Author Topic: ITS Booster Return - Final Landing and Mounting  (Read 14565 times)

Offline jsgirald

Re: ITS Booster Return - Final Landing and Mounting
« Reply #20 on: 10/04/2016 06:38 PM »

I like this.  Could be done with a barge floating on a shallow pool with a few high-powered winches arrayed around it to rapidly position it.  Or perhaps a really big air-bearing supported cradle positioned by winches.

None of that is viable in the real world

Dunno about the rest, but the pool thing was floated (sorry  :-[) by Boeing's SPS SSTO back in 1978.
It lacked the barge, though, rockets landed directly on the water.
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Offline Ludus

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #21 on: 10/04/2016 07:21 PM »
It is the ultimate in rapid reusability and that makes it an appealing goal. The most efficient possible system of getting a reusable booster from landing to back on the launch pad is obviously to have it land on the launch pad.

This seems like the sort of thing they'd experiment with so maybe there will be legless grasshoppers in the near future and then structures on the LZ pads for real falcon boosters to lock into on landing.

They have plenty of recovered boosters to play with now so I suppose that's easier than purpose building them.
« Last Edit: 10/04/2016 07:25 PM by Ludus »

Offline sanman

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #22 on: 10/04/2016 07:49 PM »
It is the ultimate in rapid reusability and that makes it an appealing goal. The most efficient possible system of getting a reusable booster from landing to back on the launch pad is obviously to have it land on the launch pad.

This seems like the sort of thing they'd experiment with so maybe there will be legless grasshoppers in the near future and then structures on the LZ pads for real falcon boosters to lock into on landing.

They have plenty of recovered boosters to play with now so I suppose that's easier than purpose building them.

When you put it that way, then perhaps this legless-landing-on-mount idea could be used to improve their regular terrestrial satellite launch operations - ie. SpaceX's "day job" - and thus be justifiable as a business investment.

And if they make it work successfully with Grasshopper and even for pads at the Cape, then could this tech even be used on the barges themselves? Or is that overkill? If it could be used to secure the landed F9 booster immediately on the barge, without having to send in a crew to quickly staple down those legs, then perhaps it could be justifiable there too.

Offline NotOnImpact

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #23 on: 10/04/2016 08:59 PM »
Can some clever geometry on the mount somehow cleverly channel the thrust of the booster to somehow force the booster to properly align itself onto the mount? Like some kind of Coanda effect?

Otherwise one bad misalignment could ruin your whole day.

I had to watch the video several times to catch this -- but Elon mentions that the purpose of the fins at the bottom of the rocket are to perfectly align the rocket on the pad on landing.   I would imagine that that would mean in the rotational orientation -- not so much laterally.

So imagine three slots that are wider at the top and narrow as they go down.  They wouldn't interfere on the launch of course.  And it would have the effect of guiding the rocket to an exact positions so that the hold-down clamps could engage appropriately.

Offline RanulfC

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #24 on: 10/04/2016 09:31 PM »
Can some clever geometry on the mount somehow cleverly channel the thrust of the booster to somehow force the booster to properly align itself onto the mount? Like some kind of Coanda effect?

Otherwise one bad misalignment could ruin your whole day.

I had to watch the video several times to catch this -- but Elon mentions that the purpose of the fins at the bottom of the rocket are to perfectly align the rocket on the pad on landing.   I would imagine that that would mean in the rotational orientation -- not so much laterally.

So imagine three slots that are wider at the top and narrow as they go down.  They wouldn't interfere on the launch of course.  And it would have the effect of guiding the rocket to an exact positions so that the hold-down clamps could engage appropriately.

It's a nice idea but I'm going to wait until they can show me a LOT more details on how they think this might work before I assume it's going to happen. That is some significantly detailed maneuvering of a rocket powered vehicle and pad playing VERY nice together which is tough enough even with something like a small drone. The fins would have to be armored and structural VERY robust to take even a glancing blow or scrape with the mass involved. (And even then how do you actually tell that no damage through the entire structure was taken during the event?)

