A general misconception on profit margins:
http://www.yardeni.com/pub/sp500margin.pdf
Genrally profit margins run <10%.
For the space industry and cost+ defense contracts they run >20%.
SpaceX probably is somewhere in the 20-30% range depending on launch rate. Fixed price but variable costs. Mu estimate was at the floor of 25%. But just because everyone else in the space industry is doing high profit margins dosen't mean SpaceX is currently doing the same.
If SpaceX profit margin for a CASSIOPE mission is 25% or $14M and their revenue is ~$15M (CASSIOPE and secondaries) then their loss for the flight is $25M. Their cost to do a test flight as part of the development costs of v1.1. Cheap by comparison.
Edit: its <10% not the previos >10%
A general misconception on profit margins:
http://www.yardeni.com/pub/sp500margin.pdf
Genrally profit margins run <10%.
For the space industry and cost+ defense contracts they run >20%.
SpaceX probably is somewhere in the 20-30% range depending on launch rate. Fixed price but variable costs. Mu estimate was at the floor of 25%. But just because everyone else in the space industry is doing high profit margins dosen't mean SpaceX is currently doing the same.
If SpaceX profit margin for a CASSIOPE mission is 25% or $14M and their revenue is ~$15M (CASSIOPE and secondaries) then their loss for the flight is $25M. Their cost to do a test flight as part of the development costs of v1.1. Cheap by comparison.
Edit: its <10% not the previos >10%
Please provide a reference for your >20% profit margin statement. Your link shows a number of 7.7% for aerospace and defense. How did you arrive at 20-30% for SpaceX?
While we twiddle out thumbs for two more weeks, here's a somewhat informative article on weather considerations for launch at VAFB. And while Capt Weiss says a launch has never been cancelled due to weather during her tenure there, the FAA waiver for this particular launch states that there's only a 40% probability of weather meeting the FAA safety criteria at any given time in September. (The waiver did not say whether that probability changes in later months in case of slips.)
http://www.vandenberg.af.mil/news/story.asp?id=123363212 (http://www.vandenberg.af.mil/news/story.asp?id=123363212)
QuoteWhile we twiddle out thumbs for two more weeks, here's a somewhat informative article on weather considerations for launch at VAFB. And while Capt Weiss says a launch has never been cancelled due to weather during her tenure there, the FAA waiver for this particular launch states that there's only a 40% probability of weather meeting the FAA safety criteria at any given time in September. (The waiver did not say whether that probability changes in later months in case of slips.)
http://www.vandenberg.af.mil/news/story.asp?id=123363212 (http://www.vandenberg.af.mil/news/story.asp?id=123363212)
Kabloona: Did you get it reversed? Wasn't there a significant chance of weather that would cause them to violate the baseline safety requirement, so that they got from the FAA an allowance to exceed one component of the Ec calculation, provided the total remained within the baseline constraints? I thought it was that inversions could reflect the energy of an explosion increasing the potential for damage on the ground close to the pad, but that other dangers were lower than allowed, and the FAA allowed them to go with a compliant total.
Is it really a range delay due to AF, or is he looking for a scapegoat to try to blame the AF for the falcon running behind schedule? Meaning , no Minuteman test and it would still be end of September?
QuoteWhile we twiddle out thumbs for two more weeks, here's a somewhat informative article on weather considerations for launch at VAFB. And while Capt Weiss says a launch has never been cancelled due to weather during her tenure there, the FAA waiver for this particular launch states that there's only a 40% probability of weather meeting the FAA safety criteria at any given time in September. (The waiver did not say whether that probability changes in later months in case of slips.)
http://www.vandenberg.af.mil/news/story.asp?id=123363212 (http://www.vandenberg.af.mil/news/story.asp?id=123363212)
Kabloona: Did you get it reversed? Wasn't there a significant chance of weather that would cause them to violate the baseline safety requirement, so that they got from the FAA an allowance to exceed one component of the Ec calculation, provided the total remained within the baseline constraints? I thought it was that inversions could reflect the energy of an explosion increasing the potential for damage on the ground close to the pad, but that other dangers were lower than allowed, and the FAA allowed them to go with a compliant total.
This waiver discussion sure seems like it's a bit overstated. Is it all just because it's a new launch vehicle? I can't imagine that the weather changes so dramatically from August 28 to early September (original v1.1. launch date) that the DIV Heavy had no issues or even discussion about this, but it's a potential showstopper for v1.1? Does the v1.1 overfly the Delta pad, for instance? I can't see toxicity being that different between the two vehicles (hydrazine or other nasty stuff - LH2 and RP1 don't count for toxicity).
Is it really a range delay due to AF, or is he looking for a scapegoat to try to blame the AF for the falcon running behind schedule? Meaning , no Minuteman test and it would still be end of September?First of all, conspiracy speculation like that is of little use here.
Bringing over from updates thread:Is it really a range delay due to AF, or is he looking for a scapegoat to try to blame the AF for the falcon running behind schedule? Meaning , no Minuteman test and it would still be end of September?First of all, conspiracy speculation like that is of little use here.
But let me take it on anyway: Now that it's known publicly that Air Force ICBM testing is holding things up, I think I'm free to say that over on L2 it was already known several days in advance that such tests were on the VAFB timetable and that SpaceX would not launch till the end of the month if they missed the Sept 15th launch date.
L2: killer of conspiracies ;D
Bringing over from updates thread:Is it really a range delay due to AF, or is he looking for a scapegoat to try to blame the AF for the falcon running behind schedule? Meaning , no Minuteman test and it would still be end of September?First of all, conspiracy speculation like that is of little use here.
But let me take it on anyway: Now that it's known publicly that Air Force ICBM testing is holding things up, I think I'm free to say that over on L2 it was already known several days in advance that such tests were on the VAFB timetable and that SpaceX would not launch till the end of the month if they missed the Sept 15th launch date.
L2: killer of conspiracies ;D
During previous launch campaigns, Elon had suggested, or maybe observers had inferred, that outside factors were to blame for launch delays when in fact it was both SpaceX and their customer who were responsible. Events like these stick in people's minds, so when the next delay comes along it causes them to wonder.
It is very interesting to see how quickly people rush to SpaceX's defense, when a similar attack on a "heritage" launch provider would virtually invite piling on and rampant speculation. That's my observation.
During previous launch campaigns, Elon had suggested, or maybe observers had inferred, that outside factors were to blame for launch delays when in fact it was both SpaceX and their customer who were responsible. Events like these stick in people's minds, so when the next delay comes along it causes them to wonder.
It is very interesting to see how quickly people rush to SpaceX's defense, when a similar attack on a "heritage" launch provider would virtually invite piling on and rampant speculation. That's my observation.
... when a similar attack on a "heritage" launch provider would virtually invite piling on and rampant speculation. That's my observation.And people don't engage in rampant speculation about SpaceX?
I'm having difficulty finding an instance of Elon having suggested such in the past. Can you cite any examples?
And people don't engage in rampant speculation about SpaceX?
Lots of people defend "heritage" launch systems, myself included.
I'm having difficulty finding an instance of Elon having suggested such in the past. Can you cite any examples?
For sure.
Since (as someone quoted above) SpaceX's stated mission is to develop reusability and not just be an expendable launch provider, the significance of these individual flights is relatively low, as long as they don't threaten the overall long-term health of the company.
There's a large manifest, the bulk of which will barely be affected by any hold-ups in the current schedule. So as far as that goes, SpaceX has done their job well, and can basically let things proceed at the best practical pace. They will suffer basically no long-term consequences if they were to announce a 2 week delay due to internal reasons. They are very much aware of this, and so I really doubt they're inventing reasons to blame others for any delays.
For sure.
Since (as someone quoted above) SpaceX's stated mission is to develop reusability and not just be an expendable launch provider, the significance of these individual flights is relatively low, as long as they don't threaten the overall long-term health of the company.
There's a large manifest, the bulk of which will barely be affected by any hold-ups in the current schedule. So as far as that goes, SpaceX has done their job well, and can basically let things proceed at the best practical pace. They will suffer basically no long-term consequences if they were to announce a 2 week delay due to internal reasons. They are very much aware of this, and so I really doubt they're inventing reasons to blame others for any delays.
Not one bit of that is true. Just a bunch of hand waving trying to justify a perception of the situation biased by the unconditional believe that spacex can do no wrong. No different than saying "ignore the man behind the curtain". Each flight puts the overall long-term health of the company on the line.
For sure.
Since (as someone quoted above) SpaceX's stated mission is to develop reusability and not just be an expendable launch provider, the significance of these individual flights is relatively low, as long as they don't threaten the overall long-term health of the company.
There's a large manifest, the bulk of which will barely be affected by any hold-ups in the current schedule. So as far as that goes, SpaceX has done their job well, and can basically let things proceed at the best practical pace. They will suffer basically no long-term consequences if they were to announce a 2 week delay due to internal reasons. They are very much aware of this, and so I really doubt they're inventing reasons to blame others for any delays.
Not one bit of that is true. Just a bunch of hand waving trying to justify a perception of the situation biased by the unconditional believe that spacex can do no wrong. No different than saying "ignore the man behind the curtain". Each flight puts the overall long-term health of the company on the line.
Actually Jim, launch companies suffered mission failures before, not to mention launch delays, and were just fine in the grand scheme of things. As people pointed out, F91.1 is not doing bad for its first launch. (You should still treat each launch as if the world's at stake of course, and as far as I can tell, they are)
Second, do I take it then that you believe SpaceX is inventing excuses to justify delays? Because that's the context of the conversation above, and if you want to take that line, then you have a lot of explaining to do - SpaceX did the hot fire (which implies they're ready), reported some anomalies and ran into the pre-scheduled test of the minuteman a few days later. Sounds perfectly reasonable to me - no need to invent a man behind the curtain.
I'm just glad they got the hot fire in, since they have this down time to take care of all the issues they found, not only of the things that were deemed critical to the launch.
Like I said, the last thing they should worry about is schedule delays. None of the 2015 flights (and the later 2014 flights) give one hoot whether this upcoming launch is delayed or not.
Dan Leone of SpaceNews wheedled a less un-specific answer out of SpaceX about the hot-fire anomalies:Quote... Following the hot-fire test, “we saw some anomalies stemming from how the pad interfaces with the vehicle,” SpaceX spokeswoman Emily Shanklin wrote in a Sept. 16 email. “These are the kinds of things you can only find out when you static fire” ...
From this article: http://www.spacenews.com/article/launch-report/37251pad-interface-anomalies-range-conflicts-push-falcon-9-11-launch-to-late
As Jim has already pointed out that the stress levels on the hold-downs isn't monitored, this narrows it down to something like:
1) Propellent feeds;
2) Hard-line pad data interfaces;
3) Ground power lines;
4) Payload A/C hose.
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg)
From some of the earlier pictures, there appears to be some type of extra support needed between the strongback and the that part of the LV near that area. Perhaps they need to re-install it for transport.
Why does the vehicle need to be lifted in the middle of it?
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg)
Why does the vehicle need to be lifted in the middle of it?
Looking at Photo ~5741.jpg they have installed an additional bunk point to the left of the fairing. I think they are preparing to slide part or all of the vehicle ahead onto the additional bunk point.
Looking at Photo ~5741.jpg they have installed an additional bunk point to the left of the fairing. I think they are preparing to slide part or all of the vehicle ahead onto the additional bunk point.
I doubt they slide the vehicle on the TEL. More likely they lift with the sling, then slide into place the truss that carries the two PLF bunks, and attach the truss to the TEL.
In the photo the truss with the PLF bunks hasn't been slid into place yet. IMO.
Okay, move is a better word than slide. But why wouldn't all of the bunks be in place before they left the HIF?
That crane does not look like it would be part of the normal erection/lowering process. Some unusual maintenance is going on.
Vehicle and erector were back in the horizontal position as of last night.
Images shared with permission of the source.
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVI_zpsed4297f0.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVI_zpsed4297f0.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVJ_zps2e4c5741.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVJ_zps2e4c5741.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg)
Enjoy.
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg)
Why does the vehicle need to be lifted in the middle of it?
Vehicle and erector were back in the horizontal position as of last night.
Images shared with permission of the source.
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVI_zpsed4297f0.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVI_zpsed4297f0.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVJ_zps2e4c5741.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVJ_zps2e4c5741.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg)
Enjoy.
Great images. Thank you.
I particularly like the one with the nearly full moon.
Are the more recent images to the "left" with the rocket horizontal?
What is the big crane doing?
It looks like they have a support cradle for the fairing, but that it is half off in the "pointy end" direction so that only one of two supports contacts the fairing. What is that about?
From looking at various photos it aplears that there are two different trusses that get bolted onto the top of the TEL. One is for transport, and has the two "bunks" that support the fairing. The other is for launch, and holds the AC ducts and umbilicals for the fairing.
But it looks like both trusses can't be attached to the TEL simultaneously. One has to be removed before the other can be attached. In the photo of the rocket horizontal, the truss with the fairing "bunks" is sitting just ahead of the truss that holds the AC ducts.
If they were/are rolling back to the HIF, presumably they'd detach the truss with the AC ducts and attach the one with the fairing bunks.
From looking at various photos it aplears that there are two different trusses that get bolted onto the top of the TEL. One is for transport, and has the two "bunks" that support the fairing. The other is for launch, and holds the AC ducts and umbilicals for the fairing.
But it looks like both trusses can't be attached to the TEL simultaneously. One has to be removed before the other can be attached. In the photo of the rocket horizontal, the truss with the fairing "bunks" is sitting just ahead of the truss that holds the AC ducts.
If they were/are rolling back to the HIF, presumably they'd detach the truss with the AC ducts and attach the one with the fairing bunks.
Doesn't that sound a bit strange from an operational point of view ?
If the fairing is attached, it needs to be supported during transport. Or at least there needs to be some support near the top end of the launcher. How much weight do you want the fairing to support while in the horizontal position ?
And of course, while the payload is attached, those umbilicals are absolutely required. You risk the spacecraft health if it doesn't get power and cooling, right ?
How can you have 2 separate truss structures when both functions are required ??
if you look at other pictures from rollout and earlier the tuning fork shaped fairing support truss is held to the TEL's top truss segments by pins and then removed after rollout.From looking at various photos it aplears that there are two different trusses that get bolted onto the top of the TEL. One is for transport, and has the two "bunks" that support the fairing. The other is for launch, and holds the AC ducts and umbilicals for the fairing.
But it looks like both trusses can't be attached to the TEL simultaneously. One has to be removed before the other can be attached. In the photo of the rocket horizontal, the truss with the fairing "bunks" is sitting just ahead of the truss that holds the AC ducts.
If they were/are rolling back to the HIF, presumably they'd detach the truss with the AC ducts and attach the one with the fairing bunks.
Doesn't that sound a bit strange from an operational point of view ?
If the fairing is attached, it needs to be supported during transport. Or at least there needs to be some support near the top end of the launcher. How much weight do you want the fairing to support while in the horizontal position ?
And of course, while the payload is attached, those umbilicals are absolutely required. You risk the spacecraft health if it doesn't get power and cooling, right ?
How can you have 2 separate truss structures when both functions are required ??
Agreed
SpaceX is not going to rent a construction crane every time they raise or lower the vehicle - something atypical is in progress in the photos.
Agreed
SpaceX is not going to rent a construction crane every time they raise or lower the vehicle - something atypical is in progress in the photos.
I agree too. Maybe they didn't have time to finish their original plan in time for this launch, so they put together some kind of hack that required the crane. Or maybe they finished their original plan and then found when the rocket arrived that there was a flaw in it, and the crane is part of a hack to make it work for this launch.
Either way, I'll bet SpaceX has a plan to make modifications so the crane isn't part of the flow eventually.
