. There might even be an optimum location based on those assets.
- Ed Kyle
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And placing it in the shallows means you can use a short legged jackup barge resting on the bottom, which eliminates any wave action motion. Top out its height and the legs extending up above the deck is pretty much eliminated.
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And placing it in the shallows means you can use a short legged jackup barge resting on the bottom, which eliminates any wave action motion. Top out its height and the legs extending up above the deck is pretty much eliminated.
Of course the larger the difference between the pad surface and the surrounding water surface, the more of a problem targeting a landing on the pad will be. I don't know what sort of ground sensing they are using (radar?, GPS?) but a pad that is significantly above the water could pose some problems.
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A question for the knowledgeable then.. will SpaceX require a permit (or updated permit) for a barge landing similar to the one they currently have for the Pad Abort Test vehicle?
AFAICT, they currently have no FAA permits to land the stages anywhere... it's strictly launch only.
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Any type of precision landing will require the the grid fins seen on the last f9r-dev1. Like the legs they will be inactive during accent and only add drag that can be easily calculated and measured in a wind tunnel.
Another configuration change that Nasa will have to accept.
It seems their flight testing is out pacing Their ground/hop testing.
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I think that the barge would have to be further away from the shore of the cape than 2 miles to satisfy that.
To satisfy what? And where does the "2 miles" reference come from? Not sure what you are referring to.
It was in response to a post by user rpapo.
"A couple of miles" does not necessarily mean two miles. I was being imprecise on purpose, since I don't have it on any particular authority as to how far that barge will be out there. I was just giving a safety zone some orders of magnitude larger than what I see at LC-13, and indicating that might be a good reason.
That said, I agree with the comments about the difficulties with the barge only getting worse as you get further from shore.
Besides, you want your audience to see what's going on...
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Confirmation that the "solid surface" landings of flights 14 & 15 will be on an unnamed barge. And second-hand word from Gwynne Shotwell that CRS-4 may also attempt barge landing.
Tweet from @Rand_Simberg:
@FLspacereport Talked to Gwynne yesterday and she confirmed that they're working permission on flyback, but next landing will be on a barge.
5:19pm - 27 Jul 14
Is it too early to start suggesting party thread names for the CRS-4 launch? How about "4 on the Floor"?
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"Falcon 9 lands on the bird farm" (or steel beach)
(look it up)
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OK, I looked it up. For the benefit of all:
Bird farm/ steel beach = aircraft carrier deck
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Confirmation that the "solid surface" landings of flights 14 & 15 will be on an unnamed barge. And second-hand word from Gwynne Shotwell that CRS-4 may also attempt barge landing.
Tweet from @Rand_Simberg:
@FLspacereport Talked to Gwynne yesterday and she confirmed that they're working permission on flyback, but next landing will be on a barge.
5:19pm - 27 Jul 14
Is it too early to start suggesting party thread names for the CRS-4 launch? How about "4 on the Floor"?
"All your base are land on us"
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"Barges? We don't need no funking Barges!"
(maybe more suitable for the first true land landing?)
Way OT though.
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OK, I looked it up. For the benefit of all:
Bird farm/ steel beach = aircraft carrier deck
There are a few ex-USN Tarawa class amphibious assault ship available. Baby Flat Tops are way cheaper than a full size Flat Top. :)
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http://www.maritimesales.com/Barges%20for%20sale.htm
Time to get shopping fellas. (Though, I'm still against this whole barge landing business. Put it down on land or nothing, let it drop in the drink IMO).
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Why aren't we including the USS Saratoga in this mix? It's due to be towed down to Brownsville shortly. Why not just park it off KSC for a few months? It will be passing by anyway. I'm sure the scrap steel outfit would be happy to accept some rent money.
The biggest drawbacks I can think of is that the flight deck is 30-40' off the water, and the bridge tower. The two factors could play havoc with the landing radar.
Looked like this a month ago, in Rhode Island:
(http://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/USS_Saratoga_%28CV-60%29_-_Newport%2C_RI.jpg/800px-USS_Saratoga_%28CV-60%29_-_Newport%2C_RI.jpg)
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"All your base are land on us"
Is this in reference to the "All our patent are belong to you"?
Cause if so it made me chuckle really hard lol
Edit/CR - fixed quote
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Why aren't we including the USS Saratoga in this mix? It's due to be towed down to Brownsville shortly. Why not just park it off KSC for a few months? It will be passing by anyway. I'm sure the scrap steel outfit would be happy to accept some rent money.
>
Saratoga was brought up shortly after the ORBCOMM landing,
http://forum.nasaspaceflight.com/index.php?topic=35243.msg1232303#msg1232303
That would be a sight though.
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You don't just reschedule a job like scrapping a carrier on a whim.
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"All your base are land on us"
Is this in reference to the "All our patent are belong to you"?
Cause if so it made me chuckle really hard lol
...and to "All your base are belong to us" before that.
Edit/CR - fixed quotes
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Is this in reference to the "All our patent are belong to you"?
Cause if so it made me chuckle really hard lol
To clarify for the parts of the forum's global audience which may not have been steeped in late-80's video game culture, it's from the intro to the game Zero Wing for the Sega Genesis:
(http://www.8-bitcentral.com/images/blog/2013/allYourBase.jpg) (http://www.allyourbasearebelongtous.com/)
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"The Rockit: There and Back Again"
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And placing it in the shallows means you can use a short legged jackup barge resting on the bottom, which eliminates any wave action motion. Top out its height and the legs extending up above the deck is pretty much eliminated.
…and quick retrieval by a helicopter to CCAFS?
I'm thinking of ways to get the stage back to land and keep coming up with some sort of auto grapple device for lifting. Because I doubt anyone is going to lower a person on a winch to do it.
Then a chopper whisks it back to land and lowers it to ground and let's the SpaceX ground crew practice procedures for returning it to horizontal.
Objectives possible:
1) pin point landing
2) Testing and development of procedures
3) Re-use of liquid first stage for the first time in human history
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No need for a chopper. These are shallow draft barges whose legs can be elevated. Hook up a tug and use KSC's barge facilities.
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And placing it in the shallows means you can use a short legged jackup barge resting on the bottom, which eliminates any wave action motion. Top out its height and the legs extending up above the deck is pretty much eliminated.
…and quick retrieval by a helicopter to CCAFS?
I'm thinking of ways to get the stage back to land and keep coming up with some sort of auto grapple device for lifting. Because I doubt anyone is going to lower a person on a winch to do it.
Then a chopper whisks it back to land and lowers it to ground and let's the SpaceX ground crew practice procedures for returning it to horizontal.
Objectives possible:
1) pin point landing
2) Testing and development of procedures
3) Re-use of liquid first stage for the first time in human history
They presumably have some arrangement for grabbing hold of grasshoppers, right? Maybe it can fit as-is on a real first stage.
Irrespective of that, a good heli pilot can thread any sort of rigid loop that they have sticking from the top of the stage.
If they use a skycrane, then there's actually a "long-line pilot" that has a high-sensitivity control which allows him to really thread a needle with the hook, even though it is such a large helicopter.
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Is the point to recover the stage or to simply prove they can do a pinpoint landing? If it's the latter, then why bother with the complex crane work after touchdown? Instead get a barge with ballast tanks on one side, not unlike the lumber barges (http://youtu.be/XLNYfTy2YkA?t=37s) used in the Pacific Northwest (although clearly without the cranes). Once the stage lands and the residuals have been vented, just have the barge tilt and let the stage tip over and fall into the ocean. It was going to end up there anyway, and it seems unlikely they'd be flying those engines again at this point.
If recovery is desired at that point with the stage lying in the ocean then they can bring in the divers and attach floatation bags from a position which much safer for the recovery team than working next to a standing rocket on a barge. After that a relatively small crane should be able to lift the stage onto another barge for transport back to CCAFS. A 20 to 30 ton stage is pretty lightweight when it comes to offshore salvage. A pair of deck cranes would likely have little trouble lifting and positioning a stage floating in the ocean onto a barge provided they didn't have to reach far.
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And placing it in the shallows means you can use a short legged jackup barge resting on the bottom, which eliminates any wave action motion. Top out its height and the legs extending up above the deck is pretty much eliminated.
…and quick retrieval by a helicopter to CCAFS?
I'm thinking of ways to get the stage back to land and keep coming up with some sort of auto grapple device for lifting. Because I doubt anyone is going to lower a person on a winch to do it.
Then a chopper whisks it back to land and lowers it to ground and let's the SpaceX ground crew practice procedures for returning it to horizontal.
Objectives possible:
1) pin point landing
2) Testing and development of procedures
3) Re-use of liquid first stage for the first time in human history
They presumably have some arrangement for grabbing hold of grasshoppers, right? Maybe it can fit as-is on a real first stage.
Irrespective of that, a good heli pilot can thread any sort of rigid loop that they have sticking from the top of the stage.
If they use a skycrane, then there's actually a "long-line pilot" that has a high-sensitivity control which allows him to really thread a needle with the hook, even though it is such a large helicopter.
Quoting myself, to clarify: I don't have an opinion on whether they'll want to heli-lift the stage from the barge... Just saying that if they did want to, they don't need to invent anything in order to grapple it.
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If the empty weight is around 19 tons as speculated, you're going to need something bigger than a Skycrane.
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If recovery is desired at that point with the stage lying in the ocean...
Hasn't it already been established that when the first stage tips over and falls, even into water, it breaks up? It is, after all, around two hundred feet tall...
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If recovery is desired at that point with the stage lying in the ocean...
Hasn't it already been established that when the first stage tips over and falls, even into water, it breaks up? It is, after all, around two hundred feet tall...
First stage is about 42 m long (plus a couple of meters clearance from nozzles to tip of legs).
Furthermore we don't know why the stage breaks up, for example could be the submersed leg on the lifting side pulls the skin of the tank, a loading case never foreseen for a "land landing".
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If the barge landings are "close" off shore, then they will be taking place in much shallower water. Recovery in that location shouldn't be too difficult. Of course, a stage in un-"Kaboom"-ed condition that hasn't been immersed in salt water would be even better.
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Would a modified jackup barge be a possibility? Big enough? Strong enough? It could plant its legs in shallower water to provide a level, stable platform. The barge would have to be elevated high enough that its corner legs didn't obstruct the landing. Once safed, the stage could be cabled to the legs for transport back to land.
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I've seen ads for jackups of up to 62x32 meters and capacities from 14 to 3,600 tons, and I'm sure some decks are larger. Legs from 15 to 50+ meters. Big enough?
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Barge anchoring question: If 20' shoal water were available would it be practical to have 1 anchor or earth screw at each corner of the barge, at an angle, and then tension the anchor lines so the barge is pulled lower into the water than its natural floating level? If possible that should create a stable platform immune to waves, but it may not be practical due to tides or the forces involved for a 100' barge. Does anyone know?
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Barge anchoring question: If 20' shoal water were available would it be practical to have 1 anchor or earth screw at each corner of the barge, at an angle, and then tension the anchor lines so the barge is pulled lower into the water than its natural floating level? If possible that should create a stable platform immune to waves, but it may not be practical due to tides or the forces involved for a 100' barge. Does anyone know?
The forces are too great - not for the chains & winches so much, but the anchors could pull right out of the sea floor without warning... and it would only take one to fail to cause a general upset of the platform. Plus it would also need to be constantly adjusted for tide.
For that sort of depth of water, a jack-up barge is a far more practical solution. :)
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In "The Human Spaceflight Report" (http://new.livestream.com/AIAAvideo/space2014/videos/58462185 (http://new.livestream.com/AIAAvideo/space2014/videos/58462185)) Garrett Reisman threw out the possibility that the next fly-backs might attempt to land on either terra firm or a barge. What I'm curious about is whether this indicates that the company has decided that high-altitude testing of reusable first stages at SpacePort America may not be necessary. It seems to me that they're aiming at flying back to the Cape in the not-too-distant future.
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In "The Human Spaceflight Report" (http://new.livestream.com/AIAAvideo/space2014/videos/58462185 (http://new.livestream.com/AIAAvideo/space2014/videos/58462185)) Garrett Reisman threw out the possibility that the next fly-backs might attempt to land on either terra firm or a barge. What I'm curious about is whether this indicates that the company has decided that high-altitude testing of reusable first stages at SpacePort America may not be necessary. It seems to me that they're aiming at flying back to the Cape in the not-too-distant future.
Yes, Gwynne Shotwell reportedly said that a barge landing attempt will occur, maybe as early as SpX-4. She has also said that SpaceX is working towards approval for landing at the Cape but they have not received that approval yet.
It's possible that the recovery attempt milestones on the F9 flights (successful leg deployments, retroburns, soft touchdowns) have been reached faster than they expected and the transition to F9R tests at SpacePort has gone more slowly than they expected.
If they could get permission to land at the Cape based on a successful barge landing, that would certainly seem to negate much of the need for F9R testing at SpacePort, though it could still be useful as a testbed for improving landing algorithms, etc.
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If they could get permission to land at the Cape based on a successful barge landing, that would certainly seem to negate much of the need for F9R testing at SpacePort, though it could still be useful as a testbed for improving landing algorithms, etc.
Very exciting.
Would the "etc." possibly include experimentation with other components of a fully reusable rocket system? FR's second stage would have to be orbited in order to test its reentry and soft landing capability, and the SpacePort facility can not be used for orbital launches. But what about using it for testing Dragon's propulsive landing system?
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It's possible that the recovery attempt milestones on the F9 flights (successful leg deployments, retroburns, soft touchdowns) have been reached faster than they expected and the transition to F9R tests at SpacePort has gone more slowly than they expected.
If they could get permission to land at the Cape based on a successful barge landing, that would certainly seem to negate much of the need for F9R testing at SpacePort, though it could still be useful as a testbed for improving landing algorithms, etc.
Yes and no. There are various supersonic and altitude combinations that F9R has not explored, that Blue Origin has, although not entirely successfully yet. This stuff is still very dangerous, and there's little experience with establishing range operations. And some history at the Cape of less than successful return tests, albeit in the distant past.
While control of the booster to demonstrate successful examples of landing with a barge might be enough to attempt a land experimental landing, it is still an experimental vehicle where unexplored flight domains might hold nasty surprises.
Perhaps a bit better to say that the SpacePort flight testing might proceed in parallel with CCAFS landing acceptance?
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Space Ghost,
I'll always be a supporter of just manning up and giving it a shot. Old school style testing. Of course with a finger on the range safety flight termination button.
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Wannamoon,
Once you've pressed that button, you do know that the debris field for an inbound termination isn't the same as an outbound termination, right?
And that you can have chaotic leveraging effects while not reliable/probable can happen that could damage other pads as well, possibly occupied.
add:
And that the incident would be unlike a pad fire, vehicle explosion, and that remedying/safeing/mitigating the incident might impact many vehicles for an unacceptable amount of time.
I think we all would like to see a first stage landing. But not a unfortunate surprise with repercussions.
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They've soft landed flawlessly in the wild twice, and many more times "in the lab" between Grasshopper and F9R-Dev1, and probably hundreds of thousands more times in HWIL and digital sims - so why should anyone be concerned about an "unfortunate surprise?"
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They've soft landed flawlessly in the wild twice, and many more times "in the lab" between Grasshopper and F9R-Dev1, and probably hundreds of thousands more times in HWIL and digital sims - so why should anyone be concerned about an "unfortunate surprise?"
If you can, eliminate them instead of recieving criticism
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They've soft landed flawlessly in the wild twice, and many more times "in the lab" between Grasshopper and F9R-Dev1, and probably hundreds of thousands more times in HWIL and digital sims - so why should anyone be concerned about an "unfortunate surprise?"
How do you know they landed "flawlessly?" How close did they come to their aim points on both these occasions?
Space Ghost makes valid points. The returning stage is "incoming." If the predicted impact point moves inland the consequences could be serious. I guess the Range might be concerned about an "unfortunate surprise." Safety is their remit, after all. And it's their call whether the stage is allowed to fly back and land. Our opinions don't count.
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Space Ghost makes valid points. The returning stage is "incoming." If the predicted impact point moves inland the consequences could be serious.
The impact point can't move inland. The returning stage needs to accelerate vertically to reach land.
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Suppose the engines fail to shut down properly during the fly back burn and deliver more delta V than required. What happens to the impact point then?
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Suppose the engines fail to shut down properly during the fly back burn and deliver more delta V than required. What happens to the impact point then?
I think in that case somebody at the range presses a red button and, in the words of Elon, "kaboom".
The point being made, I believe, is that the impact point cannot move inland after the boost back burn is complete.
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Just wanted to remind everyone that SpaceX would love to test at Spaceport America. . . they just need to, you know, finish the damn pad already.
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Suppose the engines fail to shut down properly during the fly back burn and deliver more delta V than required. What happens to the impact point then?
I think in that case somebody at the range presses a red button and, in the words of Elon, "kaboom".
Exactly.
And then Space Ghost's point about debris field comes into play. Not that I think such a failure is likely, but it's an example of how fly back could introduce new hazards. So the barge landings would be a prudent way of demonstrating landing accuracy and increasing confidence before the Range gives permission for touch down on land.
The point being made, I believe, is that the impact point cannot move inland after the boost back burn is complete.
That's true, but it wasn't what was posted.
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And then Space Ghost's point about debris field comes into play.
How?
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Space Ghost makes valid points. The returning stage is "incoming." If the predicted impact point moves inland the consequences could be serious.
The impact point can't move inland. The returning stage needs to accelerate vertically to reach land.
i would imagine that the boostback burn aims it a safe distance offshore and the lifting body effect does the rest
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And then Space Ghost's point about debris field comes into play.
How?
Sorry, I don't understand your question. Maybe you could re-phrase it.
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Space Ghost makes valid points. The returning stage is "incoming." If the predicted impact point moves inland the consequences could be serious.
The impact point can't move inland. The returning stage needs to accelerate vertically to reach land.
i would imagine that the boostback burn aims it a safe distance offshore and the lifting body effect does the rest
I think that's correct as long as the fly back burn is executed properly.
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i would imagine that the boostback burn aims it a safe distance offshore and the lifting body effect does the rest
I think that's correct as long as the fly back burn is executed properly.
If it is not executed properly then there is plenty of time and space to use the destruct button way before the debris could impact inland. It's not some last seconds thing.
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I think destroying the stage might be undesirable if there is any danger of the incoming debris spreading out in an unpredictable way. Sending a shutdown command and allowing the intact vehicle to crash offshore might be a safer solution.
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How do you know they landed "flawlessly?" How close did they come to their aim points on both these occasions?
Ok, I don't know, I'm surmising from evidence.
They know how to maneuver boosters well enough to heave a huge satellite to within a whisker of where they aimed it, making the customer fairly gush with effusive praise.
They can make a booster float and flit like a giant aluminum hummingbird while balanced on the tip of a roaring spear of flame, and alight in the dead center of a neighboring concrete pad.
With proven talents like those, and after seeing two orbital boosters alight pretty as you please at the surface, I don't see any reason to suspect that the landings were anything but flawless.
As I see it, Floridians face more daily risk from the thousands of enormous airliners constantly flying overhead than they would from a nearly-empty returning F9. Hopefully the bureaucrats will agree.
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And then Space Ghost's point about debris field comes into play.
How?
Sorry, I don't understand your question. Maybe you could re-phrase it.
How would the debris field shape be of any relevance? The stage needs the lift from the braking burn to make it to the cape. Otherwise its decent is going to be too fast for it to translate all the way to land and it will fall into the ocean or it will impact on land very close to the ocean. No debris from a half way decently chosen landing site would ever reach populated areas, especially if the self destruct was engaged. That just zipps open the stage and fuel burns up. It does not explode it. Besides, by that time the stage is almost empty anyway. Not that much fuel left to cause a lot of damage and far spread debris. If you are worried about that, you should be equally worried about an explosion on the pad.
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I think destroying the stage might be undesirable if there is any danger of the incoming debris spreading out in an unpredictable way. Sending a shutdown command and allowing the intact vehicle to crash offshore might be a safer solution.
In particular, I'd worry about the engines and thrust structure being set free as a ballistic cannonball in the event of an overshoot.
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How do you know they landed "flawlessly?" How close did they come to their aim points on both these occasions?
Ok, I don't know, I'm surmising from evidence.
They know how to maneuver boosters well enough to heave a huge satellite to within a whisker of where they aimed it, making the customer fairly gush with effusive praise.
They can make a booster float and flit like a giant aluminum hummingbird while balanced on the tip of a roaring spear of flame, and alight in the dead center of a neighboring concrete pad.
With proven talents like those, and after seeing two orbital boosters alight pretty as you please at the surface, I don't see any reason to suspect that the landings were anything but flawless.
As I see it, Floridians face more daily risk from the thousands of enormous airliners constantly flying overhead than they would from a nearly-empty returning F9. Hopefully the bureaucrats will agree.
A lot of people seem to be assuming that that some external agency (like the range) is the gating factor here. Yes, SpaceX has said that they are working on getting approval to return to land, but we don't know that SpaceX even considers themselves ready yet. We don't know how accurate the OG2 "landing" was, or even they even tried to hit a specific location. They put grid fins on F9R-dev1 for a reason. I suspect they'll want to do a couple of reentries with grid fins before attempting RTLS.
Given the fact that SpaceX has publicly stated that the range has been very helpful in identifying landing sites and that NASA's future plans include a site for RTLS I see no reason to assume that the primary issue is bureaucratic.
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And then Space Ghost's point about debris field comes into play.
How?
Sorry, I don't understand your question. Maybe you could re-phrase it.
How would the debris field shape be of any relevance? The stage needs the lift from the braking burn to make it to the cape. Otherwise its decent is going to be too fast for it to translate all the way to land and it will fall into the ocean or it will impact on land very close to the ocean. No debris from a half way decently chosen landing site would ever reach populated areas, especially if the self destruct was engaged. That just zipps open the stage and fuel burns up. It does not explode it. Besides, by that time the stage is almost empty anyway. Not that much fuel left to cause a lot of damage and far spread debris. If you are worried about that, you should be equally worried about an explosion on the pad.
OK, get you now.
When I made the point about the an over burn during the fly back maneuver, someone suggested sending a destruct command. But that would allow the debris to spread out before impact increasing the risk. That's what I meant about debris field.
Better to let the vehicle fall intact and confine the damage to a small area.
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I think destroying the stage might be undesirable if there is any danger of the incoming debris spreading out in an unpredictable way. Sending a shutdown command and allowing the intact vehicle to crash offshore might be a safer solution.
In particular, I'd worry about the engines and thrust structure being set free as a ballistic cannonball in the event of an overshoot.
They won't let them land until the risk of overshooting is very very close to 0 in every possible case.
They can achieve this by simply coming in at an angle and using the landing burn to "extend" the trajectory. We saw this quite clearly in the chase cam video of the last Orbcomm mission.
This talk of blowing up an errant incoming stage is crazy. They will never, ever have a reason to do that- just design the return so that if it fails at any point before the last half of the landing burn it dumps it into the ocean with no problem. This is inherently safer than any auto-destruct.
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I think destroying the stage might be undesirable if there is any danger of the incoming debris spreading out in an unpredictable way. Sending a shutdown command and allowing the intact vehicle to crash offshore might be a safer solution.
In particular, I'd worry about the engines and thrust structure being set free as a ballistic cannonball in the event of an overshoot.
They won't let them land until the risk of overshooting is very very close to 0 in every possible case.
They can achieve this by simply coming in at an angle and using the landing burn to "extend" the trajectory. We saw this quite clearly in the chase cam video of the last Orbcomm mission.
This talk of blowing up an errant incoming stage is crazy. They will never, ever have a reason to do that- just design the return so that if it fails at any point before the last half of the landing burn it dumps it into the ocean with no problem. This is inherently safer than any auto-destruct.
Sorry, I should have been more clear. By "overshoot" I was referring to the scenario in which the boostback burn goes wrong and imparts too much Delta V. I'd imagine doing the distruct-o thing in that scenario would be bad.
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It mighty not be bad - individual fragments from a destruct would likely have higher air friction than a whole stage.
Overshooting the boost back burn might be the ONLY time a destruct makes sense. Any other scenario can have the whole stage impact the ocean.
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I've got to say, that although I brought up this overshoot thing, I don't think it's a likely scenario at all. But we seem to have arrived a reasonable consensus that blowing up the stage would normally be a Bad Idea.
Also: mme makes some good points.
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Also Elon has expressed a desire for a flight termination system that shuts down the engine/s without "unzipping" the vehicle.
Edit: Missed a word
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My read of the grid fins is a means to stabilize and increase control authority than with the cold gas thrusters.
The issue of overshoot is very real. Remember combustion processes have instabilities yielding dispersions.
Also, keep in mind that MacGregor landings are not at the end of a ballistic arc.
Perhaps you've heard its exciting when one "receives fire". Inch sized bullets, hand sized mortar rounds, and arm long shells aren't anything to compare with a incoming stage. Remember, its not like a helicopter, it doesn't/can't hover.
For me, until the LV leaves the range and is over the water is when I worry - most of the bad stuff then hits the ocean out of range.
When its incoming on an economical trajectory, that's a impressive amount of energy that must be dissipated before it becomes safe.
And yes, FTS is not always the best answer. FTS is meant to keep a stage from running wild away from flight plan - to mitigate what all that energy could do. Pieces of metal can cut one in half at a range of miles.
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Could SpaceX legally construct an island?
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What about Shuttle?
Let's not have a hernia, here. Airplanes fly over large populated cities CONSTANTLY. Even experimental aircraft. A nearly empty stage miles away from a sparsely inhabited and likely evacuated shoreline with sophisticated smarts and even an FTS is probably safer than the city of McGregor during F9R-dev1 tests.
Let's have a little perspective.
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Could SpaceX legally construct an island?
Sure they could.. but they'd need a permit first. ;)
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Could SpaceX legally construct an island?
Omelek, Kwajalein atoll. Maybe they need to tow it somewhere.
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Some people have the impression that if the landing burn fails to come off correctly, the rocket will impact short of the landing site. That may be true, but it won't be much short of the site. In fact, if the landing site is LC-13, as has been speculated, I would guess that such an impact would still be on land. I say this because of the extreme shortness of the final landing burn.
More worrisome is the combination of the boostback and reentry burns. If the boostback burn goes overboard, you have an overshoot. If the reentry burn fails to happen, you will also have an overshoot . . . albeit probably in pieces.
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Some people have the impression that if the landing burn fails to come off correctly, the rocket will impact short of the landing site. That may be true, but it won't be much short of the site. In fact, if the landing site is LC-13, as has been speculated, I would guess that such an impact would still be on land. I say this because of the extreme shortness of the final landing burn.
More worrisome is the combination of the boostback and reentry burns. If the boostback burn goes overboard, you have an overshoot. If the reentry burn fails to happen, you will also have an overshoot . . . albeit probably in pieces.
So, a "worst case scenario" would be if the propulsion system fails at ~90% of the reentry burn, (say due to avionics failure) leaving the stage going too fast, but still slow enough to survive reentry - and now aimed further inland? Or is it a case that the stage is definitely aerodynamically unstable enough to break-up (or experience enough extra drag without active attitude control) during the atmospheric entry phase, so that all the heavy, dense bits will fall off-shore?
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Or is it a case that the stage is definitely aerodynamically unstable enough to break-up (or experience enough extra drag without active attitude control) during the atmospheric entry phase, so that all the heavy, dense bits will fall off-shore?
That's backwards. The heavier, denser bits will tend to follow the ballistic trajectory, in this case further downrange. The lighter pieces will fall short.
Rethinking things a little bit after seeing the new ORBCOMM 'landing' video. It appears that (without grid fins) almost all of the landing targeting is accomplished through the boostback and reentry burns. The final burn occurs after the rocket has been falling nearly straight down for over a minute, and that burn lasts less than twenty seconds. Some translation may occur there, but I would speculate that it would be less than a few hundred yards in any direction.
In other words, failure during the landing burn should result in cratering within a few hundred yards of the eventual landing site. Therefore, the real risk is in the first two burns. The biggest risk seems to be one of the boostback burn failing to end at all, leaving the rocket going too far inland and having no fuel left for the reentry burn, or for the FTS system to detonate.
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In other words, failure during the landing burn should result in cratering within a few hundred yards of the eventual landing site. Therefore, the real risk is in the first two burns. The biggest risk seems to be one of the boostback burn failing to end at all, leaving the rocket going too far inland and having no fuel left for the reentry burn, or for the FTS system to detonate.
ok, so trigger the FTS as soon as you see that. The stage will "unzip" and the resulting debris will probably have much higher air resistance, so they will fall on the ocean.
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In other words, failure during the landing burn should result in cratering within a few hundred yards of the eventual landing site. Therefore, the real risk is in the first two burns. The biggest risk seems to be one of the boostback burn failing to end at all, leaving the rocket going too far inland and having no fuel left for the reentry burn, or for the FTS system to detonate.
ok, so trigger the FTS as soon as you see that. The stage will "unzip" and the resulting debris will probably have much higher air resistance, so they will fall on the ocean.
Nope, that wont work - the heaver stuff like the thrust structure and engines will just 'keep going' due to its higher density and dig someone out a new swimming pool in their back yard (titanium pluming and turbo-pumps comes for free!)
So, SpaceX will have to ensure that:
1) The ballistic aim-point is fully offshore, allowing for variations in the burns+atmospheric conditions
2) The CEP (error probability) of that aim point doesn't overlap the shoreline,
3) The grid-fins give them enough control authority to "tip and glide" the stage inland enough to hit the landing pad (or actually the top of a 'vertical drop corridor' over the landing pad)
4) Using the grid-fins wont 'overshoot' and carry it farther than expected. (i.e. outside the 'airspace zone' of the landing pad)
1+2 they can probably calculate/do right now - so they can confidently claim they can hit a barge off shore, Included in that i'll assume that they are sure that the cold-gas thrusters on their own have enough control authority (given enough gas) to resolve the ballistic CEP so they can actually exactly hit the barge.
However, to ensure 3, they will need to test the grid fins. Although they will have done numerical modeling and wind tunnel tests, nothing beats firing a hunk of real metal supersonic through the upper atmosphere.
Since spacex seem to be in no big hurry to push the envelope on F9R-dev, perhaps they are aiming for a grid-fin test on a returning stage (perhaps crs4, since nasa was willing to allow expermental legs on crs3?)
And to ensure 4, they probably do need to explore the envelope with F9r-Dev 2 at spaceport america, where they have the airspace to go far and fast.
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I think SpaceX actively controls the attitude of the booster on the return segment (via RCS?), and that that is the thing that gives them accuracy on the landing point. I don't think you can time and aim the boost back burn to give that kind of accuracy, right? If this is the case, and something goes wrong with the boost back burn (giving a ballistic trajectory significantly inland), is it reasonable to think that they could aerodynamically compensate for the burn error and hit the intended spot after all?
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I think SpaceX actively controls the attitude of the booster on the return segment (via RCS?), and that that is the thing that gives them accuracy on the landing point. I don't think you can time and aim the boost back burn to give that kind of accuracy, right? If this is the case, and something goes wrong with the boost back burn (giving a ballistic trajectory significantly inland), is it reasonable to think that they could aerodynamically compensate for the burn error and hit the intended spot after all?
Aerodynamic control is what the grid fins are for, but I can't imagine they'd allow the booster to approach over land in an out of control situation before blowing it up. They'll know if it's on course after the first burn, then the second burn is to stick the landing, with the grid fins and the RCS providing control between the two burns. If the first burn doesn't go as planned... "kaboom" while it's still out over the water.
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When I made the point about the an over burn during the fly back maneuver, someone suggested sending a destruct command. But that would allow the debris to spread out before impact increasing the risk. That's what I meant about debris field.
Better to let the vehicle fall intact and confine the damage to a small area.
I might be wrong, but from what I understand, a trigger of the FTS does not cause an explosion that results in a mid air debris field. With an almost empty stage this is even less likely to happen.
I don't think the chance of an overshoot is realistic at all. In case of a loss of control during the boost back burn, the FTS would trigger.
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I think SpaceX actively controls the attitude of the booster on the return segment (via RCS?), and that that is the thing that gives them accuracy on the landing point. I don't think you can time and aim the boost back burn to give that kind of accuracy, right? If this is the case, and something goes wrong with the boost back burn (giving a ballistic trajectory significantly inland), is it reasonable to think that they could aerodynamically compensate for the burn error and hit the intended spot after all?
No.
If "something going wrong" causes a too-far inland ballistic target, that same thing "going wrong" (e.g. avionics/guidance failure) might also prevent the stage from aerodynamically flying back to the landing pad.
SpaceX can aim the basaltic aim point, but the issue is how big the error is (x-miles?). They haven't (and in all probability wont) release that publicly. (even on L2 - that is very itar-like info, since it's useful if you need to drop a warhead on someone)
The gold-gas gets will allow the returning craft to attempt null out that ballistic error. (up to a range of y-miles, again, we don't know their range. They wont release that either, since it's tied indirectly into x above.)
The issue, is that currently those thrusters might not able to sufficiently or accurately null much more than that ballistic error. (or not without loading up a lot of gas, or increasing the flowrate). i.e. y<x
Hence the need for the grid-fins, which it is implied have a control or 'divert' range of z-miles, and in fact, z>(2x+margin) (NOT z>=x !)
That will allow spacex to aim the stage x miles (plus a little margin) off-shore, and if it ends up aimed x+x miles offshore, due to worst case basaltic error, they can still fly it back to shoreline with the fins. (distance to fly = the basaltic error diameter + a little margin)
(If the balastic error is the other way, then the stage just hits off the shoreline. No significant grid-fining needed!)
But to hit a barge offshore, they only need divert authority of x-miles, (the ballastic error radius.)
So its much easier to hit the barge, instead of the landing pad, and they have sort of implied they can do that with just the gas.
But they need to test/prove that, and then also qualify the fins in order to land on the pad.
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ICBMs can hit a target pretty precisely (I think the precision is in the tens of meters and definitely better than 200 meters CEP listed on Wikipedia). Now that was with 60ies technology and computers. There was not even GPS back then!
Peacekeeper, which uses 1980ies technology has an accuracy of better than 40 meters CEP according to Wikipedia, so we can assume a real accuracy around 15 meters, or so.
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ICBMs can hit a target pretty precisely (I think the precision is in the tens of meters and definitely better than 200 meters CEP listed on Wikipedia). Now that was with 60ies technology and computers. There was not even GPS back then!
Peacekeeper, which uses 1980ies technology has an accuracy of better than 40 meters CEP according to Wikipedia, so we can assume a real accuracy around 15 meters, or so.
True, up to a point. Such warheads are relatively small and dense, and aerodynamically designed for accurate reentry, coming in at high speed (and probably spinning)
Falcon is large, non-dense, not particularly aerodynamic and has a large cross-sectional area subject to wind loads. Its also coming in slower so it suffers wind loads for longer, and it can't spin too much or else it will centrifuge its fuel.
So the error might actually be in the range of 100s of meters or even more - we just don't know.
But, my point that it is more then twice as hard to hit the landing pad as to hit the barge still holds.
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True, up to a point. Such warheads are relatively small and dense, and aerodynamically designed for accurate reentry, coming in at high speed (and probably spinning)
Falcon is large, non-dense, not particularly aerodynamic and has a large cross-sectional area subject to wind loads. Its also coming in slower so it suffers wind loads for longer, and it can't spin too much or else it will centrifuge its fuel.
So the error might actually be in the range of 100s of meters or even more - we just don't know.
But, my point that it is more then twice as hard to hit the landing pad as to hit the barge still holds.
Falcon 9s first stage is also not coming in from orbital velocities. It is not going around half the globe on its way back to the launch site. It (most likely) has better and faster avionics. It has GPS navigation. It has active controls for attitude and acceleration and so on. Plus, much of the trajectory is determined by the RTLS burn, which is happening way off the landing pad. If something goes wrong there, they will terminate and that's it. I think that it is very unlikely for anything to go wrong with the trajectory, or even that the stage would make it to land if something went wrong.
Also, lets not forget that we had no problem with the shuttle flying all across the US on its way to the runway where it landed. It just seems like a non issue to me that is blown way out of proportion.
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...I don't think the chance of an overshoot is realistic at all...
I would say that it is not a very likely failure mode, but that it was worth discussing.
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Could SpaceX legally construct an island?
Sure they could.. but they'd need a permit first. ;)
What if they did it in international waters?
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Could SpaceX legally construct an island?
Sure they could.. but they'd need a permit first. ;)
What if they did it in international waters?
Then Elon would become a Bond villain and M would have to send in 007. :)
Seriously, I'm not sure, but I did find a thesis on the subject at seasteading.org.
http://www.seasteading.org/wp-content/uploads/2012/02/Proposed-Inhabited-Artificial-Islands-in-International-Waters.pdf (http://www.seasteading.org/wp-content/uploads/2012/02/Proposed-Inhabited-Artificial-Islands-in-International-Waters.pdf)
It seems rather complicated to me, with UN treaties and such.
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To recap:
* FTS is intended for outbound termination. The primary intent is to safely expend the propellants before they can be used harmfully. You don't care about the debris field, because it is a cone/funnel spraying away from launch site(s) and towards downrange.
* Inbound is an entirely different situation. Shuttle was a stable in horizontal flight hypersonic/supersonic glider of a spent stage, with fine energy management to allow one pass and land, with the risks of crew and hydrazine incoming. Its dispersions were carefully controlled all along the mostly horizontal glide path with contingencies. F9R is a unstable airframe (N.B. grid fins may help this considerably) in the vertical live stage with propellent, on a mostly vertical descent, where final flight termination entirely rests on a single engine burning on time the right amount, in the right inertial platform, thrust, and thrust vector.
* The advantage of a barge landing first is that a miss is much like an outbound failure - if there is enough propellant to be considered a danger, you FTS trigger and there's no difference in range safety (the wide end of the funnel never is too close to the launch facilities).