You're talking very much a 'hover-settle' maneuver computer controlled or no.

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Offline RanulfC

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #25 on: 10/04/2016 09:38 PM »

I like this.  Could be done with a barge floating on a shallow pool with a few high-powered winches arrayed around it to rapidly position it.  Or perhaps a really big air-bearing supported cradle positioned by winches.

None of that is viable in the real world

Dunno about the rest, but the pool thing was floated (sorry  :-[) by Boeing's SPS SSTO back in 1978.
It lacked the barge, though, rockets landed directly on the water.

As noted the Boing "Big Onion" booster was very different from the ITS being short, squat and immune from 'tip-over' events. The reason it landed IN the pool was because the settling motion of any platform for such a large vehicle is significant. (In other words the barge could 'ground' if the landing is significantly off-center)

Mostly though I suspect Jim means that using winches is not a viable option. You'd use azmi-pods like the SpaceX barge already has rather than mechanical devices as more practical BUT in general if you can get the booster close enough you don't need the pool and CAN use something like the 'positioning' table suggested earlier built into the pad. (I'm not sure it's actually going to work though as that's a lot of gear exposed to a lot of heat and vibration just to save some mass instead of landing gear. I don't think the scheme is going to work as well as they expect toward reducing their turn around time)

I have a suspicion we'd be looking at an off-shore pad set up rather than actually using the Cape for the majority of flights.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #26 on: 10/04/2016 09:41 PM »
Given that the fully-loaded and fully-fueled ITS only has a SL TWR of around 1.007 (given that the RVacs can't be used safely at SL), I'd anticipate the addition of a compact secondary LES inside the interstage. In an AMOS-6 style RUD, the LES would push the ITS clear of the fireball to give the SL raptors enough time to spin up, but on nominal launches, the LES would remain with the booster and return for reuse. That way you aren't lifting the LES all the way to orbit for no reason each time.

If that was the case, then it's conceivable that the LES could be configured to pull the booster free of the pad in a Very Bad Day situation. Moreso if it was a hypergolic LES rather than a SF one.

Not that this has anything do with mount landings - but is it a given that there's no LES for Mars-side launches then?
Where would you abort to?
Surface or orbit. In either case, you'll have a budding which could send a rescue mission to you.

Remember, this isn't Apollo. There would be hundreds or thousands of people on Mars.

You won't have more than dozens to maybe a couple of hundred for a while so any 'abort' is going to leave someone stranded on the surface with a wrecked ship and maybe the assistance of a 'buddy' flight to pick them up. Of course that might mean both crews end up on non-optimum return timetables so it will behoove early flights to fly short on crew just in case.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Martin.cz

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #27 on: 10/04/2016 10:40 PM »
I've been thinking about how to land the booster since seeing the video & slides for the first time and I think a combination off powerful RSC thrusters and an "active pad" can accomplish that in a rather efficient manner.

The 10-ton class gaseous oxygen/methane thrusters mentioned up-thread could be the ones used & should allow a much better & finer control authority than the basic nitrogen based RCS on the Falcon N9. Also - I guess they could basically run of the autogenous pressurization system as long as at least some raptors are running, so should have a plenty of fuel & oxidizer available during the final landing phase.

As for the "active pad" - the basic idea is that the launch mount elements would not be fixed in position but movable in multiple axes and with some limited reach - kinda like a giant cross-over between the Soyuz launch mount element and a robotic hand.

During the final stage of the landing the booster would maneuver as closely as possible to the correct landing orientation and attitude and then the movable launch mount elements would latch to their corresponding hold down points, correct any remaining deviations in booster rotation/position/angle and let it gently settle down as the landing raptors wind down.

I say settle-down as I don't thinks you want to hold a 275+ tons booster - it should be much easier to rate the launch mount element for high loading in the full-down position (they can be supported from below, etc.) than in the "agile" mode when they move in multiple axes.