Hopefully they fix the paint job for next time also.
It's weird every time I look at the rocket and see that the "SpaceX" on the first stage is 90 degrees off from the stickers on the fairing. Let's get all the logos and flags lined up correctly guys.
It's weird every time I look at the rocket and see that the "SpaceX" on the first stage is 90 degrees off from the stickers on the fairing. Let's get all the logos and flags lined up correctly guys.
That's okay, the shortened SpaceX logo on the First stage annoys the <words Chris would ban me forever> out of my OCD. It's like marketing looked at the rocket, OMG there is frost over part of the SpaceX logo and that is more important than an ascetically pleasing rocket logo.You guys are a real-life version of the Dilbert cartoon ( http://dilbert.com/strips/comic/2013-02-23 ) where his company gets the contract to blast an incoming asteroid out of its collision course with Earth. But they use a non-corporate-approved font on the nose cone, then miss the launch window trying to erase it....
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg)
Why does the vehicle need to be lifted in the middle of it?
The "gripper arms" are not "gripping"
Why does the vehicle need to be lifted in the middle of it?
The "gripper arms" are not "gripping"
And where are the workers?
That makes sense; remember they had to let the LOX boil off after the last hot fire.
From looking at various photos it aplears that there are two different trusses that get bolted onto the top of the TEL. One is for transport, and has the two "bunks" that support the fairing. The other is for launch, and holds the AC ducts and umbilicals for the fairing.
But it looks like both trusses can't be attached to the TEL simultaneously. One has to be removed before the other can be attached. In the photo of the rocket horizontal, the truss with the fairing "bunks" is sitting just ahead of the truss that holds the AC ducts.
If they were/are rolling back to the HIF, presumably they'd detach the truss with the AC ducts and attach the one with the fairing bunks.
Doesn't that sound a bit strange from an operational point of view ?
If the fairing is attached, it needs to be supported during transport. Or at least there needs to be some support near the top end of the launcher. How much weight do you want the fairing to support while in the horizontal position ?
And of course, while the payload is attached, those umbilicals are absolutely required. You risk the spacecraft health if it doesn't get power and cooling, right ?
How can you have 2 separate truss structures when both functions are required ??
That makes sense; remember they had to let the LOX boil off after the last hot fire.
?? There would be workers under the vehicle, but the rest are still waiting for lox to boil off after taking the vehicle to horizontal?
From looking at various photos it aplears that there are two different trusses that get bolted onto the top of the TEL. One is for transport, and has the two "bunks" that support the fairing. The other is for launch, and holds the AC ducts and umbilicals for the fairing.
But it looks like both trusses can't be attached to the TEL simultaneously. One has to be removed before the other can be attached. In the photo of the rocket horizontal, the truss with the fairing "bunks" is sitting just ahead of the truss that holds the AC ducts.
If they were/are rolling back to the HIF, presumably they'd detach the truss with the AC ducts and attach the one with the fairing bunks.
Doesn't that sound a bit strange from an operational point of view ?
If the fairing is attached, it needs to be supported during transport. Or at least there needs to be some support near the top end of the launcher. How much weight do you want the fairing to support while in the horizontal position ?
And of course, while the payload is attached, those umbilicals are absolutely required. You risk the spacecraft health if it doesn't get power and cooling, right ?
How can you have 2 separate truss structures when both functions are required ??
Both functions are required, but not at the same time. One truss is for transport, and one is for launch. These presumably get swapped out just before the vehicle is erected at the pad.
Here's a photo sequence showing clearly the TEL with the different trusses on its front (top) end, and one with no truss at all on top:
TEL with transport cradle truss:
http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=31429.0;attach=542202
TEL with fairing umbilical truss:
http://s1351.photobucket.com/user/spacecoaster1/media/LVD_zpsdb8891fa.jpg.html?&_suid=1379597697648027071598544716835
TEL with both trusses side by side:
http://s1351.photobucket.com/user/spacecoaster1/media/LVJ_zps2e4c5741.jpg.html?&_suid=137959961163005051272702403367
TEL with neither truss attached:
http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=32685.0;attach=543627
(Note the transport truss sitting on the pad in background)
So, once you go vertical, you never want to go horizontal (and back to the HIF) again or else you need to bring in the crane ?
That makes sense; remember they had to let the LOX boil off after the last hot fire.
?? There would be workers under the vehicle, but the rest are still waiting for lox to boil off after taking the vehicle to horizontal?
The LOX would have to boil off before going horizontal.
Figured that. ;) Just trying to understand what "makes sense" to JBF - if he was talking about the lack of people around the vehicle or something else.
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVK_zpse6f3022a.jpg)
http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg (http://i1351.photobucket.com/albums/p783/spacecoaster1/LVL_zps45ef0230.jpg)
Why does the vehicle need to be lifted in the middle of it?
The "gripper arms" are not "gripping"
It appears to me that when the vehicle is horizontal the ground car with the cradle can move in or out from under the fairing without having to make any changes to the TEL because the truss with the umbilicals is not under the fairing but off to one side:
http://s1351.photobucket.com/user/spacecoaster1/media/LVE_zps057b7e38.jpg.html?sort=9&o=4
http://forum.nasaspaceflight.com/index.php?topic=32685.msg1099107#msg1099107That looks impressive. The previous Falcon 9 flights had a lot more vapor clouds. Is this because of the higher humidity at the Cape vs. Vandenburg?
good news, 2nd hot fire went well, now just waiting on the launch window to open
...this test looked solid to me. I think it is the angle, but it just looks more...professional? than their previous tests.Exactly what I thought too, although looking back on the COTS 2 hot-fire video it doesn't seem that different.
The previous Falcon 9 flights had a lot more vapor clouds. Is this because of the higher humidity at the Cape vs. Vandenburg?
Look at the white clouds coming from the side of the vehicle and from the LOx vent ports. Looks far more dramatic on the v1.0 tests than with v1.1.The previous Falcon 9 flights had a lot more vapor clouds. Is this because of the higher humidity at the Cape vs. Vandenburg?
What do you mean by more water vapor? Check out for example the CRS-2 static fire.
One noticeable thing is that the shutdown on M1D is much more abrupt than M1C, the latter chugging and flaming for quite a while.
It's all down to wind and temperature/humidity on any given day. Also, for most of the video the GOX vents were closed since the vehicle was pressurized for flight.
Edited this down to just the information for you.
What are you saying with this?
That Patch makes it seem like the fairing is much larger than it needs to be. Maybe I just haven't been paying attention but is this true? Has SpaceX simply decided to offer 1 fairing size for simplicity sake?SpaceX will use exactly the same fairing for the next mission, SES-8, where the payload is substantially larger than CASSIOPE. So this time they just test the fairing, just like the whole thing below :)
As I didn't see it posted here yet, the mission patch for Falcon 9 Flight 6.Where did you find that? Can you provide a link?
That Patch makes it seem like the fairing is much larger than it needs to be. Maybe I just haven't been paying attention but is this true? Has SpaceX simply decided to offer 1 fairing size for simplicity sake?
maybe it is the patch but why would the design the base of the rocket to look like the f9 v1 instead of the v1.1?
What's the significance of the three (white) stars?
!CARF 09/183 (KZLA A2319/13) ZLA AIRSPACE DCC 2 ROPS AIROP DO-1307 STAGE 1 AND DEBRIS AREA STATIONARY RESERVATION WITHIN AN AREA BNDD BY 3133N/11934W 2848N/11910W 2809N/12000W 2300N/12000W 2300N/12005W 2622N/12104W 3007N/12119W 3133N/12113W SFC-UNL WEF 1309291600-1309291953
!CARF 09/181 (KZLA A2318/13) ZLA AIRSPACE DCC 2 ROPS AIROP DO-1307 DEBRIS DISPERTION AREA STATIONARY RESERVATION WITHIN AN AREA BNDD BY 3445N/12100W 3445N/12034W 3236N/11947W 3133N/11934W 3133N/12113W SFC-UNL WEF 1309291600-1309291930
But if SpaceX is successful doing the brake burn the first stage will go downrange much less than usual.
But if SpaceX is successful doing the brake burn the first stage will go downrange much less than usual.
Would the ISS crew have a view of the launch?
As I didn't see it posted here yet, the mission patch for Falcon 9 Flight 6.
wellNope, it was discussed back when spacex updated their new website.
check out Cmd hadfield tweet (https://twitter.com/Cmdr_Hadfield/status/383942437262995457)..
never seen that pic before..is it new?
jb
American Islander is heading toward recovery zone.
Why not? Just have to tow it!American Islander is heading toward recovery zone.
That's certainly interesting. But what can that ship do? It is not big enough to salvage the stage, I think. Maybe it can anchor and stabilize it until a bigger salvage ship arrives?
i wonder what gear they have to help get the 1st stage?
SFN has the timelines:Hmm. Also, why such a long delay between SECO and payload separation (cca 5 minutes)?
http://spaceflightnow.com/falcon9/006/countdowntimeline.html (http://spaceflightnow.com/falcon9/006/countdowntimeline.html)
http://www.spaceflightnow.com/falcon9/006/launchtimeline.html (http://www.spaceflightnow.com/falcon9/006/launchtimeline.html)
However, they report two of the first stage's engines shutting down moments before the others, which I'm pretty sure is wrong. The engines on v1.1 throttle down together and shut down almost at the same time.
SFN now also has the press kit:
http://www.spaceflightnow.com/falcon9/006/UpgradedF9DemoMission_PressKit.pdf (http://www.spaceflightnow.com/falcon9/006/UpgradedF9DemoMission_PressKit.pdf)
"Around two and a half minutes into the flight, two of the first-stage engines will shut down to reduce the rocket’s acceleration."
Why not? Just have to tow it!American Islander is heading toward recovery zone.
That's certainly interesting. But what can that ship do? It is not big enough to salvage the stage, I think. Maybe it can anchor and stabilize it until a bigger salvage ship arrives?
It's this big:
http://spacexlaunch.zenfolio.com/p278054961/h499c29de#h499c29de
And the smaller it is, the cheaper it is to operate.
Judging from the stated max Q timing, this thing is likely to have the same liftoff acceleration as v1.0. Which, given the vehicle is taller, should make it look slower.
Judging from the stated max Q timing, this thing is likely to have the same liftoff acceleration as v1.0. Which, given the vehicle is taller, should make it look slower.
Even with a substantially under-weight payload like CASSIOPE?
SFN now also has the press kit:
http://www.spaceflightnow.com/falcon9/006/UpgradedF9DemoMission_PressKit.pdf (http://www.spaceflightnow.com/falcon9/006/UpgradedF9DemoMission_PressKit.pdf)
"Around two and a half minutes into the flight, two of the first-stage engines will shut down to reduce the rocket’s acceleration."
Vs. another quote further down:
"The first stage engines are gradually throttled near the end of first-stage flight to limit launch vehicle acceleration as the rocket’s mass decreases with the burning of fuel."
Also, inconsistent durations of the 2nd stage burn in different places in the kit - 5m57s vs. 6m17s ?
In fact, the whole "Flight" section is suspiciously similar to the CRS-1 press kit.
No target orbital parameters or other juicy stuff. The highlight seems to be a couple of unseen pictures, one also showing the individual engine RP-1 feedlines coming directly off the tank bottom as opposed to the "octopus" on v1.0.
I wonder if the flight plan includes any throttling down for transsonic flight? Judging from the stated max Q timing, this thing is likely to have the same liftoff acceleration as v1.0. Which, given the vehicle is taller, should make it look slower.
Why not? Just have to tow it!American Islander is heading toward recovery zone.
That's certainly interesting. But what can that ship do? It is not big enough to salvage the stage, I think. Maybe it can anchor and stabilize it until a bigger salvage ship arrives?
It's this big:
http://spacexlaunch.zenfolio.com/p278054961/h499c29de#h499c29de
you can track American Islander position on marinetraffic.com
American Spirit is also headed at the same speed and direction as American Islander, but about 100 km to the south.
If one of the American Marine vessels was towing a barge, would it show up on the tracking resource?
Around two and a half minutes into the flight, two of the first-stage engines will shut down to reduce the rocket’s acceleration.
I think it's actually technically more efficient to shut-off engines, because throttling down means a lowering of the chamber pressure which means a worsening of the pressure ratio which means lower Isp.QuoteAround two and a half minutes into the flight, two of the first-stage engines will shut down to reduce the rocket’s acceleration.
That was the v1.0 method, I was sure that one of the benefits of M1D was the 70% throttle capability eliminates the need to shut down engines.
Being able to throttle does not imply that they HAVE to throttle. I presume it will all depend on the mission profile, i.e. on a case by case basis. Also, since the v1.1 is a hefty upgrade, they might be replicating the v1.0 flight profile as much as possible to avoid adding unnessary unknowns to the test flight.QuoteAround two and a half minutes into the flight, two of the first-stage engines will shut down to reduce the rocket’s acceleration.
That was the v1.0 method, I was sure that one of the benefits of M1D was the 70% throttle capability eliminates the need to shut down engines.
Bit strange that there's no special banner or mention of this launch on the SpaceX website
Bit strange that there's no special banner or mention of this launch on the SpaceX website
40 minutes before opening of launch window. 10 minutes before NASA's Cygnus presser...
40 minutes before opening of launch window. 10 minutes before NASA's Cygnus presser...
And when is that? Or in other words, is the 12pm EDT mentioned on the webcast page the beginning of the launch window or the beginning of the webcast?
Thanks. It's as if SpaceX would like to minimize public awareness of this launch...
Thanks. It's as if SpaceX would like to minimize public awareness of this launch...
Putting this on both threads, as it's superb:
http://www.nasaspaceflight.com/2013/09/spacex-debut-falcon-9-v1-1-cassiope-launch/
Thanks. It's as if SpaceX would like to minimize public awareness of this launch...
Perhaps this says something about their confidence about the vehicle, who knows...
Thanks. It's as if SpaceX would like to minimize public awareness of this launch...
Perhaps this says something about their confidence about the vehicle, who knows...
The pax on the starboard side of that Qantas A380 are going to have a memorable flight.
Sorry if this been asked a million times already, but are they really going to land this puppy back into the ocean or what?They will try to get first stage down in one piece, yes.
^^^ They're going to try. We'll find out soon enough.deluge system - engines are chilled with lox vapor.
Is that water pouring out the bottom of the 1st stage right now? They mentioned chilling the engines, but water? Or are they testing the deluge system?
Anyone know anything about the 1st stage recovery yet?just confirmed for relighted
Commentary back, they look really happy as they should!Yes, looked like a beaut through the end of coverage...hopefully we'll get to see some other views of the liftoff, climbout, and maybe some (pseudo) recovery operations down the road.
...hopefully we'll get to see some other views of the liftoff, climbout, and maybe some (pseudo) recovery operations down the road.
Is this the first in-flight relight of a first stage ever in history?
Is this the first in-flight relight of a first stage ever in history?
So... A November launch, somebody said? ;)
Awesome launch!!! :)
I knew someone would bring those up... Neither were first stages on multi-stage vehicles and neither were they orbital flights.
arguably oms are the third stage (!).I knew someone would bring those up... Neither were first stages on multi-stage vehicles and neither were they orbital flights.
Never said they were; just that they were the only two other relights of a first stage-like rocket.
Of course, if you count Shuttle's OMS as a first stage (a stretch, I know), then you have count most of the later Shuttle flights... :)
Musk: rolling "centrifuged" propellant, shut down engine early. Did recover "portions" of 1st stage after splashdown. #falcon9
Jeff Foust @jeff_foust 44s
Musk: attempted relight of upper stage, encountered anomaly. Understand what it is and will fix before next flight. #falcon9
Re-light is a must for the SES flight. Wonder if this will delay it.