* You can also observe the novel operations of such a landing, so as to refine range safety considerations for land landing, such as automated/manual perimeter/corridor check-off conditions for "final approach" as a part of range safety policy.
* Keep in mind that the FTS is as much a hazard as the stage itself in a terminal land landing. It doesn't magically erase the stage from existence, just impares active thrust from propellants. On land, FTS makes the hazards much higher for the launch facilities. And an active, returning stage, until it has landed and is safed, is a very dangerous craft - potentially a "hang fire" situation.
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The FTS is needed for the launch phase as an explosive that can destroy the LV, what is needed on the stage recover is a FTS on the vehicle that will terminate propulsion, with no explosive actions that can case the "cone debris field". if the propulsion is cut short, on entry the stage will disintegrate in the upper atmosphere and most likely fall into the sea. If the stage makes it further down and does not ignite for the landing burn then it will fall short, again into the sea. FTS, thus must be selective of vehicle phase. If the vehicle fails in the landing phase, then it may make a crater in the landing pad if it makes it that far.
I understand that the lift of the stage controlled to some degree by the "feathers" will allow for precise targeting in the free-fall phase, we see that done to some degree with smart bombs, so its nothing new.
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The FTS is needed for the launch phase as an explosive that can destroy the LV, what is needed on the stage recover is a FTS on the vehicle that will terminate propulsion, with no explosive actions that can case the "cone debris field".
Wrong.
Does not necessarily detonate/destroy the vehicle. In most cases it is a linear shaped charge that massively vents the LRE's propellant tanks, allowing the propellants to deflagrate.
To do a controlled termination of the propulsion, one shuts down the engines, usually by eventual spin down of the turbopumps/gas generator and or propellant valves. Combustion is starved. On Russian LV's, that is all they do usually.
The debris field is a result of various causes including RUD, possible detonations of subsystems, effects of the propellant deflagration, and impact.
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Does not necessarily detonate/destroy the vehicle. In most cases it is a linear shaped charge that massively vents the LRE's propellant tanks, allowing the propellants to deflagrate.
I'm given to understand that the long vertical fixture attached to the right side of the body in the photo below (from Innerspace.net) (http://innerspace.net/tag/falcon-9-v1-1/) is the FTS charge, which would split the stage open like a well-done Ball Park hot dog. :'(
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I assumed that this was the where most of the wiring that connects the upper stage to the engines was run. But I could be wrong. Or maybe it has both.
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I assumed that this was the where most of the wiring that connects the upper stage to the engines was run. But I could be wrong. Or maybe it has both.
its extremely narrow so either one large cable or two small ones. there is a wider recessed tray on the other side so it could be fts or fibre cable as its near a camera in pictures further up on the vehicle.
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Ensign-Bickford Aerospace and Defense Co. linear shaped charge assembly (LSCA).
(http://www.eba-d.com/assets/product-images/_resampled/resizedimage329220-Linear-Shaped-Charge-Aerospace.jpg) (http://www.eba-d.com/products/linear-shaped-charge-lsc-2/)
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It's kind of ironic that SpaceX have got to accept FTS explosives on their vehicle when they've made efforts to eliminate explosive bolts.
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It's kind of ironic that SpaceX have got to accept FTS explosives on their vehicle when they've made efforts to eliminate explosive bolts.
=) Explosions are destructive and work against reusability, so it makes sense that the last place you'd find it was on the "destroy and prevent reuse" system
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To recap:
* FTS is intended for outbound termination.
Snip:
* Keep in mind that the FTS is as much a hazard as the stage itself in a terminal land landing. It doesn't magically erase the stage from existence, just impares active thrust from propellants. On land, FTS makes the hazards much higher for the launch facilities. And an active, returning stage, until it has landed and is safed, is a very dangerous craft - potentially a "hang fire" situation.
No wonder Elon wants an engine shut down FTS.
Snip:
To do a controlled termination of the propulsion, one shuts down the engines, usually by eventual spin down of the turbopumps/gas generator and or propellant valves. Combustion is starved. On Russian LV's, that is all they do usually.
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To do a controlled termination of the propulsion, one shuts down the engines, usually by eventual spin down of the turbopumps/gas generator and or propellant valves. Combustion is starved. On Russian LV's, that is all they do usually.
On July 2, 2013, it looked like they didn't even do that much as the Proton-M pretty much drilled itself into the landscape.
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Could SpaceX legally construct an island?
Sure they could.. but they'd need a permit first. ;)
What if they did it in international waters?
They'd still need to negotiate a "sea-bed lease" with someone. Even outside of international boundaries, there are fishing leases, oil drilling leases and a host of marine sanctuary and maritime navigational safety arrangements that come into play (IIRC, that's one reason floating private residential communities like MV "The World" are still classed as cruise ships - being able to move requires less paperwork than standing still).
That's not to say fortuitous circumstances (pls pardon the pun) can't allow it to happen:
http://en.wikipedia.org/wiki/Principality_of_Sealand (http://en.wikipedia.org/wiki/Principality_of_Sealand) ..only that it's unlikely to happen for SpaceX.
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To do a controlled termination of the propulsion, one shuts down the engines, usually by eventual spin down of the turbopumps/gas generator and or propellant valves. Combustion is starved. On Russian LV's, that is all they do usually.
On July 2, 2013, it looked like they didn't even do that much as the Proton-M pretty much drilled itself into the landscape.
Russian LV have a thrust termination inhibit built into them to avoid falling back on the pad and destroying it. It was institutionalized after the thrust termination system made a whole N-1 fall back on its pad. Thus, I believe that for the first 45 seconds or so, no thrust is terminated.
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Slightly OT: I believe there is an inhibit on Russian rockets which prevents shut down commands for number of seconds after launch. I seem to remember reading that the rationale was to allow the vehicle to get well clear of the pad to prevent damage to infrastructure. I believe the inhibit prevented shutting down the engines in the recent Proton accident. Despite looping, the Proton didn't damage the pad.
I wonder what FTS con ops SpaceX will use for their Texas pad.
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My apologies for dragging this thread off topic about FTS and recoverable vehicles.
Talk about them on the Reusable First Stage Abort and Range Safety (http://forum.nasaspaceflight.com/index.php?topic=35431.msg1244200#msg1244200) thread I just created.
Meanwhile, this thread is about attempting "solid surface" landings.
If the earlier answer by Kabloona(this is his thread) is acceptable, perhaps this should be locked?
add:
This includes all abort handling, discussion of Russian/other range safety issues. anything about inbound/outboard for F9R basically.
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My apologies for dragging this thread off topic about FTS and recoverable vehicles.
Talk about them on the Reusable First Stage Abort and Range Safety (http://forum.nasaspaceflight.com/index.php?topic=35431.msg1244200#msg1244200) thread I just created.
Meanwhile, this thread is about attempting "solid surface" landings.
If the earlier answer by Kabloona(this is his thread) is acceptable, perhaps this should be locked?
add:
This includes all abort handling, discussion of Russian/other range safety issues. anything about inbound/outboard for F9R basically.
I concur. But some of the posts on that topic have been both informative about the past, and interesting analytical speculation about the future.
Maybe those posts could be moved over to the new thread you created for the discussion???
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My apologies for dragging this thread off topic about FTS and recoverable vehicles.
Talk about them on the Reusable First Stage Abort and Range Safety (http://forum.nasaspaceflight.com/index.php?topic=35431.msg1244200#msg1244200) thread I just created.
Meanwhile, this thread is about attempting "solid surface" landings.
If the earlier answer by Kabloona(this is his thread) is acceptable, perhaps this should be locked?
add:
This includes all abort handling, discussion of Russian/other range safety issues. anything about inbound/outboard for F9R basically.
Thanks for the nod, but I don't think it's time to lock the thread yet. We know now that the "solid surface" will be a barge, but it's still unknown where the barge will be parked, so the topic question hasn't been answered yet. Hopefully someone will hear some news on the subject soon.
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I am not sure if this has been posted already:
SpaceX's Shotwell, to me at NewSpace2014: 1st stage dry landings to be tailored (barge position or launch site) to payload delta V needs.
https://twitter.com/TheLurioReport/status/493630773074067456
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Guessing that means launches without margin to RTLS will be targeted for a barge landing and not simply expended... interesting...
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I am not sure if this has been posted already:
SpaceX's Shotwell, to me at NewSpace2014: 1st stage dry landings to be tailored (barge position or launch site) to payload delta V needs.
https://twitter.com/TheLurioReport/status/493630773074067456
Meaning some landings may be attempted downrange on a barge with no boostback in cases where not enough propellant remains for boostback?
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An interesting tweet, but difficult to to conclude if Shotwell was referring to the barge use for the near term landing test, or if barges were part of a longer strategy. (which would be more surprising)
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An interesting tweet, but difficult to to conclude of Shotwell was referring to the barge use for the near term landing test, or if barges were part of a longer strategy. (which would be more surprising)
I continued the long-term part of the discussion over on the thread already discussing the overall floating platform questions (http://forum.nasaspaceflight.com/index.php?topic=35248.msg1244564#msg1244564). Leaving this thread on-topic per OP to have a scope of just flights 14 and 15.
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Acknowledge. Its likely that:
* Offshore near CCAFS on shoals/shallows(< 50ft deep)
* Location within permitted maritime regulations for short term use (i.e. "salvage")
* Returning flight path(s) impact/overshoot debris field causes no risk to CCAFS/KSC/Space Florida facilities
* Jack up flat top barge (50x100ft?) for solid landing surface
* Access to safe stage
* Some means (separate jack up barge w/crane?, anchor stage and move barge?) to handle safed stage to move/land it
* Means to remediate/dispose of failed landing attempts
The Shotwell comment seems to indicate efforts to optimize reuse costs, which has been my observation of all F9.1.1 flights and many of the F9R-dev1 flights as well. How little does it take to recover a stage, so as to find a lower bound as to the hit on performance. In these cases, recovery is not operational, but as the endpoint of an experiment.
Two location use cases:
+ Operational (i.e. proving land landing case with boostback - likely CCAFS shoals)
+ Experimental (i.e. flight performance - likely on flight path downrange to minimize retroburn/stabilization loss relying on air drag most for recovery
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An interesting tweet, but difficult to to conclude if Shotwell was referring to the barge use for the near term landing test, or if barges were part of a longer strategy. (which would be more surprising)
It would make sense for them to be part of a continuing strategy if we consider that the FH central core will have difficulty with RTLS under a number of scenarios.
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An interesting tweet, but difficult to to conclude if Shotwell was referring to the barge use for the near term landing test, or if barges were part of a longer strategy. (which would be more surprising)
It would make sense for them to be part of a continuing strategy if we consider that the FH central core will have difficulty with RTLS under a number of scenarios.
But not if you think that a reusable single-core BFR will replace the FH in all scenarios.
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It would make sense for them to be part of a continuing strategy if we consider that the FH central core will have difficulty with RTLS under a number of scenarios.
But not if you think that a reusable single-core BFR will replace the FH in all scenarios.
Statements from SpaceX indicate both BFR and FH will be used, in complementary ways, for Mars.
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And it's the FH that will be integral to their profit structure for years to come. The BFR is out there for an undetermined amount of time in the future. They aren't going to wait on it before developing an economical return technique.
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So does anyoneone else think that the idea of landing Falcon 9 first stages on barges is a bit ad hoc and takes SpaceX off on a tangent away from the simple concept of operations that return-to-launch-site represents? When compared to that idea, my suggestion for the development of side boosters with 2 Merlin 1D engines seems almost simple. What I had previously called the Falcon 13 might be called the "Falcon Medium". The boosters, with tanks in the range of the notional Falcon 1E, could possibly use 1 merlin for the boostback and rentry burns, but likely need a set of super-draco's for final descent. Their sole purpose would be to let the core booster throttle back enough to allow ample propellant to complete the full return after lofting payloads such as the Asiasat 8. If reusability can be verified, a small fleet of say 8 boosters might serve for this generation of Falcon 9 1.1. So the question is: would this be cheaper in the long run than the barges? It was suggested that Falcon Heavy can fly these missions, but I think we need some serious numbers to convince me that flying 18 engines in a suboptimal configuration with G-load issues would ultimately cost less.
Edit/Lar: moved from SpaceX Texas launch site Discussion and Updates - Thread 3
Edit/CR: deleted multiple paragraph breaks
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So does anyoneone else think that the idea of landing Falcon 9 first stages on barges is a bit ad hoc and takes SpaceX off on a tangent away from the simple concept of operations that return-to-launch-site represents? When compared to that idea, my suggestion for the development of side boosters with 2 Merlin 1D engines seems almost simple. What I had previously called the Falcon 13 might be called the "Falcon Medium". The boosters, with tanks in the range of the notional Falcon 1E, could possibly use 1 merlin for the boostback and rentry burns, but likely need a set of super-draco's for final descent. Their sole purpose would be to let the core booster throttle back enough to allow ample propellant to complete the full return after lofting payloads such as the Asiasat 8. If reusability can be verified, a small fleet of say 8 boosters might serve for this generation of Falcon 9 1.1. So the question is: would this be cheaper in the long run than the barges? It was suggested that Falcon Heavy can fly these missions, but I think we need some serious numbers to convince me that flying 18 engines in a suboptimal configuration with G-load issues would ultimately cost less.
No the barges are only temporary until SpaceX can prove out pin-point landing.
Edit/Lar: moved from SpaceX Texas launch site Discussion and Updates - Thread 3
Edit/CR: deleted multiple paragraph breaks in quote
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So does anyoneone else think that the idea of landing Falcon 9 first stages on barges is a bit ad hoc and takes SpaceX off on a tangent away from the simple concept of operations that return-to-launch-site represents?
No, absolutely not.
ULA's business model is to sell you an LV which is just big enough for your payload, by fine-grained scaling via solids.
SpaceX has two options - F9+RTLS & F9-E. (Eventually replaced with F9+RTLS, F9-E & FH+RTLS.)
Barge (what I like to call Forward To Sea Landing, FTSL) offers an intermediate option with greater payload, through not having to perform boostback.
The only additional costs are hire of the barge, transport of the barge back to the launch site, and offloading of the stage onto the transporter. (Actually, I'll add inventory cost of a longer turnaround time, and maybe an actuarial cost of a greater likelihood of losing the stage.)
If reuse gets to the stage where the cost is substantially below expendable, then there's millions of dollars on the table to fund those and still offer a cheaper deal than F9-E.
The big questions are whether it's cheaper than FH with all cores RTLS'd, and if it solves the issue around recovering FH's core.
Why is that important?
SpaceX will eventually look to recover their upper stages, which will add a substantial mass penalty (a huge penalty if they can make it work for GTO). Suddenly, FH with 3x RTLS isn't up to the job of launching the larger payloads - and maybe even the not-so-big ones.
That puts them in the crazy position that they’d need to expend FH's core in order to recover the upper stage.
Downrange recovery of FH's core may be the answer to that. Possibly at Florida for Boca Chica launches - if they can get permission. And that doesn't help for CCAFS. Barge recovery of FH core (and maybe even boosters) may be required for upper stage recovery.
TL;DR downrange recovery gives finer grained cost vs payload options in the short term and may be required for upper stage recovery in the long term.
Cheers, Martin
PS yes, I know about MAC, and it should help *if* it pans out. But there will still be a mass penalty, just not quite so daunting.
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Actually the comments on second stage recovery bolsters my case, IMO. I can imagine using an expendable end-of-life core first stage in my Falcon Medium configuration for an LEO mission that would allow the prop margins to at least test a recoverable second stage. Otherwise you have to use a Falcon Heavy.
I know there were several others that dismissed barge landings due to cost and logistics issues - maintaining a barge with crew, possible weather issues, etc. Just because SpaceX has chosen this path does not mean it is optimal. And even if reusability "leaves millions on the table" I would speculate that Mr. Musk would rather use those towards his Mars ambitions if a Falcon Medium were cheaper. Who would you rather retain in your workforce, rocket engineers designing a 2 engine F2-R (which could fly standalone) or a bunch of barge operators?
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So does anyoneone else think that the idea of landing Falcon 9 first stages on barges is a bit ad hoc and takes SpaceX off on a tangent away from the simple concept of operations that return-to-launch-site represents? When compared to that idea, my suggestion for the development of side boosters with 2 Merlin 1D engines seems almost simple. What I had previously called the Falcon 13 might be called the "Falcon Medium". The boosters, with tanks in the range of the notional Falcon 1E, could possibly use 1 merlin for the boostback and rentry burns, but likely need a set of super-draco's for final descent. Their sole purpose would be to let the core booster throttle back enough to allow ample propellant to complete the full return after lofting payloads such as the Asiasat 8. If reusability can be verified, a small fleet of say 8 boosters might serve for this generation of Falcon 9 1.1. So the question is: would this be cheaper in the long run than the barges? It was suggested that Falcon Heavy can fly these missions, but I think we need some serious numbers to convince me that flying 18 engines in a suboptimal configuration with G-load issues would ultimately cost less.
Edit/Lar: moved from SpaceX Texas launch site Discussion and Updates - Thread 3
Edit/CR: deleted multiple paragraph breaks
Well, I agree that I think barges have serious problems. The main one being that after landing, what are the odds of the rocket tipping over? After all there is almost always sea swells and what about storms?
Not so sure SpaceX would be interested in your small booster variation, but it is an interesting proposal.
When Brownsville and FH-R are operational, I think the need for barges becomes moot.
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Hasn't SpaceX stated that the proposed barge landings are a temporary experimental recourse until pinpoint landing accuracy and safety have been established. It's a test platform for proving the technology. To the best of my knowledge, no spokesperson for the company has ever proposed landing the core booster on a barge at sea as a long-term solution to reduced payload capacity. Their plan has always been to return all of FH's boosters to their launch facility. Please correct me if I'm wrong.
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It was my understanding of the latest announcements - to my great surprise - that they are seriously considering landing FH cores downrange on barges if required.
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If this was only going to be a temporary measure, I'm not sure why SpaceX would go to the trouble of requesting PTAB review Blue Origin's patent on sea landings.
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If this was only going to be a temporary measure, I'm not sure why SpaceX would go to the trouble of requesting PTAB review Blue Origin's patent on sea landings.
If they do it even once... without licensing, and it's a valid patent, they would have to fight a battle later anyway. So perhaps their legal counsel said it's more effective to fight now, perhaps because it's a different kind of fight. That's idle speculation, I am not an IP law layer.
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It was my understanding of the latest announcements - to my great surprise - that they are seriously considering landing FH cores downrange on barges if required.
Was that the Charles Lurio tweet at https://twitter.com/TheLurioReport/status/493630773074067456 ?
It would be helpful to have official confirmation of that before concluding that the company has undertaken a new policy.
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If this was only going to be a temporary measure, I'm not sure why SpaceX would go to the trouble of requesting PTAB review Blue Origin's patent on sea landings.
If they do it even once... without licensing, and it's a valid patent, they would have to fight a battle later anyway. So perhaps their legal counsel said it's more effective to fight now, perhaps because it's a different kind of fight. That's idle speculation, I am not an IP law layer.
I think they would have to reuse the stage on a profit making flight for it to be problematic. Landing a stage on a barge for internal R&D purposes would not create any legal issues as far as I'm aware. But ditto, not an IP/patent expert.
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The US has no research exception for patents.
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It was my understanding of the latest announcements - to my great surprise - that they are seriously considering landing FH cores downrange on barges if required.
Was that the Charles Lurio tweet at https://twitter.com/TheLurioReport/status/493630773074067456 ?
It would be helpful to have official confirmation of that before concluding that the company has undertaken a new policy.
I can't see why anybody would be surprised about cores landing downrage, especially FH cores. It was always a big question here whether the central core of FH, particularly in a x-feed config, could be brought back to the launch site.
For F9, they've already offered customers the option of launching in expendable mode, so why would it be much of a surprise that they offer a barge landing mode for payloads a tad to high for return-to-launch-site?
SpaceX's/Elon's ultimate aim is of course for return-to-launch-site only modes, but "rockets are tricky" and all that, so they're obviously making comprises for the short to medium term. No big deal.
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The US has no research exception for patents.
Wow, interesting. Did not know that. Must not be easy to enforce. I worked for a short while with a semiconductor tool company in Silicon Valley, and researching on already patented stuff was the norm. In fact, R&D would have been impossible otherwise.
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It was my understanding of the latest announcements - to my great surprise - that they are seriously considering landing FH cores downrange on barges if required.
Was that the Charles Lurio tweet at https://twitter.com/TheLurioReport/status/493630773074067456 ?
It would be helpful to have official confirmation of that before concluding that the company has undertaken a new policy.
Unfortunately my memory is not clear on the source. I think it was in the latest presentation of Tom Mueller on propulsion.
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The US has no research exception for patents.
Wow, interesting. Did not know that. Must not be easy to enforce. I worked for a short while with a semiconductor tool company in Silicon Valley, and researching on already patented stuff was the norm. In fact, R&D would have been impossible otherwise.
I think I'm wrong anyway.
http://en.wikipedia.org/wiki/Research_exemption
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The US has no research exception for patents.
Wow, interesting. Did not know that. Must not be easy to enforce. I worked for a short while with a semiconductor tool company in Silicon Valley, and researching on already patented stuff was the norm. In fact, R&D would have been impossible otherwise.
I think I'm wrong anyway.
http://en.wikipedia.org/wiki/Research_exemption
No, it looks like you're right. Research exemption appears valid only for "amusement, to satisfy idle curiosity, or for strictly philosophical inquiry"
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De facto, nobody sues for infringement until there's revenue.. But Billionaires can do things just for kicks.
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De facto, nobody sues for infringement until there's revenue.. But Billionaires can do things just for kicks.
Patent law is also used to hinder innovation and competition (see Patent Thicket). One frustration must be that SpaceX is not disclosing methods or even filing patents, so it can be difficult for competitors to determine if a patent has been infringed. Back in July Congressmen Gardner and Coffman were pressing NASA to require SpaceX to disclose more information about the "epidemic of anomalies". This may have been no more than a thinly guised effort to force SpaceX to reveal technologies for review by patent trolls.
My expectation is that BO's patent will be overturned now that it has been challenged based on prior art or failure of non-obviousness.
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De facto, nobody sues for infringement until there's revenue.. But Billionaires can do things just for kicks.
Patent law is also used to hinder innovation and competition (see Patent Thicket). One frustration must be that SpaceX is not disclosing methods or even filing patents, so it can be difficult for competitors to determine if a patent has been infringed. Back in July Congressmen Gardner and Coffman were pressing NASA to require SpaceX to disclose more information about the "epidemic of anomalies". This may have been no more than a thinly guised effort to force SpaceX to reveal technologies for review by patent trolls.
My expectation is that BO's patent will be overturned now that it has been challenged based on prior art or failure of non-obviousness.
Read above regarding BO's BS patent, we're in agreement.
The patent system is sometimes abused, but so is practically any law. It is still a good system though.
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If this was only going to be a temporary measure, I'm not sure why SpaceX would go to the trouble of requesting PTAB review Blue Origin's patent on sea landings.
And this serves as an important reminder as everyone thinks about launch costs: reality is sometimes messy and hard to predict. Little unexpected details like permits and paperwork for stage landings can end up making the "non-optimal" solution be a better choice for low cost.
Not that it will always be true in this case, but there will inevitably be some detail everyone is sure of right now where this principle will apply and the end result will be "messy" and "dumb."
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My expectation is that BO's patent will be overturned now that it has been challenged based on prior art or failure of non-obviousness.
The best they can hope for is clearance of certain claims.. usually the first few, making the patent less broad.
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It would be interesting to learn the back-story on this. In the mobile phone industry, we would use $50K as the starting estimate for a patent including engineering time, attorney fees, filing fees, and leg work. This can be money well spent since royalty costs per phone can be over $100 per unit.
If sea landings were a one-time research event, it could be as easy as a phone call from Elon to Jeff asking for a temporary waiver. BO may have decided that they at least recoup the patent costs, and after judging that the patent is invalid due to prior art or failure to meet the non-obvious requirement, SpaceX may have made the decision that it is less costly to challenge the patent than license.
BTW, the BO patent covers floating platforms, so if you can extend legs from the barge so it is no longer floating, SpaceX could be off the hook there. There is also a claim regarding use of aerodynamic control surfaces to re-orient the stage, and to control it on a flight path, and this might be an issue with grid-fins, so another possible reason to challenge.
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it could be as easy as a phone call from Elon to Jeff asking for a temporary waiver.
Setting Jeff up for the line: my unicorns say nay.
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it could be as easy as a phone call from Elon to Jeff asking for a temporary waiver.
Setting Jeff up for the line: my unicorns say nay.
Bezos delayed the 39A decision for months and a year later BO still has nothing new to show. Musk called him out and even gave him a 5-year window to qualify a vehicle, and so far Musk's assessment is proving true. I would still make the call and remind Bezos how he once said, "Patents are supposed to encourage innovation and we're starting to be in a world where they might start to stifle innovation." Bezos also said, "Governments may need to look at the patent system and see if those laws need to be modified because I don't think some of these battles are healthy for society."
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My expectation is that BO's patent will be overturned now that it has been challenged based on prior art or failure of non-obviousness.
The best they can hope for is clearance of certain claims.. usually the first few, making the patent less broad.
I think the entire house of cards is about to fall. A handful of prior art examples have torn apart most of Blue Origin's claims, and the remainder are so weak they will fail as 'obvious to a person of ordinary skill'. The only real question remaining is how long will it take the Appeal Board to decide that all of the original claims are unpatentable.
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Not sure if this is the right thread for this, but if CRS 4 doesn't have legs, which now seems to be the case, would they try to 'land' legless, in the ocean close to the barge? Most of the return flight elements could be tested, sans legs and touch down, plus assets could be placed on the barge to gather information such as telemetry and video. Has to be better than pizza dish in the window. It would also help prove accuracy before trying to actually touch down on the barge.
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Not sure if this is the right thread for this, but if CRS 4 doesn't have legs, which now seems to be the case, would they try to 'land' legless, in the ocean close to the barge? Most of the return flight elements could be tested, sans legs and touch down, plus assets could be placed on the barge to gather information such as telemetry and video. Has to be better than pizza dish in the window. It would also help prove accuracy before trying to actually touch down on the barge.
Presumably there's already terminal precision guidance on the pad to supplement internal rocket guidance (itself likely GPS based), else Grasshopper/F9R wouldn't already be landing nearly on a dime every time. Shouldn't be hard to dial in an offset 1000 feet or less to land in the water a very precise distance from the barge. I had the impression that error is on the order of centimeters with high precision GPS, though perhaps moving targets might raise it to a meter or so.
That ought to be 'close enough' unless they want to reinsert the first stage right back into the holddown sockets... (I'm sure they're not seriously attempting >that< level of precision)
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Right here with a barge driven up on shore or just off the cost in shallow water with jack up legs so the platform will be stable
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That ought to be 'close enough' unless they want to reinsert the first stage right back into the holddown sockets... (I'm sure they're not seriously attempting >that< level of precision)
I wouldn't put it past them. Embedded systems are pretty fancy these days. ;) Maybe they should weld a dime to the barge deck for the first solid-surface landing.
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To be that precise I think they would need the grid fins. Or extremely beefed up cold gas thrusters. I think they are going for grid fins. But seeing them on SpX-4 would be a surprise.
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To be that precise I think they would need the grid fins. Or extremely beefed up cold gas thrusters. I think they are going for grid fins. But seeing them on SpX-4 would be a surprise.
My impression is that grid fins do not add precision to the terminal maneuver. They add cross-range ability, or alternatively, the ability to counter stronger winds on the way down. Once the engine starts, it can overpower anything, and besides the stage is slowed down so that the fins are ineffective anyway.
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Right here with a barge driven up on shore or just off the cost in shallow water with jack up legs so the platform will be stable
That's an interesting speculation (or maybe you have intel?). But why put the barge there (Georgia) instead of offshore of the Cape?
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It’s less distance than returning to the cape for launches to the ISS.
It’s possibly more desolate of an area.
It’s in Georgia just east of their proposed space port. So if Georgia wants to host a space port it would be a good first step for them to help in any way they can with a stage landing. Nothing better for business than doing what they can to help space company’s conduct their operations.
I don’t know if the whole area is a National Seashore or what type of influence they could have over regulations or permits. And if that isn’t workable then maybe they could go further inland. But I think for the first landings right on the shore would be best
No inside information
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I think that this whole patent infringment situation is a bunch of horsepuckey.
Unless SpaceX was infringing on some VERY specific technologies, Blue Origin has no case.
This is a technology that has been in the public domain for more years than I've been alive.
Unless SpaceX was using a specific design of a barge that Blue Origin had patented, or used a specific guidance that they had patented, there is no case.
Personally, I don't think it's Bezos pushing this case, but rather his lawyers. Unfortunately, sometimes, with big corporations, lawyers will get off the leaseh and start biting at anything that they see as a threat to their income. (Gosh... I hope Elon and SpaceX got all thier shots!)
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Update: Per Chris's latest article, barge landing attempt is likely slated for CRS-5:
http://www.nasaspaceflight.com/2014/09/soyuz-tma-12m-return-iss-trio-to-earth/
Which seems like further confirmation that Orbcomm has slipped past CRS-5 into 2015 as previously rumored. Otherwise they would presumably be trying the first barge landing on the Orbcomm launch.
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Update: Per Chris's latest article, barge landing attempt is likely slated for CRS-5:
http://www.nasaspaceflight.com/2014/09/soyuz-tma-12m-return-iss-trio-to-earth/
Which seems like further confirmation that Orbcomm has slipped past CRS-5 into 2015 as previously rumored. Otherwise they would presumably be trying the first barge landing on the Orbcomm launch.
Barge landing is definitely a better concept than 'swamp' landing. Remember, much of Florida is swamp/everglades (I know) filled with plenty of poisonous snakes and alligators. Would you want to be an SpaceX employee in such conditions?
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Right here with a barge driven up on shore or just off the cost in shallow water with jack up legs so the platform will be stable
That's an interesting speculation (or maybe you have intel?). But why put the barge there (Georgia) instead of offshore of the Cape?
It wouldn't have to boost back as far, using less fuel. However, Cumberland Island is a National Seashore. The National Park Service would never allow a barge next to shore. 20 to 30 miles offshore the water is still less than 100 feet deep. That would be far beyond the horizon, outside of US territorial waters, and still close to the Georgia site if SpaceX wants to get the first stage to land quickly. Of course, they could just sail it straight back to the launch site.
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Would you want to be an SpaceX employee in such conditions?
Yes. Recovering spacecrafts from alligator-infested swamps is too sci-fi-ish for me to pass up.
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Would you want to be an SpaceX employee in such conditions?
Yes. Recovering spacecrafts from alligator-infested swamps is too sci-fi-ish for me to pass up.
Except in the old B&W movies, isn't there always at least one monster nearby (either created on Earth by "space radiation" or directly brought back in the spacecraft), ready to attack any investigating humans? Probably a giant mutant alligator, in this case.
Granted, the alligators might simply eat the monster at the end of the movie, as ironic justice after it has killed several humans (this means you, unless you are the hero who saves the life of the professor's beautiful daughter).
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Would you want to be an SpaceX employee in such conditions?
Yes. Recovering spacecrafts from alligator-infested swamps is too sci-fi-ish for me to pass up.
Maybe if SpaceX ever decides to start plopping Dragon's into the Indian River they'll give you a call.
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Would you want to be an SpaceX employee in such conditions?
Yes. Recovering spacecrafts from alligator-infested swamps is too sci-fi-ish for me to pass up.
Except in the old B&W movies, isn't there always at least one monster nearby (either created on Earth by "space radiation" or directly brought back in the spacecraft), ready to attack any investigating humans? Probably a giant mutant alligator, in this case.
Granted, the alligators might simply eat the monster at the end of the movie, as ironic justice after it has killed several humans (this means you, unless you are the hero who saves the life of the professor's beautiful daughter).
Just don't be the one wearing the red sweater.
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From CRS-4 discussion thread:
Exclusion areas for CRS-4 (courtesy of Darga):
https://www.google.com/maps/d/viewer?mid=zp15b_P5ERVk.krdQml9d0HR0
Bathimetric lines of the coast: picture below (NOAA)
Typical detailed depth chart for up to 24 NM:
http://www.charts.noaa.gov/OnLineViewer/11536.shtml
The three lines are 3, 12, 24 NM
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So does the exclusion map from CRS-4 give us any more hints as to where the barge will be?
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Doubtful, considering there was a boost back burn but no boost back.
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So does the exclusion map from CRS-4 give us any more hints as to where the barge will be?
Too many pieces of the puzzle still missing (trajectories, authorizations, performance margins, etc.)
What's sure is that a jack-up rig for 100 ft / 30 m depth isn't something so difficult to find / rent.
Placing one 20-30 NM off the coast of NC should not be impossible (cost & permits).
A "dogleg" boost (not a boostback) would be needed.
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The sideways divert they pulled was interesting. Suggests that for ISS launches they could boost forward to Cape Lookout (looks uninhabited) or perhaps do a more pronounced dogleg to a barge in the shallows by Cape Fear.
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In the CRS-5 thread, @laika_fr pointed out this YouTube clip with Hans Koenigsmann in the CRS-4 pre-launch briefing.
Around 19:00 Hans talks about upcoming landing attempts. He seems to imply that they will be attempting a terra firma landing in an upcoming mission ("gonna be one of the next missions...working actively with Range Safety...bringing vehicle back to the Range..."). But when James Dean follows up to clarify whether that will be a barge landing or a terra firma landing, Hans says that the barge is only in "trade study" status and is a "possibility for the future" but is not going to be one of the next missions.
So he seems to be saying that a terra firma landing back at the Range will come sooner than a barge landing attempt. Maybe I'm misinterpreting what he said, but that's what it sounded like to me.
All of which seems to put in doubt SpaceX's July 22 statement that flights 14 and 15 would attempt to land on a solid surface. CRS-5 is certainly not coming back to the Cape, and from Hans' statements the barge seems unlikely to make an appearance any time soon.
https://www.youtube.com/watch?v=88lxNeNmQms
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Hans says that the barge is only in "trade study" status and is a "possibility for the future" but is not going to be one of the next missions.
I'd guess they're hung up on the Blue Origin patent.
...which is not entirely a bad thing for them. The patent gives them a good reason why they have to boost it back toward land, which is what they prefer to be doing anyway, without demonstrating a barge landing first, which is probably what the range and FAA would prefer.
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Hans says that the barge is only in "trade study" status and is a "possibility for the future" but is not going to be one of the next missions.
I'd guess they're hung up on the Blue Origin patent.
That's possible, but they presumably knew about the patent back in July when they made the statement about solid surface landings for #14 and #15. So what changed between July 22 and September when Hans made those comments?
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That's possible, but they presumably knew about the patent back in July when they made the statement about solid surface landings for #14 and #15. So what changed between July 22 and September when Hans made those comments?
The filing challenging the patent.
http://spaceref.biz/company/spacex/spacex-challenges-patent-filed-by-blue-origin.html
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Hans says that the barge is only in "trade study" status and is a "possibility for the future" but is not going to be one of the next missions.
I'd guess they're hung up on the Blue Origin patent.
...which is not entirely a bad thing for them. The patent gives them a good reason why they have to boost it back toward land, which is what they prefer to be doing anyway, without demonstrating a barge landing first, which is probably what the range and FAA would prefer.
Actually it IS a bad thing. No matter if they have a "good reason" for trying a land landing the point would be what the FAA/Range demands is going to be paramount. If they are demanding a demonstrated accurate landing ability then SpaceX has no choice but to perform a down-range/short-of-RTLS "landing" prior to being allowed to bring the stage back.
Having said that though my take on this is that SpaceX is planning on using the barge landing as an operational procedure and not a test. This would allow "expendable" operation of a booster stage with propulsive recovery down-range rather than actually expending the booster. If this was only a "test" landing series then there would be no need to fight the patent.
It may be that SpaceX will be allowed to aim some of the up-coming flights back towards the launch site but still well off-shore at all times in order to increase FAA/RAnge Safety confidence. If, somewhere along the line SpaceX can find someone with "solid-land" somewhere along the flight path that will allow a powered landing that would go a long way towards providing evidence that they can do what they claim as well.
Randy
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I am not a patent lawyer so I don't know if a test landing on a barge would violate the patent.
But if the precision of targeting needs proof before return is allowed, they can just place a beacon and hit that. Should be well good enough for FAA as proof.
Challenging the patent is entirely separate.
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That's possible, but they presumably knew about the patent back in July when they made the statement about solid surface landings for #14 and #15. So what changed between July 22 and September when Hans made those comments?
The filing challenging the patent.
http://spaceref.biz/company/spacex/spacex-challenges-patent-filed-by-blue-origin.html
True statement, but I don't see the logic. "We're challenging the patent and therefore we cannot land on a barge as we had planned to do before we decided to challenge the patent?"
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I am not a patent lawyer so I don't know if a test landing on a barge would violate the patent.
I don't think it will for "tests" but operations would.
But if the precision of targeting needs proof before return is allowed, they can just place a beacon and hit that. Should be well good enough for FAA as proof.
We can hope the FAA would take your advise but I doubt it. For one thing there's a lot of "post-landing" and such that could be required to demonstrate and in the end its going to be the FAA/Range Safety call. Period.
If they want and require more then SpaceX has no choice but to provide what they require.
Challenging the patent is entirely separate.
As I said it would seem to have to do with operations, possibly planned down-range recovery of what would otherwise be expended boosters perhaps.
Randy
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True statement, but I don't see the logic. "We're challenging the patent and therefore we cannot land on a barge as we had planned to do before we decided to challenge the patent?"
When submitting to the authority of a court, perhaps the most disrespectful thing you can do is proceed as if the court's decision doesn't matter.
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True statement, but I don't see the logic. "We're challenging the patent and therefore we cannot land on a barge as we had planned to do before we decided to challenge the patent?"
When submitting to the authority of a court, perhaps the most disrespectful thing you can do is proceed as if the court's decision doesn't matter.