And if you can make this work - you are ready to quickly fly again once the booster lands as it would be already connected to the launch mount kinda by definition in this case. No need to crane it/move it from a landing pad, etc. :) Just connect the umbilicals, load the consumable & place an ITS on top and you are ready to go. :)

Offline jsgirald

Re: ITS Booster Return - Final Landing and Mounting
« Reply #28 on: 10/05/2016 09:40 AM »
I can live with the idea of this ginormous Booster, what I really don't get is the logistics of the plan.
I mean, they'r basically saying that the booster becomes part of the launch pad. It makes no sense to have more than one booster per pad.

Let's look at it:
1) Booster launches ITS, it all goes to plan (meaning the SC reaches the intended orbit), only a couple Raptors fail, nothing too serious.
2) Booster goes back to launch pad ok. What happens now?
- a) We've got the power, ignore it and keep launching away.
- b) Repair/replace the failing engines ON THE PAD?
- c) Take the thing to a nearby workshop for repair and use your backup booster (there go your previous savings in ground handling equipment and crew).

If the answer is a) you assume some uncomfortable risk, if b) your whole system has to stop working for an unknown period and if c) then you are really not saving with this return to launch mount thingy. So what is the point anyway?

And this is the most benign hiccup I can think of right now (nothing went bang ...)
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Offline guckyfan

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #29 on: 10/05/2016 01:43 PM »

Let's look at it:
1) Booster launches ITS, it all goes to plan (meaning the SC reaches the intended orbit), only a couple Raptors fail, nothing too serious.
2) Booster goes back to launch pad ok. What happens now?
- a) We've got the power, ignore it and keep launching away.
- b) Repair/replace the failing engines ON THE PAD?
- c) Take the thing to a nearby workshop for repair and use your backup booster (there go your previous savings in ground handling equipment and crew).

Replacing engines on the pad is not that hard. They said once for Falcon 9 access to engines is easier vertical on the pad than horizontal.

They will need means of moving the booster anyway. So they can land on the launch mount and move it away. Or they can build another dedicated landing mount. Much easier and cheaper than the launch/landing mount. Having a second booster available would be very reassuring during a Mars launch campaign.

Online rsdavis9

Re: ITS Booster Return - Final Landing and Mounting
« Reply #30 on: 10/05/2016 02:46 PM »
How quick can you translate horizontally with a 10 ton rcs thruster top and bottom?
How about with multiple 10 ton thrusters?
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Offline jsgirald

Re: ITS Booster Return - Final Landing and Mounting
« Reply #31 on: 10/05/2016 05:41 PM »
Replacing engines on the pad is not that hard. They said once for Falcon 9 access to engines is easier vertical on the pad than horizontal.

They will need means of moving the booster anyway. So they can land on the launch mount and move it away. Or they can build another dedicated landing mount. Much easier and cheaper than the launch/landing mount. Having a second booster available would be very reassuring during a Mars launch campaign.

That's more or less the point I was trying to get across, why bother with the launch/land mount? There's nothing to gain other than a pretty video, and a high risk of unplanned decommision of your launch pad if things go pear shaped.
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Offline guckyfan

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #32 on: 10/05/2016 06:45 PM »
That's more or less the point I was trying to get across, why bother with the launch/land mount? There's nothing to gain other than a pretty video, and a high risk of unplanned decommision of your launch pad if things go pear shaped.

There is everything to gain in simplicity, cost reduction and speed of operations. The risk to the pad is small as the returning vehicle contains very little fuel. Even worst case they can get the pad operational again quickly. See their turn around of the ASDS.

Offline jsgirald

Re: ITS Booster Return - Final Landing and Mounting
« Reply #33 on: 10/05/2016 07:33 PM »
That's more or less the point I was trying to get across, why bother with the launch/land mount? There's nothing to gain other than a pretty video, and a high risk of unplanned decommision of your launch pad if things go pear shaped.

There is everything to gain in simplicity, cost reduction and speed of operations. The risk to the pad is small as the returning vehicle contains very little fuel. Even worst case they can get the pad operational again quickly. See their turn around of the ASDS.