Musk: rolling "centrifuged" propellant, shut down engine early. Did recover "portions" of 1st stage after splashdown. #falcon9
First I've ever heard of centrifuged propellant causing a shutdown. This has probably happened before somewhere though, does anyone know?
First I've ever heard of centrifuged propellant causing a shutdown. This has probably happened before somewhere though, does anyone know?
Jeff Foust @jeff_foust now
Musk: will next attempt recovery on 4th F9 v1.1 launch, of CRS-3. That vehicle may also have landing legs. #falcon9
First I've ever heard of centrifuged propellant causing a shutdown. This has probably happened before somewhere though, does anyone know?
Falcon 1 flight 2 comes to mind.
Too bad the 1st stage recovery failed. This also probably means we don't get to see a video of it as SpaceX probably doesn't want to show off failures :(
Too bad the 1st stage recovery failed. This also probably means we don't get to see a video of it as SpaceX probably doesn't want to show off failures :(
https://twitter.com/jeff_foust/status/384402628962451456
I wonder if the first stage ACS ran out of gas to overcome the torque of the turbopump because the flight duration was longer than the Grasshopper flights.
I wonder if the first stage ACS ran out of gas to overcome the torque of the turbopump because the flight duration was longer than the Grasshopper flights.
I wonder if the first stage ACS ran out of gas to overcome the torque of the turbopump because the flight duration was longer than the Grasshopper flights.
I'm speculating it was aerodynamic forces that imparted the roll and the ACS used up all the juice again, failing to null it. The stage isn't completely left-right mirror symmetrical so it could be susceptible to spin-up even if coming straight down.
I wonder if the first stage ACS ran out of gas to overcome the torque of the turbopump because the flight duration was longer than the Grasshopper flights.
As was wondering on another thread what might have started the roll and what you suggest makes a lot of sense.
The exhaust might not - but what about the pump itself? lot's of things spinning in there, right?I wonder if the first stage ACS ran out of gas to overcome the torque of the turbopump because the flight duration was longer than the Grasshopper flights.
As was wondering on another thread what might have started the roll and what you suggest makes a lot of sense.
Again, M1D turbopump exhausts straight down, so it doesnt create any roll torque. And at any rate per Elon's twitter the spin up was cause by aerodynamic torque:
https://twitter.com/elonmusk/status/384407846349062144
The exhaust might not - but what about the pump itself? lot's of things spinning in there, right?I wonder if the first stage ACS ran out of gas to overcome the torque of the turbopump because the flight duration was longer than the Grasshopper flights.
As was wondering on another thread what might have started the roll and what you suggest makes a lot of sense.
Again, M1D turbopump exhausts straight down, so it doesnt create any roll torque. And at any rate per Elon's twitter the spin up was cause by aerodynamic torque:
https://twitter.com/elonmusk/status/384407846349062144
( please note - I don't say that it was the cause, just that it might be a factor. Elon certainly states that aero-induced forces where the main cause, instead of the pump torque. )
Ugh, viscosity. Learn some real physics.
Ugh, viscosity. Learn some real physics.Hmm, viscosity requires that the roll movement started sometime before relight, to be trasmitted to the propellant.
Sorry, if this has already been covered, but when is that SpaceX post-launch news conference? I keep surfing around the SpaceX site, and hope I haven't missed it.
Nextly, regarding the aero-torqued fuel -- would the stuff purely show torque/centrifugal motion, or would it likely be sloshing around too?
Ugh, viscosity. Learn some real physics.Hmm, viscosity requires that the roll movement started sometime before relight, to be trasmitted to the propellant.
Inside the turbopump.
Sorry, if this has already been covered, but when is that SpaceX post-launch news conference? I keep surfing around the SpaceX site, and hope I haven't missed it.
...
No, inside the tanks.Inside the turbopump.Ugh, viscosity. Learn some real physics.Hmm, viscosity requires that the roll movement started sometime before relight, to be trasmitted to the propellant.
No, inside the tanks.Inside the turbopump.Ugh, viscosity. Learn some real physics.Hmm, viscosity requires that the roll movement started sometime before relight, to be trasmitted to the propellant.
That wasn't a question.
It's over, it was covered by Jeff Foust on twitter
https://twitter.com/jeff_foust
Elon Musk @elonmusk 56m
Rocket booster relit twice (supersonic retro & landing), but spun up due to aero torque, so fuel centrifuged & we flamed out
Elon Musk @elonmusk 43m
Between this flight & Grasshopper tests, I think we now have all the pieces of the puzzle to bring the rocket back home.
It's over, it was covered by Jeff Foust on twitter
https://twitter.com/jeff_foust
Thanks for that :)
So Musk tweetedQuoteElon Musk @elonmusk 56m
Rocket booster relit twice (supersonic retro & landing), but spun up due to aero torque, so fuel centrifuged & we flamed out
Elon Musk @elonmusk 43m
Between this flight & Grasshopper tests, I think we now have all the pieces of the puzzle to bring the rocket back home.
What exactly is the solution to this? When the fuel centrifuged, how did that cause the flameout? Did it somehow interfere with the turbopump's ability to draw in fuel?
So is the best way to solve this by countering the aero-torque as it occurs? I'm assuming this refers to rotation around the booster's long axis. Or can you put up with the aero-torque and just implement some counter-measure at the turbopump side?
If you have to counter the aero-torque, then does this require some extra new thruster, or can the existing octoweb/center-rocket be tweaked to stop the roll on the way down?
There are viscous forces and rolling friction inside a turbopump that tend to spin whatever is holding it in the opposite direction.
There are viscous forces and rolling friction inside a turbopump that tend to spin whatever is holding it in the opposite direction.
If that was the case, they would've tested it with Grasshopper and found a solution for it.
Grasshopper held much more fuel at this point (ballast) which might have countered or at least lowered the effect through pure mass inertia.There are viscous forces and rolling friction inside a turbopump that tend to spin whatever is holding it in the opposite direction.
If that was the case, they would've tested it with Grasshopper and found a solution for it.
I'm contending it wasn't aero forces that caused the spin. Aero roll moment of a symmetric vehicle is tiny.
well, the Kerbel solution is fins. Aerodynamic control surfaces.
I'm contending it wasn't aero forces that caused the spin. Aero roll moment of a symmetric vehicle is tiny.
I'm contending it wasn't aero forces that caused the spin. Aero roll moment of a symmetric vehicle is tiny.Bull. You're disagreeing with Elon directly. You're wrong. He has data, you don't. Pick your battles better.
I'm contending it wasn't aero forces that caused the spin. Aero roll moment of a symmetric vehicle is tiny.
I'm contending it wasn't aero forces that caused the spin. Aero roll moment of a symmetric vehicle is tiny.
1) Propellants well settled. Single engine starts. Heavy rotor spinning several thousand RPM in one direction.
2) All ACS gas gone to overcome rolling torque due to viscous and rolling friction forces inside the single-shaft turbopump transmitting roll torque to the housing and therefore the entire vehicle.
3) Roll moment imparted to the vehicle draws propellant out of the sumps, up the walls. Engine starved.
I'm not getting paid enough to explain this.
1) Propellants well settled. Single engine starts. Heavy rotor spinning several thousand RPM in one direction.
2) All ACS gas gone to overcome rolling torque due to viscous and rolling friction forces inside the single-shaft turbopump transmitting roll torque to the housing and therefore the entire vehicle.
3) Roll moment imparted to the vehicle draws propellant out of the sumps, up the walls. Engine starved.
I'm not getting paid enough to explain this.
Then come come second stage managed to fly without ending up rolling wildly?
Then come come second stage managed to fly without ending up rolling wildly?It's active roll control works so long as the main engine works.
1) Propellants well settled. Single engine starts. Heavy rotor spinning several thousand RPM in one direction.
2) All ACS gas gone to overcome rolling torque due to viscous and rolling friction forces inside the single-shaft turbopump transmitting roll torque to the housing and therefore the entire vehicle.
3) Roll moment imparted to the vehicle draws propellant out of the sumps, up the walls. Engine starved.
I'm not getting paid enough to explain this.
Then come come second stage managed to fly without ending up rolling wildly?
It's active roll control works so long as the main engine works.
Then come come second stage managed to fly without ending up rolling wildly?It's active roll control works so long as the main engine works.
Certainly, but how come it didn't get saturated during minutes of firing when first stage failed quickly.
well, the Kerbel solution is fins. Aerodynamic control surfaces.
Too inefficient. Grid fins would be better. Better control, less mass.
Would also contribute to deceleration.
They've already got landing legs to deploy (and a few suggestions that they might be part of a roll control strategy); would it make sense to try to attach control surfaces of some kind to these?
Both stages have roll control thrusters. Stage 1 may have run out of ACS propellant on the way down.
Recognizing cooked eggs from raw eggs is easy, you spin them on a table; if the egg is cooked the rotating movement easily transmits to the inside, giving some momentum to the rotation, if it's raw doesn't trasmit, and the rotation is short (only the eggshell rotates).
What has this to do with F9?
To get centrifuging of propellant it's not enough to spin the tanks, it's necessary to transmit the movement to the propellant inside.
This can't happen in a few second burn, had to begin before, probably from aero forces.
Recognizing cooked eggs from raw eggs is easy, you spin them on a table; if the egg is cooked the rotating movement easily transmits to the inside, giving some momentum to the rotation, if it's raw doesn't trasmit, and the rotation is short (only the eggshell rotates).
What has this to do with F9?
To get centrifuging of propellant it's not enough to spin the tanks, it's necessary to transmit the movement to the propellant inside.
This can't happen in a few second burn, had to begin before, probably from aero forces.
An egg doesn't have slosh baffles, F9 has.
Recognizing cooked eggs from raw eggs is easy, you spin them on a table; if the egg is cooked the rotating movement easily transmits to the inside, giving some momentum to the rotation, if it's raw doesn't trasmit, and the rotation is short (only the eggshell rotates).
What has this to do with F9?
To get centrifuging of propellant it's not enough to spin the tanks, it's necessary to transmit the movement to the propellant inside.
This can't happen in a few second burn, had to begin before, probably from aero forces.
An egg doesn't have slosh baffles, F9 has.
How many propellant you think is needed for final burn?
It's all in the domes, without baffles.
They've already got landing legs to deploy (and a few suggestions that they might be part of a roll control strategy); would it make sense to try to attach control surfaces of some kind to these?
Correct. The domes are the sumps.
I think the problem was two fold. First, they did not have legs on this rocket. Elon has stated in the past that the legs would be used to help slow and stabilize the rocket, so without them this stage would have had less margin than it would on a normal flight. Second, somehow they used more RCS gas/required more ACS compensation than anticipated. Calculating how much stabilization is needed for a system that will be doing something no one has ever done before requires some big assumptions for variables. They can likely find some efficiencies in the flight path along the way to increase margin, and then once the legs are on and deploying that margin will be well above where it needs to be. No major redesign (fins, aerodynamic control surfaces, etc) necessary.
... And there are baffles at the sumps.Recognizing cooked eggs from raw eggs is easy, you spin them on a table; if the egg is cooked the rotating movement easily transmits to the inside, giving some momentum to the rotation, if it's raw doesn't trasmit, and the rotation is short (only the eggshell rotates).
What has this to do with F9?
To get centrifuging of propellant it's not enough to spin the tanks, it's necessary to transmit the movement to the propellant inside.
This can't happen in a few second burn, had to begin before, probably from aero forces.
An egg doesn't have slosh baffles, F9 has.
How many propellant you think is needed for final burn?
It's all in the domes, without baffles.
Correct. The domes are the sumps.
Anyone want to speculate what the MerlinDvac nozzle extension is made of? Looks like Niobium to me...
Anyone want to speculate what the MerlinDvac nozzle extension is made of? Looks like Niobium to me...
Steve Jurvetson says it's "niobium halfnium [sic]" : http://www.flickr.com/photos/jurvetson/10008137326/
It does look like the same stuff as on v1.0 to me.
If you have to counter the aero-torque, then does this require some extra new thruster, or can the existing octoweb/center-engine be tweaked to stop the roll on the way down?
If you have to counter the aero-torque, then does this require some extra new thruster, or can the existing octoweb/center-engine be tweaked to stop the roll on the way down?
Why not just aerodynamic control surfaces like fins?
Because tail fins, once over a certain size, are going to make the stage harder to control as it re-enters the atmosphere tail first. Like throwing a dart in reverse.
If you have to counter the aero-torque, then does this require some extra new thruster, or can the existing octoweb/center-engine be tweaked to stop the roll on the way down?
Why not just aerodynamic control surfaces like fins?
Because tail fins, once over a certain size, are going to make the stage harder to control as it re-enters the atmosphere tail first. Like throwing a dart in reverse.
Fins on the interstage? Never mind, they will fix the roll issue without fins.If you have to counter the aero-torque, then does this require some extra new thruster, or can the existing octoweb/center-engine be tweaked to stop the roll on the way down?
Why not just aerodynamic control surfaces like fins?
Because tail fins, once over a certain size, are going to make the stage harder to control as it re-enters the atmosphere tail first. Like throwing a dart in reverse.
Launch video is up:
The legs are going to be aerosurfaces.
The legs can be used as a steam-engine style rotary governor. :)
I guess you could fix this by having legs that are bilaterally symmetric but not rotationally symmetric. Then you could modulate roll with them by extending/retracting them.
I guess you could fix this by having legs that are bilaterally symmetric but not rotationally symmetric. Then you could modulate roll with them by extending/retracting them.
Well, what about using legs which generate lift when spinning? Worst case scenario, the rocket still spins, but you get positive Gs which prevent the fuel from sticking to the sides.
Maybe I'm just "seeing things", but I got the impression that the v1.1 flame exhaust is significantly tighter (& longer) than the v1.0 flame exhaust - see attached comparison image. This would indicate the improved efficiency, right?
On the other hand the difference could be an optical illusion caused different light conditions, camera exposures, and atmospheric conditions.
Soyuz uses these for the abort systemwell, the Kerbel solution is fins. Aerodynamic control surfaces.
Too inefficient. Grid fins would be better. Better control, less mass.
Would also contribute to deceleration.
For DANDE the planned insertion orbit was 300 x 1500:I found a planned DANDE orbit somewhere in the DANDE site that listed a planned 324 km perigee, so achieved is close. I'm still wondering about the inclination. It seems to have been aimed at 81 deg though prelaunch information suggested 80 deg.
semi-major axis: 7271 km
period: 6,171 sec
Ed Kyle derived the actual orbit is 328 x 1493 (from the DANDE-provided TLE):
semi-major axis: 7281.5 km
period: 6,184 sec
ratio of orbital periods: 1.002
So they put almost exactly the right amount of oomph into that payload, giving them a "better" orbit by 0.2%. For most payloads, though, the measure of better they want might be expected time it will remain in orbit before decay. I speculate the 28 km of added height at perigee buys them a lot. The attached atmoshpere info (from Vallado) seems to imply that....
The idea of using the legs as a governor was facetious, for the record.Designing and debugging aero surfaces that really work for controlling the reentry ( unless its passively stable, which it obviously isnt ) is no small task. "Just add fins" or "use your legs, Luke" are pretty simplistic non-answers.
Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg)
Some insider info:
The attitude control system was railed, wanted more thrust, but engines couldn't provide anymore. Doubts that they would solve it by stockpiling more RCS fuel.
Me:
Apparently there was so much aero roll that the RCS couldn't dampen it away. They probably just need to make some changes to the outside aero surface to fix things. I doubt they'll add pop out fins though.
Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg)
Thanks for posting! Mighty interesting stuff going on after stage separation....
Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg)
Thanks for posting! Mighty interesting stuff going on after stage separation....
But the pulses that follow are very cool, and could be from the S1 relighting or reorienting itself. But those thruster firing are much more visible than I expected cold gas thruster to be.
Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg)
Thanks for posting! Mighty interesting stuff going on after stage separation....
Looked like first stage RCS firing maybe, for flipping over.
Maybe I'm just "seeing things", but I got the impression that the v1.1 flame exhaust is significantly tighter (& longer) than the v1.0 flame exhaust - see attached comparison image. This would indicate the improved efficiency, right?Quite possibly an effect of GG exausts; dispersed outside the main flow in v1.0, inside the main flow (then forced to stay compact) in v1.1.
On the other hand the difference could be an optical illusion caused different light conditions, camera exposures, and atmospheric conditions.
Maybe I'm just "seeing things", but I got the impression that the v1.1 flame exhaust is significantly tighter (& longer) than the v1.0 flame exhaust - see attached comparison image.
Maybe I'm just "seeing things", but I got the impression that the v1.1 flame exhaust is significantly tighter (& longer) than the v1.0 flame exhaustQuite possibly an effect of GG exausts; dispersed outside the main flow in v1.0, inside the main flow (then forced to stay compact) in v1.1.
These two things make it possible for the outboard engine vectors to point less outward than on v1.0 (watch some closeup footage of the engine nozzles before flight) in order to pass through the CoG (for control reasons). It's not clear to me if v1.1 cants the outer ring outward at all or if they all just thrust straight "up".
Quite possibly an effect of GG exausts; dispersed outside the main flow in v1.0, inside the main flow (then forced to stay compact) in v1.1.
There's no need to point all (or any for that matter) engines through CG in any cluster, only resultant net force vector.
There's no need to point all (or any for that matter) engines through CG in any cluster, only resultant net force vector.
There is if you don't want sudden disturbances after an engine out. Lose an engine and even though the rest of the engines are still firing up and the total vector is still up, the "hook" of the thrust vector is no longer along the vehicle centerline which means the total thrust vector is also no longer pointing through the CoG and you get a torque.
Which would cause a sudden pitch, which would be detected and immediately countered by the control system. Something that long, with that much aerodynamic pressure can't rotate that fast.
Which would cause a sudden pitch, which would be detected and immediately countered by the control system. Something that long, with that much aerodynamic pressure can't rotate that fast.
There is a good reason they did that on v1.0. Heck, even a Zenit vectors out the individual nozzles of the RD-171 immediately after liftoff, despite having only one engine.
Which would cause a sudden pitch, which would be detected and immediately countered by the control system. Something that long, with that much aerodynamic pressure can't rotate that fast.
The center of pressure for a vehicle is typically above the center of gravity, making vehicles inherently aerodynamically unstable. This sudden pitch and angle-of-attack increase can spell disaster if it happens at max-Q. Having each individual engine thrust if not through the CoG, at least *closer* to the CoG does improve controlability. If all vehicles were capable of correcting attitude disturbances that promptly, I assume they also wouldn't be worrying about things like wind shear at altitude, etc.
There is a good reason they did that on v1.0. Heck, even a Zenit vectors out the individual nozzles of the RD-171 immediately after liftoff, despite having only one engine.
Out of curiosity where did you hear they did it on v1.0. Before you mentioned it here, that was the first I'd heard of it.
And why would Zenit do it with only one engine?? It doesn't have "chamber-out" capability.
Net vector would change even if you were pointing all engine through CG so you have to do TVC to point it towards intended trajectory.
Out of curiosity where did you hear they did it on v1.0. Before you mentioned it here, that was the first I'd heard of it.
It's hard to see without closeup shots of the engine, see for example the CRS-2 webcast at the 38:40 mark: www.youtube.com/watch?v=ik0ElKl5kW4#t=2320And why would Zenit do it with only one engine?? It doesn't have "chamber-out" capability.
I have *no* idea. Makes little sense to me as well.
It's hard to see without closeup shots of the engine, see for example the CRS-2 webcast at the 38:40 mark: www.youtube.com/watch?v=ik0ElKl5kW4#t=2320
Yes I knew about the angling, but is it really for engine out purposes? I think they're mounted that way, not gimbaled to that. Shuttle has each engine angled as well.
There's no need to point all (or any for that matter) engines through CG in any cluster, only resultant net force vector.
And why would Zenit do it with only one engine?? It doesn't have "chamber-out" capability.On vehicles with RCS, aligning the thrust vector with the CG makes the RCS use less fuel. I have no idea if this is why Zenit does it.
Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg)
Thanks for posting! Mighty interesting stuff going on after stage separation....
There's no need to point all (or any for that matter) engines through CG in any cluster, only resultant net force vector.That is a standard practice for many, if not all launch vehicles with multiple engines.
I wonder about those puffs. If they were cold gas (He or N2) thrusters, I'm not sure we'd be seeing them. Could the ACS have been rigged to use the GOX from the tank boiloff instead?
I have a possible explanation for the roll experienced by the first stage the way down. When the vehicle is subsonic, the air impinging on the bottom of the stage must escape sideway to return in the airstream.
The passage between nozzles is partially obstructed by the fuel lines, carrying fuel to the nozzle; this way air is forced to have a swirling motion, causing roll.
In pic 1 is clearly visible the fuel pipe, pic 2 is a reminder of the relative positions of the engines, finally the sketch explain the movement of air.
When the stage is still supersonic, the shock wave from the nozzles should shield the bottom minimizing this effect.
I have a possible explanation for the roll experienced by the first stage the way down. When the vehicle is subsonic, the air impinging on the bottom of the stage must escape sideway to return in the airstream.
The passage between nozzles is partially obstructed by the fuel lines, carrying fuel to the nozzle; this way air is forced to have a swirling motion, causing roll.
In pic 1 is clearly visible the fuel pipe, pic 2 is a reminder of the relative positions of the engines, finally the sketch explain the movement of air.
When the stage is still supersonic, the shock wave from the nozzles should shield the bottom minimizing this effect.
In that case I would think just cheap aero "baffles" oriented to redirect half of the air flow the other direction could entirely eliminate the torque... if that's the cause after all.
Agreed, some aero baffles integrated into the bottom panels.
Maybe a crazy idea, but could gimbaling all eight outer engines in the direction of rotation produce preferential vortex shedding that opposes rotation?
Agreed, some aero baffles integrated into the bottom panels.
Sounds good and involves no additional drag on the way up.
This theory requires that the additional spin came up only when the stage was falling already at a relatively low speed. So SpaceX should know.
Maybe a crazy idea, but could gimbaling all eight outer engines in the direction of rotation produce preferential vortex shedding that opposes rotation?
It depends on how cold the gas is and how moist the air is. If they just using LN2 for the propellant, the exhaust could be plenty cold enough to precipitate ice crystals an produce a little cloud.
I have a possible explanation for the roll experienced by the first stage the way down. When the vehicle is subsonic, the air impinging on the bottom of the stage must escape sideway to return in the airstream.
The passage between nozzles is partially obstructed by the fuel lines, carrying fuel to the nozzle; this way air is forced to have a swirling motion, causing roll.
In pic 1 is clearly visible the fuel pipe, pic 2 is a reminder of the relative positions of the engines, finally the sketch explain the movement of air.
When the stage is still supersonic, the shock wave from the nozzles should shield the bottom minimizing this effect.
In that case I would think just cheap aero "baffles" oriented to redirect half of the air flow the other direction could entirely eliminate the torque... if that's the cause after all.
Maybe a crazy idea, but could gimbaling all eight outer engines in the direction of rotation produce preferential vortex shedding that opposes rotation?
There is a really large plume right at the end of the video from what seems to be the first stage. Possibly the Merlins re-lighting?Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg)
Thanks for posting! Mighty interesting stuff going on after stage separation....
Great video, here's my take:
I have a possible explanation for the roll experienced by the first stage the way down. When the vehicle is subsonic, the air impinging on the bottom of the stage must escape sideway to return in the airstream.
The passage between nozzles is partially obstructed by the fuel lines, carrying fuel to the nozzle; this way air is forced to have a swirling motion, causing roll.
In pic 1 is clearly visible the fuel pipe, pic 2 is a reminder of the relative positions of the engines, finally the sketch explain the movement of air.
When the stage is still supersonic, the shock wave from the nozzles should shield the bottom minimizing this effect.
Remember, whatever Elon says about time frames for recovery and re-use of the first stage - triple it.
Remember, whatever Elon says about time frames for recovery and re-use of the first stage - triple it.
I have a possible explanation for the roll experienced by the first stage the way down. When the vehicle is subsonic, the air impinging on the bottom of the stage must escape sideway to return in the airstream.
The passage between nozzles is partially obstructed by the fuel lines, carrying fuel to the nozzle; this way air is forced to have a swirling motion, causing roll.
In pic 1 is clearly visible the fuel pipe, pic 2 is a reminder of the relative positions of the engines, finally the sketch explain the movement of air.
When the stage is still supersonic, the shock wave from the nozzles should shield the bottom minimizing this effect.
I like that. Burt Rutan would hook up an octaweb to a truck (on a rotary shaft!) and go cruising around the runway :)
Maybe a crazy idea, but could gimbaling all eight outer engines in the direction of rotation produce preferential vortex shedding that opposes rotation?
I see your crazy idea and raise you another one; how about venting GOX in addition to gimbaling? Would it be possible to let some LOX expand in each combustion chamber without fuel, not using the turbopumps, and exit through the nozzle as GOX? (a "hack")
There is a really large plume right at the end of the video from what seems to be the first stage. Possibly the Merlins re-lighting?Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg)
Thanks for posting! Mighty interesting stuff going on after stage separation....
Great video, here's my take:
^^^ Why would the 1st stage tanks vent before re-entry? Don't they need pressurization for strength and rigidity? And the tanks just got done emptying, they shouldn't be overpressurized.
^^^ Why would the 1st stage tanks vent before re-entry? Don't they need pressurization for strength and rigidity? And the tanks just got done emptying, they shouldn't be overpressurized.
Because the residual LOX (and the LOX for relights) is still boiling off and pressure is increasing in the tanks.
Do we have a firm consensus at this point re: whether the awesome-looking spurts were boring GOX venting or awesome ACS firings of some sort?
While this "triple" remark was pulled out of nether regions...Remember, whatever Elon says about time frames for recovery and re-use of the first stage - triple it.And your data-points would be...?
Remember that this recover attempt came far earlier that most of us outside observers would have anticipated.... it is indeed very advisable to be sceptic about schedule announced by SpaceX for anything. For example, this very flight was originally supposed to fly in 2008 on F1. Here is your data point. Want more?
Remember, whatever Elon says about time frames for recovery and re-use of the first stage - triple it.
And your data-points would be...? Remember that this recover attempt came far earlier that most of us outside observers would have anticipated.
While this "triple" remark was pulled out of nether regions...Remember that this recover attempt came far earlier that most of us outside observers would have anticipated.... it is indeed very advisable to be sceptic about schedule announced by SpaceX for anything. For example, this very flight was originally supposed to fly in 2008 on F1. Here is your data point. Want more?
- I think we all expected more v1.0 flights before the block-II/v1.1 was introduced
Is there an audio or video recording of yesterdays post-flight press conference somewhere?
Is there an audio or video recording of yesterdays post-flight press conference somewhere?
No video exists. It was teleconference (audio only).
You're missing something, here. I think just about everyone who knew what they were talking about knew that the very first "Block I" version of Falcon 9 was only going to be used on a handful of flights. After all, the user's guide was written for Block II and presumably they sold just Block IIs to their customers (since that is what was advertised) except for COTS and the initial CRS, since they didn't require anything better. So we assumed some sort of upgrade for the majority of the CRS flights, just not as big.
- I think we all expected more v1.0 flights before the block-II/v1.1 was introduced
I should not that we really didn't know that V 1.0-powered ISS re-supply flights could not carry enough cargo to meet CRS requirements. SpaceX was not clear that the original Falcon 9 could not fly a completely loaded Dragon to ISS.
If we had known that, then we would all have predicted that the 1.1 first launch would come early in CRS.
Didn't Musk say that he was going to put up some further video relating to the 1st stage flameout, or something like that? Is that out yet - and if so, where can I get a look at it? If not, then when's it coming out?
You're missing something, here. I think just about everyone who knew what they were talking about knew that the very first "Block I" version of Falcon 9 was only going to be used on a handful of flights. After all, the user's guide was written for Block II and presumably they sold just Block IIs to their customers (since that is what was advertised) except for COTS and the initial CRS, since they didn't require anything better. So we assumed some sort of upgrade for the majority of the CRS flights, just not as big.
- I think we all expected more v1.0 flights before the block-II/v1.1 was introduced
I should not that we really didn't know that V 1.0-powered ISS re-supply flights could not carry enough cargo to meet CRS requirements. SpaceX was not clear that the original Falcon 9 could not fly a completely loaded Dragon to ISS.
If we had known that, then we would all have predicted that the 1.1 first launch would come early in CRS.
The big thing is that they skipped Block II and went straight to a much, much improved vehicle (v1.1), not just an incremental improvement to Block II.
Sigh, does this discussion need to come up again - and here - just because someone challenged yo on your "triple it" remark?Especially now that v1.1 has flown, and its capabilities are strictly greater than any of the above, and that's the only thing they'll sell.
Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg) Credit here http://www.reddit.com/r/spacex/comments/1nevaf/external_video_with_first_views_of_first_stage/ (http://www.reddit.com/r/spacex/comments/1nevaf/external_video_with_first_views_of_first_stage/)
Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg) Credit here http://www.reddit.com/r/spacex/comments/1nevaf/external_video_with_first_views_of_first_stage/ (http://www.reddit.com/r/spacex/comments/1nevaf/external_video_with_first_views_of_first_stage/)
Let's see...
4:01 first stage separation
4:12 first stage re-light / deceleration burn
4:24-4:47 first stage aero control system firing
Am I right?
Yup, the user's guide only shows block 2. They never released the Block I equivalent publicly, but there is information on it in the NASA's NLS II contract performance query tool.You're missing something, here. I think just about everyone who knew what they were talking about knew that the very first "Block I" version of Falcon 9 was only going to be used on a handful of flights. After all, the user's guide was written for Block II and presumably they sold just Block IIs to their customers (since that is what was advertised) except for COTS and the initial CRS, since they didn't require anything better. So we assumed some sort of upgrade for the majority of the CRS flights, just not as big.
- I think we all expected more v1.0 flights before the block-II/v1.1 was introduced
I should not that we really didn't know that V 1.0-powered ISS re-supply flights could not carry enough cargo to meet CRS requirements. SpaceX was not clear that the original Falcon 9 could not fly a completely loaded Dragon to ISS.
If we had known that, then we would all have predicted that the 1.1 first launch would come early in CRS.
The big thing is that they skipped Block II and went straight to a much, much improved vehicle (v1.1), not just an incremental improvement to Block II.
You are revising history.
Attached is the official F9 data sheet from 2007 (post COTS award) showing performance from the standard F9 as 10,000+ kg.
There is no mention of a Block II or 1.1 or anything other than a single F9 variant (plus the Heavy).
The emergence of an "evolved" F9 is relatively recent. I started up a thread way back when complaining that the payload numbers of the F9 as published did not make sense, and the vast majority of the responses from the SpaceX amazing people was that I was simply wrong. It took a couple of years for the SpaceX crowd to understand that the plan was to meet the numbers via an evolved F9, and then the official story became that it was Block II/Falcon 9 1.1 that was going to be the standard CRS launcher.
Looking through my files, I see a mention of Block II becoming the standard variant in the 2009 Falcon 9 User Guide. Does anyone have anything published by SpaceX mentioning a Block II or 1.1 earlier than 2009?
Is there an audio or video recording of yesterdays post-flight press conference somewhere?
No video exists. It was teleconference (audio only).