Well said. Elon's lawyers probably told him just that, very firmly.
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True statement, but I don't see the logic. "We're challenging the patent and therefore we cannot land on a barge as we had planned to do before we decided to challenge the patent?"
When submitting to the authority of a court, perhaps the most disrespectful thing you can do is proceed as if the court's decision doesn't matter.
Well said. Elon's lawyers probably told him just that, very firmly.
OK, thank you for that explanation. Evidently I don't know how to think like a lawyer.
So...barge landing is on hold until the courts sort it out, and terra firma landing is being worked with Range Safety but nothing definite yet.
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Ok, let me attempt to try and explain this dilemma.
What we have here is an intersection into policy and legal procedure domains, in terms of both safety and patent in attempting to "land" either way.
First, there is a very great difference between litigation and other aspects of the law. Specifically, in patent litigation, the steps/stages are different than the initial case of filing a patent, something many here may have significant experience with. You choose patent counsel differently on filing / attacking / defending.
Litigators and court actions are like actors on the stage of a play - unlike that of filing which is more like using process, conventions, and methodologies to address temporary "ownership of an idea or process. There's a competition among the litigants for who provides the most convincing "storyteller" read.
What may have happened here is that the story competition may have turned to commercial benefit in the near term, perhaps under the theory of an immediate commercial value of even the CRS 5 mission! In litigation you can develop your case without it needing to be true, because the key point you may be attempting to prove doesn't need it to be true for the point to be considered valid.
Like the difference between "practical" and "practicable".
So Kabloona's post above actually teaches us on the nature of where the litigation lies, more than on the operational nature of the SpaceX endeavor. Enough said to that point.
Back to Range Safety policy and establishment of the new safety guidelines for returning launch vehicles. Govt is too cautious in filling in this "white space" - they don't want to be blamed for getting it wrong (likely RCO in this case given where the vehicle is launched from). However, there are few places better suited for this than CCAFS - its been a longstanding part of the mission and there is a national imperative for its development that actually trumps the securitization of existing assets arbitrarily - falls out of the ICBM days in terms of "settled law" so to speak.
So sooner or later, SpaceX will get a chance to land, albeit after significant hurdles to address such risks.
In offering to land on an offshore barge, SpaceX shows a willingness to demonstrate an acceptance criteria without range risk (on the other hand, in patent litigation likely BO would offer then some free/low cost licenses for this to buttress the position of commercial viability, SpaceX would likely demurer with a "its a long term option for us" e.g. downrange with the FH core example). SpaceX can go back to govt, say "hey we tried, but these BO/ULA guys won't play ball, and just like 39A want to own the bat and ball otherwise go home".
This then takes away a nice safe position for the RCO - he'd want to have a nice example with an autonomous termination profile/box already pre proven before range example. I know I'd want that. Note - GH example termination does count here too.
So he either asks through govt intermediary as, say an "amicus" approach (actually quite different as governmental override, but again that isn't quite right given the stage of litigation present) to allow such, or he "baby steps" somehow a flight example.
Here's one:
1) buoy with coordinates
2) ocean landing on buoy with diversion burn from virtual graveyard
3) tracking assets on station to prove trajectory and autonomous termination validation
Now RCO has a bounded situation with enough CYA for a refined policy on returning vehicle range safety. Adequate for the policy side.
He's not completely out of the woods though. Any crash will call for investigations, no matter what. A part could shoot out and cause damage/injury. But major calamity is highly unlikely with this. And the range safety overall is served by more not less critical tests.
Did this help any of you to understand better?
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Barge landing is definitely a better concept than 'swamp' landing. Remember, much of Florida is swamp/everglades (I know) filled with plenty of poisonous snakes and alligators.
Actually, mostmost of Florida is farmland. The swampy, snakey part is in the south.
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There's a competition among the litigants for who provides the most convincing "storyteller" read.
What may have happened here is that the story competition may have turned to commercial benefit in the near term, perhaps under the theory of an immediate commercial value of even the CRS 5 mission!
Well, under that theory, SpaceX certainly has a better story ("We're about to try to land our rocket on a barge as a step towards launch vehicle reusability and lowering the cost of access to space") than BO ("We have no rocket.")
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There's a competition among the litigants for who provides the most convincing "storyteller" read.
What may have happened here is that the story competition may have turned to commercial benefit in the near term, perhaps under the theory of an immediate commercial value of even the CRS 5 mission!
Well, under that theory, SpaceX certainly has a better story ("We're about to try to land our rocket on a barge as a step towards launch vehicle reusability and lowering the cost of access to space") than BO ("We have no rocket.")
If that was the story told, then the patent might be judged to have merit in a benefit. Even if it is SpaceX that proves a benefit to BO. BO doesn't have to be first to exploit it. Just "first filed" so to speak.
My guess is that "non obviousness" is under attack, as well as prior art. Probably a BO long rear guard action of definitive value is underway as a "hold on to the bitter end" strategy as both examine options to contend.
In that case, a possible counter strategy would be to dilute with "vehicles land many ways, in many places, we don't yet know the economics of the cycle to know best, one of many". Attacks model, diagrams/art, and claims. Death by 1,000 cuts.
add:
Oh, and the "we have no rocket" is better put as "we haven't yet examined this trade space yet with actual experience, so we shot gunned a patent through to deny others who might". Meaning that the true non-obvious elements of the true invention, not necessarily this patent, were not addressed in its filing.
Of such are these battles.
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I read BO’s patent (http://www.google.com/patents/US8678321), and I’m wondering if anybody else thinks it’s complete BS. (I'd like to hear a patent attorney's take on it.) Although the language in the application describes “Sea landing of space launch vehicles and associated systems and methods” as an “invention,” I question that characterization. To my mind, it’s an idea, a concept, that nowhere provides any technical solution(s) for the mechanical processes it details. I was reminded in reading it of Tom Hanks’s character in the movie “Big” when he has to give a presentation to his toy company's executives about his imaginative idea for an amazing product. When the questioning starts, his boss asks him, “Is this stuff really possible?” That’s when the boy in a man’s body realizes that he’s way out of his depth; he doesn’t have a clue.
Perhaps someone familiar with patent law can explain how this catalogue of gee-whiz imaginings qualifies as an invention. Basically, it says, “You can launch a rocket out over the ocean or another body of water, and the reusable first stage can come back and land on a sea-going platform.” Oh, really? And how do you do that, Jeff? Can you show me?
If SpaceX isn't able to convince a judge that BO doesn’t deserve any ownership rights to the unelaborated idea of landing a rocket on a barge, there’s something very wrong with patent law or our legal system or both.
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So.. the parts of the patent that explicitly describe the communications between the rocket and the platform.. did ya not get to that part?
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Blue Origin cannot patent the basic concept of a rocket communicating with a landing platorm. That's complete BS.
BO can patent a new modulation scheme that they invented, or a comms protocol, or a specific set of hardware. But no, they cannot patent something so basic as the concept of communicating.
If they can, then the operators of every single GEO satelite owe the estate of Aurthur C Clarke a hell of a lot of money!
SpaceX isn't going to use anything that BO actually invented. It's nonsense.
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It’s 1768 and Jeff Bezos’s ancestor wants to patent the following: a four-wheeled carriage that moves without the employment of animals or human beings to pull or push it. The motive power for this device is an engine that uses a combustible gas or fuel. This “horseless carriage” can be steered from its “stable” to a variety of destinations where its operator can stop its engine and station it. This destination can either be flat terrain or an inclined surface. In the latter case, the horseless carriage requires a device to “rein” its motion; this device is called its “bridle” or “brake”. When the operator desires to return the horseless carriage to its stable, he first resupplies it with fuel and then ignites the engine. By means of a steering mechanism, he guides it back along the same path that he traveled to reach his destination. Upon reaching the stable, he steers the horseless carriage into its designated resting place and stops the engine.
If this patent had been granted and upheld, Nicolas-Joseph Cugnot would have had to go to court to gain the right to market “the first steam powered automobile capable of human transportation,” which he successfully demonstrated in 1769 (Wikipedia). Cugnot had a working invention that showed the feasibility of horseless carriages. It would take over a hundred years before they became more than curiosities. Imagine if Old Bezos had been able to profit from his mere concept of a horseless carriage, possibly hindering the development of a real technology.
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Not sure if this has been posted yet; "SpaceX Bringing the Right Stuff to Patent Slog with Blue Origin, Expert Says"
http://www.spacenews.com/article/civil-space/42007spacex-bringing-the-right-stuff-to-patent-slog-with-blue-origin-expert-says
The patent lawyer interviewed for the article seemed to believe the patent was likely to be overturned.
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It’s 1768 and Jeff Bezos’s ancestor wants to patent the following: a four-wheeled carriage that moves without the employment of animals or human beings to pull or push it.
...
If this patent had been granted and upheld, Nicolas-Joseph Cugnot would have had to go to court to gain the right to market “the first steam powered automobile capable of human transportation,” which he successfully demonstrated in 1769 (Wikipedia). Cugnot had a working invention that showed the feasibility of horseless carriages. It would take over a hundred years before they became more than curiosities.
Back in ye olde dayes, people found ways around more troublesome patents, like this cheesy workaround of patents involving the crank:
https://en.wikipedia.org/wiki/Sun_and_planet_gear
The thing about patents is that they are supposed to be how-to-do, not what-to-do. When somebody patents a what-to-do, it's generally only good for legal thuggery.
One thing SpaceX has is fierce legal representation. Of the various possible outcomes of the patent conflict, I think we can be pretty sure there won't be a court ruling that the Blue Origin patent is valid and covers any and all methods of propulsively landing a rocket on anything in the water.
If the patent isn't struck down entirely, a sufficiently clear and narrow interpretation of it should be established for SpaceX to work around it.
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I think that if SpaceX is unsuccessful against BO's patent in court, there might be several ways around it, such as:
1) Use GPS. I know that the problem is that barges drift due to current, wind, etc., so the exact GPS coordinates for landing will not be known ahead of time. Therefore, have the barge periodically tell the stage what its present updated coordinates are. Would this still constitute a 'beacon' in the normal sense of the word?
2) Use GPS to aim the stage for the (rough) initially known coordinates of the barge. When the stage is in the 'neighborhood' of the barge, have cameras on the stage optically find the barge in the ocean, and zero in on the prominent black and white 'bulls-eye' painted on the deck. I'd think that optical processing state of the art could easily accomplish this, don't you (especially in clear weather conditions)? I don't think even BO could make the case that 'using reflected ambient light for the purpose of locating an object' (i.e. 'seeing') constitutes a 'beacon'. :-)
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A jack-up barge would be out of the scope of Blue Origin patent, isn't it?
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You could have the barge stay precisely at gps position defined before flight. All you need is several sets of propellers (one for each direction) or pod propellers. If you use gps on the rocket for positioning during the final descent, you get a very good accuracy (as good as differential gps)
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A jack-up barge would be out of the scope of Blue Origin patent, isn't it?
Answer it for yourself.
Look at the claims - the single, most important part of the patent. Do the claims as stated appear to address a landing on a jack-up barge?
Among other things, the claims address the boundary of infringement, usually in a grey zone way - "litigation cross sectional area" if you will.
My read is that they do.
Enough on patents - start another thread. Back to where "solid surface" landings will occur.
My guess is back to the usual suspects prior to the barge distraction - anyone care to dispute this?
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A jack-up barge would be out of the scope of Blue Origin patent, isn't it?
Answer it for yourself.
Look at the claims - the single, most important part of the patent. Do the claims as stated appear to address a landing on a jack-up barge?
Among other things, the claims address the boundary of infringement, usually in a grey zone way - "litigation cross sectional area" if you will.
My read is that they do.
Enough on patents - start another thread. Back to where "solid surface" landings will occur.
My guess is back to the usual suspects prior to the barge distraction - anyone care to dispute this?
Well, "solid surface" is quoted because the thread originator, Kabloona, was willing to discuss barge landings (see reply #2).
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My guess is back to the usual suspects prior to the barge distraction - anyone care to dispute this?
I would not care to dispute Space Ghost. ;)
But the premise of this thread is now pretty much out the window (ie that #14 or #15 would be a solid surface landing, per SpaceX July 22 statement). Clearly it won't be either of those missions.
Hans' comments make it sound like we're back to square one, ie working with Range Safety to get approval for RTLS at the Cape. He didn't say the word "Cape," but it's hard to imagine FAA/Range approving any other site.
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There's always Vandenberg...
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There's always Vandenberg...
Yes, but the vast majority of upcoming launches will be from the Cape.
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Hans' comments make it sound like we're back to square one, ie working with Range Safety to get approval for RTLS at the Cape. He didn't say the word "Cape," but it's hard to imagine FAA/Range approving any other site.
Technically, any region that has ever fallen under the scope/administration/"jurisdiction" of CCAFS/KSC. :)
Does not need to be in the current boundaries of CCAFS/KSC, but if outside the boundaries must be under exclusive use (possible with lease/rent).
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True statement, but I don't see the logic. "We're challenging the patent and therefore we cannot land on a barge as we had planned to do before we decided to challenge the patent?"
When submitting to the authority of a court, perhaps the most disrespectful thing you can do is proceed as if the court's decision doesn't matter.
Historically, (McDonalds Coffee-case for one specific case) that's very much true. Blow off the notion that whatever the court decides is beside the point and you in all likely-hood lost the case before it starts :)
Randy
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There's always Vandenberg...
Yes, but the vast majority of upcoming launches will be from the Cape.
Yes but what they need is proof of concept. If they get permission for Vandenberg and fly successfullly it is unlikely they will be denied at the Cape or Brownsville.
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It’s 1768 and Jeff Bezos’s ancestor wants to patent the following: a four-wheeled carriage that moves without the employment of animals or human beings to pull or push it. The motive power for this device is an engine that uses a combustible gas or fuel. This “horseless carriage” can be steered from its “stable” to a variety of destinations where its operator can stop its engine and station it. This destination can either be flat terrain or an inclined surface. In the latter case, the horseless carriage requires a device to “rein” its motion; this device is called its “bridle” or “brake”. When the operator desires to return the horseless carriage to its stable, he first resupplies it with fuel and then ignites the engine. By means of a steering mechanism, he guides it back along the same path that he traveled to reach his destination. Upon reaching the stable, he steers the horseless carriage into its designated resting place and stops the engine.
If this patent had been granted and upheld, Nicolas-Joseph Cugnot would have had to go to court to gain the right to market “the first steam powered automobile capable of human transportation,” which he successfully demonstrated in 1769 (Wikipedia). Cugnot had a working invention that showed the feasibility of horseless carriages. It would take over a hundred years before they became more than curiosities. Imagine if Old Bezos had been able to profit from his mere concept of a horseless carriage, possibly hindering the development of a real technology.
History has examples of this actually :) One of the more irritating portions of the Wright-Curtiss airplane foolishness was that the Wrights lawyers and investors were backed by a Federal Judge who had earlier upheld a obviously bogus "patent" claim on "internal combustion engines" that was being touted as THE patent that covers ALL ICE power plants and that everyone, everywhere owed the patent holder fees before they could build an ICE. Like the Wright claim to patenting all types of controls for aircraft Europe simply ignored the claim for the ICE but in the US it caused all sorts of issues because the people like Henry Ford had to fight this patent while trying to revolutionize car manufacturing. (I don't think anyone ever pointed out the afore mentioned Judge that his ruling should have meant the Wrights were liable for patent infringment due to building their own ICEs though :)
My main contention with the BO patent is simply that it trys far to hard to be far to inclusive while ignoring a great deal of "previous" art that was never patented but obviously assumed to be a non-patent issue. Similarly to the someone who tried right after the winning of the X-Prize to "patent" adventure flight by claiming patent to any and all possible "suborbital adventure trajectories"... Anyone recall that one?
Randy
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You could have the barge stay precisely at gps position defined before flight. All you need is several sets of propellers (one for each direction) or pod propellers. If you use gps on the rocket for positioning during the final descent, you get a very good accuracy (as good as differential gps)
If it had propellers it wouldn't be a barge. It would be a boat. Maintaining exact position and orientation is hard enough for a real ship that isn't specially equipped for it.
IIRC azmi-pods (GPS based thruster pods) can be used on barges without them being registered as boats.
Randy
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You could have the barge stay precisely at gps position defined before flight. All you need is several sets of propellers (one for each direction) or pod propellers. If you use gps on the rocket for positioning during the final descent, you get a very good accuracy (as good as differential gps)
If it had propellers it wouldn't be a barge. It would be a boat. Maintaining exact position and orientation is hard enough for a real ship that isn't specially equipped for it.
IIRC azmi-pods (GPS based thruster pods) can be used on barges without them being registered as boats.
Randy
You mean "azi-pods".. and I'd expect barges so fitted would still need to be registered as such.
A "landing platform" fitted with 4 x azi-pods and a precision nav system similar to those used for cable-laying is still a fairly specialised custom-built piece of kit and, unlike a jack-up, is not going to be something you can hire from just down the road. It'd still be no good for landing a rocket on in anything other than flat calm sea, but may well be an option SpX might choose to look into.
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There's always Vandenberg...
Yes, but the vast majority of upcoming launches will be from the Cape.
Yes but what they need is proof of concept. If they get permission for Vandenberg and fly successfullly it is unlikely they will be denied at the Cape or Brownsville.
Of course, the reverse is equally true. Is there reason to believe permission would be easier to obtain at Vandenberg than at the Cape?
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They are constructing a landing platform at a shipyard in louisiana
dimensions:
300' X 170'
"We are going to try to land on that on the next flight"
"50% chance or less of landing on the platform"
"80-90% likely that one of the upcoming flights will do it."
Edit: source : MIT Aeronautics and Astronautics Department's 2014 Centennial celebration Centennial Symposium
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Heheh, I thought they were going to lease a jack-up barge. Clearly not impressive enough for Elon Musk!
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Can someone look that up on satellite imagery? possible?
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Sounds like a modified (stripped down) LSD from Huntington Ingalls in Louisiana
Care to elaborate? Is this something that would not only be useful for the landing, but something that could ferry the landed stage back to the launch site?
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They are constructing a landing platform at a shipyard in louisiana
dimensions:
300' X 170'
Let's see. That's almost exactly soccer field sized.
Can you say "Naming Rights"!!
<Announcer> John, it's a beautiful day out here in the Gulf at NSF.com landing field. SpaceX is 8 for 1 this season against gravity, and I think they're going to try to improve on their record today.</Announcer>
<John Madden> Yeah uh, I'm thinking if they're going to maintain that record, they'll need to stick the landing today in these heavy seas. You know who else can stick the landing? Brett Favre!</John Madden>
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Barge landing attempt for CRS-5? Game on! So much for the BO patent. ;D
http://forum.nasaspaceflight.com/index.php?topic=35908.msg1275986#msg1275986
Some snippets from Elon's recorded comments:
Before RTLS, need to show they can land with precision over and over again (on floating platform).
For upcoming launch (CRS-5), will attempt landing on the new barge.
Barge will not be anchored, but will have engines that keep it located at GPS coordinates.
50% chance of success landing CRS-5 booster on barge.
If successful, Elon says he thinks they will be able to refly booster.
If not successful, will continue attempts with upcoming launches.
80-90% chance that one of the upcoming launches will succeed in landing booster on the barge.
And kudos to the folks upthread who correctly predicted a barge with engines/thrusters maintaining position via GPS. ;) (As opposed to a jack-up barge in shallow water)
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I hope there is free taco bell this time :D
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Sounds like a modified (stripped down) LSD from Huntington Ingalls in Louisiana
Care to elaborate? Is this something that would not only be useful for the landing, but something that could ferry the landed stage back to the launch site?
The LSD is a large, very capable ship. And presumably quite expensive.
http://en.wikipedia.org/wiki/Dock_landing_ship
What Elon described sounds more like a traditional barge, basically a floating football field, with some thruster pods for stationkeeping.
Presumably it would be towed out to sea, left on station, then recovered after landing attempt and towed back into port.
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Sounds like a modified (stripped down) LSD from Huntington Ingalls in Louisiana
Care to elaborate? Is this something that would not only be useful for the landing, but something that could ferry the landed stage back to the launch site?
The LSD is a large, very capable ship. And presumably quite expensive.
http://en.wikipedia.org/wiki/Dock_landing_ship
What Elon described sounds more like a traditional barge, basically a floating football field, with some thruster pods for stationkeeping.
Presumably it would be towed out to sea, left on station, then recovered after landing attempt and towed back into port.
Was thinking something with the hull form & layout of the Whidbey Island class LSD. Without the well dock and cargo capability. Just with Azi-pod in place of the propellers plus bow thrusters giving underway speed of about 14 knots. Obivously the helo landing deck will have to extended with sponsons to the 170 ft width. A ship like this could be build for about $150m or less, since it doesn't handle or carry any cargo, landing boats or landing vehicles. It is just a mobile platform.
However I deleted my previous post upon the realization that the platform have to be unmanned during landing operations :-[. So a wide beam barge with station keeping thrusters is more applicable.
Somehow landing an AV-8 Harrier or a F-23 Joint Strike Fighter on a LSD is not quite the same as a Falcon 9 1st stage. :o
Added: Some info on this thread (http://forum.nasaspaceflight.com/index.php?topic=35914.msg1276050;topicseen#msg1276050) about this subject.
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I'm thinking they just buy a used barge of the desired dimensions and do the necessary refit. From earlier posts by others, it sounds like barges with azipods are commonly used for cable-laying, so maybe something already exists with the right layout and propulsion.
Buying used and doing a refit would be much faster/cheaper than building new, I would think.
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Sources tell me its being built at Conrad Shipyards, of Morgan City Louisiana.
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Sources tell me its being built at Conrad Shipyards, of Morgan City Louisiana.
Any idea whether it's a brand new barge, or a refit?
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Sources tell me its being built at Conrad Shipyards, of Morgan City Louisiana.
Oh, if we google for Conrad Shipyards what could be found there?
Do you remember? ;)
It's "only" 200'x100'.
http://www.marinelink.com/maritime/CONRAD-SHIPYARDS
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True statement, but I don't see the logic. "We're challenging the patent and therefore we cannot land on a barge as we had planned to do before we decided to challenge the patent?"
When submitting to the authority of a court, perhaps the most disrespectful thing you can do is proceed as if the court's decision doesn't matter.
Well said. Elon's lawyers probably told him just that, very firmly.
OK, thank you for that explanation. Evidently I don't know how to think like a lawyer.
So...barge landing is on hold until the courts sort it out, and terra firma landing is being worked with Range Safety but nothing definite yet.
That's not disrespect to the authority of the court. After all SpaceX is litigating it, and it believes the patent will be invalidated, so until a ruling is reached, they can proceed. What matters is wilfull infringement allows for treble damanges (tripled punishment). If SpaceX is sure the patent is invalid and they win, whatever they do with the patent IP doesn't matter retroactively. If they loose then it would be really bad for SpaceX, if a large $$$ sum can be attributed to the landing attempt. Treble damages would allow BO to collect 3x that ammount attributed to the landing attempt value.
Since prior art can be shown with confidence, SpaceX should be free to ignore the patent until the lawsuit is settled or reaches a verdict.
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I think the SpaceX barge will most likely be non-infringing in any case because of a lack of communication between barge and rocket.
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Are we going to have to follow BargeX now?
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James Dean/Florida Today is on the ball:
http://www.floridatoday.com/story/tech/science/space/spacex/2014/10/24/spacex-attempt-falcon-booster-landing-floating-platform/17847817/
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Sources tell me its being built at Conrad Shipyards, of Morgan City Louisiana.
Coincidentally, Conrad is also refitting NASA's Pegasus barge that was used for Shuttle ET transport. Refit will allow it to be used for SLS:
http://www.nasa.gov/centers/marshall/news/news/releases/2014/14-081.html#.VErL_yJ4pYQ
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Google Earth image of Conrad ship yards. From 2012 but there are a couple of large barges there.
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Those two large buildings in the photo seem to match the photo from their website, which says they do all construction of vessels up to 350' in length indoors...probably in those sheds.
http://www.conradindustries.com/facilities/morgan-city.php
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Are we going to have to follow BargeX now?
Well, we've been already following CapsuleX. Soon to be joined by HeavyX.
We'll have to look forward to SpaceSuitX and AstronautX too. And probably more to come.
Whee! Am I having fun Zippy?
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Did this transform into a party thread? Just because party threads exist doesn't mean that irrelevant stuff needs to filter into EVERY thread.
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Interesting they are apparently building one rather than renting. This implies that either they needed a custom design that doesn't exist on the market or that they plan on using it many times in the future, or both. For instance, could it be the much debated solution for down range recovery of a FH core?
Another thought crossed my mind. Say it lands but there are rough seas, what is the risk of it tipping over? Could it steady itself using the RCS until it can be secured?
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Interesting they are apparently building one rather than renting. This implies that either they needed a custom design that doesn't exist on the market or that they plan on using it many times in the future, or both. For instance, could it be the much debated solution for down range recovery of a FH core?
Another thought crossed my mind. Say it lands but there are rough seas, what is the risk of it tipping over? Could it steady itself using the RCS until it can be secured?
They definitely plan on using multiple times, since Elon said they need to demonstrate "repeatable" precise landings before Range will allow RTLS. Plus mods needed for autonomous stationkeeping, etc. Plus possible future use for FH core recovery. All means owning better than renting.
Stability will be interesting issue. RCS of doubtful use there. Stage will have to be stable on its own several hours before recovery ship can return to the zone. But given the leg span and the relatively low CG with empty tanks and engines/octaweb down low, the stage could turn out to be surprisingly stable. And a barge that size might be surprisingly stable with respect to sea state as well.
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Elon saying maybe 50% chance of successful barge landing at first attempt sounds very positive to me.
He must be pretty confident in their landing accuracy and they've only had one successful test flight with grid fins. Really makes me curious about how accurate the two previous soft water landings were!
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BTW, that barge is huge... 300 feet long. If pointed into the waves, that means a wave height of ten feet will mean only 30 miliradians of an angle, less than 2 degrees of tilt! So it may be plenty steady enough even in moderately rough seas, as long as the natural frequency isn't too close to the wave frequency.
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Its highly probable the barge will actually be two barges lashed tightly together to form a single rigid structure with a flush deck.
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Its highly probable the barge will actually be two barges lashed tightly together to form a single rigid structure with a flush deck.
That sounds mechanically unlikely to me (unless by "lashed" you mean bolted, riveted, or welded), but I trust you have it on a good source?
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Sources tell me its being built at Conrad Shipyards, of Morgan City Louisiana.
Oh, if we google for Conrad Shipyards what could be found there?
Do you remember? ;)
It's "only" 200'x100'.
http://www.marinelink.com/maritime/CONRAD-SHIPYARDS
That guy is 300'x100' http://www.graybarge.com/sites/graybarge.com/files/julius_spec_shts_12mar14_0.pdf Conrad has the ability to create up to 350' length but I cannot find any info on width. Wonder if they will tie two together and put a deck on it or actually build the one big sucker.
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Its highly probable the barge will actually be two barges lashed tightly together to form a single rigid structure with a flush deck.
That sounds mechanically unlikely to me, but I trust you have it on a good source?
I would tend to believe it. If you look at the Conrad website link above, they say they build all their vessels indoors, up to 350' length. But the big buildings don't look wide enough to handle a 170' wide barge. So maybe they build two 80' or so indoors, then take them outside and weld them together.
Yes, mechanically difficult because of the huge bending stresses in the middle, but with enough steel it should be possible.
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Its highly probable the barge will actually be two barges lashed tightly together to form a single rigid structure with a flush deck.
That sounds mechanically unlikely to me, but I trust you have it on a good source?
I would tend to believe it. If you look at the Conrad website link above, they say they build all their vessels indoors, up to 350' length. But the big buildings don't look wide enough to handle a 170' wide barge. So maybe they build two indoors, then take them outside and weld the, together.
Yes, mechanically difficult because of the huge bending stresses in the middle, but with enough steel it should be possible.
Welded, riveted, bolted I buy. I just questioned the word "lashed" since I'm imagining big ropes...
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Yes, "lashed" made me think of Kon Tiki. But maybe they use really big steel cables instead.
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Welded, riveted, bolted I buy. I just questioned the word "lashed" since I'm imagining big ropes...
The platform might have a seam and not need to be completely rigid. In that case big wire ropes are actually not such a bad engineering solution for keeping two vessels in close proximity, they allow some flex. Because of the overall size not a lot of flex is needed but I would expect welds to be torn to pieces in heavy seas more easily.
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Welded, riveted, bolted I buy. I just questioned the word "lashed" since I'm imagining big ropes...
The platform might have a seam and not need to be completely rigid. In that case big wire ropes are actually not such a bad engineering solution for keeping two vessels in close proximity, they allow some flex. Because of the overall size not a lot of flex is needed but I would expect welds to be torn to pieces in heavy seas more easily.
It is a Catamaran barge.
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Interesting they are apparently building one rather than renting. This implies that either they needed a custom design that doesn't exist on the market or that they plan on using it many times in the future, or both.
I'd opine that both your speculations are correct, and that even if they could find one to rent that fits the bill, the owners likely aren't enthusiastic about the possibility of a 14 story building dropping out of the sky and exploding on their boat. The security deposit probably doesn't cover that level of damage.
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It is a Catamaran barge.
Ah, that explains it. Makes sense because a catamaran barge will have less wetted hull surface area and thus be easier to tow/propel. And it won't be carrying but minimal weight relative to its size, so large hull volume is not needed.
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in the final landing fire of the engines, how much force is likely to be imparted on the barge?
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in the final landing fire of the engines, how much force is likely to be imparted on the barge?
Same as that exerted on the rocket. :) So to first order no more than about 65 tons, the thrust of one Merlin 1D.
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where's the d'oh smiley? :)
thanks!
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So we're back to the barge distraction, from the patent distraction, and somewhere back was the range safety distraction. You'll note we get no additional advisement on all of these. The most is learning of a barge being constructed, and its size.
So yes range won't countenance it until more precision landings. Perhaps they won't say. Which means an alternative.
That they have a barge under construction means little, because such a barge could prove useful for stage/BFR transport as well.
At this point, the key issue is to advance a landing that just doesn't topple over for a few minutes. Not necessarily stage recovery/reuse. Just something firm to land on. Hard for that to be precluded by patent license on the face of it.
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That they have a barge under construction means little
You lost me there...Elon said categorically they will attempt several landings on the barge in order to demonstrate repeatable precision landing to the Range.
That they have a barge under construction means it may be ready in time for CRS-5, and if not, it will be for future landing attempts.
Just to reiterate, here are some snippets from Elon's comments at MIT yesterday:
Before RTLS, need to show they can land with precision over and over again (on floating platform).
For upcoming launch (CRS-5), will attempt landing on the new barge.
Barge will not be anchored, but will have engines that keep it located at GPS coordinates.
50% chance of success landing CRS-5 booster on barge.
If successful, Elon says he thinks they will be able to refly booster.
If not successful, will continue attempts with upcoming launches.
80-90% chance that one of the upcoming launches will succeed in landing booster on the barge.
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From the MIT discussion, Elon said that SpaceX most likely will have the barge ready for the CRS 5 launch. Take from that what you will.
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That they have a barge under construction means little
You lost me there...Elon said categorically they will attempt several landings on the barge in order to demonstrate repeatable precision landing to the Range.
Forgive me.
Means little to "infringement" on a patent.
Been trained to say fewest words.
add:
"We have a barge. Useful for many things. Like landing practice. No different than Grasshopper landing practice."
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Ah, thank you for the clarification.
Yes, the barge means little to the patent issue until they actually land on it. ;)
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Ah, thank you for the clarification.
Yes, the barge means little to the patent issue until they actually land on it. ;)
"Landing? No, no, no. Practice!" ;)
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I think it is pretty clear to anyone who has any knowledge of the industry and its history that the barge landing patent wont hold due to a significant amount of prior art.
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I don't think that whether the barge is used for "research" or not matters. The patent system doesn't seem to care much, it's just probably less likely you'll be sued if it stays in the lab, but I don't believe it makes it more legal.
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I'm not a lawyer, but I do have some thirty patents, I've been involved in a few suits, and I used to coordinate between engineers and lawyers in my division at Microsoft, so I know a few things. I have read the Blue Origin patent, and I think Elon is probably okay. Here's why.
If you read the detailed description, paragraphs four and five say this:
"Concepts exist for landing a booster stage on land. These concepts include landing the booster stage horizontally, like an airplane, or vertically, under its own power or by parachute or other means. All of these approaches, however, limit operational flexibility because they require a ground landing site for every launch azimuth and potential downrange landing area.
"Other concepts have been proposed in which the booster stage restarts its rocket engines after separation from the upper stage(s), and then flies back to the launch site. Once at the launch site, the booster stage would either execute a horizontal landing on a runway or a vertical landing by power or other means, such as a parachute. Both of these approaches, however, reduce the payload capability to orbit because they require the rocket to carry a substantial load of propellant to perform the fly-back maneuver."
Boostback is clearly outside the scope of this patent--in its own words. Has no one argued this already?
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Unless I'm missing something, boostback is irrelevant to the patent dispute.
SpaceX will be attempting to land on the barge downrange, without boostback, as a preliminary step. Once they eventually master barge landings downrange, they will try to take the next step and boostback for terra firma landings (or maybe another interim step with boostback to a barge near shore).
But in the meantime, barge landings downrange. Which is what the BO patent is about.
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I thought they already did some boostback with the last two attempts. Boostback is their goal, after all.
For the FH middle core, they may not want to do boostback, so I can see them fighting to invalidate the patent entirely. But for the forseeable future, it seems clear that the patent is explicitly a way to avoid boostback, and if SpaceX is doing boostback, then they're not infringing.
They have real lawyers, so I assume this is old news. I read the prior art they're referencing, and I'll be surprised if any of this patent survives the review. So, no, boostack isn't the big show here, but it seems to me to be a good reason for Elon not to have any immediate worries.
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it seems clear that the patent is explicitly a way to avoid boostback, and if SpaceX is doing boostback, then they're not infringing.
The patent is a way to avoid boostback to land. If you boostback partially and land on a barge, is that still infringing? I'm not the expert but I'm guessing BO would argue yes.
Anyway, that doesn't seem like the strongest argument for SpaceX given the clear case for prior art.
(And they've done a sort of boost-sideways, not really boost"back" yet.)
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You know... You might be able to land a BFR first stage on the same barge. Because the height would be roughly the same (most likely), the legs' span would only need to expand about 38% due to the wider core. Just a random thought I had. Back to your regularly scheduled programming.
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it seems clear that the patent is explicitly a way to avoid boostback, and if SpaceX is doing boostback, then they're not infringing.
The patent is a way to avoid boostback to land. If you boostback partially and land on a barge, is that still infringing? I'm not the expert but I'm guessing BO would argue yes.
Anyway, that doesn't seem like the strongest argument for SpaceX given the clear case for prior art.
(And they've done a sort of boost-sideways, not really boost"back" yet.)
To be more specific, the BO stuff avoids the need for supersonic retropropulsion/other - they just travel ballistically down range and then brake/terminal burn subsonically as the platform adapts.
The main "thrust" of the net difference is the ability to cancel down range progression, possibly leading to boost back and RTLS.
My guess is that consistent with SpaceX stated goals and flight test program, they will eventually boostback short of launch site and land in the ocean offshore enough for safety/regulatory/navigability requirements. To prove the survival, a hard landing is required for the vehicle to prove the success of the flight test, which obviously barge/land is required.
Longer term, flexibility in options might vary the CONOPS recipe or not. Too little flight test data in this area to conclude on recipes, because of few active vehicles ever becoming flight worthy to do so, although there is a vast space of proposed means to achieve reuse to be explored over a half century.
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Again, there is prior art to the patent. So why would it hold?
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Just as amateur engineers/rocket scientists can promptly conclude complex things that annoy real ones, the same is true for amateur lawyers here. Painful to those who actually do things for a living here.
You can tell the smartest members here who figure this out implicitly. Others, like the internet is dominated by, appear to know far more about everything than even those who do so for a living. I stand in awe.
By the way, patent litigation, like other litigation, can be quite indefinite for various reasons. You can also reverse decisions a decade later.
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Once the barge has been used a few times and returning stage accuracy is confirmed enough for the landings to shift to land, I would imaging the barge would be useful for the first propulsive returns of Dragon capsules from orbit and for the very same reason, the natural buffer of being far offshore for tests of new risky technologies.
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Once the barge has been used a few times and returning stage accuracy is confirmed enough for the landings to shift to land, I would imaging the barge would be useful for the first propulsive returns of Dragon capsules from orbit and for the very same reason, the natural buffer of being far offshore for tests of new risky technologies.
Only problem with that: Do they really intend to return the Dragon to KSC (as in the artwork), or to Vandenberg (closer to Hawthorne)? At this point, all six returns have been off the California/Mexico coast, and a land landing would then logically be to the new landing pad(s) being constructed at Vandenberg. Apart from that, that barge will probably never be taken to the west coast, as it is too wide for the Panama Canal, and taking it down around Cape Horn would probably not be a good idea (it's a stormy place), apart from the expense and time required.
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Interesting they are apparently building one rather than renting. This implies that either they needed a custom design that doesn't exist on the market or that they plan on using it many times in the future, or both.
I'd opine that both your speculations are correct, and that even if they could find one to rent that fits the bill, the owners likely aren't enthusiastic about the possibility of a 14 story building dropping out of the sky and exploding on their boat. The security deposit probably doesn't cover that level of damage.
Building a new one instead of renting one... maybe it will be utilized in the logistical stream in the future, to transport rockets such as BFR from assembly and testing locations to the pad.
Wonder what they will name the barge?
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Wonder what they will name the barge?
Suggestion: Falcons Nest
On a more serious note: If they need a barge on the west coast, they most probably still need one on the east coast. So the obvious solution to that is: get an other one. But other than this fruitless speculation: who knows what spacex plans or wants to do? Its obvious we dont have enough information to fuel an informed discussion. So why bother?