But if they need to be able to move the thing on the ground, and will probably have a spare landing area and a backup booster, where are the savings?

And a 200 t cylinder smashing into your pad is bound to cause some damage even if it's empty.
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Offline Jim

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #34 on: 10/05/2016 07:57 PM »
[
There is everything to gain in simplicity, cost reduction and speed of operations. The risk to the pad is small as the returning vehicle contains very little fuel. Even worst case they can get the pad operational again quickly. See their turn around of the ASDS.

Not a relevant analogy, AMOS-5 is closer

Offline guckyfan

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #35 on: 10/05/2016 07:59 PM »

There is everything to gain in simplicity, cost reduction and speed of operations. The risk to the pad is small as the returning vehicle contains very little fuel. Even worst case they can get the pad operational again quickly. See their turn around of the ASDS.

But if they need to be able to move the thing on the ground, and will probably have a spare landing area and a backup booster, where are the savings?

And a 200 t cylinder smashing into your pad is bound to cause some damage even if it's empty.

Some structure that is able to move the booster slowly is not in any way similar in cost and complexity to a system required for fast turn around. Same for a landing mount. It is vastly simpler and cheaper than a launch mount.

For a spare booster they may or may not decide they need one. IMO they will need one as long as they have only one launch pad. Maybe not, when they have two or more. I guess for the safety of the Mars settlement they will need more than one launch pad sooner rather than later. Initially they can have emergency spares on Mars so they can survive if supplies don't arrive for one synod.

Online rsdavis9

Re: ITS Booster Return - Final Landing and Mounting
« Reply #36 on: 10/05/2016 08:24 PM »
If they can reliably get to 1 meter, like we have seen on the falcon 9. I see no reason with added hover time they can't get to cm's.
I was thinking about the rcs gaseous thrusters.
So
10 ton thruster.
100 ton vehicle
10/100 = accel
accel * t = v
t=1 sec
so 10/100*1=.1 m/s or 10 cm/s
So just translate horizontally while staying straight up and down.
So the key is to have an engine(s) which can exactly cancel weight allowing hover.
Small rcs's capable of shoving the vehicle around until we have mate.
 
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Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Offline jsgirald

Re: ITS Booster Return - Final Landing and Mounting
« Reply #37 on: 10/05/2016 08:32 PM »
Some structure that is able to move the booster slowly is not in any way similar in cost and complexity to a system required for fast turn around. Same for a landing mount. It is vastly simpler and cheaper than a launch mount.

Well, if it's kind of cheap and simple, why bother with the other option?
In other words, how fast do you want your turnaround?

Quote
For a spare booster they may or may not decide they need one. IMO they will need one as long as they have only one launch pad. Maybe not, when they have two or more. I guess for the safety of the Mars settlement they will need more than one launch pad sooner rather than later. Initially they can have emergency spares on Mars so they can survive if supplies don't arrive for one synod.

The sequence might look like this:

Booster1 + ITS crew launch Booster2 on landing pad (doubling as holding area)
Booster1 to landing pad Booster2 moving to launch pad
Booster1 refited Booster2 integrated with tanker and refueled
Booster1 ready at landing pad Booster2 with tanker launched

I doubt you can go any faster than that, and I don't think they'll need to, anyway.
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Offline RoboGoofers

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Re: ITS Booster Return - Final Landing and Mounting
« Reply #38 on: 10/05/2016 08:38 PM »
Now that they know they can easily land back at the launch site, I suspect we will see the drone ships soon modified to support ITS Booster-like landing for F9 and FH core. They're the perfect experimental landing site, and will only be used for high energy launches, which will benefit from dropping the legs.


Online rsdavis9

Re: ITS Booster Return - Final Landing and Mounting
« Reply #39 on: 10/05/2016 08:45 PM »
Now that they know they can easily land back at the launch site, I suspect we will see the drone ships soon modified to support ITS Booster-like landing for F9 and FH core. They're the perfect experimental landing site, and will only be used for high energy launches, which will benefit from dropping the legs.

Merlins can't throttle enough.
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

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