The best summary of the call is the live tweeting by Jeff Foust at https://twitter.com/jeff_foust Still not as good as a recording.
Is there an audio or video recording of yesterdays post-flight press conference somewhere?
No video exists. It was teleconference (audio only).
The best summary of the call is the live tweeting by Jeff Foust at https://twitter.com/jeff_foust Still not as good as a recording.
Does anyone have the audio?
Looking at the orbital elements for the various objects in orbit, it seems that the prime payload is in the highest orbit, whereas the upper stage is in a slightly lower orbit. And then there are a bunch of objects that seem randomly scattered between the satellite and upper stage orbits.
Presumably the various CubeSATS are near the upper stage orbital altitude, but there are probably another dozen objects that are not accounted for, and which are randomly scattered. Since some of these are lower than the upper stage, I would have to guess that it is because their drag coefficient is greater than an upper stage, meaning that they could be empty small objects, or flat objects like panels that are not flying edge on.
I don't think that SpaceX intended to leave the upper stage and these objects in such a high orbit, as the FAA AST frown upon that sort of thing.
Looking at the orbital elements for the various objects in orbit, it seems that the prime payload is in the highest orbit, whereas the upper stage is in a slightly lower orbit. And then there are a bunch of objects that seem randomly scattered between the satellite and upper stage orbits.
Presumably the various CubeSATS are near the upper stage orbital altitude, but there are probably another dozen objects that are not accounted for, and which are randomly scattered. Since some of these are lower than the upper stage, I would have to guess that it is because their drag coefficient is greater than an upper stage, meaning that they could be empty small objects, or flat objects like panels that are not flying edge on.
I don't think that SpaceX intended to leave the upper stage and these objects in such a high orbit, as the FAA AST frown upon that sort of thing.
How can you tell which is the prime payload? (I wouldn't assume that the A object is Cassiope at this stage, it usually
takes them a few days or more to assign the right objects to the right catalog numbers
SpaceX statement re. speculation about F9 upper stage anomaly: "our data confirms there was no rupture of any kind on the second stage."
Presumably the various CubeSATS are near the upper stage orbital altitude, but there are probably another dozen objects that are not accounted for, and which are randomly scattered. Since some of these are lower than the upper stage, I would have to guess that it is because their drag coefficient is greater than an upper stage, meaning that they could be empty small objects, or flat objects like panels that are not flying edge on.
I guess the flat objects are pieces of foam insulation from the upper stage dome.
I guess the flat objects are pieces of foam insulation from the upper stage dome.
If that turns out to be the case then are they the cause (prop temp not within limits?), the effect or unrelated to the engine relight anomaly?
Musk offered a similar explanation in an email to Jay Barbree, NBC News' Cape Canaveral correspondent: "During venting to safe the stage, some foil insulation on the engine came loose. This is very lightweight, so will quickly re-enter and burn up, but it is reflective on radar."
http://i.imgur.com/I88VNlY.jpg
http://i.imgur.com/I88VNlY.jpg
http://i.imgur.com/I88VNlY.jpg
The full reddit thread with imgur album and bonus pics (http://www.reddit.com/r/spacex/comments/1nh3o0/we_went_skydiving_next_to_the_falcon_9_v11_during/).
I've been contemplating why they were able to successfully relight 3 first stage engines, and then relight the first stage center engine yet again during the "water landing" test, but did not succeed in relighting the second stage.
As far as I can tell it boils down to
1. A difference in the environment such as gravity settling or the lack there off, ambient temp or pressure etc.
2. A difference in the engine between the booster and vacuum versions of the Merlin-1D such as the nozzle shape or control software etc.
3. A random failure that could have happened on any of the restarts and the luck of the draw was the upper stage
It sounds like #1 has the inside track. Anyone have any informed speculation about specific parameters though?
On a related track, thinking about the reflective foil that apparently got knocked loose when safeing the stage after the restart didn't happen, how is that done, just open the valves and let oxidizer spew out under tank pressure? Anyone have any thoughts about why that would knock stuff loose that stayed put under some pretty severe vibration during launch? Seems odd if it exits via the nozzle, just not burning.
b) loss of pressurization in the tank.
Effect b) makes restart impossible.
b) loss of pressurization in the tank.
Effect b) makes restart impossible.
In fact, it would probably preclude even attempting to restart the engine. Loss of inlet pressure is one of those engine start box things. Yet it was reported that the engine got to 400 psi before aborting, suggesting it was within the start box as it attempted ignition. Elon speculated something about an extended spin-start, but said they really need to look into the data first.
Just for reference, MVac 1C was known to vent heavily as well - granted, this was before ignition, not after: www.youtube.com/watch?v=BqCELhkXtsY#t=206s at 3:26 into the video, view from inside the interstage.
"The second-stage engine initiated ignition, got up to about 400 psi, encountered a condition it didn't like and initiated an abort," SpaceX spokeswoman Emily Shanklin said Oct. 2. "We need more time to review the data before we come to any sort of definitive conclusion, but we are confident we will be able to address it before the next flight," she said, adding that the abort "wasn't anything fundamental" and that a planned late-October launch of the SES-8 satellite for Luxembourg fleet operator SES "is still on track to launch in about a month."
http://www.aviationweek.com/Blogs.aspx?plckBlogId=Blog:04ce340e-4b63-4d23-9695-d49ab661f385&plckPostId=Blog:04ce340e-4b63-4d23-9695-d49ab661f385Post:59d72274-2bb3-4d33-aa94-fd879fe649b2
Have we seen this video yet? https://www.youtube.com/watch?v=z48ziaJ9RVg (https://www.youtube.com/watch?v=z48ziaJ9RVg) Credit here http://www.reddit.com/r/spacex/comments/1nevaf/external_video_with_first_views_of_first_stage/ (http://www.reddit.com/r/spacex/comments/1nevaf/external_video_with_first_views_of_first_stage/)
You're missing something, here. I think just about everyone who knew what they were talking about knew that the very first "Block I" version of Falcon 9 was only going to be used on a handful of flights. After all, the user's guide was written for Block II and presumably they sold just Block IIs to their customers (since that is what was advertised) except for COTS and the initial CRS, since they didn't require anything better. So we assumed some sort of upgrade for the majority of the CRS flights, just not as big.
- I think we all expected more v1.0 flights before the block-II/v1.1 was introduced
I should not that we really didn't know that V 1.0-powered ISS re-supply flights could not carry enough cargo to meet CRS requirements. SpaceX was not clear that the original Falcon 9 could not fly a completely loaded Dragon to ISS.
If we had known that, then we would all have predicted that the 1.1 first launch would come early in CRS.
The big thing is that they skipped Block II and went straight to a much, much improved vehicle (v1.1), not just an incremental improvement to Block II.
You are revising history.
Attached is the official F9 data sheet from 2007 (post COTS award) showing performance from the standard F9 as 10,000+ kg.
There is no mention of a Block II or 1.1 or anything other than a single F9 variant (plus the Heavy).
The emergence of an "evolved" F9 is relatively recent. I started up a thread way back when complaining that the payload numbers of the F9 as published did not make sense, and the vast majority of the responses from the SpaceX amazing people was that I was simply wrong. It took a couple of years for the SpaceX crowd to understand that the plan was to meet the numbers via an evolved F9, and then the official story became that it was Block II/Falcon 9 1.1 that was going to be the standard CRS launcher.
Looking through my files, I see a mention of Block II becoming the standard variant in the 2009 Falcon 9 User Guide. Does anyone have anything published by SpaceX mentioning a Block II or 1.1 earlier than 2009?
• First stage powered by 9 SpaceX Merlin engines
o 101,900 lbs-f sea level thrust per engine
o Total thrust on liftoff of just under 1 Million lbs-f
Some insider info:
The attitude control system was railed, wanted more thrust, but engines couldn't provide anymore. Doubts that they would solve it by stockpiling more RCS fuel.
Me:
Apparently there was so much aero roll that the RCS couldn't dampen it away. They probably just need to make some changes to the outside aero surface to fix things. I doubt they'll add pop out fins though.
By my count, 4 of the 5 attempted relights on this flight were successful. Who wants to speculate, with the limited information we have, what the difference is with the the M1Dvac that may have caused the issue?
Attached video is a cutout of the coverage and show the leak after SECO.
Some insider info:
The attitude control system was railed, wanted more thrust, but engines couldn't provide anymore. Doubts that they would solve it by stockpiling more RCS fuel.
Me:
Apparently there was so much aero roll that the RCS couldn't dampen it away. They probably just need to make some changes to the outside aero surface to fix things. I doubt they'll add pop out fins though.
Me:
What about if they put RCS thrusters at the end of the legs. Wouldn't that provide a lot more roll control authority for the same amount of prop?
cheers, Martin
What about some simple 'flaps' or wing tips on the legs. If roll is consistent, countering should be relatively easy, right? Probably not even required to make them adjustable.
Ps: not a rocket scientist, not even close, so using educated guessing... Feel free to explain how this would not work. :)
What about some simple 'flaps' or wing tips on the legs. If roll is consistent, countering should be relatively easy, right? Probably not even required to make them adjustable.
Ps: not a rocket scientist, not even close, so using educated guessing... Feel free to explain how this would not work. :)
What about some simple 'flaps' or wing tips on the legs. If roll is consistent, countering should be relatively easy, right? Probably not even required to make them adjustable.
Ps: not a rocket scientist, not even close, so using educated guessing... Feel free to explain how this would not work. :)
I think not even that is necessary. Just a slight unsymmetry of the legs could cause some roll moment countering the unwanted roll.
Are you talking about a permanent asymmetry or something you can dynamically modify? A permanent asymmetry is unlikely to be helpful because the roll forces are likely variable. And dynamically modifying the asymmetry means it's a control surface.
Are you talking about a permanent asymmetry or something you can dynamically modify? A permanent asymmetry is unlikely to be helpful because the roll forces are likely variable. And dynamically modifying the asymmetry means it's a control surface.
I am talking permanent asymmetry just like flaps, nothing variable. And while it is true that the roll forces are variable they go with the wind speed and so will be the roll induced by asymmetry of the legs. Any residual roll will be low enough to be countered by the RCS hopefully.
What about some simple 'flaps' or wing tips on the legs. If roll is consistent, countering should be relatively easy, right? Probably not even required to make them adjustable.
What about some simple 'flaps' or wing tips on the legs. If roll is consistent, countering should be relatively easy, right? Probably not even required to make them adjustable.
What about small fins at/near the top of the stage? It can even *save* weight since actuated fins don't need to spend propellant to affect the roll, unlike thrusters.
What about some simple 'flaps' or wing tips on the legs. If roll is consistent, countering should be relatively easy, right? Probably not even required to make them adjustable.
What about small fins at/near the top of the stage? It can even *save* weight since actuated fins don't need to spend propellant to affect the roll, unlike thrusters.
Credit to WetMelon on the SES general discussion thread.Quote"The second-stage engine initiated ignition, got up to about 400 psi, encountered a condition it didn't like and initiated an abort," SpaceX spokeswoman Emily Shanklin said Oct. 2. "We need more time to review the data before we come to any sort of definitive conclusion, but we are confident we will be able to address it before the next flight," she said, adding that the abort "wasn't anything fundamental" and that a planned late-October launch of the SES-8 satellite for Luxembourg fleet operator SES "is still on track to launch in about a month."
http://www.aviationweek.com/Blogs.aspx?plckBlogId=Blog:04ce340e-4b63-4d23-9695-d49ab661f385&plckPostId=Blog:04ce340e-4b63-4d23-9695-d49ab661f385Post:59d72274-2bb3-4d33-aa94-fd879fe649b2
What about some simple 'flaps' or wing tips on the legs. If roll is consistent, countering should be relatively easy, right? Probably not even required to make them adjustable.
What about small fins at/near the top of the stage? It can even *save* weight since actuated fins don't need to spend propellant to affect the roll, unlike thrusters.
Small fins at the bottom of the stage.
http://forum.nasaspaceflight.com/index.php?topic=32859.msg1103830#msg1103830
http://forum.nasaspaceflight.com/index.php?topic=32859.msg1103859#msg1103859
1) Propellants well settled. Single engine starts. Heavy rotor spinning several thousand RPM in one direction.This does not seem plausible from the physics. Spin is imparted to the rocket only during turbine spin up. When the rotor reaches constant speed, the acceleration ceases, as the rotor torques and viscous and other drag cancel - otherwise the rotor would speed up or slow down. At this point the entire rocket is rotating in the opposite sense at a constant angular rate.
2) All ACS gas gone to overcome rolling torque due to viscous and rolling friction forces inside the single-shaft turbopump transmitting roll torque to the housing and therefore the entire vehicle.
3) Roll moment imparted to the vehicle draws propellant out of the sumps, up the walls. Engine starved.
I'm not getting paid enough to explain this.
This does not seem plausible from the physics. Spin is imparted to the rocket only during turbine spin up>
In steady state operation, the helicopter rotor torque is balanced by the torque imparted by the external air. In the rocket turbopump case, the corresponding drag from the pump rotor and impeller are against the vehicle itself. That's why the helicopter keep accelerating, but the rocket only acquires a constant rate dictated by conservation of angular momentum. The helicopter, in a vacuum chamber, would pick up a constant angular rate just like the rocket does. But in air, it will first acquire the same rate, then keep accelerating, unless the tail rotor stops it.
This does not seem plausible from the physics. Spin is imparted to the rocket only during turbine spin up>
So a helicopter only needs the tailrotor during engine start up?
Objects with recent TLEs
Time DR DV DP, DA
D 1640 28 97 +79 -57
H 1623 27 61 -49 -70
U 1638 6 63 -1 -81
L 1638 4 79 -1 -110
M 1645 45 91 +120 +98
N 1645 10 85 +83 +106
R 1652 10 118 +9 +78
T 1646 3 74 +66 +83
'Lost' objects
Time DR DV DP, DA
A 1634 21 81 -63 -150
C 1654 17 3 -48 -18
E 1644 13 12 -60 -29
F 1634 32 61 -90 -29
G 1643 78 162 +86 -69
J 1638 11 93 -32 -100
K 1636 15 47 -48 -86
V 1638 29 70 +43 +108
P 1638 30 64 +45 +105
Q 1645 14 78 +47 +94
S 1634 6 40 +67 +100
In steady state operation, the helicopter rotor torque is balanced by the torque imparted by the external air.
I agree the helicopter spins the opposite way. I was speaking of the torque as seen by the rotor. The helicopter is exerting torque on the rotor, trying to speed it up. The air is exerting torque trying to slow it down. So in steady state the rotor's torques are balanced. From the helicopter's point of view, it sees the torque it is exerting to spin the rotor, which tries to accelerate the body of the helicopter in the opposite direction.In steady state operation, the helicopter rotor torque is balanced by the torque imparted by the external air.
Wrong. In steady state operation, a helicopter that loses its tail rotor starts spinning in the opposite direction of the main rotor.
Jim has his helicopter physics correct. Source: first hand knowledge. Torque is always present so long as the rotor is being powered. I would expect the impeller and turbines in a rocket engine would also impart torque so long as they were being driven by combustion gasses.
Jim has his helicopter physics correct. Source: first hand knowledge. Torque is always present so long as the rotor is being powered. I would expect the impeller and turbines in a rocket engine would also impart torque so long as they were being driven by combustion gasses.That's because you never run a helicopter in a vacuum. If you did, you would still be exerting torque on the rotor, to overcome bearing friction. But the bearings would be exerting the exact same torque back, and the helicoptor would not experience any angular acceleration.
That's because you never run a helicopter in a vacuum. If you did, you would still be exerting torque on the rotor, to overcome bearing friction. But the bearings would be exerting the exact same torque back, and the helicoptor would not experience any angular acceleration.