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You can tell the smartest members here who figure this out implicitly. Others, like the internet is dominated by, appear to know far more about everything than even those who do so for a living. I stand in awe.
http://en.wikipedia.org/wiki/Dunning–Kruger_effect (http://en.wikipedia.org/wiki/Dunning–Kruger_effect)
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Wonder what they will name the barge?
Attitude Adjuster.
but then Elon doesn't like AI. :/
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Once the barge has been used a few times and returning stage accuracy is confirmed enough for the landings to shift to land, I would imaging the barge would be useful for the first propulsive returns of Dragon capsules from orbit and for the very same reason, the natural buffer of being far offshore for tests of new risky technologies.
Only problem with that: Do they really intend to return the Dragon to KSC (as in the artwork), or to Vandenberg (closer to Hawthorne)? At this point, all six returns have been off the California/Mexico coast, and a land landing would then logically be to the new landing pad(s) being constructed at Vandenberg. Apart from that, that barge will probably never be taken to the west coast, as it is too wide for the Panama Canal, and taking it down around Cape Horn would probably not be a good idea (it's a stormy place), apart from the expense and time required.
I'd call it a pretty safe bet that the Dragon will return to the west coast as you would not want it doing reentry over land.
As for moving the barge, they could tow it around the tip of Africa vs. South America which I believe has better weather as long as they move it during the southern hemisphere summer. As for if it is worth moving, that comes down to how much customization they are doing. If it is just a flat surface then use it a few times before selling it (perhaps for scrap). If it will have onboard equipment for handling a vehicle after landing then it would be worth keeping it around for use later on one or the other coast.
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Wonder what they will name the barge?
how about something simple.. like: fPad.
(Maybe not my most worthy post, but it is my 100th...)
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Once the barge has been used a few times and returning stage accuracy is confirmed enough for the landings to shift to land, I would imaging the barge would be useful for the first propulsive returns of Dragon capsules from orbit and for the very same reason, the natural buffer of being far offshore for tests of new risky technologies.
Only problem with that: Do they really intend to return the Dragon to KSC (as in the artwork), or to Vandenberg (closer to Hawthorne)? At this point, all six returns have been off the California/Mexico coast, and a land landing would then logically be to the new landing pad(s) being constructed at Vandenberg. Apart from that, that barge will probably never be taken to the west coast, as it is too wide for the Panama Canal, and taking it down around Cape Horn would probably not be a good idea (it's a stormy place), apart from the expense and time required.
I'd call it a pretty safe bet that the Dragon will return to the west coast as you would not want it doing reentry over land.
As for moving the barge, they could tow it around the tip of Africa vs. South America which I believe has better weather as long as they move it during the southern hemisphere summer. As for if it is worth moving, that comes down to how much customization they are doing. If it is just a flat surface then use it a few times before selling it (perhaps for scrap). If it will have onboard equipment for handling a vehicle after landing then it would be worth keeping it around for use later on one or the other coast.
If the barge is constructed of two (three?) separate smaller units as indications are that it will be, Panama Canal transit is quite possible.
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Once the barge has been used a few times and returning stage accuracy is confirmed enough for the landings to shift to land, I would imaging the barge would be useful for the first propulsive returns of Dragon capsules from orbit and for the very same reason, the natural buffer of being far offshore for tests of new risky technologies.
They could land Dragon in the desert at first.
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Barge construction: I suspect the multiple hull design is correct. It should be recalled that they are going to need to have a "open" spot to let the thrust through along with active (water spray) cooling of the deck to land the stage. THEN they are going to require some sort of deployable crane/tower to secure the stage and possibly lower it for shipping.
Randy
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Once the barge has been used a few times and returning stage accuracy is confirmed enough for the landings to shift to land, I would imaging the barge would be useful for the first propulsive returns of Dragon capsules from orbit and for the very same reason, the natural buffer of being far offshore for tests of new risky technologies.
They could land Dragon in the desert at first.
That would require land overflight (unless you're talking "Dragonfly") which was mentioned as a concern until its proven :)
Randy
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Barge construction: I suspect the multiple hull design is correct. It should be recalled that they are going to need to have a "open" spot to let the thrust through along with active (water spray) cooling of the deck to land the stage. THEN they are going to require some sort of deployable crane/tower to secure the stage and possibly lower it for shipping.
Randy
Why do you presume any cooling is required? It is a single, throttled down engine, firing for a very short period of time. There is no hole for the exhaust being used on any of the grasshopper tests. Why do you presume that an open area is necessary either?
It's not even clear to me that much more than a smaller crane might be necessary: the first stage is very bottom heavy with 9 engines at the bottom. Some guy wires to ensure that even in a wind and larger waves the stage does not topple might be all that is necessary. That saves having to lower the stage to the deck and all the hair of some sort of a cradle to put it in...
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Once the barge has been used a few times and returning stage accuracy is confirmed enough for the landings to shift to land, I would imaging the barge would be useful for the first propulsive returns of Dragon capsules from orbit and for the very same reason, the natural buffer of being far offshore for tests of new risky technologies.
Would they really try landing the Dragon on a barge? I don't think they'd ever do that for a manned mission, and I don't think NASA would really want them doing it for a cargo mission either. If a first stage is a little off and hits the edge of the barge the customer hasn't lost anything. If a loaded capsule is a little off and hits the edge of the barge you probably lost your cargo. And if you're intending to use parachutes as backup you don't want that thing anywhere near a barge. A military base in the desert somewhere would make a lot more sense.
Even for an orbital test flight with no cargo (of which there would probably only be one or two) would want to test the real landing conditions.
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Once the barge has been used a few times and returning stage accuracy is confirmed enough for the landings to shift to land, I would imaging the barge would be useful for the first propulsive returns of Dragon capsules from orbit and for the very same reason, the natural buffer of being far offshore for tests of new risky technologies.
They could land Dragon in the desert at first.
That's almost surely going to be the case. I believe that's what SpaceX proposed in CCtCap (not saying based on any inside info). Basically the same as Boeing's CST-100, but (after parachutes) powered terminal landing instead of airbags.
As far as over-flight: that's not much of a concern for a small, manned and man-rated capsule with redundant (and backup) parachutes. There's already over-flight for Shuttle (which is much larger) and X-37b, besides all the CCtCap main proposers (Dreamchaser, CST-100, and Dragon 2).
And besides, cargo Dragon has already proven that it can do reentry precision good enough for landing in a desert.
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Why do you presume any cooling is required? It is a single, throttled down engine, firing for a very short period of time.
It's ONLY "70%" of full thrust impinging on a meltable surface :) Harrier's don't take off vertically under full power from a deck. They either use a ski-ramp (not seeing F9 backing down one of those despite some ideas around here :) ) or they fly off a specially treated section of deck that can handle the full heat. (Expensive which is why the whole deck is not done in that material)
70% of full thrust is still really, really hot.
There is no hole for the exhaust being used on any of the grasshopper tests.
It's a heat resistant concrete pad, not a steel deck. IIRC they still use a water spray which helps even though its main purpose was sound suppression.
Why do you presume that an open area is necessary either?
Deflecting the exhaust away from under the vehicle helps with limiting the heat damage both to the pad and the vehicle. The water is there so I "assume" they will use it. A deluge system for the hulls would be easy to have and handy in case of incident :)
Most of this is stuff that BO doesn't mention in their patent but WHICH is very much "prior art" thinking about the situation :)
It's not even clear to me that much more than a smaller crane might be necessary: the first stage is very bottom heavy with 9 engines at the bottom. Some guy wires to ensure that even in a wind and larger waves the stage does not topple might be all that is necessary. That saves having to lower the stage to the deck and all the hair of some sort of a cradle to put it in...
Imagine the barge making its way through some light chop. How much and how far is that "top" going to be whipping around and straining against the guy wires? Why can't SpaceX transport the F9 to the launch pad in a vertical position? It would seem "easy" until you think about how and why they designed the stage to be transported large distances. It has to get horizontal at some point in the process and the sooner the better. It's MADE to be held in a horizontal position so they will want to transport it that way.
Besides I ALSO "assume" they will be checking out and doing some minor servicing on the ride back to shore and they can't do that in a vertical position. We've actually discussed these issues when talking servicing to return to flight readyness after RTLS this isn't really that much different.
Randy
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Would they really try landing the Dragon on a barge?
Dragon powered landing has to resolve the same issues as the first stage and it's quite possible that "those-in-charge" won't simply take the example of the first stage for a manned VTVL vehicle.
I don't think they'd ever do that for a manned mission, and I don't think NASA would really want them doing it for a cargo mission either. If a first stage is a little off and hits the edge of the barge the customer hasn't lost anything. If a loaded capsule is a little off and hits the edge of the barge you probably lost your cargo. And if you're intending to use parachutes as backup you don't want that thing anywhere near a barge. A military base in the desert somewhere would make a lot more sense.
Even for an orbital test flight with no cargo (of which there would probably only be one or two) would want to test the real landing conditions.
I don't think that's all that likely because if the first stage isn't going to land "square" on the barge it pretty much will demonstrate they ain't ready for the real thing either. Likewise I'd be highly surprised if the Dragon (which has better and more accurate throttling capability) weren't able to accuratly hit a landing pad the size of the barge. Bonus is that if the Dragon has to abort there will probably be a crane and crew nearby to haul it out of the water. Similarly the first stage.
That's almost surely going to be the case. I believe that's what SpaceX proposed in CCtCap (not saying based on any inside info). Basically the same as Boeing's CST-100, but (after parachutes) powered terminal landing instead of airbags.
As far as over-flight: that's not much of a concern for a small, manned and man-rated capsule with redundant (and backup) parachutes. There's already over-flight for Shuttle (which is much larger) and X-37b, besides all the CCtCap main proposers (Dreamchaser, CST-100, and Dragon 2).
And besides, cargo Dragon has already proven that it can do reentry precision good enough for landing in a desert.
There's some differences that are probably more perception than fact but in fact both the Shuttle and X-37b are "gliders" nominally under control at all times whereas Dragon under power is another fish entirely. Dreamchaser falls under the same catagory as the Shuttle/X-37B and while "they" may give the OK for a landing at Edwards with the CST-100 I can already see where SpaceX might want to NOT follow suit if they can avoid it with Dragon V2. (Its a perception thing but in this case its very much NOT doing things like Boeing is doing :) )
Randy
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They could land Dragon in the desert at first.
That would require land overflight
[/quote]
The Commercial Crew versions of both CST-100 and Dragon V2 are coming down on land, which is what Soyuz does as well.
Land overflight is apparently not a problem.
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Why do you presume any cooling is required? It is a single, throttled down engine, firing for a very short period of time.
It's ONLY "70%" of full thrust impinging on a meltable surface :) Harrier's don't take off vertically under full power from a deck. They either use a ski-ramp (not seeing F9 backing down one of those despite some ideas around here :) ) or they fly off a specially treated section of deck that can handle the full heat. (Expensive which is why the whole deck is not done in that material)
70% of full thrust is still really, really hot.
Harriers use the ramp to increase their max takeoff weight beyond what can be done with VTOL, not (primarily) due to exhaust. They still land vertically with the nozzles directed downward. Though sustained exhaust heat from exhaust can cause problems (See LHA-6 USS America and MV-22/F-35 exhaust issues), the couple of seconds of blast from a Merlin hover slam could probably be compensated for pretty easily...
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They could land Dragon in the desert at first.
That would require land overflight
The Commercial Crew versions of both CST-100 and Dragon V2 are coming down on land, which is what Soyuz does as well.
Land overflight is apparently not a problem.
Edwards is a special case actually, the needed "permissions" are available. Not so much Kennedy and environs despite the Shuttle runway. CST is coming down by parachute which actually (weird as it sounds) makes it easier to get permissions. Soyuz is a case of "its already being done here" working where as Soyuz landing anywhere else would be an issue. Dragon is supposed to be a powered landing, with rockets, which is NOT seen as obvious and requires some finese to get done. Edwards IS a possible landing site but so far NASA hasn't bought off on that idea yet.
Randy
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Wonder what they will name the barge?
When the "Barge landings" was first announced CameronD posted this same question on the "Floating Launchpad- Speculation thread" (http://forum.nasaspaceflight.com/index.php?topic=35248.msg1235294#msg1235294). Recognizing that this was prime party thread material but lacking a party thread to use it in, I posted it on Reddit in /r/SpaceX (https://www.reddit.com/r/spacex/comments/2c0fnq) to have some fun with. There were some good ones.
Top vote: USS Trampoline (the announcement was around the time of US/Russia flap blowing up)
Most clever: A Dime (so SpaceX can claim that they are capable of landing on a dime)
My personal submission: All Your Base Are Land On US (play on an internet meme)
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Now that a floating, self-propelled,
custom-made purpose-built, barge with GPS positioning and azi-pods are all officially "go" here's a couple more predictions: ;)
It's a heat resistant concrete pad, not a steel deck. IIRC they still use a water spray which helps even though its main purpose was sound suppression.
1. I see no reason they wouldn't choose to install a heat resistant concrete pad as a landing deck. It's not "new tech" and concrete has many uses aboard steel ships, including use as ballast. Salt-water spray from on-board fire-water pumps might be a good thing also.
2. I expect this barge will have fairly low freeboard to maximise stability and more closely simulate "zero feet", especially with the heavy-weight deck and a heavy weight rocket on top of it.
From my BOTE calculations, a low-freeboard (say 6' above water) flush-decked barge of the quoted dimensions (300' x 175') should be quite stable in waves of at least 3 feet. That means they'll need to limit landing operations to relatively good weather, but they'll likely want that anyway to ensure quality video of their landing attempts.
3. To ensure no personnel are in harm's way should something go wrong, the barge will be un-manned with all barge operations remotely monitored from a short distance away using a radio telemetry link, presumably from some kind of command vessel/tug, also serving as observation platform.
Any others?
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Now that a floating, self-propelled, custom-made, barge with GPS positioning and azi-pods are all officially "go" here's a couple more predictions: ;)
Custom made?
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Now that a floating, self-propelled, custom-made, barge with GPS positioning and azi-pods are all officially "go" here's a couple more predictions: ;)
Custom made?
Well, a barge spec'd to their requirements certainly ain't available off the shelf!.. ;)
Seriously though, IIRC the name of the crowd building it was quoted earlier.
EDIT: In hindsight, perhaps "purpose-built" would have been a better choice of words.. PP edited accordingly.
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From my BOTE calculations, a low-freeboard (say 6' above water) flush-decked barge of the quoted dimensions (300' x 175') should be quite stable in waves of at least 3 feet.
The barge doesn't necessarily need to be stationary, especially not in the up-down direction. It may be enough that its movement is predictable.
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I listen to the MIT webcast with Elon again. He said 175x300 platform. Could it be a re-fitted semi-submersible oil drilling platform instead of a barge?
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Barge construction: I suspect the multiple hull design is correct. It should be recalled that they are going to need to have a "open" spot to let the thrust through along with active (water spray) cooling of the deck to land the stage. THEN they are going to require some sort of deployable crane/tower to secure the stage and possibly lower it for shipping.
Randy
Why do you presume any cooling is required? It is a single, throttled down engine, firing for a very short period of time. There is no hole for the exhaust being used on any of the grasshopper tests. Why do you presume that an open area is necessary either?
Few seconds of direct impingement are enough to deform a steel deck (unless very thick).
A pump creating a water flow or water spray seems the easy solution.
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Well, if it is a catamaran design with a somewhat elevated deck, they could ballast the two floats with water which should drastically improve stability. Also, it's a huge barge, so pointing into the waves will lessen the impact of wave action significantly.
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Having the first stage land on a barge could be done IMO if the wave action is very limited. I'm not so much concerned about toppling of the stage but more about the stage shifting around the deck after landing.
The cog for the empty stage is positioned very low and the footprint of the four landing legs is fairly large. You would have to tilt the barge pretty far for the landed stage to topple. I suspect it will start shifting long before that.
So, how would SpaceX prevent the stage from shifting upon (and after) landing?
I've thought about this and done some sketches (I'm a terrible drawer) of on board foldable cranes, temporary shelters, etc. what I like the most, from a use ability and transport off the barge is a reverse transporter erector.
The size of the deck for the barge is almost twice as long as it is wide. I see that as a hint that one end of the deck can handle having 'stuff' on it, namely recovery equipment. The reverse erector would be mobile, roll under the base after it lands. Grapple the base of the stage, secure itself to the deck for stability, raise the strong back, grapple the stage then lower it to horizontal.
I wish I was a better drawer or graphic artist and could put pictures to my mental imagines.
The recovery crew would be miles away, not likely on board.
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Steel decking with switchable electropermanent magnets in the landing feet? Once you're down, you give them a pulse of power to turn the magnet on, and then you're stuck to the surface? That's how I'd do it.
~Jon
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I listen to the MIT webcast with Elon again. He said 175x300 platform. Could it be a re-fitted semi-submersible oil drilling platform instead of a barge?
Didn't you say a few pages ago that it was a catamaran barge? That seems to me the likely solution. A catamaran is the optimum for minimum hull surface and therefore ease/speed of towing. And as pointed out above, a barge that size should be quite stable.
An oil drilling platform is definitely not fast/easy to tow, so that seems unlikely to me.
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EDIT: In hindsight, perhaps "purpose-built" would have been a better choice of words.. PP edited accordingly.
I don't think they are do that.
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I don't think they are do that.
Please elaborate...Elon said it would have "engines" for stationkeeping to GPS coordinates...and how many barges/platforms have been built for rockets to land on? So how can it not be "purpose built?"
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EDIT: In hindsight, perhaps "purpose-built" would have been a better choice of words.. PP edited accordingly.
I don't think they are do that.
Please elaborate...
"purpose-built" would mean new/built from the keel up. They are likely taking existing barges and modifying them.
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EDIT: In hindsight, perhaps "purpose-built" would have been a better choice of words.. PP edited accordingly.
I don't think they are do that.
Please elaborate...
"purpose-built" would mean new/built from the keel up. They are likely taking existing barges and modifying them.
I would agree that they're likely modifying existing barges. From what has been rumored, it sounds like a catamaran arrangement with a deck.
Still, the resulting vessel will have been built for a specific purpose, call it what you will.
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Steel decking with switchable electropermanent magnets in the landing feet? Once you're down, you give them a pulse of power to turn the magnet on, and then you're stuck to the surface? That's how I'd do it.
~Jon
Big junkyard electromagnet with marine generator might be more powerful and perhaps simpler.
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Steel decking with switchable electropermanent magnets in the landing feet? Once you're down, you give them a pulse of power to turn the magnet on, and then you're stuck to the surface? That's how I'd do it.
~Jon
Big junkyard electromagnet with marine generator might be more powerful and perhaps simpler.
Aren't the legs carbon fiber/aluminum?
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Steel decking with switchable electropermanent magnets in the landing feet? Once you're down, you give them a pulse of power to turn the magnet on, and then you're stuck to the surface? That's how I'd do it.
~Jon
Big junkyard electromagnet with marine generator might be more powerful and perhaps simpler.
Aren't the legs carbon fiber/aluminum?
But the feet might not be.
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Steel decking with switchable electropermanent magnets in the landing feet? Once you're down, you give them a pulse of power to turn the magnet on, and then you're stuck to the surface? That's how I'd do it.
~Jon
Sounds neat, "Altius clever" and sophisticated, but it's more to carry and control on the rocket.
How about little robotic "thumbs" that roll up to and over the unmodified and passive rocket feet, and then clamp themselves to the deck with magnets, switchable electromagnets like you suggested or even mecanically switched permanent magnets, or just bolts?
P.S. Do we think the barge will flex along the centerline joint or be held rigid by some structure? Wouldn't want to clamp the rocket across a flexing joint. :P
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Steel decking with switchable electropermanent magnets in the landing feet? Once you're down, you give them a pulse of power to turn the magnet on, and then you're stuck to the surface? That's how I'd do it.
~Jon
Sounds neat, "Altius clever" and sophisticated, but it's more to carry and control on the rocket.
How about little robotic "thumbs" that roll up to and over the unmodified and passive rocket feet, and then clamp themselves to the deck with magnets, switchable electromagnets like you suggested or even mecanically switched permanent magnets, or just bolts?
The idea is to have the whole landing area capable of 'holding' the stage once its down. Otherwise you have to be REALLY accurate at touchdown. Missing by an inch would be an issue. For some reason though your idea makes me think of giant "Roomba's" that scramble around the deck to end up under the "feet" and clamp on to them and the deck :)
P.S. Do we think the barge will flex along the centerline joint or be held rigid by some structure? Wouldn't want to clamp the rocket across a flexing joint. :P
Sounds to me like it will be a catamaran design with a solid "decking" structure to bridge the hulls and between... Which now that I think about it... Ok, maybe too much like the "Catamaran Aircraft Carrier" from "King Kong Escapes" for me...
Seriously I fully expect that the stage won't need to be clamped down unless the seas are REALLY rough and will be lowered to horizontal before being moved.
Randy
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Grid decking would allow both flame flow-through and opportunities for simple lock-down of the feet without precisely-aligned landing.
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Seriously I fully expect that the stage won't need to be clamped down unless the seas are REALLY rough and will be lowered to horizontal before being moved.
Yes, and how might it be lowered to horizontal on the barge? Doesn't that imply some sort of arm like the one on the TEL?
No doubt this is quite a fun little mechanical design project. BUT...unless some of that work is re-usable on a RTLS pad, it's wasted effort (and added expense and construction delay for the barge). Better to just let it land, prove it can hit the target, and then if it falls over or gets banged up a bit while being secured, no big deal. Save the really ornate solutions for the pad back at the Cape.
Grid decking would allow both flame flow-through and opportunities for simple lock-down of the feet without precisely-aligned landing.
Yes, grid decking and an open, flooded deck below would roughly approximate a water deluge system in some ways, wouldn't it?
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Seriously I fully expect that the stage won't need to be clamped down unless the seas are REALLY rough and will be lowered to horizontal before being moved.
I'm wagering the booster is so weak in terms of bending and then collapsing that the barge will have a cradle and crane on board for the return trip to safe the booster. Or the barge will have a tender with a crane on it, but that makes things more complicated.
Without a cradle, the potential number of acceptable launch days goes way down; they'd have to have perfect seas offshore to avoid the risk of damaging the booster on the return cruise. With a crane and cradle, they still need acceptable landing conditions, but they don't have to have an acceptability window open as long.
(Obviously, the crane won't look like it does in this photo, but you get the idea).
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Seriously I fully expect that the stage won't need to be clamped down unless the seas are REALLY rough and will be lowered to horizontal before being moved.
Yes, and how might it be lowered to horizontal on the barge? Doesn't that imply some sort of arm like the one on the TEL?
No doubt this is quite a fun little mechanical design project. BUT...unless some of that work is re-usable on a RTLS pad, it's wasted effort (and added expense and construction delay for the barge). Better to just let it land, prove it can hit the target, and then if it falls over or gets banged up a bit while being secured, no big deal. Save the really ornate solutions for the pad back at the Cape.
Pretty much I expect that the means will be a "prototype" of the mobile "clamp" that will be used to retrieve and move the booster when RTLS operations begin. It will be something that can be manueverd up to the booster and "clamp" onto it and then lower it down and act as a 'cradle' at the same time. I've seen several different pieces of equipment that could serve as a basis for such a vehicle so I'm not worried that this will be difficult for SpaceX.
I'm wagering the booster is so weak in terms of bending and then collapsing that the barge will have a cradle and crane on board for the return trip to safe the booster. Or the barge will have a tender with a crane on it, but that makes things more complicated.
Without a cradle, the potential number of acceptable launch days goes way down; they'd have to have perfect seas offshore to avoid the risk of damaging the booster on the return cruise. With a crane and cradle, they still need acceptable landing conditions, but they don't have to have an acceptability window open as long.
(Obviously, the crane won't look like it does in this photo, but you get the idea).
Oh no.. You realize that pic is going to give people ALL the wrong ideas... Again...
"Hey they could use that crane with a giant hand and grab the stage in mid-air!" Think Man! Think before you post! ;)
Randy
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SpaceX really won't have much leeway to change their launch schedule for landing attempts, they'll really just have to look at the weather on launch day and decide if it's worth sending out the barge or not. If they do eventually land on barges from their commercial site it would be an interesting contract clause for them to use, maybe a discount if the customer would let them shift the launch a couple days for offshore weather.
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Seriously I fully expect that the stage won't need to be clamped down unless the seas are REALLY rough and will be lowered to horizontal before being moved.
Yes, and how might it be lowered to horizontal on the barge? Doesn't that imply some sort of arm like the one on the TEL?
FWIW, I envisage a completely-flat (ie. flush-decked) landing barge, since if they were even slightly off in their positioning the last thing they'd want to risk is putting a leg on something else on deck that might cause the stage to topple. Sure it would make for a spectacular belly-flop/kaboom, but I'd not think that was a risk worth taking especially if they don't need to. :)
The portable tower/crane could be installed on the "support ship" - either temporarily or permanently - which might or might not also remove the stage from the barge and take the stage back to dry land fixed in a horizontal position. Bigger versions of ships like this are readily available for hire in most parts of the world:
(http://sea-jobs.net/files/135886211235051.jpg)
It's not rocket science. ;D
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I listen to the MIT webcast with Elon again. He said 175x300 platform. Could it be a re-fitted semi-submersible oil drilling platform instead of a barge?
Didn't you say a few pages ago that it was a catamaran barge? That seems to me the likely solution. A catamaran is the optimum for minimum hull surface and therefore ease/speed of towing. And as pointed out above, a barge that size should be quite stable.
An oil drilling platform is definitely not fast/easy to tow, so that seems unlikely to me.
Found picture of generic self-mobile semi submersible drilling rig. Just minus all drilling equipment to act as landing platform. It is a catamaran design with thrusters for station keeping & self mobility. There should be some retired rigs of this type available for conversion to landing platform.
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Certainly possible but it looks like overkill to me. KISS.
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Question: Is there an existing ship available for hire that can safely lay down a first stage along its deck?
I ask this because my first thought for how to get the stage horizontal for the trip back is to contract a ship that has a crane to remove the stage from the barge and place it somewhere (probably on its own deck) for the trip back. This makes the barge ridiculously simple to build because now there is nothing you need to do with it other than land the stage on it.
EDIT: D'oh, CameronD's answer is pretty much what I was thinking.
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Steel decking with switchable electropermanent magnets in the landing feet? Once you're down, you give them a pulse of power to turn the magnet on, and then you're stuck to the surface? That's how I'd do it.
~Jon
Welp, there go the stage's avionics!
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Steel decking with switchable electropermanent magnets in the landing feet? Once you're down, you give them a pulse of power to turn the magnet on, and then you're stuck to the surface? That's how I'd do it.
~Jon
Welp, there go the stage's avionics!
I'm not saying the idea is practical, but would it really damage the avionics?
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Once the barge has been used a few times and returning stage accuracy is confirmed enough for the landings to shift to land, I would imaging the barge would be useful for the first propulsive returns of Dragon capsules from orbit and for the very same reason, the natural buffer of being far offshore for tests of new risky technologies.
Only problem with that: Do they really intend to return the Dragon to KSC (as in the artwork), or to Vandenberg (closer to Hawthorne)? At this point, all six returns have been off the California/Mexico coast, and a land landing would then logically be to the new landing pad(s) being constructed at Vandenberg. Apart from that, that barge will probably never be taken to the west coast, as it is too wide for the Panama Canal, and taking it down around Cape Horn would probably not be a good idea (it's a stormy place), apart from the expense and time required.
Not the Super Panamax canal! It's friggin' huge!
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Unless I'm missing something, boostback is irrelevant to the patent dispute.
SpaceX will be attempting to land on the barge downrange, without boostback, as a preliminary step. Once they eventually master barge landings downrange, they will try to take the next step and boostback for terra firma landings (or maybe another interim step with boostback to a barge near shore).
But in the meantime, barge landings downrange. Which is what the BO patent is about.
As I understood it, the idea was to boost back to a barge fairly close to shore, within visual range. They'd be far enough out that there'd be no danger from debris or explosion, but close enough to observe the actual landing. This is part of why I've been a bit concerned about sea state and winds. Closer to shore waves tend to get pretty big, while winds coming in from the sea at night or going out to sea during the day, can be an issue.
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Not the Super Panamax canal! It's friggin' huge!
The currently proposed (but not implemented) Panamax size is 49m wide. That's still too narrow for this barge.
See http://en.wikipedia.org/wiki/Panamax
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As I understood it, the idea was to boost back to a barge fairly close to shore, within visual range. They'd be far enough out that there'd be no danger from debris or explosion, but close enough to observe the actual landing. This is part of why I've been a bit concerned about sea state and winds. Closer to shore waves tend to get pretty big, while winds coming in from the sea at night or going out to sea during the day, can be an issue.
We've speculated here that the final step before terra firma landings would be barge landings close to shore, near the intended landing site in order to prove terminal guidance accuracy for RTLS.
But as a first step, it's possible that they will start with the barge far out from shore. As Elon said at MIT, the barge will be "out in the Atlantic," which doesn't sound like near-shore, at least not for starters.
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Found picture of generic self-mobile semi submersible drilling rig. Just minus all drilling equipment to act as landing platform. It is a catamaran design with thrusters for station keeping & self mobility.
Interesting thought. Basicly a SWATH ship. Which brings up a possible point, if the barges of the catamaran submerge and the deck is on pylons such as shown that would greatly reduce the effects of any wave action....
Welp, there go the stage's avionics!
I'm not saying the idea is practical, but would it really damage the avionics?
Not unless the magnetic surge/magnets are SERIOUSLY powerful. IIRC the avionics are higher up than the landing feet :)
I'm going to go out on a limb and guess they are somewhat protected :)
Randy
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SWATH, catamaran, semisubmersible drill platform, or they could just lash a few barges together like Elon said in the interview. I think you are underestimating the utility of lashing marine vehicles plus overestimating the seakeeping accelerations of a 40 ton stationary barge.
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SWATH, catamaran, semisubmersible drill platform, or they could just lash a few barges together like Elon said in the interview. I think you are underestimating the utility of lashing marine vehicles plus overestimating the seakeeping accelerations of a 40 ton stationary barge.
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Does this results in a 170x300 foot platform? That is the reason I am leaning toward a self-mobile drilling rig conversion rather than a barge as the platform in question.
note - please attached rather than embedded image files.
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SWATH, catamaran, semisubmersible drill platform, or they could just lash a few barges together like Elon said in the interview. I think you are underestimating the utility of lashing marine vehicles plus overestimating the seakeeping accelerations of a 40 ton stationary barge.
Bingo
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Does this results in a 170x300 foot platform? That is the reason I am leaning toward a self-mobile drilling rig conversion rather than a barge as the platform in question.
Here we go! San Marco (http://en.wikipedia.org/wiki/Broglio_Space_Centre). Again.
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SWATH, catamaran, semisubmersible drill platform, or they could just lash a few barges together like Elon said in the interview. I think you are underestimating the utility of lashing marine vehicles plus overestimating the seakeeping accelerations of a 40 ton stationary barge.
..and I think you're underestimating the twisting forces applied to large clusters of barges "lashed together" outside of a flat-calm river system.
(Ooh, I get to disagree with Jim!! That HAS to be worth a few extra points.. :) )
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..and I think you're underestimating the twisting forces applied to large clusters of barges "lashed together" outside of a flat-calm river system.
If sea state is an issue for that, then it will be an issue for any other type,
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..and I think you're underestimating the twisting forces applied to large clusters of barges "lashed together" outside of a flat-calm river system.
If sea state is an issue for that, then it will be an issue for any other type,
Not necessarily, Jim. A single rigid catamaran or SWATH platform will roll and pitch as a single unit since the hull's point-of-contact with the ocean is at the extreme sides only, and not in the middle - whereas "lashed" together barges have many points of contact across the entire platform resulting in twisting and buckling forces also. :)
That's actually why the SWATH plan-form was developed... not that I could ever imagine SpaceX building one of those for landing stages on: as great as it would be, it's probably overkill.
http://en.wikipedia.org/wiki/Small-waterplane-area_twin_hull
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I quote CameronD
I also like the idea to have the landing point at the end of the parabolic trajectory, it allows fuel savings compared to fly back to land, and thus more payload
The matter is: will the extra cost of building and managing such a platform worth the extra allowed payload ?
Just my 2 cents :)
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SWATH, catamaran, semisubmersible drill platform, or they could just lash a few barges together like Elon said in the interview. I think you are underestimating the utility of lashing marine vehicles plus overestimating the seakeeping accelerations of a 40 ton stationary barge.
...
Does this results in a 170x300 foot platform? That is the reason I am leaning toward a self-mobile drilling rig conversion rather than a barge as the platform in question.
note - please attached rather than embedded image files.
A single barge can be used to make a 170' x 300' platform, which is moderately large, but not huge. Usually a barge that length would have around 100' beam. 35' deck extensions cantilevered off the sides would not be out of the question for such a light cargo. Back of the envelop beam calcs suggest about 300 tons of steel (compared to a 5000 ton or so deadweight) for such a deck, which for material and simple fab would be in range of $1 million. Since you can buy just about anything on the internet, I went ahead and looked up barges and it looks like $2-4 million for used barges in that size range. Add a couple engines and a control system and we're talking about an investment easily in the $10 million range for slightly over an acre of flat surface at a point of Elon's choosing in the Atlantic. Not a trivial cost for a very small chunk of non-water.
When talking about stability, keep in mind that despite it's height, the center of gravity of the Falcon 9 first stage is quite low. I'm sure SpaceX will take a fairly detailed look at how deck movement affects things, but my intuition is a typical sea state won't be a major issue.
If they're concerned about stability during the trip home, presumably a tug and crane barge can wait outside of the exclusion zone, be up next to it an hour or two after touch down, and attach either a strongback to support it while laying it down or guy wires.
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Does this results in a 170x300 foot platform? That is the reason I am leaning toward a self-mobile drilling rig conversion rather than a barge as the platform in question.
Here we go! San Marco (http://en.wikipedia.org/wiki/Broglio_Space_Centre). Again.
That might be a long term solution, especially for downrange recovery of Falcon Heavy core stages, but it is also certainly overkill for any flights in the next year (at least).
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Helodriver has said upthread that it's "highly probable" the platform will be two barges "lashed" together. That may be based on some knowledge since he has a source that told him the platform was being built at Conrad.
From Helo's "highly probable" comment that may be based on inside info, the two-barge platform still seems most likely IMO.
As far as iamlucky13's idea above for a barge with "wings," there are some problems with that approach. Hanging 30 foot wings off the sides decreases stability, and with that amount of extension even minor tipping angles combined with high seas could mean waves breaking over the wing edges.
If you're a naval architect, for maximum stability you want floatation right at the edge of the platform, and the easiest way to achieve that is to have two hulls that extend right to the edges of the platform.
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Helodriver has said upthread that it's "highly probable" the platform will be two barges "lashed" together. That may be based on some knowledge since he has a source that told him the platform was being built at Conrad.
From Helo's "highly probable" comment that may be based on inside info, the two-barge platform still seems most likely IMO.
As far as iamlucky13's idea above for a barge with "wings," there are some problems with that approach. Hanging 30 foot wings off the sides decreases stability, and with that amount of extension even minor tipping angles combined with high seas could mean waves breaking over the wing edges.
If you're a naval architect, for maximum stability you want floatation right at the edge of the platform, and the easiest way to achieve that is to have two hulls that extend right to the edges of the platform.
Yes, you are right. Catamarans (= 2 or 3 hulls briged together by one structure) are supposedly most stabile water boats. See one bellow :)
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I quote CameronD
I also like the idea to have the landing point at the end of the parabolic trajectory, it allows fuel savings compared to fly back to land, and thus more payload
The matter is: will the extra cost of building and managing such a platform worth the extra allowed payload ?
Just my 2 cents :)
plus the limitations of having to consider the weather out at sea all the time. Having to take into account the weather in one location is bad enough.
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plus the limitations of having to consider the weather out at sea all the time. Having to take into account the weather in one location is bad enough.
plus the fact that EM has to change idea about 1st stage recycling duty time. This was his original main driver for RTLS. But he likes flexibility rather than sticking on older ideas and I'm sure he considered that (or drillships (http://en.wikipedia.org/wiki/Drillship)).
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What does Sea Launch, launch from?
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plus the limitations of having to consider the weather out at sea all the time. Having to take into account the weather in one location is bad enough.
What says this is going to be used more than a couple of launches?
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What does Sea Launch, launch from?
I'm afraid Sea Land (http://en.wikipedia.org/wiki/Principality_of_Sealand) would be more appropriate in this case, actually.
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What does Sea Launch, launch from?
Sea Launch (used to) launch from a converted oil drilling rig...way overkill for this application.
(http://www.spaceflightnow.com/news/n1010/28sealaunch/odyssey.jpg)
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As far as iamlucky13's idea above for a barge with "wings," there are some problems with that approach. Hanging 30 foot wings off the sides decreases stability, and with that amount of extension even minor tipping angles combined with high seas could mean waves breaking over the wing edges.
If you're a naval architect, for maximum stability you want floatation right at the edge of the platform, and the easiest way to achieve that is to have two hulls that extend right to the edges of the platform.
It's not specifically a problem. It's a limitation that this application doesn't come close to in terms of vessel stability. They don't launch in strong winds anyways.
For rocket stability, it's a little more relevant. The slight increase in CoG of the platform will increase roll a bit, and roll will naturally be greater for a narrower platform to begin with, further limiting the weather conditions during which a landing attempt is likely to succeed, but the tradeoff for a catamaran is greater cost for the custom barge.
Not that I know what SpaceX is doing, but that's my 2 cents.
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For yea sayeth Elon:
"We actually have a huge platform that's being constructed at a shipyard in Louisiana right now. Which is - well, it's huge, huge-ish, it's about 300 feet long by 170 feet wide. That looks very tiny from space, and the leg span of the rocket is 60 feet, and this is going to be positioning itself out in the ocean with engines that will try to keep it in a particular position - but it's tricky, you've got to deal with these big rollers and GPS errors. It's not anchored, because it's out in the Atlantic."
So I thought to myself,
- If its being built with the goal to be off the Atlantic coast in early December its got to be getting near its finished size about now though as previously speculated possibly with 35' folding wings on either side of a standard barge.
- You can't build something like that in a basement, you'd need some larger place near the water, such as a shipyard, and Elon confirms my brilliancy here. Shipyards don't have roofs.
- He goes further in saying that something like that looks very tiny from space, but I don't look down from space, I look down from Google Earth, and something that large is hard to hide at the altitude I can fly Google Earth at. I can fly that thing scary low.
- Google Earth has platform measuring tools.
- Active ship building projects have a beehive of pickup trucks and Carhart colored workers buzzing about to give themselves away.
So I spent some time looking at "shipyards in Louisiana" through the lens of Google Earth. There are many, 5 pages of them, approximately 50. I was surprised to find that nearly all of them are not on the gulf coast but inland, on rivers. The size of the rivers may eliminate quite a few if the assumption is made that the platform goes out full width, but most look like they'd handle a folded 100' version. After reviewing the first 30 shipyards I halted my search because none of the image dates were current, most being 2012 and 2013. But my point is that one of us (who is not in a hurry to get to bed as I currently am) probably has a go to earth image server that has more current images and its not rocket science to tour the shipyards looking for such a large object which is currently in the late stages of completion. So how's about someone taking up the search for this platform in a haystack???
And as for Elon's word "platform" above, that could be the generic version of platform or the oil industry version of the word platform. Since we're in Louisiana I lean toward it being an oil industry type platform, probably a modification of a retired oil platform, and for stability (and to fit the word "engine") a SWATH platform. All speculation of course, but speculating toward higher probability of success in finding it. So I'd look at shipyards specializing in SWATH platforms (though if just a modification there is probably no specialization needed), and shipyards with enough draft to get a SWATH platform into dock. Also, if a person was really intent on finding this huge chunk of metal he could look at the "Ship Trader" (or whatever it may be called) web site both current and archived versions from ~6 months back. Whatever fits the bill and was for sale (sail?) a few months ago but isn't any more is suspect.
Once we have identified (a) candidate(s) we can send in ground personnel to determine if there are sparks coming off the vessel. And I'll pay for him to have lunch with the workers at their favorite lunch restaurant.
Mark
p.s. - Does anyone know how to look up ship registration information? I'm interested in finding one that is registered to Space Exploration Technologies of Hawthorne California. Though this may be a lease.
pss - My speculation is that the platform will stay out to sea and the cores will come back separately.
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Comparison between imagery at Google maps and Bing (both dated (C) 2014, don't know if this indicates capture date?) shows the construction of piers at Conrad Shipyards LLC - the Bing imagery seems more recent, there's a blue crane over the southern pier (or I suppose the the imagery could show *destruction* of the piers and then the age of the imagary would be the other way around :) )
Anyway, These piers seem to enclose an area that might reasonably contain a barge of the dimensions discussed.
Disclaimer: I'm not a nautical engineer; it could be somewhere else entirely!
(edited to clarify image date)
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plus the limitations of having to consider the weather out at sea all the time. Having to take into account the weather in one location is bad enough.
What says this is going to be used more than a couple of launches?
Using a barge for tee t purposes as your are implying is fine, but look at the context of my comment.
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I think I found it. Anyone want to head over to River Rd in Morgan City and see if they see any SpaceX vehicles around there?
It's in both Bing and Google Maps:
edit: I don't mean that this is where it's being built, but maybe it's where they took them to line them up. It could just be a storage space though.
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Here's the same pier image at Conrad Shipyards I posted above, with a box of the quoted dimensions of the barge (300' x 170') super-imposed. Pretty nice fit.
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Comparison between imagery at Google maps and Bing (both dated (C) 2014, don't know if this indicates capture date?) shows the construction of piers at Conrad Shipyards LLC - the Bing imagery seems more recent
Something I learned about the image dates, at least within Google Earth - When you're zoomed out it'll say (C) 2014, but as you zoom in to the point that (presumably) you're looking at a single image, not a compositing of multiple images you'll still see the (C) 2014, but below it in the margin bar will appear something like "Image date 2/27/2014". That's the good info you want. I think we'll want images since March. Much more recent than March.
EDIT / ADD-
Perhaps we need to get someone in a cessna with a decent camera to take a flight over Morgan City. I'm in for $50, who else? $300 should be enough to get it done commercially even if we don't have a volunteer on this board. Here's a service a few miles away that we could use: http://perryflyingcenter.com/
Another thought on this though not that helpful. We're looking for the shipyard that's running three shifts, look for massive illumination and stirring about in the middle of the night. Its the Spacex way.
I don't dispute the Spacex trucks but I don't understand why they'd be needing trucks and I don't understand even why Spacex owns (vs. rents) trucks. That is a gift to us. I would have been looking for rental cars from the airport, which is to be saying that I wouldn't have been looking for Spacex vehicles.
Mark
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Interesting to note that Conrad is very roughly midway between Brownsville and The Cape.
edit: assuming like Jim said it's used for more than 2 launches.
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At some point they will need a barge to transport BFR stages. I image it will be covered like NASA's but a cover could be added and 300ft is a good length. Just saying.
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From the now scantier thread "SpaceX Falcon 9 v1.1 - Dragon - CRS-4/SpX-4 - Sept 20, 2014 - DISCUSSION"
as might be relevant to the discussion; cscott is asking for a link
There is video shot by an observer of a light in the distance near the surface of the ocean where the first stage was expected to be . The light translated a significant number of degrees before going out.
IMO they did a "How far can we move to one side" test near the surface, a la the last original grasshopper test.
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Conrad Shipyards ...I posted above, with a box of the quoted dimensions of the barge (300' x 170') super-imposed. Pretty nice fit.
Evidence is strangling closer to your Conrad Shipyards conclusion for sure but I've convinced myself that the space between the piers is not necessarily the space. Notice that the upper "pier" isn't a pier, but rather a drydock. You can see its depth by the shadow cast by the top of the wall on the much deeper floor. Compare that shadow with the shadowing on the pier at the bottom of the space.
First, there are suggestions (but not evidence) in other corners of the internets that Conrad Shipbuilding in Morgan City is doing the deed.
Second, and this is may be something new that I've pieced together (though certainly not un-obvious to those in the know) is that NASA has just in the last few days had their Pegasus barge delivered to Conrad Shipbuilding in Morgan City (or the Conrad Shipbuilding yard in Amelia, (a bike ride away) depending on who's version is right) so that it can be lengthened to *310 feet* to enable it to haul SLS cores from Michoud to Stennis and Florida. The Pegasus is a dumb un-engined barge with a quanset hut on top so I don't think its THE platform but it shows that Conrad is the source for NASA's work and we know SpaceX gets advice from NASA. It may be a bit conflictical that they'd be working on two 300' barges at once but they do have two quite large shipyards there so it wouldn't be much of a stretch.
http://www.nasaspaceflight.com/2014/07/pegasus-barge-renovations-sls-core-shipping/
http://www.nasa.gov/sls/anchors-aweigh-on-modifications-to-pegasus-barge.html#.VFVpOvnF-sk
http://www.nasa.gov/centers/marshall/news/news/releases/2014/14-081.html#.VFVo9fnF-sk
The naval architecture firm doing NASA's barge: http://bristolharborgroup.com/vessels/barges Perhaps snooping on this angle may give some information.
Conrad Shipbuilding's facility in Amelia La is known as their "deepwater" operation. As I said in a previous post, we should be looking at candidate facilities with the deep draft to handle a SWATH platform. http://www.conradindustries.com/facilities/deepwater.php
And its the source of the picture we've been seeing lately: http://www.banner-tribune.com/business/conrad-shipyard-delivers-first-barge-new-amelia-facility Was this picture originally put out by SpaceX? If so this is mega-confirmatory.
And Conrad's Morgan City operation: http://www.conradindustries.com/facilities/morgan-city.php
Keep in mind that these two facilities are so close together that its feasible that SpaceX's folks would stay in a Morgan City hotel as observed.
Not much in the local newspaper: http://www.banner-tribune.com/
Like I said before, we need to get a cessna and a camera up. Who's going to pitch some money in to make it happen, on top of my $50? ...Or we at least need to get some shots from a fishing boat going down the river. But let's now be aware that there is another 300 foot barge in the suspect area that isn't our target platform.
Mark
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but it shows that Conrad is the source for NASA's work and we know SpaceX gets advice from NASA.
Not quite true, especially on things like this. Spacex does its own thing when it comes to support equipment.
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How long would it take to construct or modify a barge for this though? Surely not in time for the December attempt?
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How long would it take to construct or modify a barge for this though?
Two months could be enough, heavily depending on design (still unknown).
Surely not in time for the December attempt?
Why? Maybe SpaceX started the thing in august...
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Gwynne Shotwell mentioned the upcoming "solid surface" landing attempt back in July, so this barge has likely been in work for quite some time.
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What's the weather usually like there in December? Is it realistic to expect sea conditions to be good enough (the North Sea near here would be a definite no!)
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What's the weather usually like there in December? Is it realistic to expect sea conditions to be good enough (the North Sea near here would be a definite no!)
Maybe the barge could be placed leeward of some island...
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What's the weather usually like there in December? Is it realistic to expect sea conditions to be good enough (the North Sea near here would be a definite no!)
Maybe the barge could be placed leeward of some island...
I don't think that there's any convenient islands for that. In many cases, you are better out at sea and in deep water. It's when sea, wind and bottom come into conflict that things get sharp (outside of storm conditions). At any rate, I'm sure somebody at SpaceX has thought this through and we will just have to see!
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New FCC application shows where SpaceX is planning to put the barge.
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=62792
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Nice find. This appears to place it a few hundred miles off shore, farther than I would have expected:
North 30 49 54 West 78 6 29 BARGE, within 20 nautical miles 38.00
https://www.google.com/maps/place/30%C2%B049'54.0%22N+78%C2%B006'29.0%22W/@31.0522115,-78.9527224,9z
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New FCC application shows where SpaceX is planning to put the barge.
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=62792
Here, then?
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Just wait, they'll have to scrub because there's a flotilla of gawkers that shows up...
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Darga updated his hazard map (https://mapsengine.google.com/map/viewer?mid=zp15b_P5ERVk.krdQml9d0HR0) from the CRS-4 launch to also show the position of the boat. It's the blue boat icon. So it looks like they'll be attempting to boost back about a third the distance to the Cape.
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Darga updated his hazard map (https://mapsengine.google.com/map/viewer?mid=zp15b_P5ERVk.krdQml9d0HR0) from the CRS-4 launch to also show the position of the boat. It's the blue boat icon. So it looks like they'll be attempting to boost back about a third the distance to the Cape.
Thank God! It's not in the Bermuda Triangle...
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The FAA doc identifies that 4 Quasonix transmitters with be used on the barge (model QSX-VSR-110-20S).
I took a quick look at the Quasonix web page (http://www.quasonix.com/home),
found this product catalog (http://www.quasonix.com/sites/default/files/qsx_product_catalog_0.pdf),
but did not quickly locate exactly which transmitter is the VSR 110 20S.
Would it be a good bet to think that the barge would be transmitting it's GPS coordinates and orientation up to the returning booster? What other info might be useful to the returning booster?
What else do others think this might be used for? Barge to shore? Barge-to-ship (e.g., Coast Guard, service tug, or supply ship)? Barge-to-aircraft for location reference to capture better air-to-rocket video next time at the final landing?
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Couldn't they simply be hazard warning transmitters? You don't want other ships ramming the barge at night or in a fog...
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Or else SpaceX wants the position of the barge clearly identified to show the precision of landing.
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1. Would it be a good bet to think that the barge would be transmitting it's GPS coordinates and orientation up to the returning booster? What other info might be useful to the returning booster?
2. What else do others think this might be used for? Barge to shore? Barge-to-ship (e.g., Coast Guard, service tug, or supply ship)? Barge-to-aircraft for location reference to capture better air-to-rocket video next time at the final landing?
1. No, the booster is autonomous
2. "transmitting it's GPS coordinates and orientation" to the LCC for prelaunch updates to load into the guidance system. And just to keep track of the barge.
My take.
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1. Would it be a good bet to think that the barge would be transmitting it's GPS coordinates and orientation up to the returning booster? What other info might be useful to the returning booster?
2. What else do others think this might be used for? Barge to shore? Barge-to-ship (e.g., Coast Guard, service tug, or supply ship)? Barge-to-aircraft for location reference to capture better air-to-rocket video next time at the final landing?
1. No, the booster is autonomous
2. "transmitting it's GPS coordinates and orientation" to the LCC for prelaunch updates to load into the guidance system. And just to keep track of the barge.
My take.
Thanks, Jim. I quite agree that the returning booster is autonomous.
My question deals more with do we think the booster is just returning to a a fixed GPS lat/long, and trusting that the barge will "be there" because it was at the time the coordinates were set prelaunch?
Or does the barge potentially transmit long/lat (or GPS coordinates) along with six-parameter orientation and movement info, so that the rocket has, near-real-time or real-time, data to use in calculating its final control solution relative to the constrained landing surface?
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Or does the barge potentially transmit long/lat (or GPS coordinates) along with six-parameter orientation and movement info, so that the rocket has, near-real-time or real-time, data to use in calculating its final control solution relative to the constrained landing surface?
Daft question, but does the stage have the ability to receive anything other than a destruct signal from the range? If barge landing were a long term solution, then yes, you may need to know where the barge really is as you come back down, but presumably for RTLS, the aiming point is fixed, so no GPS co-ordinates of the landing site required.
Paul
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Or does the barge potentially transmit long/lat (or GPS coordinates) along with six-parameter orientation and movement info, so that the rocket has, near-real-time or real-time, data to use in calculating its final control solution relative to the constrained landing surface?
I thought I read that the Iranians GPS Spoofed one of the US military UAV aircraft to lie to it about where it was so they could force it to land, and capture the vehicle. What would stop an unscrupulous competitor or foreign agency from doing the same thing to this barge and making it think it was in one location when it wasn't, making the landings fail? Paranoid delusions maybe?
Maybe there is a back-up inertial sensing of location, or radio beacon triangulation to cross reference for the barge location in addition to GPS.
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1. No, the booster is autonomous
2. "transmitting it's GPS coordinates and orientation" to the LCC for prelaunch updates to load into the guidance system. And just to keep track of the barge.
My take.
It looks to me that the booster will be getting live updates during flight, but I may be reading it wrong. From the application:
Similar launch vehicle RF configuration as preceding SpX-4 mission, see STA grant no. 1156-EX-ST-2013, except this mission adds two frequencies for the sub-orbital first-stage (uplink only).
Comparing to 1156-EX-ST-2013 here: https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=58852
The two new frequencies are 2090 Mz and 2093 MHz. 2090 MHz will be transmitted from a 48m tower at the cape, boat and barge. 2093 MHz will be transmitted from barge only.
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Thanks, Jim. I quite agree that the returning booster is autonomous.
My question deals more with do we think the booster is just returning to a a fixed GPS lat/long, and trusting that the barge will "be there" because it was at the time the coordinates were set prelaunch?
Or does the barge potentially transmit long/lat (or GPS coordinates) along with six-parameter orientation and movement info, so that the rocket has, near-real-time or real-time, data to use in calculating its final control solution relative to the constrained landing surface?
I don't think there's enough information in the FCC docs to tell. The hints that are there are ambiguous:
* There are two new launch vehicle frequencies for this launch (compared to CRS-4) and they are listed as "uplink only" and on the "suborbital first stage" in the Explanation section.
* There are only four transmitters listed, one for each launch site, even though a larger number of different frequencies are given. It's not clear if the transmitter frequency-hops, or if it can broadcast simultaneously on multiple frequencies.
* The ground stations only transmit on a single frequency, although the barge transmits on two. All ground stations share a single emission designator. The suborbital first stage broadcasts on two different frequencies (again, this is apparently new for this flight) with a single emission designator, and the second stage broadcasts on three different frequencies with 4 different emission designators, one of which is shared with the first stage.
* The licensing is only for transmitters, it doesn't say anything about what *receivers* are aboard each station.
Here comes the *SPECULATION*:
* Multiple frequencies on the flying stages are used to communicate with different preexisting ground stations. The single transmitter frequency hops as it moves from ground station to ground station.
* Previously all telemetry was sent by a transmitter located on the second stage, but this flight adds a high power transmitter on the first stage as well. It shares an emission designator with the second stage, so presumably the content isn't new, just the location of the transmitter. This doesn't seem consistent with the "uplink only" statement about the first stage transmitter, if you assume the usual "earth terminal to satellite" definition for uplink. But in cell phone networks uplink means "mobille station to base station", which matches up better.
* We know that there was telemetry from the first stage on earlier flights, but this application seems to imply there was no first-stage transmitter on CRS-4. We haven't seen post-separation rocketcam footage from CRS-4, so that's *possible*. Perhaps the first-stage transmitter is part of the "legs package"? (Note that saliva_sweet found that CRS-3 seemed to have a first-stage transmitter, see below.) Perhaps there was a first stage transmitter on CRS-4 but it was low power and thus didn't require an FCC license. If some launches had only a low-power transmitter it would explain the poor quality of the video recovered and the pie-plate antenna, etc. Still seems strange to me!
* All ground stations share the same frequency and emission designator (with one exception, see below). I'm guessing this means that this frequency is *not* used for anything barge-specific, it's just general "launch control" capability. It's only a 1-W transmitter (with one exception), though. Can't be anything too critical, then; this might just be a voice net?
* The boat has a 61W transmitter at the ground station frequency, much higher than the other 1W ground stations. Perhaps this is for relaying voice transmissions from the boat to shore (although it doesn't seem possible for shore->to->boat communication on this frequency)?
* The barge has an additional frequency not used by the other ground stations. It's another 1W transmitter, though. This seems too weak to allow reliable transmission to the rocket. Perhaps this is just a separate barge->to->boat voice net.
* The only way a Bezos-patent-infringing communication from the barge to the rocket would be possible would be for it to be relayed from barge to boat to rocket. The boat is the only site which has sufficient power to reach the rocket at a meaningful distance. Perhaps this is done so that a large antenna isn't necessary on the otherwise-flat barge? There would be added latency, but presumably this is very small compared to the barge movement frequency.
* It's tempting to say the new first stage transmitter is part of a FTS capability, so that the first stage has an autonomous FTS in case the barge or boat is endangered. That would match the "uplink only" qualification better, but it's hard for me how to understand how a new *transmitter* on the rocket is required for an "uplink" to the rocket.
It looks to me that the booster will be getting live updates during flight, but I may be reading it wrong. From the application:
Similar launch vehicle RF configuration as preceding SpX-4 mission, see STA grant no. 1156-EX-ST-2013, except this mission adds two frequencies for the sub-orbital first-stage (uplink only).
Comparing to 1156-EX-ST-2013 here: https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=58852
The two new frequencies are 2090 Mz and 2093 MHz. 2090 MHz will be transmitted from a 48m tower at the cape, boat and barge. 2093 MHz will be transmitted from barge only.
You're comparing to SpX-3; the CRS-5 application is referencing SpX-4. I think the application is very clear that the two new frequencies are on the *launch vehicle*, but I could be reading this wrong.
EDIT: saliva_sweet set me straight, see below.
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New FCC application shows where SpaceX is planning to put the barge.
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=62792
Congratulations, you win the prize for finding the answer to the topic question! And it only took us 30 pages... ;)
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You're comparing to SpX-3; the CRS-5 application is referencing SpX-4. I think the application is very clear that the two new frequencies are on the *launch vehicle*, but I could be reading this wrong.
SpX-3 and SpX-4 are identical. By comparing them to SpX-5 it is clear that the transmitters on the two new frequencies are not on the rocket. The first stage has had two frequencies for downlink since SpX-3, this has not changed.
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My question deals more with do we think the booster is just returning to a a fixed GPS lat/long, and trusting that the barge will "be there" because it was at the time the coordinates were set prelaunch?
That's my guess. KISS. As long as the platform is given enough propulsion and a halfway decent guidance algorithm it should have no problem maintaining a preset GPS position.
Meanwhile, platform can be transmitting its actual position to LCC / recovery boat for verification. LCC can then verify correct barge position during countdown.
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You're comparing to SpX-3; the CRS-5 application is referencing SpX-4. I think the application is very clear that the two new frequencies are on the *launch vehicle*, but I could be reading this wrong.
SpX-3 and SpX-4 are identical. By comparing them to SpX-5 it is clear that the transmitters on the two new frequencies are not on the rocket. The first stage has had two frequencies for downlink since SpX-3, this has not changed.
Can you provide a reference on the FCC site? I don't know how to use the search function there.
SpX-4 didn't have legs. It was not identical to SpX-3. Presumably you've looked at the FCC application for SpX-4 and that's what you're talking about, but I'd like to see for myself.
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SpX-3: https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=58852
SpX-4: https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=61999
Here's a list: https://apps.fcc.gov/oetcf/els/reports/ELSSearchResult.cfm?callsign=WG9XHP
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I think they will use
Differential Global Positioning System (DGPS)
http://en.wikipedia.org/wiki/Differential_GPS (http://en.wikipedia.org/wiki/Differential_GPS)
http://www.armyrecognition.com/united_states_military_equipment_uk/
scaneagle_uas_uav_unmanned_aerial_vehicle_system_data_sheet_specifications_information_description.html
I have worked with the Scaneagle and it works quite well
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SpX-3: https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=58852
SpX-4: https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=61999
Here's a list: https://apps.fcc.gov/oetcf/els/reports/ELSSearchResult.cfm?callsign=WG9XHP
Thanks, saliva_sweet -- so it's clear that the two new frequencies correspond to the three new ground stations: one at the cape, one on the "boat" and one on the "barge". Every transmits at 2090 MHz, but only the "barge" can transmit at (frequency hop to?) 2093 MHz.
I think they will use
Differential Global Positioning System (DGPS)
http://en.wikipedia.org/wiki/Differential_GPS (http://en.wikipedia.org/wiki/Differential_GPS)
I don't think so -- for DGPS, the fixed station would have to be at the cape; you can't use the boat as the fixed point. But the cape only has 1W of transmit power, not enough to reach the rocket. The boat is the only transmitter that can reach the rocket at altitude.
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Or does the barge potentially transmit long/lat (or GPS coordinates) along with six-parameter orientation and movement info, so that the rocket has, near-real-time or real-time, data to use in calculating its final control solution relative to the constrained landing surface?
Daft question, but does the stage have the ability to receive anything other than a destruct signal from the range? If barge landing were a long term solution, then yes, you may need to know where the barge really is as you come back down, but presumably for RTLS, the aiming point is fixed, so no GPS co-ordinates of the landing site required.
Paul
The returning stage *could* do a lot, including landing at an angle, delay the landing a few seconds to synchronize with wave motion, use predictions of the future orientation of the barge, etc. etc. But I don't think it's worth the effort. I think the controller will land as if the barge were stationary and treat deviations as disturbances. On a day with moderate wind/waves.
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Or does the barge potentially transmit long/lat (or GPS coordinates) along with six-parameter orientation and movement info, so that the rocket has, near-real-time or real-time, data to use in calculating its final control solution relative to the constrained landing surface?
Daft question, but does the stage have the ability to receive anything other than a destruct signal from the range? If barge landing were a long term solution, then yes, you may need to know where the barge really is as you come back down, but presumably for RTLS, the aiming point is fixed, so no GPS co-ordinates of the landing site required.
Paul
And so by what source of knowledge do you know that SpaceX might not have a receiver on-board the returning rocket, one that could be a part of the many items of test equipment and additional technologies SpaceX has needed to place on-board as part of their engineering effort to support the reusable technology development program? ???
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I thought I read that the Iranians GPS Spoofed one of the US military UAV aircraft to lie to it about where it was so they could force it to land, and capture the vehicle. What would stop an unscrupulous competitor or foreign agency from doing the same thing to this barge and making it think it was in one location when it wasn't, making the landings fail? Paranoid delusions maybe?
Maybe there is a back-up inertial sensing of location, or radio beacon triangulation to cross reference for the barge location in addition to GPS.
You DID read that, but the Iranians lied when a drone malfunctioned and crashed in their terriritory. Spoofing GPS requires ANOTHER GPS system, for military applications that would be one in orbit not based on the mobile phone system (which is the majority of "civilian" GPS systems and why they can be so inaccurate) and capable of "riding-over" the main GPS signals with the exact same incryption, frequency, and information.
In order to do what your suggesting the "bad guys" would have to override the active communications with the barge AND be able to interface with the booster software at which point they could make it do whatever they wanted one would assume. In any case it would NOT be subtle or easy and would in fact be pretty easy to trace and SpaceX would always have the ability to send the destruct command :)
Randy
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Is there any possibility that this stage will be equipped with the grid fins ("falcon feathers") that were seen on the F9R-dev 1? I don't remember seeing them on pictures of any stages being tested in McGreggor but I'm not sure whether they would be evident at that point in the flow or not. Maybe their absence explains Elon's lukewarm confidence ("50%") in the success of the first landing attempt? Though they're probably still unsure exactly how difficult this test will be, so maybe it was just a slight break check on the surrounding hoopla, managing expectations, etc.
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Is there any possibility that this stage will be equipped with the grid fins ("falcon feathers") that were seen on the F9R-dev 1? I don't remember seeing them on pictures of any stages being tested in McGreggor but I'm not sure whether they would be evident at that point in the flow or not. Maybe their absence explains Elon's lukewarm confidence ("50%") in the success of the first landing attempt? Though they're probably still unsure exactly how difficult this test will be, so maybe it was just a slight break check on the surrounding hoopla, managing expectations, etc.
I have no idea, but I had to place a bet:
* Large amount of time since last flight means that there is sufficient time to mount the feathers (remember CRS-4 was so pressed for time it couldn't even get legs). So, probably.
* F9R-dev1 failure means that there haven't been additional flight tests of the feathers. So, probably not.
* Landing on a tiny barge means feathers are required. So, probably. But chance of success is only 50% because no feathers? So, probably not.
* Orbital failure means CRS-5 payload will probably be maxxed out. So, probably not. But CRS flights are usually volume-limited, not mass-limited. So, probably.
I think I'd bet on "yes, there will be feathers". But it's certainly not a sure thing.
Feathers are on the interstage, BTW, so you wouldn't see them at MacGregor.
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If they have the barge out there they will have the grid fins. Without them the chance of hitting the target would be very slim. 50% is because of lack of experience with steering by grid fins. They will gather the data for success in the next flight.
Also at the first flight, Cassiope, they played their chances for successful landing down. They are doing the same this time.
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If they have the barge out there they will have the grid fins. Without them the chance of hitting the target would be very slim. 50% is because of lack of experience with steering by grid fins. They will gather the data for success in the next flight.
Also at the first flight, Cassiope, they played their chances for successful landing down. They are doing the same this time.
I'm not convinced that the grid fins are about achieving "pinpoint accuracy" on the landing. They could be about reducing the fuel costs, and therefore weight penalty, for RTLS. e.g. Improving cross- and down-range performance of the stage in flight compared to only-RCS. I'm sure that they will improve terminal accuracy, but that may be a "bonus". As such, I'm not convinced that they are absolutely required to achieve success on these landing tests.
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Or does the barge potentially transmit long/lat (or GPS coordinates) along with six-parameter orientation and movement info, so that the rocket has, near-real-time or real-time, data to use in calculating its final control solution relative to the constrained landing surface?
Daft question, but does the stage have the ability to receive anything other than a destruct signal from the range? If barge landing were a long term solution, then yes, you may need to know where the barge really is as you come back down, but presumably for RTLS, the aiming point is fixed, so no GPS co-ordinates of the landing site required.
Paul
And so by what source of knowledge do you know that SpaceX might not have a receiver on-board the returning rocket, one that could be a part of the many items of test equipment and additional technologies SpaceX has needed to place on-board as part of their engineering effort to support the reusable technology development program? ???
Llian,
I have no source of knowledge on this whatsoever - that is why I started with the statement 'daft question' - I was asking whether the stage has the ability to receive data. Does a honest question deserve that kind of response?
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1. Would it be a good bet to think that the barge would be transmitting it's GPS coordinates and orientation up to the returning booster? What other info might be useful to the returning booster?
2. What else do others think this might be used for? Barge to shore? Barge-to-ship (e.g., Coast Guard, service tug, or supply ship)? Barge-to-aircraft for location reference to capture better air-to-rocket video next time at the final landing?
1. No, the booster is autonomous
2. "transmitting it's GPS coordinates and orientation" to the LCC for prelaunch updates to load into the guidance system. And just to keep track of the barge.
My take.
It wouldn't be a good bet to think barge will comm to the rocket. This is one issue that SpaceX wanted to avoid when setting it up. It appears to be covered by Bezos "patent" filing. Instead, the barge will be prepositioned to a certain location and it'll try to keep at that point by using its own means. So, it is going to be a fix, given landing spot.
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I think they will use
Differential Global Positioning System (DGPS)
http://en.wikipedia.org/wiki/Differential_GPS (http://en.wikipedia.org/wiki/Differential_GPS)
I don't think so -- for DGPS, the fixed station would have to be at the cape; you can't use the boat as the fixed point. But the cape only has 1W of transmit power, not enough to reach the rocket. The boat is the only transmitter that can reach the rocket at altitude.
[/quote]
Sure they could...The ScanEagle operates from ships all the time they catch a cable to land and it is done with Differential GPS
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With video shooting on Elon, it will be cool if he spray a big red "X" mark the spot on the landing barge just like Babe Ruth w/ his bat pointing at the center field where he did hit his home run at during the 1932 World Series. :o
http://en.wikipedia.org/wiki/Babe_Ruth's_called_shot
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I guess SpaceX has been working on this barge for quite a long time.
Doesn't know what the timeframe for the development of this barge would be. From concept to design then final construction.
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With video shooting on Elon, it will be cool if he spray a big red "X" mark the spot on the landing barge just like Babe Ruth w/ his bat pointing at the center field where he did hit his home run at during the 1932 World Series. :o
http://en.wikipedia.org/wiki/Babe_Ruth's_called_shot
It will be for us audience only, to show the accuracy.
The machine won't see the red cross.
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I think they will use
Differential Global Positioning System (DGPS)
http://en.wikipedia.org/wiki/Differential_GPS (http://en.wikipedia.org/wiki/Differential_GPS)
I don't think so -- for DGPS, the fixed station would have to be at the cape; you can't use the boat as the fixed point. But the cape only has 1W of transmit power, not enough to reach the rocket. The boat is the only transmitter that can reach the rocket at altitude.
Sure they could...The ScanEagle operates from ships all the time they catch a cable to land and it is done with Differential GPS
[/quote]
I think you both mean something different by dgps : using a ground station to achieve absolute accuracy in position or using the gps position of another platform to achieve relative accuracy. SpaceX only needs the latter. In this case gps is its own coordinate system.
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If they have the barge out there they will have the grid fins. Without them the chance of hitting the target would be very slim. 50% is because of lack of experience with steering by grid fins. They will gather the data for success in the next flight.
Also at the first flight, Cassiope, they played their chances for successful landing down. They are doing the same this time.
I'm not convinced that the grid fins are about achieving "pinpoint accuracy" on the landing. They could be about reducing the fuel costs, and therefore weight penalty, for RTLS. e.g. Improving cross- and down-range performance of the stage in flight compared to only-RCS. I'm sure that they will improve terminal accuracy, but that may be a "bonus". As such, I'm not convinced that they are absolutely required to achieve success on these landing tests.
Improving cross range by definition improves landing accuracy. This is simply because the difficulty in hitting the barge will not be maneuvering the stage once it is close, it will be in trying to get close to the barge by killing your re-entry burn at exactly the right millisecond and using the rcs to maybe airfoil the stage a bit. It's a Very Hard Problem.
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I think they will use
Differential Global Positioning System (DGPS)
http://en.wikipedia.org/wiki/Differential_GPS (http://en.wikipedia.org/wiki/Differential_GPS)
I don't think so -- for DGPS, the fixed station would have to be at the cape; you can't use the boat as the fixed point. But the cape only has 1W of transmit power, not enough to reach the rocket. The boat is the only transmitter that can reach the rocket at altitude.
Sure they could...The ScanEagle operates from ships all the time they catch a cable to land and it is done with Differential GPS
I think you both mean something different by dgps : using a ground station to achieve absolute accuracy in position or using the gps position of another platform to achieve relative accuracy. SpaceX only needs the latter. In this case gps is its own coordinate system.
The latter infringes bezos' patent; the former does not.
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With video shooting on Elon, it will be cool if he spray a big red "X" mark the spot on the landing barge just like Babe Ruth w/ his bat pointing at the center field where he did hit his home run at during the 1932 World Series. :o
http://en.wikipedia.org/wiki/Babe_Ruth's_called_shot
It will be for us audience only, to show the accuracy.
The machine won't see the red cross.
I hope it's an image of a trampoline.... :)
If they have the barge out there they will have the grid fins. Without them the chance of hitting the target would be very slim. 50% is because of lack of experience with steering by grid fins. They will gather the data for success in the next flight.
Also at the first flight, Cassiope, they played their chances for successful landing down. They are doing the same this time.
You mean you "suppose the chance of hitting the target would be very slim." :)
We have no information (other than YouTube videos) of how accurate their landings are without the grid fins. Those ocean landings could have been right on the money for all we know.
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How is the Rocket going to land on these legs? They have those round dots right where they will touch the ground. Should they be flat on that point?
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How is the Rocket going to land on these legs? They have those round dots right where they will touch the ground. Should they be flat on that point?
The pads on the leg tips are actually fairly flat. You can see that better in this photo.
(http://d1jqu7g1y74ds1.cloudfront.net/wp-content/uploads/2014/02/BhM-H_4CUAAWcP0.jpg)
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50% is because of lack of experience with steering by grid fins.
I personally think that this is an example of "expectation management" on Elon's part. I would not be surprised if SpaceX's internal estimates of the probability of success are significantly higher than 50%, but just in case it does fail, better to not have people thinking that this was a totally unexpected event.
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I think they will use
Differential Global Positioning System (DGPS)
http://en.wikipedia.org/wiki/Differential_GPS (http://en.wikipedia.org/wiki/Differential_GPS)
I don't think so -- for DGPS, the fixed station would have to be at the cape; you can't use the boat as the fixed point. But the cape only has 1W of transmit power, not enough to reach the rocket. The boat is the only transmitter that can reach the rocket at altitude.
Sure they could...The ScanEagle operates from ships all the time they catch a cable to land and it is done with Differential GPS
I think you both mean something different by dgps : using a ground station to achieve absolute accuracy in position or using the gps position of another platform to achieve relative accuracy. SpaceX only needs the latter. In this case gps is its own coordinate system.
The latter infringes bezos' patent; the former does not.
Both could infringe. You can infringe on a patent without copying EVERYTHING in it.
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50% is because of lack of experience with steering by grid fins.
I personally think that this is an example of "expectation management" on Elon's part. I would not be surprised if SpaceX's internal estimates of the probability of success are significantly higher than 50%, but just in case it does fail, better to not have people thinking that this was a totally unexpected event.
I doubt it's expectations management. Stuff like this is hard; Elon knows it because he's been trying to get a stage back intact since 2006 and has failed every time he tried (although Grasshopper and F9dev1 were successful).
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I think they will use
Differential Global Positioning System (DGPS)
http://en.wikipedia.org/wiki/Differential_GPS (http://en.wikipedia.org/wiki/Differential_GPS)
I don't think so -- for DGPS, the fixed station would have to be at the cape; you can't use the boat as the fixed point. But the cape only has 1W of transmit power, not enough to reach the rocket. The boat is the only transmitter that can reach the rocket at altitude.
Sure they could...The ScanEagle operates from ships all the time they catch a cable to land and it is done with Differential GPS
I think you both mean something different by dgps : using a ground station to achieve absolute accuracy in position or using the gps position of another platform to achieve relative accuracy. SpaceX only needs the latter. In this case gps is its own coordinate system.
The latter infringes bezos' patent; the former does not.
Both could infringe. You can infringe on a patent without copying EVERYTHING in it.
Or, the whole patent could be bogus.
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I don't think SpaceX will need any kind of differential-GPS or barge->stage communication. Speculation follows:
They plan to RTLS, long term, and launch sites don't move much.
The barge will be equipped with engines and systems to autonomously keep itself in a fixed position - based on GPS receivers on the barge itself.
The exact GPS coordinates will be selected well before launch.
The first stage will attempt to return to those exact GPS coordinates.
It doesn't matter if there is GPS drift, because GPS drift affects all receivers in a nearby area in the same way.
Therefore, the first stage will be attempting to return to the same position as the barge is attempting to maintain, within a few meters. Excitement will ensue, one way or another.
It's certainly hard because GPS is less accurate on rapidly moving receivers, but
This is fairly well supported by the MIT interview:
it's huge, huge-ish, it's about 300 feet long by 170 feet wide. That looks very tiny from space, and the leg span of the rocket is 60 feet, and this is going to be positioning itself out in the ocean with engines that will try to keep it in a particular position - but it's tricky, you've got to deal with these big rollers and GPS errors. It's not anchored, because it's out in the Atlantic. But we're going to try to land on that on the next flight
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I don't think SpaceX will need any kind of differential-GPS or barge->stage communication.
They may not need it, but the FCC application indicates there is a new ground-to-rocket uplink for CRS-5. They question is: what is it for?
The low power of all the transmitters except those on the chase boat is interesting.
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I don't think SpaceX will need any kind of differential-GPS or barge->stage communication.
They may not need it, but the FCC application indicates there is a new ground-to-rocket uplink for CRS-5. They question is: what is it for?
It may not be DGPS, but that uplink will be for dynamic sharing of position information for sure.