Think of reaction wheels on a spacecraft. When you spin them at constant speed, the spacecraft does not endlessly accelerate, even though the motor has to constantly apply torque to overcome bearing friction.
Think of reaction wheels on a spacecraft. When you spin them at constant speed, the spacecraft does not endlessly accelerate, even though the motor has to constantly apply torque to overcome bearing friction. That's because the motor torque (one direction) is exactly equal to the bearing torque (the other direction).
Liquid level.
The only way a rocket in steady state can gain spin is if there is a rotational component to the plume that is exiting the closed system.That seems likely without 2 counter-rotating turbopumps...
Just look at F9 flight 1, where the roll control system (turbopump exhaust gimabling) failed - it took several minutes for even a noticeable roll to build up, and even then the roll never reached a level where it centrifuged the propellant and shut the stage down.Do we know where the GG exhaust got stuck for that? The default position could be offset from center.
A spacecraft with a rotary component that's internal to itself is almost, but not entirely, absolutely unlike a helicopter. Torque is only applied when the spinning component changes rotational speed. Rev up your car, and if the engine is mounted lengthwise, you'll notice the car tilts. Momentarily. When the RPM changes.
The only way a rocket in steady state can gain spin is if there is a rotational component to the plume that is exiting the closed system. Or, if there's an interaction with the atmosphere. (Which might be affected by the presence of the plume)
A spacecraft with a rotary component that's internal to itself is almost, but not entirely, absolutely unlike a helicopter. Torque is only applied when the spinning component changes rotational speed. Rev up your car, and if the engine is mounted lengthwise, you'll notice the car tilts. Momentarily. When the RPM changes.
The only way a rocket in steady state can gain spin is if there is a rotational component to the plume that is exiting the closed system. Or, if there's an interaction with the atmosphere. (Which might be affected by the presence of the plume)
Thank you for upholding the law of conservation of angular momentum (http://en.wikipedia.org/wiki/Angular_momentum#Conservation_of_angular_momentum)! Seemed like it was under an attack for a while ;D
The only way a rocket in steady state can gain spin is if there is a rotational component to the plume
Spacecraft have multiple reactions wheels in different axis that help cancel out bearing friction torque. A spacecraft with only one RW would spin in the opposite direction. That is why there are 3 or 4 RW in spacecraft.
The only way a rocket in steady state can gain spin is if there is a rotational component to the plume
But while the turbopump is spinning up the rocket is not in a steady state. You said so yourself: "Torque is [...] applied when the spinning component changes rotational speed." That torque might have been sufficient to slosh the propellant away from the sump.
The only way a rocket in steady state can gain spin is if there is a rotational component to the plume
But while the turbopump is spinning up the rocket is not in a steady state. You said so yourself: "Torque is [...] applied when the spinning component changes rotational speed." That torque might have been sufficient to slosh the propellant away from the sump.
See blazotron's post on a BOTE calculated RPM that startup would impart to the stage. Also, you're again back to the obvious question on why ACS on 2nd stage is perfectly able to keep the startup torque *undetectable*, but ACS on 1st stage can't cope with it and ends up in a stage rolling so fast it centrifuges propellant. All that within a second or so of engine startup? Not even vastly different propellant loads can account for that huge difference, IMO of course.
Honestly, I thought this was high school physics.
A Helicopter has to constantly fight against rotation (with a tail rotor, for example) since the rotor is acting against the atmosphere, and so there is an external torque.
A spacecraft with a rotary component that's internal to itself is almost, but not entirely, absolutely unlike a helicopter. Torque is only applied when the spinning component changes rotational speed. Rev up your car, and if the engine is mounted lengthwise, you'll notice the car tilts. Momentarily. When the RPM changes.
The only way a rocket in steady state can gain spin is if there is a rotational component to the plume that is exiting the closed system. Or, if there's an interaction with the atmosphere. (Which might be affected by the presence of the plume)
I agree that's what the gyroscope does, but it's because the rotor is slowing down. If you add a motor, attached to the frame, that keeps the rotor at constant speed, then the cage will not rotate (after startup). There is indeed torque, in fact there are two torques, and they cancel. The rotor drag tries rotate the frame, but the motor applies an exactly opposite torque on the frame, while doing its work to keep the rotor at constant speed. Net result - no rotation of the cage.Honestly, I thought this was high school physics.
A Helicopter has to constantly fight against rotation (with a tail rotor, for example) since the rotor is acting against the atmosphere, and so there is an external torque.
A spacecraft with a rotary component that's internal to itself is almost, but not entirely, absolutely unlike a helicopter. Torque is only applied when the spinning component changes rotational speed. Rev up your car, and if the engine is mounted lengthwise, you'll notice the car tilts. Momentarily. When the RPM changes.
The only way a rocket in steady state can gain spin is if there is a rotational component to the plume that is exiting the closed system. Or, if there's an interaction with the atmosphere. (Which might be affected by the presence of the plume)
If there is friction in the internal component then there is constant torque and transfer of momentum. The cage around a toy gyroscope ends up spinning with the gyro rotor.
I agree that's what the gyroscope does, but it's because the rotor is slowing down. If you add a motor, attached to the frame, that keeps the rotor at constant speed, then the cage will not rotate (after startup). There is indeed torque, in fact there are two torques, and they cancel. The rotor drag tries rotate the frame, but the motor applies an exactly opposite torque on the frame, while doing its work to keep the rotor at constant speed. Net result - no rotation of the cage.Honestly, I thought this was high school physics.
A Helicopter has to constantly fight against rotation (with a tail rotor, for example) since the rotor is acting against the atmosphere, and so there is an external torque.
A spacecraft with a rotary component that's internal to itself is almost, but not entirely, absolutely unlike a helicopter. Torque is only applied when the spinning component changes rotational speed. Rev up your car, and if the engine is mounted lengthwise, you'll notice the car tilts. Momentarily. When the RPM changes.
The only way a rocket in steady state can gain spin is if there is a rotational component to the plume that is exiting the closed system. Or, if there's an interaction with the atmosphere. (Which might be affected by the presence of the plume)
If there is friction in the internal component then there is constant torque and transfer of momentum. The cage around a toy gyroscope ends up spinning with the gyro rotor.
With the turbo pumps everyone seems to be forgetting the fact that you are constantly accelerating liquid inside of the pump, imparting spin to it. So even after startup you still have a constant torque from the fluid running through the pump being imparted on the system.This would be correct if the fluid was spraying out in all directions - that's exactly how a lawn sprinkler works. But in this case the casing of the pump collects the fluid and directs (hopefully towards the combustion chamber). The moving fluid exerts forces on the pump case, plumbing, and combustion chamber. If at the end the combustion products proceed straight out the axis of the rocket, with no net spin, then these forces exactly cancel, and there is no net force after startup. (And rocket designers try very hard to insure no net spin at the output, since it's inefficient (that energy could have gone into thrust) and it takes RCS effort to null out).
no, the same thing will happen.
http://www.youtube.com/watch?v=gdAmEEAiJWo
When he lets go of the cd player before he pushes it (1:09), it is starting to rotate.
The same thing happens with a gyroscopically stabilized binoculars.
Think of reaction wheels on a spacecraft. When you spin them at constant speed, the spacecraft does not endlessly accelerate, even though the motor has to constantly apply torque to overcome bearing friction.
Wrong, there are other torques on the spacecraft that cancel this out. Look up magnetorquer
(Sorry, ended up channeling Jim there for a moment...)
Liquid level.
I've been following this discussion with some bemusement. I'm waiting to see if SpaceX is going to post the video of the descent. If it shows that the stage was spinning before the final single engine burn was started, then I'm not sure what the argument has been about.This is just a change in initial conditions. According to some of the arguments above, assuming the stage is already spinning, it will change spin rate (either up or down) once the pump is started (depending on the relation between the pump direction and the pre-existing spin). My bet, however, is that starting the pump results in no discernable change to the spin rate.
... and yet, the torque will be miniscule compared to that of the helicopter because the moment arm is tiny.Jim has his helicopter physics correct. Source: first hand knowledge. Torque is always present so long as the rotor is being powered. I would expect the impeller and turbines in a rocket engine would also impart torque so long as they were being driven by combustion gasses.
Bingo
...Precisely. I doubt any significant net steady-state torque from the turbopump survives passing through the plumbing and the injector(s).
In a steady state, with the rotating machinery at constant rotational speed and the flow of fluids established, regardless of path, if the exhaust coming out is not rotating, there is no rotary torque from the propulsion system other than from a roll-control nozzle. ...
I'm glad we could resolve this before it made xkcd "What If."Not me, I think that would be a highly amusing one... you should go suggest it! :)
So, has anyone heard any updates on the CASSIOPE mission itself? Is the satellite in a viable orbit and is it working properly?
Elon indicated in his post launch interview that the restart issue was not mechanical and that it had to do with the start sequence in zero G and vacuum.
He also indicated this issue could be easily resolved via tweaks in the automation.
This leads us to believe auto start and engine run parameters such as max / min pressure time limits for auto shut down may be changed.
S
I've been following this discussion with some bemusement. I'm waiting to see if SpaceX is going to post the video of the descent. If it shows that the stage was spinning before the final single engine burn was started, then I'm not sure what the argument has been about.
It seems like the second stage non-restart was due to some difference between the terrestrial environment where Elon says they tested restart many times (as expected) and the space environment where the first stage engines did restart and the second stage engine did not. Vacuum and micro-gravity have been posited. I guess another difference could be temporal depending on the time between shutdown and restart of the various engines. Given the supposed commonality between the booster and vacuum versions I tend to discount (but not entirely rule out) engine differences as a likely factor.
Anyone have time stamps for the various shutdown and restarts/attempts? I doubt much can be done in the way of direct testing of the micro-gravity idea (lighting a Merlin inside the vomit comet is contraindicated) but is there a vacuum chamber big enough to at least get a burp out of a Merlin here dirt side to compare with the on orbit data? For that matter, what would the ambient pressure have been during the first restart of the first stage vs the aborted second stage restart?
I'm sure they are looking at all the data in great detail, just scratching my head and pondering until there is some official word or action.
Any idea why they couldn't try re-starting the second stage again, and instead opted to vent the tanks?
I guess one could test in a vacuum via GH2.. by the time GH2 Flies , SPACEX may already be recovering stages in Florida..Umm, I think that would essentially reproduce the suborbital first stage environment where restart worked not the orbital second stage environment where it did not.
The previous M-vac was successfully restarted in orbit. Of course this is a substantially new engine. But most other contemporary launch vehicles have restartable upper stages (Ariane 5 ECA is an exception).
As you say, we have to wait to see what they decide to release about the problem and its solution.
Even still, I wonder if eventually the line will be blurred... The ability to command an upper stage must have at least SOME merit. So many launch vehicle problems are software-related, you have to wonder if the ability to fix the stage on-orbit may be a worthwhile risk-reduction capability.Any idea why they couldn't try re-starting the second stage again, and instead opted to vent the tanks?
Suppose SpaceX had programmed the second stage to wait for instructions, rather than vent, if the first restart attempt failed due to exceeding some limit. The life of the stage is measured in minutes. How many minutes would mission controllers need to decide on a new course of action, given that a wrong choice might lead the stage to rapidly disassemble itself? Would they wait until the next orbital pass over their telemetry assets, in which case the engine start conditions would have changed yet again?
As others have indicated, this is an essential difference between an ascent stage that reaches orbit, and a spacecraft. The Falcon 9 upper stage is the former, not the latter!
The previous M-vac was successfully restarted in orbit. Of course this is a substantially new engine. But most other contemporary launch vehicles have restartable upper stages (Ariane 5 ECA is an exception).
As you say, we have to wait to see what they decide to release about the problem and its solution.
Aaah, but on the first Falcon 9 flight the attempted second burn with the original M-Vac engine also failed. It led to a spiral and much Australian UFO sightings.
Indeed, this seems like a very similar situation, although the root cause might be different. But an upper stage restart was achieved on the second F9 flight.I hope it's clear from the telemetry and has an easy fix. Some times 20-20 hindsight makes things obvious - like happened with the stage "bump" on the F1 flight where thrust transients from the then-new Merlin-1C regen were not seen during atmospheric testing but were critical to allow for in vacuum operation. Adding a 5 second delay took care of it. For want of a nail ...
A reusable upper stage will need a loiter time in the range of one day and probably the ability to receive commands.Says who?
The previous M-vac was successfully restarted in orbit. Of course this is a substantially new engine. But most other contemporary launch vehicles have restartable upper stages (Ariane 5 ECA is an exception).
As you say, we have to wait to see what they decide to release about the problem and its solution.
Aaah, but on the first Falcon 9 flight the attempted second burn with the original M-Vac engine also failed. It led to a spiral and much Australian UFO sightings.
Indeed, this seems like a very similar situation, although the root cause might be different. But an upper stage restart was achieved on the second F9 flight.
The previous M-vac was successfully restarted in orbit. Of course this is a substantially new engine. But most other contemporary launch vehicles have restartable upper stages (Ariane 5 ECA is an exception).
As you say, we have to wait to see what they decide to release about the problem and its solution.
Aaah, but on the first Falcon 9 flight the attempted second burn with the original M-Vac engine also failed. It led to a spiral and much Australian UFO sightings.
Indeed, this seems like a very similar situation, although the root cause might be different. But an upper stage restart was achieved on the second F9 flight.
First F9 flight the 2nd stage developed a quite important roll due to the TPA exaust actuator that froze.
Most probably the restart failed (they got only a burp, that's what was said) due to problems in settling propellants (if someone remember something more....).
This time no roll (in 2nd stage ::)) but that unusual venting after SECO.
First F9 flight the 2nd stage developed a quite important roll due to the TPA exaust actuator that froze.
Most probably the restart failed (they got only a burp, that's what was said) due to problems in settling propellants (if someone remember something more....).
This time no roll (in 2nd stage ::)) but that unusual venting after SECO.
Was it 'unusual'? Who made that statement?
Quite energetic, not usual purging/venting.This could explain the considerable scatter of the tracked fragments - shed pieces of insulation caught up in the energetic venting and blown away from the stage at high velocity.
First F9 flight the 2nd stage developed a quite important roll due to the TPA exaust actuator that froze.
Most probably the restart failed (they got only a burp, that's what was said) due to problems in settling propellants (if someone remember something more....).
This time no roll (in 2nd stage ::)) but that unusual venting after SECO.
Was it 'unusual'? Who made that statement?
The statement is mine (did you see the clip?)
Venting was:
Not seen before with this intensity/modality in five flights.
Quite energetic, not usual purging/venting.
It's clearly visible in frames of the movie.
From http://www.flickr.com/photos/jurvetson/10008137326/
Venting was:
Not seen before with this intensity/modality in five flights.
Quite energetic, not usual purging/venting.
It's clearly visible in frames of the movie.
From http://www.flickr.com/photos/jurvetson/10008137326/
Different compared to 1.0, sure, but I don't think the data supports "unusual" where I take that to mean "off-nominal". This is a new engine, new stage, and maybe even a new relative position of camera compared to features on the stage or engine (clearly the field of view differs in some ways).
Who wants to speculate as to whether the liquid venting was LOX or RP-1?
Venting was:
Not seen before with this intensity/modality in five flights.
Quite energetic, not usual purging/venting.
It's clearly visible in frames of the movie.
From http://www.flickr.com/photos/jurvetson/10008137326/
Different compared to 1.0, sure, but I don't think the data supports "unusual" where I take that to mean "off-nominal". This is a new engine, new stage, and maybe even a new relative position of camera compared to features on the stage or engine (clearly the field of view differs in some ways).
You are correct saying that it doesn't mean "off-nominal". I don't know what's nominal on Merlin DVac, hence no possibility to say what's off-nominal.