Think of it as "Relative GPS": "A little more to the right.. that's it!.. no, back the other way.. OOPS!!" ;)
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http://en.wikipedia.org/wiki/Boeing_Insitu_ScanEagle (http://en.wikipedia.org/wiki/Boeing_Insitu_ScanEagle)
"It is recovered using the "Skyhook" retrieval system, which uses a hook on the end of the wingtip to catch a rope hanging from a 30-to-50-foot (9.1 to 15.2 m) pole. This is made possible by high-quality differential GPS units mounted on the top of the pole and UAV. The rope is attached to a shock cord to reduce stress on the airframe imposed by the abrupt stop."
It catches this rope on a wing section about 4 1/2 foot long on a ship bobbing in the ocean
It uses standard GPS until it gets close then switches over, just acting upon a different signal, very passive.
It is also common off the shelf technology.
http://www.trimble.com/gps_tutorial/dgps.aspx (http://www.trimble.com/gps_tutorial/dgps.aspx)
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It uses standard GPS until it gets close then switches over, just acting upon a different signal, very passive.
It is also common off the shelf technology.
http://www.trimble.com/gps_tutorial/dgps.aspx (http://www.trimble.com/gps_tutorial/dgps.aspx)
I tried to do a bit of websearch to figure out what the range of a 1W transmitter is (the power of the barge and cape transmitters) and the range of a 20W 61W transmitter (the one on the chase boat).
From the US Coast Guard site, we have DGPS signal strengths (http://www.navcen.uscg.gov/?pageName=dgpsSiteInfo&All) stated in the form "100uV at 370KM". Do we have a radio person here who can reference that to a transmitter strength in watts?
I'm just trying to figure out whether a 1W transmitter is powerful enough to be received by the rocket at a reasonable range, or if the three 1W transmitters are just for talking among the barge, boat, and cape.
EDIT: fixed the chase boat transmitter power. Thanks, Kabloona.
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The barge and boat transmitters are listed as "modified 2090 MHz." Don't know what "modified" means, but 2090 MHz is in UHF range, very close to the 2100 MHz used by several cell phones carriers for 3G/4G.
One watt transmitting at this freq should behave much like a 3G/4G cell phone. So figure a couple miles range using a small omni antenna for reception. Higher gain directional antenna would increase range.
By the way, the chase boat radio power is listed at 61 watts, not 20 watts as you said above.
"Modified 2090.00000000- MHz MO N/A 61.000000 W P 800KG1D "
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The barge and boat transmitters are listed as "modified 2090 MHz." Don't know what "modified" means, but 2090 MHz is in UHF range, very close to the 2100 MHz used by several cell phones carriers for 3G/4G.
One watt transmitting at this freq should behave much like a 3G/4G cell phone. So figure a couple miles range using a small omni antenna for reception. Higher gain directional antenna would increase range.
By the way, the chase boat radio power is listed at 61 watts, not 20 watts as you said above.
"Modified 2090.00000000- MHz MO N/A 61.000000 W P 800KG1D "
Right you are, I was misremembering. Thanks, I've fixed this in my post above.
But yeah, the point is that the shore transmitter most likely can't reach the boat, the barge, or the rocket after staging, and the barge transmitter probably can't reach the rocket at a significant range. So the only robust transmission here is from the chase boat to the rocket.
I can imagine that the barge can reach the chase boat fine. Perhaps signals will be relayed.
But I can't really understand the purpose of the transmitter at the cape at all, unless it's just for prelaunch testing.
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But I can't really understand the purpose of the transmitter at the cape at all, unless it's just for prelaunch testing.
That's a strange one. A small clue...coordinates for the 1W Cape transmitter are:
N 28 33 0
W 80 34 0
Which puts the antenna tower (48 meters high!) right beside Cape Road, just southeast of LC40.
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So the only robust transmission here is from the chase boat to the rocket.
You mean chase boat to barge and not rocket?
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So the only robust transmission here is from the chase boat to the rocket.
You mean chase boat to barge and not rocket?
Why does chase boat need 61W to transmit to barge, when barge has only 1W to transmit to chase boat? Implying short range comms.
And I don't really see the point of a 61W transmission to the rocket, either. That's a huge range. You've already pre-programmed the landing GPS coordinates into the rocket. Why do you need to uplink more data from 50 miles away? The barge has already been verified in correct position just before launch.
Seems to me the 61W is most likely ship-to-shore. OTOH, no similar transmitter is listed on shore.
And Jim, maybe you can comment on that planned 1W antenna location on Cape Road southeast of LC40. Purpose?
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Why does chase boat need 61W to transmit to barge, when barge has only 1W to transmit to chase boat? Implying short range comms.
It's controlling the barge while it is unmanned and wants to make sure there is no inference?
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Why does chase boat need 61W to transmit to barge, when barge has only 1W to transmit to chase boat? Implying short range comms.
It's controlling the barge while it is unmanned and wants to make sure there is no inference?
Maybe that's their jam-proof radio in case a Russian fishing trawler stops by... ;)
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61 W can get you a long long way, especially when communicating over ocean, and even more so if the thing you're communicating with is in the sky (full line of sight). In high altitude ballooning, as little as 10 mW is enough to reach repeaters hundreds of miles away.
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Chase boat to shore is a good idea -- this would be plenty of power to relay real-time video of the stage descending, for instance. That would be very cool! (/me wishes)
But my intuition says the only reason for 61W of power is to reach the rocket. Yes, this is overkill if you just need terminal guidance, but it would ensure a stable link from staging to landing, eliminating a possible mode change in the guidance program when the signal is acquired near the ground. Bitrate at 2090 MHz is probably also overkill for DGPS signals, FWIW.
WRT to the 'modified' designator -- I think that just refers to which of these transmitters are "new installations". If you notice, the transmitters on the launch vehicle and the barge are all listed as "new". The ground station and the chase boat are "modified" -- these are transmitters which are reasonably supposed to be preexisting, or at least mentioned in a previous license.
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But my intuition says the only reason for 61W of power is to reach the rocket. Yes, this is overkill if you just need terminal guidance, but it would ensure a stable link from staging to landing, eliminating a possible mode change in the guidance program when the signal is acquired near the ground. Bitrate at 2090 MHz is probably also overkill for DGPS signals, FWIW.
Entirely possible, but if you were transmitting for terminal guidance, you'd do it right from the barge, not from the chase boat several miles away, I would think.
WRT to the 'modified' designator -- I think that just refers to which of these transmitters are "new installations". If you notice, the transmitters on the launch vehicle and the barge are all listed as "new". The ground station and the chase boat are "modified" -- these are transmitters which are reasonably supposed to be preexisting, or at least mentioned in a previous license.
Aha, thanks.
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Why does chase boat need 61W to transmit to barge, when barge has only 1W to transmit to chase boat? Implying short range comms.
It's controlling the barge while it is unmanned and wants to make sure there is no inference?
Yes - shout your commands. Telemetry back doesn't need so much.
But my intuition says the only reason for 61W of power is to reach the rocket. Yes, this is overkill if you just need terminal guidance, but it would ensure a stable link from staging to landing, eliminating a possible mode change in the guidance program when the signal is acquired near the ground. Bitrate at 2090 MHz is probably also overkill for DGPS signals, FWIW.
Entirely possible, but if you were transmitting for terminal guidance, you'd do it right from the barge, not from the chase boat several miles away, I would think.
Unless you have a radar on the chase boat, and fine adjust the barge position centered under incoming vehicle's idea of GPS coordinates so that you arrive on center ... you also then have autonomous control with manual override of the pad position instead of messing with vehicle guidance ...
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61 W can get you a long long way, especially when communicating over ocean, and even more so if the thing you're communicating with is in the sky (full line of sight). In high altitude ballooning, as little as 10 mW is enough to reach repeaters hundreds of miles away.
I've bounced a packet data signal off of the ISS HAM radio relay with only 5W of power using a directional antenna on VHF (144MHz). If you have line of sight a little power can go a long ways.
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But my intuition says the only reason for 61W of power is to reach the rocket. Yes, this is overkill if you just need terminal guidance, but it would ensure a stable link from staging to landing, eliminating a possible mode change in the guidance program when the signal is acquired near the ground. Bitrate at 2090 MHz is probably also overkill for DGPS signals, FWIW.
Entirely possible, but if you were transmitting for terminal guidance, you'd do it right from the barge, not from the chase boat several miles away, I would think.
My thought -- and this is pure speculation, of course -- is that putting the high-power transmitter on the boat lets you have more flat surface area on the barge. The 1W antenna is presumably less of a landing hazard. The other aspect is that the chase boat transmitter is "modified" -- and I'm assuming that means 'preexisting'. So it's possible you've got a big huge TX/antenna on the boat already which is way overkill but you might as well use it because it's already there and has been tested and will work. (Note that the FCC license doesn't say anything about the antenna configuration on the boat. So maybe it's not *so* huge?)
So that's option 1. But I'm actually not that thrilled with the idea of transmitting ground-to-air guidance information -- that seems like it's unnecessarily begging for trouble with Bezo's patent, plus the end result isn't all that great. Something like DragonEye for terminal guidance would be a better bet. And the barge can certainly hold a rough position, so we're only talking about ~100m deviations at the very end of the flight path. Without an indication that barge landing is part of SpaceX's long term plan, I don't see them doing any significant technology development here.
I still favor option 2: real-time audio/video link from chase boat to shore, and from barge to boat to shore.
But neither of these options explains the fixed transmitter at the cape, nor the 'uplink' designation in the license application. So it's probably something else entirely.
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Unless you have a radar on the chase boat, and fine adjust the barge position centered under incoming vehicle's idea of GPS coordinates so that you arrive on center ... you also then have autonomous control with manual override of the pad position instead of messing with vehicle guidance ...
So you're saying chase boat might use radar to detect stage's inbound state vector, then uses it to command barge to reposition itself based on calculated landing point of stage??
I guess I don't understand GPS errors, but shouldn't both the barge and the stage GPS receivers be accurate to within a meter or so? And if they aren't, the scenario you describe sounds like an awfully complicated way to compensate.
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I guess I don't understand GPS errors, but shouldn't both the barge and the stage GPS receivers be accurate to within a meter or so? And if they aren't, the scenario you describe sounds like an awfully complicated way to compensate.
The barge would almost certainly use https://en.wikipedia.org/wiki/Differential_GPS#United_States_NDGPS (at least!) which can give 10cm accuracy. Which is almost certainly at least an order-of-magnitude better than the barge can hold position.
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I guess I don't understand GPS errors, but shouldn't both the barge and the stage GPS receivers be accurate to within a meter or so? And if they aren't, the scenario you describe sounds like an awfully complicated way to compensate.
The barge would almost certainly use https://en.wikipedia.org/wiki/Differential_GPS#United_States_NDGPS (at least!) which can give 10cm accuracy. Which is almost certainly at least an order-of-magnitude better than the barge can hold position.
AIUI, the DGPS depends on signals from short-range land-based transmitters. Because the barge will be 200 miles or so out, that might be beyond range of DGPS.
Maybe what they will use is the satellite-based WAAS:
https://en.m.wikipedia.org/wiki/Wide_Area_Augmentation_System
According to that article, WAAS is accurate to 1 meter, and the coverage map appears to include hundreds of miles of sea off the Eastern seaboard.
And the red-colored WAAS availability map in the Wikipedia article shows essentially 100% probability of coverage where the barge will be parked.
Edit: it does in fact look like NDGPS signals will be available at barge location, which would be even more accurate than WAAS.
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Unless you have a radar on the chase boat, and fine adjust the barge position centered under incoming vehicle's idea of GPS coordinates so that you arrive on center ... you also then have autonomous control with manual override of the pad position instead of messing with vehicle guidance ...
So you're saying chase boat might use radar to detect stage's inbound state vector, then uses it to command barge to reposition itself based on calculated landing point of stage??
Yes.
I guess I don't understand GPS errors, but shouldn't both the barge and the stage GPS receivers be accurate to within a meter or so? And if they aren't, the scenario you describe sounds like an awfully complicated way to compensate.
Multipath errors are the concern - that the signal is offset between both vehicle's coordinate systems by a few meters.
I'd think about it as a near miss kind of thing. All things concerned, the coordinate systems should be tested to be identical at each others position, but if you're looking for what could go wrong, this might allow a recovery of fine guidance -- perhaps the difference between two and three point touchdown :)
What I'd do is have a video feed from terminal impact point looking at vehicle, and a radar fiducial reflector on the barge, such that the terminal guidance perspective from the ground can be projected in time to the impact estimator. If the error grows, I'd model the repositioning required and use this to understand the nature of the error in the terminal guidance and if/how to compensate, and post flight work on a guidance refinement for the launch vehicle's navigation systems/model to eliminate the need.
I'd also allow for manual adjustment in the case of a unknown but compensatable offset/bias in the terminal guidance - e.g. "nudge it in".
Much more control authority in the LV returning, but thats as good as it is bad - you don't want to second guess your flight GNC, nor do you want to allow ground intervention of any kind except termination.
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The additional GPS equipment for high-precision landing would be located on the barge itself.
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The additional GPS equipment for high-precision landing would be located on the barge itself.
Damon, you might want to scroll back a few pages and look at the FCC license application for the barge.
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Unless you have a radar on the chase boat, and fine adjust the barge position centered under incoming vehicle's idea of GPS coordinates so that you arrive on center ... you also then have autonomous control with manual override of the pad position instead of messing with vehicle guidance ...
So you're saying chase boat might use radar to detect stage's inbound state vector, then uses it to command barge to reposition itself based on calculated landing point of stage??
Yes.
I guess I don't understand GPS errors, but shouldn't both the barge and the stage GPS receivers be accurate to within a meter or so? And if they aren't, the scenario you describe sounds like an awfully complicated way to compensate.
Multipath errors are the concern - that the signal is offset between both vehicle's coordinate systems by a few meters.
I'd think about it as a near miss kind of thing. All things concerned, the coordinate systems should be tested to be identical at each others position, but if you're looking for what could go wrong, this might allow a recovery of fine guidance -- perhaps the difference between two and three point touchdown :)
What I'd do is have a video feed from terminal impact point looking at vehicle, and a radar fiducial reflector on the barge, such that the terminal guidance perspective from the ground can be projected in time to the impact estimator. If the error grows, I'd model the repositioning required and use this to understand the nature of the error in the terminal guidance and if/how to compensate, and post flight work on a guidance refinement for the launch vehicle's navigation systems/model to eliminate the need.
I'd also allow for manual adjustment in the case of a unknown but compensatable offset/bias in the terminal guidance - e.g. "nudge it in".
Much more control authority in the LV returning, but thats as good as it is bad - you don't want to second guess your flight GNC, nor do you want to allow ground intervention of any kind except termination.
I won't underestimate SpaceX's ingenuity, nor yours, in devising a super-accurate terminal guidance system. ;)
But if satellite-based WAAS GPS is accurate to within 1 meter, which it appears to be in the barge's expected location, the cumulative error of two receivers is still only two meters, well within the bounds of landing a 60-foot circle on a 170-foot-wide deck.
As for multipath (lateral) error, that will converge to zero as the stage descends almost vertically down onto the barge.
So unless I'm missing something, two different GPS receivers using WAAS should have no problem coordinating the landing all by themselves.
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I won't underestimate SpaceX's ingenuity, nor yours, in devising a super-accurate terminal guidance system. ;)
But if satellite-based WAAS GPS is accurate to within 1 meter, which it appears to be in the barge's expected location, the cumulative error of two receivers is still only two meters, well within the bounds of landing a 60-foot circle on a 170-foot-wide deck.
So unless I'm missing something, two different GPS receivers using WAAS should have no problem coordinating the landing all by themselves.
That's a very good argument. Plus the stage does have landing radar. It should be able to identify the barge from a few hundred meters up and do pinpoint landing without involving GPS except for the barge using it for stationkeeping.
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Do we know if the landing radar gives lateral relative position as well as vertical? I think that was discussed on the Grasshopper thread but don't recall the details.
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I don't know the answer specifically for F9, but I suspect that its more like an aircraft RADALT or radar altimeter rather than a full mapping radar.
This only gives height above the surface (assuming level-ish attitude) which would be fine as you have reasonable accuracy (within 1-2m as stated above) laterally, but need a finer tolerance on altitude to schedule the throttle.
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I guess I don't understand GPS errors, but shouldn't both the barge and the stage GPS receivers be accurate to within a meter or so? And if they aren't, the scenario you describe sounds like an awfully complicated way to compensate.
The barge would almost certainly use https://en.wikipedia.org/wiki/Differential_GPS#United_States_NDGPS (at least!) which can give 10cm accuracy. Which is almost certainly at least an order-of-magnitude better than the barge can hold position.
Looking at NDGPS coverage maps, it does look like the barge will be in range of multiple land-based NDGPS transmitters, contrary to my previous statement that the barge might be out of range.
In which case, the 10-15 cm accuracy of NDGPS should give them pinpoint accuracy. An alternative is WAAS GPS, which should give around 1 meter accuracy.
But NDGPS would give them incredible accuracy, much better than the autopilot errors, as you say.
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Interesting article about using RTK to compensate for ship/wave motion during UAV landings - RTK gets down to cm accuracy. Not sure if it would be applicable for CRS-5 but it's a good read!
http://gpsworld.com/uav-shipboard-landing-with-rtk/ (http://gpsworld.com/uav-shipboard-landing-with-rtk/)
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I won't underestimate SpaceX's ingenuity, nor yours, in devising a super-accurate terminal guidance system. ;)
Thank you sir.
But if satellite-based WAAS GPS is accurate to within 1 meter, which it appears to be in the barge's expected location, the cumulative error of two receivers is still only two meters, well within the bounds of landing a 60-foot circle on a 170-foot-wide deck.
Correct. In an ideal world, it just "works as designed" from the first to the last.
I do have a lot of direct experience here with when it doesn't/didn't. Can't tell the more juicier stories. Can point to an obvious example - look at X-37's initial landing ... all went great until it went off the end of the runway.
It would be really embarrassing to deposit a precision munition, lets say, exactly 100 meters to the west of the target ... needless to say you might have someone rather steamed on your tail in minutes...
It would not surprise me if it does work as design correctly. But ... I would use the accumulated range data to refine the navigation's filter, error, and contingency models til they matched all flight data sets in all cases.
As for multipath (lateral) error, that will converge to zero as the stage descends almost vertically down onto the barge.
GPS data is from a time varying set of precision ranges (time differences) to the constellation, which are all at different altitudes/azimuths, and are dropping in and out of the set. Sometimes this set is poorly positioned, other times it is ideal. In non-ideal cases, the multipath caused by reflection/refraction can be leveraged by the bad geometry (thin angles) - you can reject solutions to limit covariance growth, but then your sample set size might drop too much as well. Nor have I mentioned antenna issues either.
So unless I'm missing something, two different GPS receivers using WAAS should have no problem coordinating the landing all by themselves.
Yes. It is also important to accumulate proof that your terminal control did work correctly, for the right reasons, in order to add evidence to support your case for landing inbound at the range. Like say with an independent system.
I don't know the answer specifically for F9, but I suspect that its more like an aircraft RADALT or radar altimeter rather than a full mapping radar.
This only gives height above the surface (assuming level-ish attitude) which would be fine as you have reasonable accuracy (within 1-2m as stated above) laterally, but need a finer tolerance on altitude to schedule the throttle.
Note also that GPS data for height needs to be reconciled when returns from the surface come in. With some, you can also tell the difference between the return pulse profile of a metal surface and water ;)
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Yeah, I think the key here is that the barge is a massy system with lots of inertia, so the GPS accuracy is likely to be much higher (like, orders of magnitude) than the station-keeping accuracy.
But I think positioning within ~60m should be sufficient, and the barge should be able to do that. http://www.thrustmaster.net/portable-dps-shallow-water-applications/ seems to indicate that 5-10m accuracy is not difficult using off-the-shelf equipment.
The altitude and possible inclination is probably much more critical. Wave heights of ~2m are probably not a big problem if the flight path is chosen carefully -- worse case is a free-fall from ~2m, which seems survivable. I'd be more worried about tilt, since leg contact with the ground inverts the control system dynamics. Armadillo/Masten/Unreasonable had some interesting experiences as a result, IIRC. But I think a simple foot switch to kill the engine would handle that. Finally folks previously have discussed landing radar unreliability due to specular reflections from the water surface. But nothing we're talking about here really addresses that issue.
It will certainly be interesting to see! And if we get real-time video (I can dream!) or stills after the fact, I'll certainly be keeping my eyes peeled for radio gear. ;)
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Interesting article about using RTK to compensate for ship/wave motion during UAV landings - RTK gets down to cm accuracy. Not sure if it would be applicable for CRS-5 but it's a good read!
http://gpsworld.com/uav-shipboard-landing-with-rtk/ (http://gpsworld.com/uav-shipboard-landing-with-rtk/)
Good find. Article also mentions Boeing's Little Bird autonomous helicopter than can land on a moving ship using a combination of GNSS and INS. The Little Bird technology looks much more complicated than Grasshopper/F9R technology since the intent is to land on a moving platform vs. a (nominally) stationary one, but interesting insight into the problem.
http://www.insidegnss.com/auto/mayjune13-Hardesty.pdf
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But I think positioning within ~60m should be sufficient, and the barge should be able to do that. http://www.thrustmaster.net/portable-dps-shallow-water-applications/ seems to indicate that 5-10m accuracy is not difficult using off-the-shelf equipment.
More info on dynamic positioning of ships/vessels using DGPS:
http://en.m.wikipedia.org/wiki/Dynamic_positioning
Strangely, no mention of accuracy.
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I wonder if the rocket plume / running engine might interfere with signal emanating from the barge?
Especially when the stage is very close to touching down?
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I understand that a bit of effort may be required to develop reliable systems to land accurately on the barge, but how much is that really necessary? The real goal is to land accurately on a permanent, stationary, concrete pad near the landing site, one that has coordinates dialed in to the gnat's hair, and a system that could easily broadcast (or reflect) any needed corrections to the incoming stage.
Putting a similar system on the barge, even if you lose accuracy in the implementation, should still be more than adequate for the proof-of-concept.
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I understand that a bit of effort may be required to develop reliable systems to land accurately on the barge, but how much is that really necessary? The real goal is to land accurately on a permanent, stationary, concrete pad near the landing site, one that has coordinates dialed in to the gnat's hair, and a system that could easily broadcast (or reflect) any needed corrections to the incoming stage.
Putting a similar system on the barge, even if you lose accuracy in the implementation, should still be more than adequate for the proof-of-concept.
I guess the point is that if they can reliably land on a tiny little barge out in the open ocean (where missing the target equals total loss of the stage) they should have no problems at all pin-pointing a stationary concrete pad surrounded by acres of paddock.
After years of watching SpaceX confounding the naysayers, I'd expect they'd welcome the additional little challenge... ;D
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Putting a similar system on the barge, even if you lose accuracy in the implementation, should still be more than adequate for the proof-of-concept.
It will be proved adequate if they can land repeatably on the barge. If they can't, they won't get the chance to try on land.
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I agree that there is no particular reason why they need to add special "barge landing" guidance equipment -- the position holding accuracy of the barge (in the horizontal plane) ought to be sufficient.
I'm a little more ambivalent about vertical positioning, but 1-2m wave heights really ought to be fine. Maybe some tuning of the gains and modelling on their altitude control loop to better predict/respond to the swell.
The tilt on the barge is what i'd be more concerned about, but there doesn't really seem to be any solid ideas about how to deal with that. Except perhaps for some sort of "harpoon grid" like Boeing's Little Bird used (thanks for that reference, @somepitch!).
*BUT* aside from my technical speculation, there's the concrete fact of the FCC license application which was dug up upthread, which clearly indicates a new rocket uplink capability on this mission, with a somewhat puzzling transmitter configuration wrt power levels & sites.
So there's some amount of speculation about what you might use that uplink for, independent of our thoughts about whether the uplink is, strictly speaking, *necessary* or *part of a long-term technology demonstration project* or whatever.
The transmitter configuration seems to best match some sort of terminal guidance broadcast from the chase boat, with position information from the barge relayed via the boat (to keep antenna size down on the barge?), and some sort of ground test purpose served by the low power transmitter on the cape. There's a secondary frequency which might be used for flight termination in the event the rocket endangers the chase boat. Of all the options, that seems to account for all the transmitters and their power levels in the simplest way.
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Putting a similar system on the barge, even if you lose accuracy in the implementation, should still be more than adequate for the proof-of-concept.
It will be proved adequate if they can land repeatably on the barge. If they can't, they won't get the chance to try on land.
I don't expect 'repeatedly' to be a large number... 2-3 at most. It cannot be considered a lucky break to land a booster on a dot in the ocean; it would be a demonstration of what has been shown by analysis, soft landings on the ocean (but for the pinpoint location), and Grasshopper/F9R Dev1 testing over the last couple years.
Confidence to allow a launch of a new rocket with its destruction potential is a far higher bar than landing an empty first stage on the same beach.
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The phasing Elon gave when he spoke of landing on a barge implied that one landing would be sufficient for approval to land on a bare concrete pad. But then he is biased.
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The phasing Elon gave when he spoke of landing on a barge implied that one landing would be sufficient for approval to land on a bare concrete pad. But then he is biased.
From Elon's MIT talk:
"But before we boost back to the launch site, and try to land there, we need to show that we can land with precision, over and over again."
http://shitelonsays.com/transcript/elon-musk-at-mits-aeroastro-centennial-part-1-of-6-2014-10-24
All that matters is how many barge landings FAA/Range will require of them.
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Meanwhile, Conrad Shipyard is building a new section for NASA's Pegasus barge. Too bad we can't see the SpaceX barge in the background of the photo.
http://www.nasa.gov/sls/anchors-aweigh-on-modifications-to-pegasus-barge.html#.VF0XBn-9KSM
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From Elon's MIT talk:
"But before we boost back to the launch site, and try to land there, we need to show that we can land with precision, over and over again."
http://shitelonsays.com/transcript/elon-musk-at-mits-aeroastro-centennial-part-1-of-6-2014-10-24
All that matters is how many barge landings FAA/Range will require of them.
I think everyone is overthinking what will be required to be able to attempt RTLS pad landings...
From a range perspective, it doesn't require that they be able to land precicely on the "X" every single time.
What is required is that they have control of the returning stage, and manage the IIP to stay within pre-planned limits, and to demonstrate destruct/abort performance to ensure that personnel and property are not put at risk outside of the agreed to parameters.
Range doesn't care if SpaceX gets a reusable booster back intact.
Range cares that the vehicle doesn't kill people, particularly the general public.
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The phasing Elon gave when he spoke of landing on a barge implied that one landing would be sufficient for approval to land on a bare concrete pad. But then he is biased.
From Elon's MIT talk:
"But before we boost back to the launch site, and try to land there, we need to show that we can land with precision, over and over again."
http://shitelonsays.com/transcript/elon-musk-at-mits-aeroastro-centennial-part-1-of-6-2014-10-24
All that matters is how many barge landings FAA/Range will require of them.
I think you can count the Grasshopper flights as showing repeated precision landings. They're not necessarily sufficient, but they are a part of the baseline capability demonstration.
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From a range perspective, it doesn't require that they be able to land precicely on the "X" every single time.
What is required is that they have control of the returning stage, and manage the IIP to stay within pre-planned limits
Agreed. Maybe the issue is what "precision" means. I think Elon is saying that as long as they can land somewhere on the barge, that will be precise enough. I don't think he's saying they have to be within a meter of the barge center every time.
If you look at his MIT comments, he said the barge "looks very tiny from space," and landing safely anywhere on the barge would be quite a feat of guidance, and certainly "precise" enough to satisfy the Range, IMO.
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Keep in mind the delta-v canceled at the last minute while inbound to the graveyard prior to divert burn, and the debris field of the booster. That's the danger to facilities/staff/etc. Thus the need for proven control and safety.
The divert burn/maneuver is more about precision and acceptable operations.
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Can anyone here make an educated guess about how long it will take the 'huge-ish' barge to transit from Louisiana to the vicinity of Cape Canaveral? Those things are not race boats and the distance substantial. I get anywhere from 4 days to 4 weeks depending on the guesses I make, and if they want to use this thing on CRS-5 then it may need to depart fairly soon.
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Can anyone here make an educated guess about how long it will take the 'huge-ish' barge to transit from Louisiana to the vicinity of Cape Canaveral? Those things are not race boats and the distance substantial. I get anywhere from 4 days to 4 weeks depending on the guesses I make, and if they want to use this thing on CRS-5 then it may need to depart fairly soon.
NASA Pegasus barge took 6 days to transit 900 miles from Michoud to the Cape.
Distance from Morgan City slightly longer, so maybe a week for SpaceX barge.
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Maybe this is a crazy idea, but it seems to me that the surface of the barge could be a "bed of nails" with similar nails on the rocket feet pointing down. This would be the equivalent of Velcro, so once landed the feet would stick to the barge and prevent the rocket toppling over in moving seas.
What do you think? Any better ideas to secure the rocket on landing?
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seems like the biggest challenge to landing on the barge will be the high altitude maneuvers that will determine whether they are even in the area of the barge for the precision low altitude stuff theyve already been able to demonstrate with grasshopper. bc of course as it's descending its possible landing zone is shrinking.
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Maybe this is a crazy idea, but it seems to me that the surface of the barge could be a "bed of nails" with similar nails on the rocket feet pointing down. This would be the equivalent of Velcro, so once landed the feet would stick to the barge and prevent the rocket toppling over in moving seas.
What do you think? Any better ideas to secure the rocket on landing?
Interesting idea, although it might make it hard for humans to walk around the stage later! What comes to my mind are essentially chocks. But they would have to be automatic chocks. Given the residual smoke and fumes around the base, I wouldn't hazard sending out a chock crew in the first 10 min, unless they were in Scott masks or scuba, something like that. Perhaps you could have big wire loops that would flip inward on command, sort of like a bear trap. They would still need to align with the landing legs, though.
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Maybe this is a crazy idea, but it seems to me that the surface of the barge could be a "bed of nails" with similar nails on the rocket feet pointing down. This would be the equivalent of Velcro, so once landed the feet would stick to the barge and prevent the rocket toppling over in moving seas.
What do you think? Any better ideas to secure the rocket on landing?
Please go back and read the posted article about the Boeing 'little bird' copter. There is apparently already a NATO standard for this.
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http://www.heligrid.com/how-it-works.html
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Maybe this is a crazy idea, but it seems to me that the surface of the barge could be a "bed of nails" with similar nails on the rocket feet pointing down. This would be the equivalent of Velcro, so once landed the feet would stick to the barge and prevent the rocket toppling over in moving seas.
What do you think? Any better ideas to secure the rocket on landing?
Any system that solely relies on holding the stage by the legs is going to run the risk of it bending/crumpling in half. The stage is basically empty when it lands. If it gets a good gust of wind, but the base is held still, I wouldn't be too surprised if it just folded.
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Maybe this is a crazy idea, but it seems to me that the surface of the barge could be a "bed of nails" with similar nails on the rocket feet pointing down. This would be the equivalent of Velcro, so once landed the feet would stick to the barge and prevent the rocket toppling over in moving seas.
What do you think? Any better ideas to secure the rocket on landing?
Any system that solely relies on holding the stage by the legs is going to run the risk of it bending/crumpling in half. The stage is basically empty when it lands. If it gets a good gust of wind, but the base is held still, I wouldn't be too surprised if it just folded.
Pressurization.
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http://www.heligrid.com/how-it-works.html
There go our patent dreams, Roy. I swear, everything's been invented! ;)
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Maybe this is a crazy idea, but it seems to me that the surface of the barge could be a "bed of nails" with similar nails on the rocket feet pointing down. This would be the equivalent of Velcro, so once landed the feet would stick to the barge and prevent the rocket toppling over in moving seas.
What do you think? Any better ideas to secure the rocket on landing?
Nailing the feet to the side of the first stage is not a good idea.
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Maybe this is a crazy idea, but it seems to me that the surface of the barge could be a "bed of nails" with similar nails on the rocket feet pointing down. This would be the equivalent of Velcro, so once landed the feet would stick to the barge and prevent the rocket toppling over in moving seas.
What do you think? Any better ideas to secure the rocket on landing?
Inflatable air bags are used with far more massive structures like ocean ships. It would not seem very difficult to have a series of (thermally protected!) bags expand after touchdown for stability. The thermal environment on landing is the biggest challenge. The issue on a barge is stability and not allowing the center of gravity of the stage to angle over to a tipping point. I have no numbers on barge degrees rocking in seas of H height.
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The F9 first stage reportedly has a very low CG at landing time (as in, near the attachment points for the legs themselves) since it's near-dry, which would logically make it stable against some tilting action, and perhaps moderate winds with the 60ft span on the legs.
Steel Velcro, airbags, automated chocks, electromagnets, superglue on the landing pads... overkill?
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Actually, I'll reply to myself. Let's use logic.
The landed stage will be stable in moderate breezes - SpaceX doesn't want their landed stages to be toppling left and right (whether at sea or on land), as that would be embarrassing, so they will have designed the legs to provide enough stability.
A huge-ish barge / platform / etc will have a lot of mass and thus, even as it tilts a few degrees in ocean swells, it will do so slowly and not to a great degree. Thus the low CG of a landed stage will be stable against this.
Exactly how they plan to get this thing back to shore is interesting (support ship crane? etc), but don't think there will be any kind of immediate/automatic device to stabilize the stage; KISS.
I like the electromagnet idea though.
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http://www.heligrid.com/how-it-works.html
That could work for initial securing (worker safety). I would also attach 4 winch lines (per stage recovered), passing thru pulleys (for a change of direction pull, more downwards, to a max cable angle of 45 degrees), fastened to the launch hold down mounts. Steel cables are cheaper, thinner, but much heavier than some of the synthetic ropes out there now. Some winch setups have the ability, to be operated by wireless remote controls as well. The pulley attachment points could, be of the flip up type, built into the barge deck (sits flush with deck, unless in use).
However, it could be problematic, using both approaches on the deck, one system potentially interfering with the other.
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Use the same system the Navy uses. Have a bunch of pad-eyes on deck. After it lands send out 3-4 people to chain it to the deck. Sail it back to the Cape.
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Use the same system the Navy uses. Have a bunch of pad-eyes on deck. After it lands send out 3-4 people to chain it to the deck. Sail it back to the Cape.
A-ha, and let the penitentiary system staff this position.
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Somebody calculated it would require a 30 degree tilt for the stage to tip, not going to happen. The worry is sliding around the deck. I have been on Navy carrier decks, and the non-skid surface is very rough and tough. With 1-2 meter seas, tilt is less than a degree if the long axis of the ship is kept into the waves. I dont think it will be a problem. I would watch from a safe distance on the first one before approaching.
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Maybe this is a crazy idea, but it seems to me that the surface of the barge could be a "bed of nails" with similar nails on the rocket feet pointing down. This would be the equivalent of Velcro, so once landed the feet would stick to the barge and prevent the rocket toppling over in moving seas.
What do you think? Any better ideas to secure the rocket on landing?
Inflatable air bags are used with far more massive structures like ocean ships. It would not seem very difficult to have a series of (thermally protected!) bags expand after touchdown for stability. The thermal environment on landing is the biggest challenge. The issue on a barge is stability and not allowing the center of gravity of the stage to angle over to a tipping point. I have no numbers on barge degrees rocking in seas of H height.
Oh geez, not the airbags again.
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Somebody calculated it would require a 30 degree tilt for the stage to tip, not going to happen. The worry is sliding around the deck. I have been on Navy carrier decks, and the non-skid surface is very rough and tough. With 1-2 meter seas, tilt is less than a degree if the long axis of the ship is kept into the waves. I dont think it will be a problem. I would watch from a safe distance on the first one before approaching.
Yeah, just a really rough non-skid surface may work just fine.
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An asphalt coating over the steel deck? Properly flooded should not get too hot during a fast landing.
Good for the antislip and sticking properties. Well, can‘t convince myself... :(
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Given that the weather conditions at launch are likely to be just as benign at this closer-to-home target position, is "sticking the landing" really a problem that needs to be solved?
Well, as long as steel velcro, nails, tar, and airbags are on the table (er, deck), I'll point out that here in Texas you just toss a lasso, otherwise known as a giant end effector. You only need 3 cables and one rotating race, and if as little as 1 pad lands inside the circle, it's snared. But between me and y'all, I don't think that Hawthorne gang will have any trouble wrangling this dogie down.
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The first stage on legs has its CG on landing very close to the ground, with the legs attached above the CG point, the empty section above the engines, i.e the tanks will be almost empty, so there is negotiable mass above top leg mount to topple the stage.. I am not sure what everyone is expecting from this barge.. basically its 10 Mississippi barges in 'standard' 5 x 2 array. in size and most like will be 10 Mississippi barges lashed together with some concrete paver's on the deck to protect the metal parts from excessive heat.. two outboard pods to maintain position
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Agreed. Recovery team will be 30-45 min max from area. The rocket will not TIP over. They will Walk Down pad/barge and Harness to it. Land ho!
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An asphalt coating over the steel deck? Properly flooded should not get too hot during a fast landing.
Good for the antislip and sticking properties. Well, can‘t convince myself... :(
And if it does get too hot, that molten tar could do an even better job of preventing it from slipping. :)
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They will Walk Down pad/barge and Harness to it. Land ho!
What does this mean? Are you saying that the stage will arrive in port in a horizontal position?
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Can anyone here make an educated guess about how long it will take the 'huge-ish' barge to transit from Louisiana to the vicinity of Cape Canaveral? Those things are not race boats and the distance substantial. I get anywhere from 4 days to 4 weeks depending on the guesses I make, and if they want to use this thing on CRS-5 then it may need to depart fairly soon.
Not just soon. Any day now. They'll need to perform check out work, testing, and operations rehearsals before towing that bad boy out to sea for the big show. And even that's assuming that this thing doesn't have to make several more stops to finish up the construction and "stuffing out" of all the systems. December 9 is less than a month away.
My $0.05 bet, is that it's either going to be revealed in a few days (this week IMHO) when they take it out of its bearth in completed, or nearly completed form, or I don't think it's going to be ready for the Dec. 9 flight. I'm thinking the latter is most likely until I see a picture of this thing in the press.
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Not just soon. Any day now. They'll need to perform check out work, testing, and operations rehearsals before towing that bad boy out to sea for the big show. And even that's assuming that this thing doesn't have to make several more stops to finish up the construction and "stuffing out" of all the systems. December 9 is less than a month away.
My $0.05 bet, is that it's either going to be revealed in a few days (this week IMHO) when they take it out of its bearth in completed, or nearly completed form, or I don't think it's going to be ready for the Dec. 9 flight. I'm thinking the latter is most likely until I see a picture of this thing in the press.
I think you might be overestimating the complexity of this barge. If it's as Avron says, it's just a big dumb piece of steel with some outboard thrusters bolted on and a radio. I don't think there's much in the way of testing and operations rehearsals other than to ensure that the off-the-shelf position-keeping system was actually installed correctly. And if it's just a big dumb piece of steel, I don't see it meriting any sort of special SpaceX announcement/unveil when it leaves port. My $0.10 bet (I see your $0.05 bet and raise you!) is that we won't see any pictures until the actual CRS-5 landing attempt, and then only if it is mostly successful. And the landing is currently scheduled after sunset...
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From Elon's MIT talk:
"But before we boost back to the launch site, and try to land there, we need to show that we can land with precision, over and over again."
http://shitelonsays.com/transcript/elon-musk-at-mits-aeroastro-centennial-part-1-of-6-2014-10-24
All that matters is how many barge landings FAA/Range will require of them.
I think everyone is overthinking what will be required to be able to attempt RTLS pad landings...
From a range perspective, it doesn't require that they be able to land precicely on the "X" every single time.
What is required is that they have control of the returning stage, and manage the IIP to stay within pre-planned limits, and to demonstrate destruct/abort performance to ensure that personnel and property are not put at risk outside of the agreed to parameters.
Range doesn't care if SpaceX gets a reusable booster back intact.
Range cares that the vehicle doesn't kill people, particularly the general public.
Agreed, though I'll add that it also mustn't take out someone else's pad / infrastructure.
Cheers, Martin
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Not just soon. Any day now. They'll need to perform check out work, testing, and operations rehearsals before towing that bad boy out to sea for the big show. And even that's assuming that this thing doesn't have to make several more stops to finish up the construction and "stuffing out" of all the systems. December 9 is less than a month away.
My $0.05 bet, is that it's either going to be revealed in a few days (this week IMHO) when they take it out of its bearth in completed, or nearly completed form, or I don't think it's going to be ready for the Dec. 9 flight. I'm thinking the latter is most likely until I see a picture of this thing in the press.
I think you might be overestimating the complexity of this barge. If it's as Avron says, it's just a big dumb piece of steel with some outboard thrusters bolted on and a radio. I don't think there's much in the way of testing and operations rehearsals other than to ensure that the off-the-shelf position-keeping system was actually installed correctly. And if it's just a big dumb piece of steel, I don't see it meriting any sort of special SpaceX announcement/unveil when it leaves port. My $0.10 bet (I see your $0.05 bet and raise you!) is that we won't see any pictures until the actual CRS-5 landing attempt, and then only if it is mostly successful. And the landing is currently scheduled after sunset...
It's not a big dumb piece of steel. It's a boat. :) We know for a fact that it's going to have radios and engines at an absolute minimum, and it may even be more complicated than that (it may have a crane and cradles, it may be a semi-submersible, plus who knows what else (we've been told of at least two other features on L2). Those two things alone need to be sea-trialed and acceptance tested before they can even begin operations and procedural testing for an operational space mission. Even at Space-X's pace, that's going to take at minimum a week to do all that, plus the time required to move the thing on station from LA to the Atlantic.
IMHO, we'll see the thing when it moves out of the barn for the first time- hopefully with some hoopla! It's too big, and too many people are watching for it not to make the press.
For the sake of good argument though, let's say the barge is ready, they sneak it down the river, and out into the Gulf, then around to the Atlantic in good weather, without any stops to refuel or stretch legs along the way. Then, they send boats with engineers out into the Atlantic right after Thanksgiving (again under the cover of darkness). In that scenario, they could launch the barge, perform their acceptance testing on station out in the Atlantic the week before the launch, and still not make the press.
Doesn't it seem simpler to issue a press release and a photo? :)
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It's not a big dumb piece of steel. It's a boat. :) We know for a fact that it's going to have radios and engines at an absolute minimum, and it may even be more complicated than that (it may have a crane and cradles, it may be a semi-submersible, plus who knows what else (we've been told of at least two other features on L2).
Link, please. I'm on L2 and I'm not aware of any non-public confirmed features of the barge. You're speculating about the crane and cradles -- I'm almost certain those would be on the *boat* not the *barge* (as per the public FCC license). So everything you're saying must be on the barge (except engines and a 1W radio transmitter) is pure speculation.
If you want to amend your statement and say that the *boat* will probably be out doing maneuvers at some point, I'd agree with you. But it has also done so for just about every previous mission, and we have yet to see pictures (except for a few shots of Dragon recovery).
Those two things alone need to be sea-trialed and acceptance tested before they can even begin operations and procedural testing for an operational space mission.
This isn't an "operational space mission". The landing part is a *test*. It is certainly not going to affect the schedule of CRS-5. If the barge is not ready, it's not ready. If it's almost ready, they'll probably put it out there and take a chance. They aren't going to issue a press release ahead of time.
IMHO, we'll see the thing when it moves out of the barn for the first time- hopefully with some hoopla! It's too big, and too many people are watching for it not to make the press.
We've known exactly what shipyard it's being built at for almost a month now, and I still haven't seen any pictures. Why is this going to change?
Doesn't it seem simpler to issue a press release and a photo? :)
That doesn't seem to be the SpaceX way. They are pretty careful not to distract from the NASA mission for the CRS flights. Even when the landing test is completely successful, we generally don't hear details or see footage for weeks after launch.
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IMHO, we'll see the thing when it moves out of the barn for the first time- hopefully with some hoopla! It's too big, and too many people are watching for it not to make the press.
Not really. You are overblowing it.
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IMHO, we'll see the thing when it moves out of the barn for the first time- hopefully with some hoopla! It's too big, and too many people are watching for it not to make the press.
Not really. You are overblowing it.
We're on page 37 of this thread, I think there's at least a passing interest among spaceflight watchers.
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We're on page 37 of this thread, I think there's at least a passing interest among spaceflight watchers.
A community that doesn't rate any press coverage.
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We're on page 37 of this thread, I think there's at least a passing interest among spaceflight watchers.
A community that doesn't rate any press coverage.
Please tell that to the numerous journalists on this site, some of whom are with mainstream outlets. :)
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We're on page 37 of this thread, I think there's at least a passing interest among spaceflight watchers.
A community that doesn't rate any press coverage.
Please tell that to the numerous journalists on this site, some of whom are with mainstream outlets. :)
Sure, but you're claiming that they would be out there trying to dig up some dirt on the barge so they can have the scoop when it launches. Really not happening. No one with a normal day job is so excited about this they are canvassing shipyards to find it.
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They will Walk Down pad/barge and Harness to it. Land ho!
What does this mean? Are you saying that the stage will arrive in port in a horizontal position?
No. 'Walk Down' means ensuring all things are good w/ barge and rocket. No contingencies. Secure load and head to land. Just my own thoughts and opinion.
Sorry for any obscurity from original post.
Was my first post here. Hope to join in more!!
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If there's much chance of high winds, though, it would probably be a good idea to be able to lower the stage somehow, because that's a long trip through potentially heavy waves on a pretty flimsy hollow tube.
Unless they just want to show a good landing, and then are ok with tossing the stage overboard...
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Unless they just want to show a good landing, and then are ok with tossing the stage overboard...
Rocket engineers the world over would be crying foul at that. Especially the SpaceX engineers, who need to know exactly what needs to be beefed up in the design, or conversely, what can be made lighter without penalty. They will want to dissect that rocket like a frog in a school biology class.
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If there's much chance of high winds, though, it would probably be a good idea to be able to lower the stage somehow, because that's a long trip through potentially heavy waves on a pretty flimsy hollow tube.
At MacGregor they don't lower the stage, instead they use a cherry-picker to hold a chain attached to the top of the stage. That might be an option.
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At MacGregor they don't lower the stage, instead they use a cherry-picker to hold a chain attached to the top of the stage. That might be an option.
Couldn't they simply attach guy-wires to it? Like a sailboat's mast?
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If most of the mass and structure is at the bottom, why not have something that clamps to the hold-down points at the bottom of the stage and holds the whole thing down to the deck of the barge? Those structures are strong enough to hold the entire loaded mass of F9 in one direction, and 20-25% of that ( t/w ratio - 1 ) in the other direction. Only thing you'd have to avoid is pulling down too hard because you could probably break the legs.
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Part of the trouble with the idea of hold downs is you don't know exactly where on the deck the stage will land, and you don't want structure sticking up that might interfere with the landing. Maybe a couple of masts that are folded down along the sides of the barge, after landing they are lifted up and locked, and from there you attach guy wires to the stage, high up enough that it can stabilize it without applying a lot of pressure.
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Part of the trouble with the idea of hold downs is you don't know exactly where on the deck the stage will land, and you don't want structure sticking up that might interfere with the landing. Maybe a couple of masts that are folded down along the sides of the barge, after landing they are lifted up and locked, and from there you attach guy wires to the stage, high up enough that it can stabilize it without applying a lot of pressure.
Tying down/holding down from the base, seems like a perfect place for some robotics work, and just a note to all those who thing that lowering the first stage is a good idea, its tank section is probably is under less stress(buckling) standing with so little weight on it and while it presents a fair cross section to wind, lying it down without support along the length of the tank is probably worse than the winds it is reasonably expected to experience.
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Tying down/holding down from the base, seems like a perfect place for some robotics work, and just a note to all those who thing that lowering the first stage is a good idea, its tank section is probably is under less stress(buckling) standing with so little weight on it and while it presents a fair cross section to wind, lying it down without support along the length of the tank is probably worse than the winds it is reasonably expected to experience.
I don't think so. If you have seen pictures on how it is road transported and which equipment is used in McGregor to erect it the stage can very well stand handling and even without pressurization. I have no doubt it will be transported horizontally.
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Tying down/holding down from the base, seems like a perfect place for some robotics work, and just a note to all those who thing that lowering the first stage is a good idea, its tank section is probably is under less stress(buckling) standing with so little weight on it and while it presents a fair cross section to wind, lying it down without support along the length of the tank is probably worse than the winds it is reasonably expected to experience.
I don't think so. If you have seen pictures on how it is road transported and which equipment is used in McGregor to erect it the stage can very well stand handling and even without pressurization. I have no doubt it will be transported horizontally.
In all those other applications of translating it from vertical to horizontal you don't have wave motion to contend with. I believe, that the translation under those circumstances would create buckling stress unlike what is seen on dry land. Maybe a mechanical engineer out there might weigh in on this? My idea is that the motion, even through only 5 degrees over a few minutes would increase the stress, the peak of this increase would be when the vehicle was at a 45 degree angle, how much it would increase and exactly where along the length of the tank section it would peak I don't know.
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Two thoughts:
1. The safety of the recovery crew is paramount. All talk about securing the stage must take this into account. People can't be safely near the stage if there's a danger of it toppling over and exploding. I expect the KISS principle is that SpaceX has done the stability and mechE studies to show that the stage won't topple over *even without additional hold-downs* if wind speed is less than X, the sea state is less than Y, the measured accelerations/tilts on the barge are less than Z, and it landed more-or-less centered. If those conditions don't hold when the stage lands, they'll leave it alone until either the conditions improve or the stage falls over by itself. The engineers will still have a field day with the pieces they recover of a fallen-over stage, you don't have to hit the home run and refly the stage on your first try. People will only approach the stage to further secure it (in whatever way, whether that's clamping the feet or lowering the stage to horizontal, etc) if the stage is already in a stable configuration for the present conditions.
2. Remember that this is an experiment and that SpaceX prefers iterative development instead of over-engineering things from the start. Even if eventually SpaceX uses <your favorite capture or guidance mechanism> and routinely <lands intact BFR stages on fully-custom offshore jackup rigs or whatever>, these first attempts are likely to be As Simple As Possible. It's not a fancy barge, it's not a fancy hold down mechanism. (Not yet, at least.) Success is not guaranteed. It's just a shot in the dark, and they'll see how close they get and what goes wrong, make some changes, and try again.
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Part of the trouble with the idea of hold downs is you don't know exactly where on the deck the stage will land, and you don't want structure sticking up that might interfere with the landing. Maybe a couple of masts that are folded down along the sides of the barge, after landing they are lifted up and locked, and from there you attach guy wires to the stage, high up enough that it can stabilize it without applying a lot of pressure.
Carrier Deck Padeyes and tie-down chains
(http://i.imgur.com/62AYSOK.jpg)
(http://ecx.images-amazon.com/images/I/81SUDVKkueL._SX466_.jpg)
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In all those other applications of translating it from vertical to horizontal you don't have wave motion to contend with. I believe, that the translation under those circumstances would create buckling stress unlike what is seen on dry land. Maybe a mechanical engineer out there might weigh in on this? My idea is that the motion, even through only 5 degrees over a few minutes would increase the stress, the peak of this increase would be when the vehicle was at a 45 degree angle, how much it would increase and exactly where along the length of the tank section it would peak I don't know.
In my experience, no, there's no issues translating a large object from vertical to horizontal on a floating stage in reasonable sea conditions so long as it's properly supported (in a portable framework of some kind presumably similar to the erector) along it's length and the framework itself is properly supported on the barge. There certainly are issues using another vessel (like a crane barge) berthed alongside to do this.. but on the same vessel, no there's none.
If they did want the landed stage horizontal for transport back to the mainland, one option is to ship a portable erector out in the back of the 'command ship' and off-load it onto the barge after landing/safeing of the stage.
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Couldn't they simply attach guy-wires to it? Like a sailboat's mast?
Lasso Cannons! ;)
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Lots of talk about returning the stage to horizontal, but in none of the comments have I seen anything allowing for the fact that the legs will be extended after landing. Are they easily retracted/stowed to allow for lowering?
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Lots of talk about returning the stage to horizontal, but in none of the comments have I seen anything allowing for the fact that the legs will be extended after landing. Are they easily retracted/stowed to allow for lowering?
No idea, but as a fall back, the legs can be detached & the extended cylinders strapped to the lower rocket body. Question is, how much additional lift height is required, prior to horizontal rotation?
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Lots of talk about returning the stage to horizontal, but in none of the comments have I seen anything allowing for the fact that the legs will be extended after landing. Are they easily retracted/stowed to allow for lowering?
No idea, but as a fall back, the legs can be detached & the extended cylinders strapped to the lower rocket body. Question is, how much additional lift height is required, prior to horizontal rotation?
If the legs can extend then there must be some way to retract them once on the ground - otherwise there'd be no way to get the stage on the back of a truck post-recovery..
..so, once grappled by portable erector on the barge similar to the one used to get it vertical at the pad in the first place, then I'd think it'd be a simple enough process to lift slightly to take the weight off and retract the legs before rotating horizontal. FWIW...
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Lots of talk about returning the stage to horizontal, but in none of the comments have I seen anything allowing for the fact that the legs will be extended after landing. Are they easily retracted/stowed to allow for lowering?
No idea, but as a fall back, the legs can be detached & the extended cylinders strapped to the lower rocket body. Question is, how much additional lift height is required, prior to horizontal rotation?
If the legs can extend then there must be some way to retract them once on the ground - otherwise there'd be no way to get the stage on the back of a truck post-recovery..
..so, once grappled by portable erector on the barge similar to the one used to get it vertical at the pad in the first place, then I'd think it'd be a simple enough process to lift slightly to take the weight off and retract the legs before rotating horizontal. FWIW...
My initial reply, was to the question of if they could be easily retracted. Are they going to pump / suck the gas back into the storage containers & re-latch the legs, while upright on the barge. Or do it afterwards, once horizontal. They may want to limit, on barge operations (at sea), for safety of the personnel.
Something wacky here, only easily retracted was to be in bold & not the remainder, think I fixed it.
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If it is rough, lifting it with crane while placing on cradle will be very difficult as stage will be swinging around.
If it is calm transporting it on barge as is, shouldn't be a problem.
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I suspect that there will be a lot of the 'KISS' principle involved with the barge operations, if the 1st stage is stable in the upright position, leave it there.
There are a number of actions which can be done to make it more secure -
1) Vent the remaining LOX, this will lower the centre of mass being that the LOX tank is above the RP-1 tank
2) Keep the remaining RP-1 on board, again keeps the centre of mass lower and avoids having to handle the stuff on the barge at sea.
3) Secure the legs to tie down points on the deck with straps/chains - as long as the stage is safe to approach by the barge team, who would not board the barge until this point.
4) do all the messing around getting it horizontal once you are safely docked.
Once this has been done a few times and barge landing is a part of the SOP - FH core?, then look to storing the stage horizontal and even below deck allowing the barge to stay out for a second launch, especially if they will have to be a long way out in the Atlantic to land the FH core with little boost back.
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Lots of talk about returning the stage to horizontal, but in none of the comments have I seen anything allowing for the fact that the legs will be extended after landing. Are they easily retracted/stowed to allow for lowering?
AIUI, the legs are extended only because of helium pressurisation.
Unless there is something that latches the legs to the extended position, or some sort of liner inside the legs, ISTM the He will leak away fairly quickly, possibly removing the stability to hold the stage upright.
Unless there are latches inside the legs, I even wonder if the legs might allow some compliance / movement of the stage once it has landed.
I'm not sure how latches on the legs would work, though. Look at the way the legs oscillate during deployment. The legs would need to get into their fully deployed position before the latches could be activated.
I wonder if one of the first actions once crew get on board the barge would be to attach an He pressurisation system to keep the legs rigidly deployed?
cheers, Martin
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Lots of talk about returning the stage to horizontal, but in none of the comments have I seen anything allowing for the fact that the legs will be extended after landing. Are they easily retracted/stowed to allow for lowering?
AIUI, the legs are extended only because of helium pressurisation.
Unless there is something that latches the legs to the extended position, or some sort of liner inside the legs, ISTM the He will leak away fairly quickly, possibly removing the stability to hold the stage upright.
Unless there are latches inside the legs, I even wonder if the legs might allow some compliance / movement of the stage once it has landed.
I'm not sure how latches on the legs would work, though. Look at the way the legs oscillate during deployment. The legs would need to get into their fully deployed position before the latches could be activated.
I wonder if one of the first actions once crew get on board the barge would be to attach an He pressurisation system to keep the legs rigidly deployed?
cheers, Martin
Or insert locking pins to lock the legs inplace. No messing around with high pressure He. :D
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Lots of talk about returning the stage to horizontal, but in none of the comments have I seen anything allowing for the fact that the legs will be extended after landing. Are they easily retracted/stowed to allow for lowering?
AIUI, the legs are extended only because of helium pressurisation.
Unless there is something that latches the legs to the extended position, or some sort of liner inside the legs, ISTM the He will leak away fairly quickly, possibly removing the stability to hold the stage upright.
Unless there are latches inside the legs, I even wonder if the legs might allow some compliance / movement of the stage once it has landed.
I'm not sure how latches on the legs would work, though. Look at the way the legs oscillate during deployment. The legs would need to get into their fully deployed position before the latches could be activated.
I wonder if one of the first actions once crew get on board the barge would be to attach an He pressurisation system to keep the legs rigidly deployed?
cheers, Martin
Or insert locking pins to lock the legs inplace. No messing around with high pressure He. :D
Er... Oh yeah!
Cheers, Martin
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Insert locking pins?
Where are the holes?
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Folks, please look at the pictures of Grasshopper sitting in MacGregor before speculating here. The stage is perfectly happy sitting on its legs for long periods of time. As I've posted before, they will occasionally have a cherry picker set up with a chain running to the top of the stage, which is speculated to be for extra safety in high winds, but the stage is perfectly happy sitting there without ground equipment.
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Folks, please look at the pictures of Grasshopper sitting in MacGregor before speculating here. The stage is perfectly happy sitting on its legs for long periods of time. As I've posted before, they will occasionally have a cherry picker set up with a chain running to the top of the stage, which is speculated to be for extra safety in high winds, but the stage is perfectly happy sitting there without ground equipment.
It is not sitting on its legs. It has a support it is attached to and the legs are just above the ground.
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Folks, please look at the pictures of Grasshopper sitting in MacGregor before speculating here. The stage is perfectly happy sitting on its legs for long periods of time. As I've posted before, they will occasionally have a cherry picker set up with a chain running to the top of the stage, which is speculated to be for extra safety in high winds, but the stage is perfectly happy sitting there without ground equipment.
It is not sitting on its legs. It has a support it is attached to and the legs are just above the ground.
And the crane was to pick it up after a landing and re-mount it on that support.
That said, it speaks volumes for the stability of the empty stage in Texas wind. We haven't seen either the old or new Grasshopper buckling due to wind pressure. Clamping the tips of the landing legs to the barge surface (somehow) should not result in buckling loads simply due to wind. Wave action + Wind = who knows?
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You guys are right -- it's a crane, not a cherry picker, and the stage isn't quite sitting on the ground.
But I took a look at the pictures again, and I'm not convinced that it's not resting its weight on the legs in MacGregor. The legs appear to be standing on pedestals which are then on the ground. There's a lot of clutter in the picture, hard to tell for sure. But launching a bit above ground level is par for the course -- Masten and Armadillo have also propped the legs up at launch, and even launching model Estes rockets you're advised to ensure your engine is 6" up to avoid Bernoulli Lock (http://armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=181 http://rocketry.wordpress.com/2006/10/17/the-krushnic-effect-and-the-bernoulli-lock/). And certainly the weight is resting completely on the feet at liftoff.
The MacGregor pictures are L2, so I shouldn't have chided folks for not having seen them. Sorry about that.
After taking the second look, I was reminded of how tall the stage is. I'm doubtful that the support boat can supply a crane tall enough to reach the top of the stage. So my vote is still on: put a locking pin in the legs if you need to, chain them to deck with padeyes, and sail into port with the stage vertical.
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You guys are right -- it's a crane, not a cherry picker, and the stage isn't quite sitting on the ground.
But I took a look at the pictures again, and I'm not convinced that it's not resting its weight on the legs in MacGregor. The legs appear to be standing on pedestals which are then on the ground. There's a lot of clutter in the picture, hard to tell for sure. But launching a bit above ground level is par for the course -- Masten and Armadillo have also propped the legs up at launch, and even launching model Estes rockets you're advised to ensure your engine is 6" up to avoid Bernoulli Lock (http://armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=181 http://rocketry.wordpress.com/2006/10/17/the-krushnic-effect-and-the-bernoulli-lock/). And certainly the weight is resting completely on the feet at liftoff.
The MacGregor pictures are L2, so I shouldn't have chided folks for not having seen them. Sorry about that.
After taking the second look, I was reminded of how tall the stage is. I'm doubtful that the support boat can supply a crane tall enough to reach the top of the stage. So my vote is still on: put a locking pin in the legs if you need to, chain them to deck with padeyes, and sail into port with the stage vertical.
Good logic, but offloading any risidual O2 would help with at sea stability. And if you're going to use locking pins, make sure to use cotter pins in those as well.
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Good logic, but offloading any risidual O2 would help with at sea stability. And if you're going to use locking pins, make sure to use cotter pins in those as well.
Sure. It would also make the stage less explosive if Bad Things happened. I'm pretty sure the vehicle can be commanded to vent the O2 tank remotely, no deck hands required for that.
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... I'm doubtful that the support boat can supply a crane tall enough to reach the top of the stage. So my vote is still on: put a locking pin in the legs if you need to, chain them to deck with padeyes, and sail into port with the stage vertical.
I've given this thought since the discussion about retrieving FH core stages down range. There are lots of concepts that could work given lots of money.
But I think a cost effective way to return the vehicle horizontal, and help remove it from 'Le Barge' once returned to port is to use something like a transporter erector. A base, maybe in two pieces, rolls up under the stage after landing. The de-erector (or horizontal-er) could have outriggers that extend it's footing to prevent tipping. A strong back is articulated up into place, the grab arms secure the stage and then it returns it to horizontal.
Once returned to port the de-erector and F9R are trucked off to SpaceX for refurbishment.
This whole thing could be done from the ships deck without the need of a crane. Added benefit is the stage could possibly be covered for protection from the elements on the way back to port.
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I think they will substantially re-engineer their approach if/when they plan to do this on a regular basis. The current solution is the cheap/fast/hacky way intended just for 2015.
The initial plan for Falcon Heavy refurb is to fly the booster stages back to Vandenberg. They've got cute little twin landing pads already under construction over there. There's a on-land site proposed for the core stage landing as well.
So any "production" barge landing system has quite a bit of lead time, there's no rush to get it built.
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I think they will substantially re-engineer their approach if/when they plan to do this on a regular basis. The current solution is the cheap/fast/hacky way intended just for 2015.
Huh? How did you reach that conclusion? Sources please! (That's a serious question, I'm not trying to be a jerk :) ).
My take is if they spent the millions custom building a brand new 300x170 ft. catamaran complete with on-station engines for landing a booster, then they're doing it for the long haul, and they're building in the features they think they need now for years of future operations.
Maybe they'll add more options down the road (I certainly hope so), but they are not taking a "hacky" approach by building a brand new boat- unless of course, they couldn't dream up any other cheaper or faster alternative, and I just don't think that's a realistic outcome.
Think about it. Once they've got their carrier deck operational, they can haul that thing anywhere. It opens up tons of different launch paths, booster return options, and the ability to recover the booster when launching larger and higher payloads. The FH core jumps right out as needing a landing spot that can't be RTLS.
Yes, it will be cheaper to return the booster back to dry land, but it's still vastly cheaper to land on the barge than loose the booster in the ocean for heavier or higher altitude launches. I bet they recover their barge construction capital with one booster recovery (and reflight).
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I think they will substantially re-engineer their approach if/when they plan to do this on a regular basis. The current solution is the cheap/fast/hacky way intended just for 2015.
Huh? How did you reach that conclusion? Sources please! (That's a serious question, I'm not trying to be a jerk :) ).
My take is if they spent the millions custom building a brand new 300x170 ft. catamaran complete with on-station engines for landing a booster, then they're doing it for the long haul, and they're building in the features they think they need now for years of future operations.
I should have stated that my conclusion was speculation, based on the hints we have obtained. It's also informed by rumors about the Falcon Heavy landing plans in L2, which do *not* involve boats.
So yeah, I don't expect to see a "brand new 300x1700ft" custom built catamaran. I expect to see a bunch of standard ocean-going-barges lashed together, with off-the-shelf outboard station-keeping thrusters welded on, and a radio. Perhaps a crane or other surface equipment bolted on, but all stock stuff. Just out-of-the-ordinary and complex enough to make it more cost effective to buy rather than lease (and/or no barge owners were thrilled about leasing when they knew it would be directly below an incoming rocket).
Considering that the landing campaign is projected to last a year (source: Elon's talk at MIT), it probably doesn't take much for it to be cheaper to buy than rent.
Anyway, that's my *speculation*. You're welcome to disagree. We'll see who's right when we get some pictures of a successful landing. If the barge is ugly as sin, I win.
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My take is if they spent the millions custom building a brand new 300x170 ft. catamaran complete with on-station engines for landing a booster, then they're doing it for the long haul, and they're building in the features they think they need now for years of future operations.
I think they're doing what they need to do in the short term, in such a way they can evolve down the road if they decide barge landings make sense in some contexts. The primary reason they are doing it right now is because they need to do it as a bridge to RTLS, which is their immediate focus.
I think it is premature for us to conclude this is something they plan on using for sure down the road, just that it is something they could use down the road depending on how things go.
SpaceX has shown a tendency to build for the short term, not the further off future. They way they have built launch pads, for example at LC40, where it was sized for F9 even though they knew FH would be coming down the pipe sooner or later. At Vandy they built the TEL for FH but not everything was sized for FH (seemingly). I'm not saying this is good or bad, but just what their MO seems to be. So I find it doubtful they are spending more money than they have to, for their immediate need.
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My take is if they spent the millions custom building a brand new 300x170 ft. catamaran complete with on-station engines for landing a booster, then they're doing it for the long haul, and they're building in the features they think they need now for years of future operations.
I think they're doing what they need to do in the short term, in such a way they can evolve down the road if they decide barge landings make sense in some contexts. The primary reason they are doing it right now is because they need to do it as a bridge to RTLS, which is their immediate focus.
Yeah, spending a lot on the barge by itself doesn't mean they plan to use it long term. It's only a sign of long-term plans if there was a cheaper alternative to prove they could land stages before they're allowed to set down on dry land. So far, I have yet to see any evidence of a cheaper alternative. Everything that's been talked about for this barge is pretty much the minimum they need to successfully set down a core at sea and bring it back intact, which is probably a prerequisite for being allowed to fly one back to the Cape.
They need the platform to remain stable during the landing attempt -- stable enough a really tall, narrow object doesn't tip over -- while far out to sea in unknown sea conditions. And they need it to be able to handle the flaming end of a large rocket engine for several seconds. And they need enough equipment to secure the stage. And very likely they need all that to work on a platform with no people aboard or nearby during the landing attempt.
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Perhaps they could use a helicopter to drop an inflatable collar affixed with coiled guy wires around the booster. Once the booster has been safed, the crew could wirelessly unspool the cables and attach the free ends to the barge.
Or more easily, perhaps, cables could be hoisted to attachment points on the collar.
I'm not an engineer, but it's fun to think about. :)
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Perhaps they could use a helicopter to drop an inflatable collar affixed with coiled guy wires around the booster. Once the booster has been safed, crews could wirelessly unspool the cables and attach the free ends to the barge.
I'm not an engineer, but it's fun to think about. :))
A helicopter capable of flying hundreds of miles out to sea with a heavy weight affixed to the bottom is. . . rather expensive.
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A helicopter capable of flying hundreds of miles out to sea with a heavy weight affixed to the bottom is. . . rather expensive.
Okay. But why couldn't it be transported on a ship to the landing area?
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They need the platform to remain stable during the landing attempt -- stable enough a really tall, narrow object doesn't tip over -- while far out to sea in unknown sea conditions. And they need it to be able to handle the flaming end of a large rocket engine for several seconds. And they need enough equipment to secure the stage. And very likely they need all that to work on a platform with no people aboard or nearby during the landing attempt.
It's really tall and narrow but it's really heavy at the bottom. Kinda like one of those punching dummies.
And they're only really aiming at a 1-in-12ish chance of recovery, since their 2015 manifest is *full*. That means they can aim for something that will work "if the sea conditions are good" and rely on probability to ensure that at least once of the launches in the next year will have adequate sea conditions.
Some of the folks with complex schemes and expensive boats seem to be trying to design something that will *always* work. I don't think SpaceX is trying to do that at all, at least not in 2015.
The only thing that they need to *always* ensure is the safety of the crew. That's why I've said I wouldn't be surprised if they managed to land one of these things but end up letting it topple over because it wasn't safe enough to approach and secure. That would still be a huge success.
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A helicopter capable of flying hundreds of miles out to sea with a heavy weight affixed to the bottom is. . . rather expensive.
Okay. But why couldn't it be transported on a ship to the landing area?
I guess you could. But now your straying into comedically overcomplicated territory.
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The only thing that they need to *always* ensure is the safety of the crew. That's why I've said I wouldn't be surprised if they managed to land one of these things but end up letting it topple over because it wasn't safe enough to approach and secure. That would still be a huge success.
Yes.
The point would be to advance the program.
Likely you vent props and passivate as much as possible autonomously. Batteries run out as you consider safe options given conditions. Likely pressurant issues are your biggest hazard.
Easiest way to get a crane out is to fly out via heli.
You might even lighten the load by vertically removing engines with limited equipment. Or inspect in place.
But to handle regular, reusable transport back might be out of scope.
add:
The issues of approaching the autonomously safed stage are no different than with flights of Grasshopper/F9R at McGregor. Likewise other handling issues. Perhaps look to them as a model?
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This whole barge system is turning into a real Rube Goldberg Machine.
Let's simplify things.
Just send these guys over to hold it up.
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Easiest way to get a crane out is to fly out via heli.
You might even lighten the load by vertically removing engines with limited equipment. Or inspect in place.
But to handle regular, reusable transport back might be out of scope.
Actually, no. The easiest way to get a crane out is on board of the command/support ship. The one that has all the people on board watching the stage land..
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The easiest way to get a crane out is on board of the command/support ship. The one that has all the people on board watching the stage land..
Like this:
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The easiest way to get a crane out is on board of the command/support ship. The one that has all the people on board watching the stage land..
Like this:
I guess that's one they prepared earlier. :)
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I'm sure SpaceX has already figured out how to handle the stage to their satisfaction. One thing I'm wondering is if they plan to ever move the first stage around while in a vertical position. Say, once RTLS is up and running: the stage lands, is safed and then what? Obviously they have a plan to stow the legs, move it horizontal and process for re-flight. My question is: where? Do they have a crane at the launch site (as in Texas) that moves to the rocket, or do they have some sort of wheeled gear that jacks up the four feet of the legs and then they tow the stage a short distance to wherever a more permanent "tip-it-over-and-lay-it-on-the-trailer" set-up is?
I'm sure they've got a handle on it, I'm just curious about the trade-offs, especially if this is successful and the flight rate picks up.
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Assuming the 1st stage lands in one piece, is secured and taken to port. Where would that port be?
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Assuming the 1st stage lands in one piece, is secured and taken to port. Where would that port be?
I think it will be Cape canaveral, and perhaps where the Pegasus/ET landed.
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First just land it, then if it falls over, too bad. If not, then just send some guys/gals out on a speedboat and spot weld it to the deck (or weld some chains to the deck that loop over and through the feet)
To be honest though Just landing the damn thing is momentous enough. What are the seas like out there at this time of year?
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December is very calm. Storms are infrequent.
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I'm sure SpaceX has already figured out how to handle the stage to their satisfaction.
Looking at the dragon pictures, I'm actually struck by the fact that they seem to be using different boats and crane arrangements each time. So I think they haven't actually figured it out, but are still in the process of trying different things and seeing what works. Alternatively, their requirements are very flexible, so they just hire whatever boat/barge/crane is cheapest and available on the dates they need it. The actual SpaceX equipment (tracking radios, etc) seems to be mounted in those rectangular modules, so they can just pick it up and put it on whatever boat they have handy.
The barge-mounted crane above is quite large. I might take back my previously expressed belief that they wouldn't try to lay the stage down horizontally. I'd have to work harder to figure out the exact size of that crane compared to the MacGregor crane and the height of the stage to be sure.
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Assuming the 1st stage lands in one piece, is secured and taken to port. Where would that port be?
I think it will be Cape canaveral, and perhaps where the Pegasus/ET landed.
Pic of Pegasus barge docked in the turning basin near the VAB.
(http://www.nasa.gov/centers/marshall/images/content/602908main_2011-7703_516x344.jpg)
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If the stage comes back vertical, cabled to the deck I would expect the Middle Turning Basin docks of Port Canaveral to be a logical place to dock and offload. There are large wharves, large cranes already on site, and a 175 wide foot barge does not have to be threaded through the drawbridges and narrow channel all the way up to the foot of the VAB. Its a shorter road transport back to Spacex's pad hangar or the CCAFS industrial area from there as well.
http://goo.gl/55XpRB (http://goo.gl/55XpRB)
An almost as likely place would be the old SRB recovery docks at CCAFS, although a crane will need to be brought in and a drawbridge passed through.
http://goo.gl/sgXfAU (http://goo.gl/sgXfAU)
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If the stage comes back vertical, cabled to the deck I would expect the Middle Turning Basin docks of Port Canaveral to be a logical place to dock and offload. There are large wharves, large cranes already on site, and a 175 wide foot barge does not have to be threaded through the drawbridges and narrow channel all the way up to the foot of the VAB. Its a shorter road transport back to Spacex's pad hangar or the CCAFS industrial area from there as well.
http://goo.gl/55XpRB (http://goo.gl/55XpRB)
If it comes back horizontal, probably lots of ports would be suitable. Since the landing site is north, it might not back sense to come back all the way south to Port Canaveral.
For CRS-3 there was speculation that one of the search boats left from Port Canaveral and returned to Jacksonville: http://forum.nasaspaceflight.com/index.php?topic=34500.msg1186042#msg1186042
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Remember though, this is mostly temporary. The real goal is to enable landing on a pad near the launch site, where a forklift-mounted cradle can be driven up to it so that they can lay the whole thing down.
Then we can argue about what the barge will do with the FH center core.
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Assuming the 1st stage lands in one piece, is secured and taken to port. Where would that port be?
I think it will be Cape canaveral, and perhaps where the Pegasus/ET landed.
Pic of Pegasus barge docked in the turning basin near the VAB.
(http://www.nasa.gov/centers/marshall/images/content/602908main_2011-7703_516x344.jpg)
I did not imagine that dock is relatively deep inland, forget about it then. There are other docks at cape canaveral though.
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Assuming the 1st stage lands in one piece, is secured and taken to port. Where would that port be?
I think it will be Cape canaveral, and perhaps where the Pegasus/ET landed.
It can't come up the channel to the turn-around basin unless they off-loaded it to another vessel. For a barge 160 feet wide, the Banana River Bridge and the Canaveral locks are too narrow.
Besides, the turn-around basin is further up than they want to go. The Trident Pier makes a great off-loading point with easy road access back to the SpaceX facilities and a 120 ton stevador crane (with an operator who is presumably familiar with handling missiles!) :) there already. Port Canaveral could also handle a barge 160 feet wide just fine, and I can see the thing living there between flights.