I wrote the word unusual because that venting was not seen before (hence not usual) and not standard purging/venting (hence not usual).
That's it, a little bit of speculation on something outside some expected boundaries.
Venting was:
Not seen before with this intensity/modality in five flights.
Quite energetic, not usual purging/venting.
It's clearly visible in frames of the movie.
From http://www.flickr.com/photos/jurvetson/10008137326/
Different compared to 1.0, sure, but I don't think the data supports "unusual" where I take that to mean "off-nominal". This is a new engine, new stage, and maybe even a new relative position of camera compared to features on the stage or engine (clearly the field of view differs in some ways).
You are correct saying that it doesn't mean "off-nominal". I don't know what's nominal on Merlin DVac, hence no possibility to say what's off-nominal.
I wrote the word unusual because that venting was not seen before (hence not usual) and not standard purging/venting (hence not usual).
That's it, a little bit of speculation on something outside some expected boundaries.
It was my understanding that it is now international practice to not leave derelict upper stages full of propellant hanging around in orbit due to agreements over managing orbital debris risk. Some of the largest single sources of current orbital debris are detonated upper stages from old GTO launches. I'd think that by now all modern upper stages have provisions to vent all propellants overboard to reduce the debris pollution risk. So while SpaceX might have prefered to burn the propellants instead, once the failure to restart was evident, intentional clearing of the tanks is the obvious next step, and very nominal for that situation.
It was my understanding that it is now international practice to not leave derelict upper stages full of propellant hanging around in orbit due to agreements over managing orbital debris risk. Some of the largest single sources of current orbital debris are detonated upper stages from old GTO launches. I'd think that by now all modern upper stages have provisions to vent all propellants overboard to reduce the debris pollution risk. So while SpaceX might have prefered to burn the propellants instead, once the failure to restart was evident, intentional clearing of the tanks is the obvious next step, and very nominal for that situation.
It was my understanding that it is now international practice to not leave derelict upper stages full of propellant hanging around in orbit due to agreements over managing orbital debris risk. Some of the largest single sources of current orbital debris are detonated upper stages from old GTO launches. I'd think that by now all modern upper stages have provisions to vent all propellants overboard to reduce the debris pollution risk. So while SpaceX might have prefered to burn the propellants instead, once the failure to restart was evident, intentional clearing of the tanks is the obvious next step, and very nominal for that situation.
Not all, Chinese LH upper stages still break up and Russia Briz-M's that fail do not vent and then have a tendency to rather violently break up after about a year.
The Chinese vehicles fixed this a while ago, according to http://adsabs.harvard.edu/full/1997ESASP.393..689Z, " Elimination of the Potential Hazard of the Long March 4 Launch Vehicle's On-Orbit Breakup". In practice, I don't recall any recent breakups of Chinese upper stages.It was my understanding that it is now international practice to not leave derelict upper stages full of propellant hanging around in orbit due to agreements over managing orbital debris risk.
Not all, Chinese LH upper stages still break up and Russia Briz-M's that fail do not vent and then have a tendency to rather violently break up after about a year.
A general question about venting. Would they vent both the LOX and the RP-1? Venting LOX may be easier and without LOX RP-1 will be harmless. That assumption may be wrong, please correct me.
No one did notice this? https://twitter.com/Wolfram66/status/387280929514725376
If you look closely, engine bell does not seams to be in good shape...
Sfabris
No one did notice this? https://twitter.com/Wolfram66/status/387280929514725376
If you look closely, engine bell does not seams to be in good shape...
Sfabris
Didn't previous Vac Merlin's use stiffing bands to protect nozzle during first stage flight then came off in flight? Might this be one?
Didn't previous Vac Merlin's use stiffing bands to protect nozzle during first stage flight then came off in flight? Might this be one?
The stiffeners come off at ignition.
Marsman has suggested elsewhere in the forum that the piece seen coming off here is merely residual adhesive from the stiffeners, and I believe he is correct.
If stiffeners are needed for the first MVac start wouldn't they be needed for a restart?
Bingo, the Merlin isn't the only second stage engine that uses them. They are designed to come off once they are no longer needed.If stiffeners are needed for the first MVac start wouldn't they be needed for a restart?More likely the stiffener is required for ground handling and/or vibrations during first stage flight.
Bingo, the Merlin isn't the only second stage engine that uses them. They are designed to come off once they are no longer needed.If stiffeners are needed for the first MVac start wouldn't they be needed for a restart?More likely the stiffener is required for ground handling and/or vibrations during first stage flight.
Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?
Would the stiffener also cause problems (e.g. mechanical stress) once the bell metal begins to thermally expand?Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?On second stage 1 kg more of structure=1 kg less of payload.
Don't know, but likely; I guess thermal cycle warping of the thin metal is possible.Would the stiffener also cause problems (e.g. mechanical stress) once the bell metal begins to thermally expand?Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?On second stage 1 kg more of structure=1 kg less of payload.
Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?
On second stage 1 kg more of structure=1 kg less of payload.
This is an old picture of the nozzle extension (2009 press release)
The Merlin Vacuum engine expansion nozzle measures 2.7 meters (9 feet) tall, and most of it has a wall thickness of about 1/3 of a millimeter (1/64 of an inch). Photo credit: SpaceX.
Venting was:There are a couple of videos of Merlin 1D ground tests, though not the Vacuum version. They show these engines venting immediately after shutdown in some fashion. The on board video looks like an expected type of event to me. It could be a purge.
Not seen before with this intensity/modality in five flights.
Quite energetic, not usual purging/venting.
It's clearly visible in frames of the movie.
From http://www.flickr.com/photos/jurvetson/10008137326/
Not to beat the "has nothing to do with Cassiope stiffener" thing to death, but didn't they have to remove the stiffener before launch on the first flight? Or did they put a shortened version back on after the nozzle was shortened?
Not to beat the "has nothing to do with Cassiope stiffener" thing to death, but didn't they have to remove the stiffener before launch on the first flight? Or did they put a shortened version back on after the nozzle was shortened?
Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?
On second stage 1 kg more of structure=1 kg less of payload.
This is an old picture of the nozzle extension (2009 press release)
The Merlin Vacuum engine expansion nozzle measures 2.7 meters (9 feet) tall, and most of it has a wall thickness of about 1/3 of a millimeter (1/64 of an inch). Photo credit: SpaceX.
Here is a newer (and closer to flight status) picture of a nozzle extension. The way it appears to rest on the ground probably supports the theory that the liner/stiffener is there to protect it during ground handling.
Does anyone know if SpaceX still intends to release the video of first stage descent?
I saw this in the update thread - new video from Spacex, some addition views...
- Clean IR stage separation view
- First view of stage 1 relight! (from S1, not great quality) :)
Mission overview
http://www.spacex.com/news/2013/10/14/upgraded-falcon-9-mission-overview
Now we just wait for the footage they shot from a small plane flying near the first stage descent area...Looks like you did not have to wait long ;)
Is the second photo pictures perspective of the stage just above the water and we are seeing the exhaust on the ocean surface?
If so, wow, they got pretty (can't say without running afoul of the language filter) close to the objective!
I know its a blurry photo, but there's a strange white anomaly just above the thrust structure extending midway up. Is that the stage venting fuel/lox?
Now we just wait for the footage they shot from a small plane flying near the first stage descent area...Looks like you did not have to wait long ;)
Now we just wait for the footage they shot from a small plane flying near the first stage descent area...Looks like you did not have to wait long ;)
I should say things like that more often, maybe I have some hithertoo unknown powers!
I'm assuming this is a screencap from the full video, so hopefully the full thing gets put up on youtube sometime soon.
Is the second photo pictures perspective of the stage just above the water and we are seeing the exhaust on the ocean surface?
If so, wow, they got pretty (can't say without running afoul of the language filter) close to the objective!
No, it appears to be a picture higher up in the air. Probably a cloud puff from the final braking burn restart.
It doesn't look like video screencaps - this might just be long telephoto shots. There's a chance there might not be any better ones.
Now we just wait for the footage they shot from a small plane flying near the first stage descent area...Looks like you did not have to wait long ;)
I should say things like that more often, maybe I have some hithertoo unknown powers!
I'm assuming this is a screencap from the full video, so hopefully the full thing gets put up on youtube sometime soon.
It doesn't look like video screencaps - this might just be long telephoto shots. There's a chance there might not be any better ones.
It doesn't look like video screencaps - this might just be long telephoto shots. There's a chance there might not be any better ones.
I just remember hearing something about SpaceX having gotten footage of the first stage coming back in, taken from a small airplane. IIRC Elon mentioned he had seen the video but I don't remember where he (if it was even him) said it.
There's this tweet, too https://twitter.com/jeff_foust/status/384402628962451456
No mention of where the video is from however, so it might just mean the video we got today.
wowza!It doesn't look like video screencaps - this might just be long telephoto shots. There's a chance there might not be any better ones.
I just remember hearing something about SpaceX having gotten footage of the first stage coming back in, taken from a small airplane. IIRC Elon mentioned he had seen the video but I don't remember where he (if it was even him) said it.
There's this tweet, too https://twitter.com/jeff_foust/status/384402628962451456
No mention of where the video is from however, so it might just mean the video we got today.
Asked my friend at SpaceX and yes those photos are screen caps from a video taken by a chase plane (of some sort) and that second image is indeed just before it hits the water.
Asked my friend at SpaceX and yes those photos are screen caps from a video taken by a chase plane (of some sort) and that second image is indeed just before it hits the water.
Asked my friend at SpaceX and yes those photos are screen caps from a video taken by a chase plane (of some sort) and that second image is indeed just before it hits the water.
Or "just before it hits the water" could be on the order of tens of seconds, at several hundred meters altitude, with just some odd atmospheric plume effect that makes it look pancaked and obstructed.Could be. I think the plume is actually a spray of foam from the stage hitting the water. This would imply the photo is taken from above and all the blue in the background is water. The rocket would possibly be angled towards the observer slightly.
Both shots ARE from the video, which I've seen. And yes the second one is literally a sec before it hits the water.
... The composite tanks I understand - light weight, probably buoyant, consistent with breakup on impact ...
What composite tanks?
A caption in the video at 3:19 says "ground station signal acquired over Antarctica." It's little hard to parse that, but it seems to imply that there's a ground station in Antarctica. What's actually going on?
Asked my friend at SpaceX and yes those photos are screen caps from a video taken by a chase plane (of some sort) and that second image is indeed just before it hits the water.
There is a contradiction between that claim and what someone else posted about the meta-data on the first of the two photos. Perhaps your friend is mistaken about the first of those two images, and only the second is a screen capture. Even working at SpaceX, he or she might not realize one of them is not from the video. It's hard to explain how else the first image would have meta data attached to it saying it was a still taken by Canon DSLR.
Even working at SpaceX, he or she might not realize one of them is not from the video. It's hard to explain how else the first image would have meta data attached to it saying it was a still taken by Canon DSLR.Canon DSLRs take excellent Full HD video. IIRC they have full 35mm sensors and allow attachment of extremely large lenses. So I could totally see them use those for filming.
The fact that the first stage hit the water intact or nearly intact is definately a WOW moment. ;DAgreed, I thought that the stage was torn to shreds.
A caption in the video at 3:19 says "ground station signal acquired over Antarctica." It's little hard to parse that, but it seems to imply that there's a ground station in Antarctica. What's actually going on?McMurdo Ground Station
http://amrc.ssec.wisc.edu/meetings/MGS/history.html
http://www.spacex.com/sites/spacex/files/11_c439042b-ee14-45c7-aa50-6f0f6396b0db.pngIt has been postulated by other more knowledge posters than I that there was enough propellant in the feed lines for the engine to start and burn for a little while. It might have been spinning already when the engines started.
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.
If this image literally is 1 second before impact, as Padrat said, and the engine is firing, that means the rocket spun up and flamed out in less than a second, immediately after this shot. But in that case it must have already decelerated significantly and couldn't have had much braking left to do, and thus didn't hit *that* hard.
Anyone have a guess how fast it might have been going at impact? Is it already spinning significantly in this shot?
http://www.spacex.com/sites/spacex/files/11_c439042b-ee14-45c7-aa50-6f0f6396b0db.pngIt has been postulated by other more knowledge posters than I that there was enough propellant in the feed lines for the engine to start and burn for a little while. It might have been spinning already when the engines started.
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.
If this image literally is 1 second before impact, as Padrat said, and the engine is firing, that means the rocket spun up and flamed out in less than a second, immediately after this shot. But in that case it must have already decelerated significantly and couldn't have had much braking left to do, and thus didn't hit *that* hard.
Anyone have a guess how fast it might have been going at impact? Is it already spinning significantly in this shot?
Sure, but an engine flaming out and starving for fuel isn't going to be a clean shutdown step function. Imagine it sputtering and coughing all the way into the drink? Especially as the turbo pumps are driven by a pre-burner that needs fuel as well to turn- the pumps would have slowed, forcing the last spurts of fuel through much more slowly than full blast to empty.http://www.spacex.com/sites/spacex/files/11_c439042b-ee14-45c7-aa50-6f0f6396b0db.pngIt has been postulated by other more knowledge posters than I that there was enough propellant in the feed lines for the engine to start and burn for a little while. It might have been spinning already when the engines started.
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.
If this image literally is 1 second before impact, as Padrat said, and the engine is firing, that means the rocket spun up and flamed out in less than a second, immediately after this shot. But in that case it must have already decelerated significantly and couldn't have had much braking left to do, and thus didn't hit *that* hard.
Anyone have a guess how fast it might have been going at impact? Is it already spinning significantly in this shot?
I am certain it was spinning before the engine started. But the engine must start a fair distance from the surface to have time for braking. So if this is immediately before impact the engine cannot be running unless it was started way too late.
I am certain it was spinning before the engine started. But the engine must start a fair distance from the surface to have time for braking. So if this is immediately before impact the engine cannot be running unless it was started way too late.
Jeff Foust
@jeff_foust
Shotwell shows a picture of the F9 1st stage from the previous launch just 3 meters above the ocean before splashdown, "fully intact" #ispcs
Here is a tweet: https://twitter.com/jeff_foust/status/390503333561401344QuoteJeff Foust
@jeff_foust
Shotwell shows a picture of the F9 1st stage from the previous launch just 3 meters above the ocean before splashdown, "fully intact" #ispcs
Presumably this is the picture we have been discussing.
Really?Here is a tweet: https://twitter.com/jeff_foust/status/390503333561401344QuoteJeff Foust
@jeff_foust
Shotwell shows a picture of the F9 1st stage from the previous launch just 3 meters above the ocean before splashdown, "fully intact" #ispcs
Presumably this is the picture we have been discussing.
Where can we see that picture?
Kasper
that's only 10 feet off the water. Fully intact
The final braking burn NEEDS to start very late - there isn't enough propellant to do a nice slow descent. (at least once operational - this flight probably had more margin) But until the video is released, I guess we won't see exactly how late it was started.
Why do people keep asking questions that are proprietary to SpaceX?
Why do people keep asking questions that are proprietary to SpaceX?
Jeff Foust
@jeff_foust
This is the photo Shotwell showed of the F9 1st stage just before splashdown (h/t @kkairq): http://bit.ly/1byP9S3
Braking at 2g, it would take slightly more than 4 seconds (~1km height) to slow down from a terminal velocity of 300km/h. Considering engine startup transients, make that 5, maybe 6 (making it 1500-1700m height). Centrifugation won't have starved the engine right away, but rather thinned out the propellant supply: if the engine managed to start up to some degree, some acceleration will have built up, up to the nominal, notional 2g.
http://www.spacex.com/sites/spacex/files/11_c439042b-ee14-45c7-aa50-6f0f6396b0db.png
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.