Jim may be able to speculate best on this question.
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During CRS-3 it was supposed to happen this way if not for the Kaboom -
The returned first stage is supposed to go back into Charleston if they find it. It's where the commercial recovery boats were coming from originally, but the sea states were too bad and SpaceX ended up getting the Navy to do it.
I don't know whether Charleston S.C. was the closest port with barge to truck infrastructure for that particular landing or if Charleston is of some special significance which may come into play this time.
Now changing states to Louisiana, how about somebody posting a picture of that barge.!? Now is three weeks from then, its gotta be either ready to roll or rolling by now.
Mark
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By the way, some people don't realize, that ESA calculated a trajectory for their Rosetta mission, which traveled for 10 years, billions of miles and guess what? They made it! I think SpaceX has more than a decent chance of landing on the barge, comparing it to Rosetta, the barge is easy...
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I think SpaceX has more than a decent chance of landing on the barge, comparing it to Rosetta, the barge is easy...
Noah - I like your positive attitude... but no. As a pilot I can tell you that transitioning a vehicle through supersonic, transonic, and subsonic flight regimes (all in an atmosphere that is moving in 3 dimensions while you also transit through it in 3 dimensions) is much harder than coasting through open space and simply accounting for gravity and an occasional stray gas molecule!
--Noel
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Well thanks for letting me know. I'm sure both is hard ;)
I'm still pretty optimistic though.
Can we expect grid fins for landing on the barge?
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The first mission is the mission- CRS-5.
Everything else will proceed with as much leeway as the customer- NASA in this case- will agree to permit on any given flight.
Every change adds risk and possibility of delay- so SpaceX will just have to proceed if/as they can.
Has anyone that would actually know commented on whether there is anything funky protruding from the interstage for CRS-5?
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Coming into this discussion late. Not sure how much of this may have been mentioned. Some comments, thoughts, and speculation of possibilities. It'll be very interesting to see what Space-X ends up doing to solve some of the issues.
A potential way to help secure the landed Falcon on the deck of a barge would be for the foot pads of the landing gear to have a number of small "barbs" attached to the bottom of each one. While the landing surface of the Barge would have something like a steel grid system that the barbs would fit and hook into when it landed.
(http://upload.ecvv.com/upload/Product/20111/China_Floor_Steel_Grating20111111704492.jpg)
The Russians were going to do something along this line for docking their Lunar Lander. No real docking port. When it returned from the surface of the moon, it would have dozens of barbs on the top of the lander that would hook into a net-like device attached to the orbiting Soyuz 7K-LOK spacecraft. Then the cosmonaut would space-walk to get inside.
Anyway, if Space-X only plans to do this for a very small number of test flights, and are banking on doing landings on solid ground after a few barge tests, then it may not be worth the $ to temporarily rig up a rented barge this way.
Even with a "high tech velcro" foot pad system, that might not be enough by itself, so I have given some thought to a way to help to tie it down from the top, like guy wires. The crude (but perhaps effective) way would be to have a person on a helicopter lowered down to attach 3 to 4 lines to easy-attachment points on top of the first stage. The logistics and cost, and some risk, are a drawback. An easier way would be if the top of the stage they had a system installed that once fired would act like a mortar to eject 4 kevlar ropes to fall down the sides of the rocket, no need for a copter. But of course the mass of the system, plus the R&D to develop it and build it and needing to have a "Plan B" if it failed to work. So for a few test flights that might not be worth it.
A higher-tech method with no risk to humans would be to use a model Multicopter (some call them "drones") to attach the Kevlar lines.
BTW - some of the Grasshopper videos scenes were shot by an airborne multicopter. Perhaps that's 100% purely for documentation. But longer term, if the multicopter crew is in-house and not 100% relying on hobby parts, perhaps some part of Space-X's work could go towards use of multicopters for practical assistance with flight operations beyond just video.
It is amazing how automated and stable a $500 modern R/C multicopter can be, where to some extent a human "interrupts" it to make it move someplace else. I have seen a video where one multcopter accidentally landed on top of an old castle tower and fell over, impossible for a person to climb up to get it. Another person used a multicopter (Live FPV video beamed back) with a line and hook, to grab and rescue it.
Another aspect of the problem of making the system capable of handling rough seas is simple enough. No need to. Don't launch. These flights are not time-critical, no special launch window where delaying a few days or a week or two for better weather will ruin the mission. Now in the long term they would want to avoid limitations like that. But in the short term for just a few test landings on a barge, it doesn't seem to be a much of a problem compared to potentially toppling over in rough seas.
I can't see much purpose in landing on a barge, just for landing on a hard surface, and then letting it topple over by plan or neglect. Now of course the landing itself would be historic, in the sense of a first stage of an orbital launch vehicle to soft-land intact on a hard surface. But when the whole point is practical reusability, not history, not some "prize", they will want to be able to bring it back intact to their facilities. For one, to check it over for damage, see how much refurbishment it needs and what changes may be needed down the road depending on what they see. And the cherry on top will be to actually re-fly it.
If it works, and they re-fly it and that second flight also lands successfully, at that point they might want to retire it and donate it to the Smithsonian.
- GeorgeG
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so basically steel velcro. I like it :)
I don't. Think of the thermal environment at landing time. I am not sure any type of "velcro" can tolerate Merlin1D exhaust and still be reliable seconds after that.
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They should land it on an ocean-going trampoline...just for spite and irony!!
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At the very least paint one somewhere on the deck and/or take an earlier suggestion and name it Trampoline.
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How about a Reverse Russian Gantry, using a retension strap between the gripping pads.
Once the stage had landed, the gantry would be tripped using counterweights to bring up the gantry uniformly around the stagea kevlar strap would be run between each of the gripper pads, that would retract as the gantry tipped up once upright, the grantry's gripper pads, (about a foot and a half thick with a thermal blanket around each pad) would either press against the sides of the stage holding it rigid, or they would be cranked into position, (assuming an off center landing) then locked down holding it into position until towed back into port.
The gantry would grip the stage about half way up, to both stablize it and prevent it from shifting.
Maybe a dumb idea, but it seems more practical than most other ideas.
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Why does everyone assume that the 1st stage is in danger of tipping over after it lands on the barge?
Anyone know what angle the barge would have to attain before there was a danger of that?
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so basically steel velcro. I like it :)
I don't. Think of the thermal environment at landing time. I am not sure any type of "velcro" can tolerate Merlin1D exhaust and still be reliable seconds after that.
oh I am not saying it would work, I just like the concept. That said, I'm not sure you're right about what is basically a steel grid being unable to tolerate the Merlin 1D exhaust. the melting point of steel is 2500F and a pretty high specific heat capacity/latent heat of fusion and it would have to be under pretty sustained heating over the entire area of the grid to melt it. Given that the contact point would only be at the ends of the feet, those regions of a mesh would not be heated significantly (if they were, the feet themselves would be heated. The legs are made of Carbon Fiber/Aluminium - the latter has a melting point of 1660F). They could also have water hosing the whole thing down too.
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Without flooding, a thin steel grid (member thick 5mm) will deform badly after a single landing.
Flooding is (IMHO) a must to keep the deck at a reasonable mass.
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so basically steel velcro. I like it :)
I don't. Think of the thermal environment at landing time. I am not sure any type of "velcro" can tolerate Merlin1D exhaust and still be reliable seconds after that.
oh I am not saying it would work, I just like the concept. That said, I'm not sure you're right about what is basically a steel grid being unable to tolerate the Merlin 1D exhaust. the melting point of steel is 2500F and a pretty high specific heat capacity/latent heat of fusion and it would have to be under pretty sustained heating over the entire area of the grid to melt it. Given that the contact point would only be at the ends of the feet, those regions of a mesh would not be heated significantly (if they were, the feet themselves would be heated. The legs are made of Carbon Fiber/Aluminium - the latter has a melting point of 1660F). They could also have water hosing the whole thing down too.
Maybe, but ISTM that structural deficiencies start well below the melting point, especially under load of a Falcon9 booster.
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Empty can, not much load.
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Why does everyone assume that the 1st stage is in danger of tipping over after it lands on the barge?
Anyone know what angle the barge would have to attain before there was a danger of that?
As far as is currently known, the plan involves the use of a barge that uses thrusters to maintain its position. Should the stage return in heavy weather, it would highly likely that the barge itself may be in an unstable position, or made unstable depending on wind and weather conditions. Being East Coast of Florida weather, it could EASILY change in minutes.
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Why does everyone assume that the 1st stage is in danger of tipping over after it lands on the barge?
Anyone know what angle the barge would have to attain before there was a danger of that?
As far as is currently known, the plan involves the use of a barge that uses thrusters to maintain its position. Should the stage return in heavy weather, it would highly likely that the barge itself may be in an unstable position, or made unstable depending on wind and weather conditions. Being East Coast of Florida weather, it could EASILY change in minutes.
You're waving your arms at the problem. That never works.
-It is landing in December. The weather 200 miles out to sea is not usually so unstable it changes in minutes.
-There is an amount of instability that is tolerable. There is an amount that isn't. The question is how much is too much. We can calculate center of gravity for the stage. We can calculate how much wave action would translate into motion of the platform. Then we can add them together to see what's too much.
To answer the original question, I saw some math done by some folks on here (I think upthread) and the general answer that they came up with was that 10 foot waves would cause a roll of 2 degrees for a barge 300 feet long, and this would be no problem for a stage that would not tip until it was tilted 28 degrees (though it would likely fail far before tipping this far for other reasons like stress in the tanks at the leg junctions).
All these rube goldberg ideas are cute, but completely unnecessary for what they are trying to do.
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Remember: it doesn't have to land in *all* conditions. It just has to successfully land once in 2015.
If people have read the Armadillo/Masten blogs, they might remember that the real risk of a tipping deck is *not* that the stage will fall over once landed -- the stage is bottom heavy and very stable.
The tricky part about landing on a pitching barge is that you get control law inversion once a foot is in contact with the deck.
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Remember: it doesn't have to land in *all* conditions. It just has to successfully land once in 2015.
If people have read the Armadillo/Masten blogs, they might remember that the real risk of a tipping deck is *not* that the stage will fall over once landed -- the stage is bottom heavy and very stable.
The tricky part about landing on a pitching barge is that you get control law inversion once a foot is in contact with the deck.
I did a quick search and looks like pretty heavy reading..
https://www.google.com/search?client=opera&q=control+law+inversion&sourceid=opera&ie=utf-8&oe=utf-8&channel=suggest&gws_rd=ssl
any suggestions of a good article or source to start with to learn more about "control law inversion" ??? Thanks!
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http://armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=331
Carmack notes that this only applies if the gimbal point is below the CG ... at the time he was starting to work with their 4-tank vehicle which has the engine in the middle and thus actually has the gimbal point above CG.
I think you can easily draw a stick figure force diagram and convince yourself that the friction of the foot that's dragging on the ground causes the inversion, and why putting the gimbal above CG fixes this issue (basically that reverses the direction you gimbal the engine in order to yaw the vehicle).
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any suggestions of a good article or source to start with to learn more about "control law inversion" ??? Thanks!
http://armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=311 also mentions the control law inversion.
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I agree that it is likely that the issues of Falcon toppling over will probably not require special solutions. But they had crossed my mind, and some aspects had been discussed earlier, so I wanted to mention them anyway. Also to get them on the record just in case Space-X actually did any of it…. :)
Obviously by now they've already decided what to do and are preparing the barge.
It is funny to see some of what I mentioned dismissed as "science fiction". Hello, re-useable rocket re-entering the atmosphere to land vertically under thrust back where it was launched from. A CLASSIC Science Fiction concept, coming true. While the things I mentioned are either technically possible today or downright brute-force not hard (the barbed foot pads on steel grating). It's more of a matter of whether they are necessary and/or worth the cost of doing, and/or they have much better ways of addressing the problems that do seem to be more serious.
I will mention about the idea of barbs on the foot pads, landing on steel grating, that while it is not likely they would do this, some of the issues brought up about it would not be deal-breakers technically. The grating would not be exposed to the exhaust but for a few seconds. The area right under the exhaust would not have to hold up any weight, simply not melt to the point of fragmenting and throwing debris around. The areas the feet would land on would not get THAT hot to structurally weaken the grating. But the grating would definitely need to be strong enough to withstand the structural loads of the landing and Falcon's foot pads sitting on top of it….. far more than the lightweight grating as used for people to walk on (as in the picture I attached before). The grating directly under the exhaust would indeed probably be damaged/weakened too much for future landings and would need to be replaced. If the grating was in say 6 x 6 or 10 x 10 foot sections, the damaged areas would be replaced as-needed. I must admit that I do not know the specs for what kind of pre-existing thick and sturdy-enough steel grating might be out there. And it would need to be pre-existing since it would not be worth having dozens of custom steel grate panels welded up. .
I would not assume Falcon will land so precisely that any pre-mounted fixture can clamp itself around it (Neat idea though). If Falcon lands say 12.8 feet from dead center, they need to have some method of securing it that is not keyed to it landing on an exact spot..
Now that I have read about a 300 foot long barge, I could imagine they might simply have a crane or cherry-picker at a far end (lets say north), with the targeted landing spot a bit south of dead center of the barge, to keep it a bit more away from the end with the crane/cherry-picker. After landing, then one or more people could go aboard to run the crane or cherry-picker so that lines could be run to the top to help secure it. Unless they have some other method of securing it that would not require a tall reach. There could be many other ways, especially if they could use some sort of moveable anchoring system that could be attached directly to the same hard points the rocket is attached to the launch pad with. But it would take time to move those into place and everything secure, so, not ideal.
To answer the original question, I saw some math done by some folks on here (I think upthread) and the general answer that they came up with was that 10 foot waves would cause a roll of 2 degrees for a barge 300 feet long, and this would be no problem for a stage that would not tip until it was tilted 28 degrees (though it would likely fail far before tipping this far for other reasons like stress in the tanks at the leg junctions).
I also think the problem has been somewhat overblown. If only due to one of the last things I mentioned… don't launch when the seas will be too rough, and/or winds likely to gust too much.
Still, stuff happens, and it would be bad to assume that a decent to average day at sea is the same as standing on the dock. So, there are issues, just a matter of what level can be expected as most likely, and working up flight rules with constraints to limit some of those issues (predicted ocean waves and winds during landing and until the barge can be brought back to port). And what level is Space-X prepared to deal with them for a few flights. To the point that perhaps rather than solve some of them they would accept the temporary risk of the tests, unlike what they would need to do for routine landings that way.
But I do wonder about the numbers for a 300 foot long barge. Because it's not going to be a 300 foot square barge. If it's a 300 by 75 foot wide barge and the rolling comes from the sides (and indeed rolling for ships and aircraft is along the lengthwise roll axis, not the pitch axis), then if it is true that 10 foot waves would cause it to pitch 2 degrees over a 300 foot length, then a crude approximation would be for waves along the sides could make it roll 8 degrees (4x) for a 75 foot wide barge or 6 degrees (3x) for a 100 foot wide barge. Now, they could perhaps address that by using the thrusters to orient it so the barge always has the "bow" pointed into the waves, but that would only help for the landing and not to tow it back to port as the waves could come from 90 degrees.
But the maximum roll in degrees is not the full extent of the problem. It is the MOMENTUM of the rolling back and forth. We are not talking of just a slow static tilt of say 8 degrees, it is swinging back and forth 16 degrees over a span of a few seconds, over and over. This can set up a harmonic cycle where the Falcon could in worst case literally fall over in response to the cycle of the rolling back and forth. But before it got so bad that it could fall over, assuming the landing gear didn't collapse first, it would have problems of "walking", where it tips very slightly on two legs and moves across the deck a little bit with each cycle. Eventually it could end up moving to the edge of the barge, then falling over.
After all, the Falcon is pretty tall with not a very wide footprint, even though the CG is lower down due otte tanks being almost completely empty. It's not like the Apollo Lunar module which had sort with a very wide footprint.
Also the Apollo LM did not have to deal with winds but if it ever did it could handle wind way better than Falcon can.
So, let's say 10-foot seas, it is on the deck of a barge that is now being towed back to port, at 10 mph. There are headwinds that are coming from the opposite direction, only 10 mph but gusting to 20 mph. The result would be a total of sometimes 30 mph winds on the totally unsecured Falcon, plus potentially rolling seas at 90 degrees to the direction of travel. A pretty reasonable chance that something bad would happen in that case, during the hours of towing it back. And that is not a far-fetched or extreme scenario.
Now if it is close to shore, and in sheltered waters then it would be less of an issue.
So, they will probably have a need to do something to help secure it so it won't slide or walk or move due to deck motion and wind. What they do will depend on how serious the problem may be according to their analysis, and what is the most cost-effective and time-practical compromise choices (including accepting some risk level) to make given that they will only do this a few times.
Meaning that they would not put as much money and time into ideally solving the problems for a few test flights as they would if they planned to do this dozens or hundreds of times on a barge. They could afford for one to topple over after landing in the current test series as opposed to later when they are banking on reusing them (though a prudent part of the business plan would be that they won't expect to re-use them every time, one will be lost every once in awhile or perhaps no longer cost-effective to refurbish after "X" number of flights or whatever random factor).
- George Gassaway
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George, please read the earlier pages in this thread. Most of the topics you mention have already been discussed at length here.
Now that I have read about a 300 foot long barge, I could imagine they might simply have a crane or cherry-picker at a far end (lets say north)
The crane/cherry-picker will be on the support boat, not the barge. Look up-thread, we actually have pictures of it already on previous flights.
I also think the problem has been somewhat overblown. If only due to one of the last things I mentioned… don't launch when the seas will be too rough, and/or winds likely to gust too much.
This has also been discussed at length. SpaceX will not delay their primary mission for landing conditions. They will launch when the primary mission says. If the weather is okay in the landing area, maybe they'll land all right. If it's not -- well, maybe they will get lucky. They only expect to land at sea one or a few times in 2015, not *every* time they launch, and only until they get range clearance to land at the Cape.
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More good info from Chris on the upcoming CRS-5 barge landing attempt, including confirmation of grid fins:
http://www.nasaspaceflight.com/2014/11/crs-5-dragon-mission-iss-evaluating-december-target/
Also noteworthy is the confirmation that LC-13 continues to be the prime candidate for future landings at the Cape.
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Remember: it doesn't have to land in *all* conditions. It just has to successfully land once in 2015.
If people have read the Armadillo/Masten blogs, they might remember that the real risk of a tipping deck is *not* that the stage will fall over once landed -- the stage is bottom heavy and very stable.
The tricky part about landing on a pitching barge is that you get control law inversion once a foot is in contact with the deck.
It's not so much the mass balance issue I'm thinking of but the height and width of the stage as well. An empty fuel tank shaped like that could act very much like a sail, moving or even tipping the stage over.
High winds off of the Florida East coast can whip up in seconds. And while you may have calm winds on the barge, fifty feet up you could be getting 50 to 60 mph wind gusts and never even know it. The gantry idea that I mentioned is more to stabilize it in case of winds that could even cause the whole stage to buckle.
So, unless they lay the stage down pretty quick after landing, it runs the risk of damage, one way or another, from the wind.
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George, please read the earlier pages in this thread. Most of the topics you mention have already been discussed at length here.
Now that I have read about a 300 foot long barge, I could imagine they might simply have a crane or cherry-picker at a far end (lets say north)
The crane/cherry-picker will be on the support boat, not the barge. Look up-thread, we actually have pictures of it already on previous flights.
I also think the problem has been somewhat overblown. If only due to one of the last things I mentioned… don't launch when the seas will be too rough, and/or winds likely to gust too much.
This has also been discussed at length. SpaceX will not delay their primary mission for landing conditions. They will launch when the primary mission says. If the weather is okay in the landing area, maybe they'll land all right. If it's not -- well, maybe they will get lucky. They only expect to land at sea one or a few times in 2015, not *every* time they launch, and only until they get range clearance to land at the Cape.
And once they start actually returning to the launch site, I'll guess that they can land in any weather they can launch in, so there would be no issues.
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And once they start actually returning to the launch site, I'll guess that they can land in any weather they can launch in, so there would be no issues.
That's one major advantage of RTLS over downrange recovery. I learned to appreciate that over time reading all the discussions about it and seeing launch delays due to weather.
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So, unless they lay the stage down pretty quick after landing, it runs the risk of damage, one way or another, from the wind.
Yup, that's a risk they take with these experimental flights. They'd just lose the hardware anyway otherwise.
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The main reason to think they will have the means to lay the stage down for 'transportation' is the fact that's how the stage is designed and built to BE moved.
Randy
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Further to the discussion of will-the-stage-be-laid-back or steel-velcroed, and AITHABD*, but recall that there were SpaceX job postings asking for folks to engineer fully automated service equipment for landed stages. This always struck me as a little over-engineered compared to "dude/tte with a forklift." It also struck me that building the barge just to demonstrate pinpoint landing was going a tad far compared to "floating ring of pool noodles". Could it be that they are planning on using such automated systems on the barge, presumably for FH center cores, as SOP? Consequently, no expensive and dangerous human-tending required. The stage could then be recovered by boat-with-cherry-picker or (oh god yes YES) self-ferry back. Perhaps the down-range island notion is a backup plan?
(*Apologies If This Has Already Been Discussed)
(and a tad OT, but not deserving of its own thread)
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And once they start actually returning to the launch site, I'll guess that they can land in any weather they can launch in, so there would be no issues.
That's one major advantage of RTLS over downrange recovery. I learned to appreciate that over time reading all the discussions about it and seeing launch delays due to weather.
Agree about the operational advantage of RTLS over downrange recovery. But the other point, can you always land safely at the launch site if the weather is safe to launch, I'm not so sure about.
It seems to me that a fully loaded vehicle lifting off with the control authority of 9 engines might be less vulnerable to gusty winds than an almost empty stage landing using only one engine and grid fins for control. If that's true, the weather limits might have to be set more narrowly for the launch of a recoverable vehicle than for an expendable one.
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Agree about the operational advantage of RTLS over downrange recovery. But the other point, can you always land safely at the launch site if the weather is safe to launch, I'm not so sure about.
I won't say you are wrong but there are factors. At launch you don't want a gust of wind push the rocket towards the TE. At landing you have more leeway. So different situations at launch and landing may cancel out. Also at landing they may be willing to take a 1% chance of failure due to weather that they won't accept on launch. It all depends on how flexible the launch time is. Can they afford to delay a day, an hour for better conditions for RTLS or not?
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And once they start actually returning to the launch site, I'll guess that they can land in any weather they can launch in, so there would be no issues.
That's one major advantage of RTLS over downrange recovery. I learned to appreciate that over time reading all the discussions about it and seeing launch delays due to weather.
Agree about the operational advantage of RTLS over downrange recovery. But the other point, can you always land safely at the launch site if the weather is safe to launch, I'm not so sure about.
It seems to me that a fully loaded vehicle lifting off with the control authority of 9 engines might be less vulnerable to gusty winds than an almost empty stage landing using only one engine and grid fins for control. If that's true, the weather limits might have to be set more narrowly for the launch of a recoverable vehicle than for an expendable one.
You are missing the obvious point. The core advantage with RTLS for weather is that you only have to worry about weather at ONE site, not TWO.
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You are missing the obvious point. The core advantage with RTLS for weather is that you only have to worry about weather at ONE site, not TWO.
Look at the discussion starting with this post.
http://forum.nasaspaceflight.com/index.php?topic=35244.msg1291061#msg1291061
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You are missing the obvious point. The core advantage with RTLS for weather is that you only have to worry about weather at ONE site, not TWO.
No I'm not. I was raising a different point to see what the response would be.
@guckyfan: that's an interesting point. There are certainly a number of factors to consider.
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Further to the discussion of will-the-stage-be-laid-back or steel-velcroed, and AITHABD*, but recall that there were SpaceX job postings asking for folks to engineer fully automated service equipment for landed stages. This always struck me as a little over-engineered compared to "dude/tte with a forklift." It also struck me that building the barge just to demonstrate pinpoint landing was going a tad far compared to "floating ring of pool noodles". Could it be that they are planning on using such automated systems on the barge, presumably for FH center cores, as SOP? Consequently, no expensive and dangerous human-tending required. The stage could then be recovered by boat-with-cherry-picker or (oh god yes YES) self-ferry back. Perhaps the down-range island notion is a backup plan?
(*Apologies If This Has Already Been Discussed)
(and a tad OT, but not deserving of its own thread)
The only ways reusability will succeed is if the price of a rocket launch falls a lot. Elon knows this. He also knows that launching a rocket is very expensive, even once you take the actual physical rocket cost out of the equation. An automated system, while expensive and time consuming to build in the extreme, would do almost as much for reusability as the actual reusing of the first stage would. It is also the only way the BFR will ever be cheap enough for people to pay to go to mars.
As far as Heavy center cores landing on a barge. . . Chris wrote an article that stated they were thinking of a pacific island for that. FWIW
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Until I saw the video of core production at SpaceX that Lars-J posted (thanks Lars-J!) I had convinced myself that the core would be laid down after landing on the barge. Either using a crane and cradle on the barge (simpler and safer in rolling seas), or by offloading onto a separate boat (makes for a simpler barge but isn't as safe or cheap an operation).
In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
Now I'm thinking they may just stick blocks (metal screw jacks and chains on the deck) underneath it wherever it lands on the barge to lock it down and eliminate stress on the legs for the trip home, and then lay it down on it's transporter using the stevador crane after they get to port instead of attempting all that out at sea. Much simpler, much cheaper, and much safer for the booster and work crews.
An upright booster will be a phenomenal sight coming into Port Canaveral from the rooftop deck at Fishlips!! :)
http://www.youtube.com/watch?v=vrR31nHCV-U
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredibly rigid.
EDIT: I think I see the moment folks are looking at, when the front of the stage is lifted to hook it up to the tractor, but I don't think it's possible to distinguish between bending and pivoting rigidly.
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredible rigid.
It looked to me like about 6-8 inches of elastic (non-permanent) downward deflection at the center of the stage as it bounced onto the carts that were used to carry the stage outside for a bit. Considering the size and lightness of the stage, that is not much at all.
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredible rigid.
It looked to me like about 6-8 inches of elastic (non-permanent) downward deflection at the center of the stage as it bounced onto the carts that were used to carry the stage outside for a bit. Considering the size and lightness of the stage, that is not much at all.
That's my point. It looks very strong compared to self-collapsing the Atlas rockets of old. We've spent a lot of ink on this thread debating whether or not the booster could survive a vertical trip back to the shore. I was in the "no it can't" camp until I saw the video.
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredible rigid.
It looked to me like about 6-8 inches of elastic (non-permanent) downward deflection at the center of the stage as it bounced onto the carts that were used to carry the stage outside for a bit. Considering the size and lightness of the stage, that is not much at all.
I don't see that at all. You are reading an awful lot into footage where A) it is a time-lapse and B) 6-8 inches would be what... a pixel?
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredible rigid.
[/quote]
I'm a mechanical engineer, not structural, but from the few structural classes I did take I don't think being pressurized is going to make very much difference on how much a stage would sag when lifted at both ends.
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I don't see that at all. You are reading an awful lot into footage where A) it is a time-lapse and B) 6-8 inches would be what... a pixel?
It may have been a figment (a pixel) of my imagination. Looking at the video again, I don't see it this time. What I do see is a lower one end, then lower the other end sequence, with the stage visibly straight between the ends the whole time. Perhaps my mind did one of those "bend the pencil" illusion tricks to itself...
EDIT: Somebody in one of the other topic threads posted a high resolution, slowed down version of the video, and the rigidity of the stage is even more apparent there.
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredibly rigid.
I'm a mechanical engineer, not structural, but from the few structural classes I did take I don't think being pressurized is going to make very much difference on how much a stage would sag when lifted at both ends.
http://shellbuckling.com/papers/classicNASAReports/NASASP-8007.pdf figure 6
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredible rigid.
It looked to me like about 6-8 inches of elastic (non-permanent) downward deflection at the center of the stage as it bounced onto the carts that were used to carry the stage outside for a bit. Considering the size and lightness of the stage, that is not much at all.
That's my point. It looks very strong compared to self-collapsing the Atlas rockets of old. We've spent a lot of ink on this thread debating whether or not the booster could survive a vertical trip back to the shore. I was in the "no it can't" camp until I saw the video.
Note that this rigidity will also make it more feasible to pivot the cylinder at sea. So it's probably a wash.
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredibly rigid.
I'm a mechanical engineer, not structural, but from the few structural classes I did take I don't think being pressurized is going to make very much difference on how much a stage would sag when lifted at both ends.
http://shellbuckling.com/papers/classicNASAReports/NASASP-8007.pdf figure 6
Pressurization is going to make a lot of difference in final bending strenght of the tank, but stiffness of the stage (i.e. deflection under a given load) remains the same with or without pressure.
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I wonder if the yellow harness is at the centre of mass. If so you might be able to tip the whole thing over with a much smaller rig if you can hook to that point.
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I wonder if the yellow harness is at the centre of mass. If so you might be able to tip the whole thing over with a much smaller rig if you can hook to that point.
Center of mass of empty tank by itself has no relation to the center of mass of a complete F9 first stage with engines and interstage.
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Aren't the engines on there at the far end?
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredibly rigid.
I'm a mechanical engineer, not structural, but from the few structural classes I did take I don't think being pressurized is going to make very much difference on how much a stage would sag when lifted at both ends.
http://shellbuckling.com/papers/classicNASAReports/NASASP-8007.pdf figure 6
Pressurization is going to make a lot of difference in final bending strenght of the tank, but stiffness of the stage (i.e. deflection under a given load) remains the same with or without pressure.
I find that very unlikely and would like a citation. Pressurization makes a huge difference in stiffness.
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Guys, use the grey stuff between your ears! I am no mechanic and I dont know anything about the stiffness of any rocket or anything related to the topic. But at times when knowledge is low, it sometimes helps to go to the extremes. Take a rubber balloon. If it is flat, it is floppy. If it is pressurized, it is stiff. I dont see why that should be different for a rocket.
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In the video you can see how they repeatedly pick the booster up at each end with no center slings (go to 0:13) and how the booster on the right is visibly bent in the middle until the hook it up to the semi truck (0:05). Now I can see how strong the things are against bending forces and lateral stress.
I don't see any evidence of bending. With a little bit of pressurization, the stage ought to be incredibly rigid.
I'm a mechanical engineer, not structural, but from the few structural classes I did take I don't think being pressurized is going to make very much difference on how much a stage would sag when lifted at both ends.
http://shellbuckling.com/papers/classicNASAReports/NASASP-8007.pdf figure 6
Pressurization is going to make a lot of difference in final bending strenght of the tank, but stiffness of the stage (i.e. deflection under a given load) remains the same with or without pressure.
I find that very unlikely and would like a citation. Pressurization makes a huge difference in stiffness.
Stiffness ( http://en.wikipedia.org/wiki/Stiffness ) is the property of an object (due to a combination between material properties and geometry) to resist to deformation under load.
Flexural stiffness of the stage is due to the reaction of the skin; gas inside gives no contribution to resistance to flexing forces.
This must not be confused with strenght (or resistance):
-axial resistance in vertical position -> skin in tension because pressure is actually relieved by applied static load;
-overall resistance to bending -> pressure applied stabilizes shape and avoid local buckling and collapse.
Strenght (or resistance http://en.wikipedia.org/wiki/Strength_of_materials) has no direct reference to deformation, is related to the breaking point of material or objects.
Rubber can be very strong, but for his nature never stiff.
Structural classes. as cited by wannamoonbase, are for that: understanding how it works, and ain't always simple.
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Take a rubber balloon. If it is flat, it is floppy. If it is pressurized, it is stiff. I dont see why that should be different for a rocket.
It is stiffer because his shape changes, this is the effect of pression on your rubber balloon.
Take a sheet of paper, flex it; that's easy.
Roll it forming a tube and try to flex it; suddenly it becames stiffer, much stiffer.
Shape is a very important parameter for stiffness: more distance between members in tension and members in compression means more stiffness.
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From Musk's twitter:
Testing operation of hypersonic grid fins (x-wing config) going on next flight
https://twitter.com/elonmusk/status/536258543675252739 (https://twitter.com/elonmusk/status/536258543675252739)
(https://pbs.twimg.com/media/B3EsTeDIUAAO86M.jpg)
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This isn't Engineering 101, but it isn't post-graduate study either. The rocket walls are relatively thin metal. They are somewhat reinforced (with stringers) against losing their shape, but that strength lies mostly along the walls, not through them. Furthermore, that strength is mostly in tension, not in compression.
When you apply a transverse force to the rocket (for instance, by fixing the bottom end to the ground and then pulling the top sideways (or blowing wind across it)), then in the absence of other forces there will be a compressive force on the rocket wall away from the wind, and a tensile force on the rocket wall that has the wind pushing on it. If nothing else were done, there would be a tendency for the tube to buckle on the side away from the wind, once the compressive force exceeds the compressive strength of the wall.
But, if you pressurize the tank, then you have a tensile force added uniformly to the all sides of the rocket. The side away from the wind will not buckle until the compressive force due to the wind exceeds the tensile force due to the internal pressure. That net compressive force must exceed the rocket's wall strength for buckling to occur.
It is possible, if the pressurization is too high, for the windward side to suffer tensile failure, but that would take some doing...
Another example would be in how concrete is reinforced for use in bridges. Concrete is the opposite of metal: it is good for compression and poor in tension. So to make it stronger, you compress it, so you don't have a net tension right away.
Was that clear as mud? My profession is computer programmer, but my degree was mechanical engineering.
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From Musk's twitter:
Testing operation of hypersonic grid fins (x-wing config) going on next flight
And they're WHITE!
Also notice the leading edge fairings that weren't on Grasshopper.
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While I agree with what you said, remember that F9R Dev 1 spent a lot time in TX upright with no other support than at the base and it can get pretty windy in McGregor.
I wasn't saying that Falcon was doomed to buckle. I was simply trying to explain how pressurization can help stabilize the rocket's structure. Too many people here seemed to be having trouble understanding why, so I tried to explain it as simply as I could. Not that it was "simple"...
But if the rocket can hold its own without internal pressurization, so much the better. Apparently there have been rockets around that couldn't do it on their own.
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Let's give the cool ship a standalone thread:
http://forum.nasaspaceflight.com/index.php?topic=36140.0
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Was that clear as mud? My profession is computer programmer, but my degree was mechanical engineering.
Very clear, thanks.
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(https://pbs.twimg.com/media/B3EsTeDIUAAO86M.jpg)
The grid fins are different to the McGregor ones. The new ones have a straigt edge, the old ones had a pointy end. The new ones are also curved, the old ones were flat.
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Ah, another design feature of N1 also found on F9. Getting more and more :)
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Ah, another design feature of N1 also found on F9. Getting more and more :)
What are the others?
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Engine arrangement. Use of large number of small engines on F9H, all-kerosene design, same engine design for first and second stage,... If I think about it I'll probably find more :)
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Oh, supposed engine-out capability (now that's just a result of the many small engines)
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Oh, supposed engine-out capability (now that's just a result of the many small engines)
It actually worked for Falcon 9 v1.0 (and Saturn V).
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Yea, but right now I don't remember whether it worked on N1. Pi know there was one engine-failure related failure when KORS failed but I don't remember whether on other flights failed engines at least weren't the cause of failures. Vibrations and lack of control authority were the reasons for the two other failures, weren't they?
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Can anyone here make an educated guess about how long it will take the 'huge-ish' barge to transit from Louisiana to the vicinity of Cape Canaveral? Those things are not race boats and the distance substantial. I get anywhere from 4 days to 4 weeks depending on the guesses I make, and if they want to use this thing on CRS-5 then it may need to depart fairly soon.
Not just soon. Any day now. They'll need to perform check out work, testing, and operations rehearsals before towing that bad boy out to sea for the big show. And even that's assuming that this thing doesn't have to make several more stops to finish up the construction and "stuffing out" of all the systems. December 9 is less than a month away.
My $0.05 bet, is that it's either going to be revealed in a few days (this week IMHO) when they take it out of its bearth in completed, or nearly completed form, or I don't think it's going to be ready for the Dec. 9 flight. I'm thinking the latter is most likely until I see a picture of this thing in the press.
Booyah! Nailed it!!!
Elon Musk @elonmusk
Autonomous spaceport drone ship. Thrusters repurposed from deep sea oil rigs hold position within 3m even in a storm.
Elon Musk @elonmusk
Base is 300 ft by 100 ft, with wings that extend width to 170 ft. Will allow refuel & rocket flyback in future.
How's that hat tasting this morning fellas? Do you like fedoras with salt or ketchup? :)
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Kudos to sghill for correctly predicting wings. I was a doubter, but fortunately did not promise to eat my hat if I was wrong. Will be having my normal tasty breakfast of a glazed doughnut instead. ;)
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(https://pbs.twimg.com/media/B3EsTeDIUAAO86M.jpg)
The grid fins are different to the McGregor ones. The new ones have a straigt edge, the old ones had a pointy end. The new ones are also curved, the old ones were flat.
I believe the old fins were curved to the shape of the rocket body. The shape is definitely different.
Matthew
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Yes, the Dev1 fins were curved. I got some decent photos when I was there and the flight video makes it pretty evident. These are wider due to the added grid on either side. Nice to see the fairing design - more blunt than I was picturing.
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(https://pbs.twimg.com/media/B3EsTeDIUAAO86M.jpg)
The grid fins are different to the McGregor ones. The new ones have a straigt edge, the old ones had a pointy end. The new ones are also curved, the old ones were flat.
I believe the old fins were curved to the shape of the rocket body. The shape is definitely different.
Matthew
Ha, they’re going with my MOAB idea from a few years ago... :)
http://forum.nasaspaceflight.com/index.php?topic=21923.msg787784#msg787784
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Ha, they’re going with my MOAB idea from a few years ago... :)
http://forum.nasaspaceflight.com/index.php?topic=21923.msg787784#msg787784
They sure did! Or maybe great minds think alike. ;)