The sea surface gets a prenotice when something large is falling fast but subsonic towards it.
So I wonder if we[1] can work out how fast the stage was spinning :) [2]
We have the estimated fuel load remaining or can get it, and we should be able to work out how long the engine had to burn to get to 3M above sea level, so that maybe can tell us how much fuel was left when it ran out? THAT should tell us the shape of the parabola and THAT should tell us the rotation ???
Easy peasy.
Ok maybe not.
1 - by "we" I mean people smarter than me :)
2 - yes I know, arrant uninformed speculation...
http://www.spacex.com/sites/spacex/files/11_c439042b-ee14-45c7-aa50-6f0f6396b0db.png
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.
This post has been ignored, but could it be the answer? IE a fast-falling stage will have a pressure wave in front of it and that may be what we're seeing.The sea surface gets a prenotice when something large is falling fast but subsonic towards it.
cheers, Martin
Why do people keep asking questions that are proprietary to SpaceX?Since the dawn of this forum? ;) Why get annoyed over it now? Asking is one thing... getting an answer is another.
Which would also make the "rectangular-ish" shape of the spray make more sense, if the stage was pointing roughly towards the observer, making an asymmetrical spray cloud towards the camera.
Ergo, a public question of what the thrust of the center engine is just before splashdown is essentially unknowable.
Which would also make the "rectangular-ish" shape of the spray make more sense, if the stage was pointing roughly towards the observer, making an asymmetrical spray cloud towards the camera.
Considering this was taken with a large zoom (meta data said 400mm) from a plane safely outside the drop zone, you are most likely looking at the image at a very oblique angle. Meaning, at it from the side. You are unlikely able to determine if you are looking at a circle, ellipse, or even trapezoid.
I suspect it is a nice symmetrical circular spray pattern observed from the side.
I don't think so from the image enhancement analysis from before, which was later verified: the background is all sea surface.
Ergo, a public question of what the thrust of the center engine is just before splashdown is essentially unknowable.The question is perfectly knowable ;) but I know what you mean. However, if I recall correctly, the thrust of the engine at sea level is given by Space-X (at least in rough numbers), I also recall seeing a statement that is it throttleable to 70% or therebouts of max. thrust. That should give you an indication of the minimum thrust of the engine.
I would argue that first photo is of the second burn. First burn was 40miles up or so and without specialized equipment they could not have take such picture/video.
It is hard to judge angle, but it looks like stage was still pretty high up above water when first photo/video frame was taken. If it burned for several seconds and then shut down, it had enough time to get some speed. If second frame was showing second or so after shutdown, stage would probably stayed intact.
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.The second photo does not show the engine lit. If it were lit then it would be a lot brighter. This is not a cloud ring we are looking at. It is ocean spray from the impact of the stage like a whale hitting the water.
One more curious thing from the video.That is an interesting theory about why they included the footage downlinked from the Antarctic station, but the footage included says "re-acquisition of signal" implying it is the first footage received from this station. When you combine that implication with the interview statements given by Elon that SpaceX waited until it had good telemetry/data links with the second stage over the Antarctic receiving window to attempt the restart, one would conclude that the restart happened after acquisition of signal from the Antarctic station, and therefore after the footage shown in the video. This would imply that reason for showing that last segment of video couldn't have been to prove the stage survived the restart attempt. (Or if it is then their left hand isn't talking to their right hand so to speak)
The final frames of the video are focused on second stage (I think to show it didn't blew up).
that's only 10 feet off the water. Fully intact
Why is that surprising? If the stage had been torn up by aero, it would have happened at higher q (or q-alpha) when it was traveling much faster. Impact would have been much more destructive than low q aero.
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.The second photo does not show the engine lit. If it were lit then it would be a lot brighter. This is not a cloud ring we are looking at. It is ocean spray from the impact of the stage like a whale hitting the water.
Just one detail folks are missing. I've noticed a few people assuming that 70% throttle is the plan, but to my memory it isn't the plan at all.. The most fuel efficient landing is at full throttle, not at 70%, so use the full value of merlin 1D thrust in all calcs, not the throttled value.
That's just what Jeff Foust wrote when he saw the image the first time. Did Shotwell actually say 3m or is Jeff interpreting that?I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.The second photo does not show the engine lit. If it were lit then it would be a lot brighter. This is not a cloud ring we are looking at. It is ocean spray from the impact of the stage like a whale hitting the water.
No, according to Shotwell the picture shows the stage ~3m before impact: https://twitter.com/jeff_foust/status/390503333561401344
My speculation: the "spray" might be residual smoke from the engine that just shot down a second or two before the picture was taken/captured.
Is the first stage + interstage roughly ~48 meters in length? I don't see how the stage can be 3 meters above the water surface in that photo then, given the apparent gap between tail-end and surface. What's wrong with this picture? Am I totally misinterpreting the various fuzzy objects here?
One more curious thing from the video.That is an interesting theory about why they included the footage downlinked from the Antarctic station, but the footage included says "re-acquisition of signal" implying it is the first footage received from this station. When you combine that implication with the interview statements given by Elon that SpaceX waited until it had good telemetry/data links with the second stage over the Antarctic receiving window to attempt the restart, one would conclude that the restart happened after acquisition of signal from the Antarctic station, and therefore after the footage shown in the video. This would imply that reason for showing that last segment of video couldn't have been to prove the stage survived the restart attempt. (Or if it is then their left hand isn't talking to their right hand so to speak)
The final frames of the video are focused on second stage (I think to show it didn't blew up).
That's just what Jeff Foust wrote when he saw the image the first time. Did Shotwell actually say 3m or is Jeff interpreting that?
If you compare these two frames (T+10 min and T+36 min) you can see (circled in red) a buildup of material.
Fair enough. One thing I think we can be certain of however: the engine is not lit in the second photo.That's just what Jeff Foust wrote when he saw the image the first time. Did Shotwell actually say 3m or is Jeff interpreting that?
Here is another blog's partial transcript of her talk: http://www.transterrestrial.com/?p=51818 Three meters was mentioned again, so this is unlikely to be Jeff's invention.
Ergo, a public question of what the thrust of the center engine is just before splashdown is essentially unknowable.The question is perfectly knowable ;) but I know what you mean. However, if I recall correctly, the thrust of the engine at sea level is given by Space-X (at least in rough numbers), I also recall seeing a statement that is it throttleable to 70% or therebouts of max. thrust. That should give you an indication of the minimum thrust of the engine.
Just one detail folks are missing. I've noticed a few people assuming that 70% throttle is the plan, but to my memory it isn't the plan at all.. The most fuel efficient landing is at full throttle, not at 70%, so use the full value of merlin 1D thrust in all calcs, not the throttled value.
Which would also make the "rectangular-ish" shape of the spray make more sense, if the stage was pointing roughly towards the observer, making an asymmetrical spray cloud towards the camera.
Considering this was taken with a large zoom (meta data said 400mm) from a plane safely outside the drop zone, you are most likely looking at the image at a very oblique angle. Meaning, at it from the side. You are unlikely able to determine if you are looking at a circle, ellipse, or even trapezoid.
I suspect it is a nice symmetrical circular spray pattern observed from the side.I don't think so from the image enhancement analysis from before, which was later verified: the background is all sea surface.
So? A very oblique angle does not imply seeing sky in a highly zoomed image. That is an image of a very distant object as the atmospheric haze and jitter distorting and blurring the stage image indicates.
I highly doubt the the final burn could have taken place even briefly if the stage was tumbling end over end. Just what is being implied by the term tumbling? Maybe you mean wobbling?
Is the first stage + interstage roughly ~48 meters in length? I don't see how the stage can be 3 meters above the water surface in that photo then, given the apparent gap between tail-end and surface. What's wrong with this picture? Am I totally misinterpreting the various fuzzy objects here?
Weighing in for the first time after much lurking here. Doing a simple width to height ratio of the image of the first stage as it is coming down, some of the first stage is in the white cloud/splash/plume object.
Comparing the sizes from a high-resolution image (http://upload.wikimedia.org/wikipedia/commons/c/c2/Falcon_9_1.1_at_Vandenberg_AFB_-_cropped.jpg) to the landing one, I get a ~18-20% difference in height - probably the stage was at a angle.
I agree 3m is an underestimation however, 3m would be ~5 pixels, and the distance between the bottom of the stage and the upper edge of the cloud is, at best, more than 10 pixels.
Comparing the sizes from a high-resolution image (http://upload.wikimedia.org/wikipedia/commons/c/c2/Falcon_9_1.1_at_Vandenberg_AFB_-_cropped.jpg) to the landing one, I get a ~18-20% difference in height - probably the stage was at a angle.
I agree 3m is an underestimation however, 3m would be ~5 pixels, and the distance between the bottom of the stage and the upper edge of the cloud is, at best, more than 10 pixels.
Same length, what you are seeing as the "end" of the stage is really just the end of the somewhat-clean part. Below that is more of the stage, covered in soot and not very visible.
.
I believe the 3m reference is quite correct, and the bottom of the stage is right in there with the "cloud", about to hit the surface.
That O2 guess seems a good one. My intuition is this: Unless the avionics had shut the O2+kero valves of as soon as the engine starved, the unlit engine would have been spewing far more O2 than kero because gaseous O2 would still be at high pressure over its sump regardless of the liquid part having been centrifuged away.
I highly doubt the the final burn could have taken place even briefly if the stage was tumbling end over end. Just what is being implied by the term tumbling? Maybe you mean wobbling?
Not end over end, but a precession around the z axis. I used "tumbling" to mean a non-pure-Z rotation.
Comparing the sizes from a high-resolution image (http://upload.wikimedia.org/wikipedia/commons/c/c2/Falcon_9_1.1_at_Vandenberg_AFB_-_cropped.jpg) to the landing one, I get a ~18-20% difference in height - probably the stage was at a angle.
I agree 3m is an underestimation however, 3m would be ~5 pixels, and the distance between the bottom of the stage and the upper edge of the cloud is, at best, more than 10 pixels.
Same length, what you are seeing as the "end" of the stage is really just the end of the somewhat-clean part. Below that is more of the stage, covered in soot and not very visible.
.
I believe the 3m reference is quite correct, and the bottom of the stage is right in there with the "cloud", about to hit the surface.
Don't think so. I roughly agree to the pictorial representation by sittingduck (http://forum.nasaspaceflight.com/index.php?topic=32859.msg1109597#msg1109597): there's a clear hint of orange/red between the stage bottom and the cloud, which would be the plume.
I disagree. It makes sense that the area surrounding the engines would be darkest.... Here is what I believe is the true outline, in red. (your pic, modified)
Dunno about anyone else but I'm having a lot of fun watching everybody scramble over this blurry picture, makes me think of discussions about bigfoot ;)
I would argue that first photo is of the second burn. First burn was 40miles up or so and without specialized equipment they could not have take such picture/video.
I would argue that first photo is of the second burn. First burn was 40miles up or so and without specialized equipment they could not have take such picture/video.
Has it been mentioned yet that the first picture has the letters "usaf" in the file name? That immediately made me think "tracking camera". I believe the first photo was of the first burn, at high altitude, with three engines firing.
Both shots ARE from the video, which I've seen. And yes the second one is literally a sec before it hits the water.
If that was the case, then they got through most of the burn, and it is possible that spin started after the engine re-lit.
Do you think the stage might have been programmed to allow some roll so as to conserve cold gas propellant for pitch and yaw control? Roll is not as bad as the stage tumbling.
If that was the case, then they got through most of the burn, and it is possible that spin started after the engine re-lit.
No, this has been discussed ad nauseum. There's simply not enough time or rotational torque to start the spin after second ignition. It would have had to have started sometime during free fall, in atmospheric deceleration. This would have to be prior to second ignition.
Was the stage tumbling as suggested before?
I'm a little confused as to why some think that the stage roll had anything to do with engine ignition. It seems SO much more likely that the stage developed the roll durning the 300km/hr freefall, centrifuged the propellant away from the piping connection to the tank, and then started the engine on residual fuel in the piping. Why would we think that the stage remained stable all the way until the last few seconds, and then try to come up with some unusual mechanism of spinning up the stage?In addition, Musk said that the legs would mitigate the spin. This lends more evidence toward the aero spin theory than engine startup. I also like to keep in mind the KISS principle.
Musk said it was aero, and they ran out of roll control authority. Doesn't it make more sense that slight aerodynamic proturbances at 300km/hr spun it up after running out of cold gas for the thrusters?
This discussion about torques on the stage in the final approach are confusing to me. My bet is the video will show a rapidly-spinning stage dropping into view, a short burn of the single engine in the last seconds, and the stage hitting the water at a pretty good velocity.
Still an amazing feat.
I would argue that first photo is of the second burn. First burn was 40miles up or so and without specialized equipment they could not have take such picture/video.
Doubtful. They couldn't start the 2nd burn that far up... This is a picture with sky background. And this isn't a very clear picture to begin with. I don't see why a good telephoto lens (with an unknown number of telephoto extensions) couldn't have captured it. And we don't know it it was attached to some tracking hardware or stabilizing platform. Nor do we know the length of the burn, and how far it descended during the burn.
stage developed the roll durning the 300km/hr freefall
I can't. All I was saying that if engine shut down just 1-2s before second picture, then stage would have probably stayed intact. Or at least not in pieces. Burn must have killed most of velocity already.It is hard to judge angle, but it looks like stage was still pretty high up above water when first photo/video frame was taken. If it burned for several seconds and then shut down, it had enough time to get some speed. If second frame was showing second or so after shutdown, stage would probably stayed intact.How can you judge speed from that single blurry picture?
stage developed the roll durning the 300km/hr freefall
Where did the 300 figure come from?
. I just know skydiver freefall is somewhat less than that. I see that Cambrianera has much more precise calculations (showing even higher speeds).stage developed the roll durning the 300km/hr freefall
Where did the 300 figure come from?
That O2 guess seems a good one. My intuition is this: Unless the avionics had shut the O2+kero valves of as soon as the engine starved, the unlit engine would have been spewing far more O2 than kero because gaseous O2 would still be at high pressure over its sump regardless of the liquid part having been centrifuged away.
The feed line for O2 is also much longer so it's likely that there was a large volume of liquid O2 that could have been expelled by the pressure of the gaseous O2.
I imagine it would be the same effect as a CO2 fire extinguisher.
I doubt the programers spent any time writing code to shut down the engines 1 second before landing, no matter what problems arise, but maybe they did out of an overabundance of caution.
I still think that first image is of the second burnIt would mean stage falling almost exactly on head of photographer. Forget about it.
I have been arguing against "rotational torques" (I assume you mean something to do with the turbo pump) - I'm very confident it was aerodynamic forces - but those can be show up only after the engines are thrusting.
But - if the burn nominally takes 10 seconds, and the effect kicked in as a result of ignition, and they did burn for 7-8 seconds (as the 3m picture seems to suggest), then that's plenty enough time to build up spin on a mostly-empty stage.
It's still an open race in my book.
Was the stage tumbling as suggested before?
There was never any reason to believe the stage was tumbling, and every reason to believe it was not.
Is there any reason the "roll" had to be an end over end tumble & not a wobbly barrel roll with the business end oriented correctly?
ISTM that would better explain the plume we're seeing in the picture.
Dunno about anyone else but I'm having a lot of fun watching everybody scramble over this blurry picture, makes me think of discussions about bigfoot ;)
I would argue that the blurring in the image is causing both Eeergo and Lars_J to draw the stage wider than it is.
I'm a little surprised that we haven't seen photos of some major rocket parts recovered. I guess they broke up and sank.
I'm a little confused as to why some think that the stage roll had anything to do with engine ignition. It seems SO much more likely that the stage developed the roll durning the 300km/hr freefall, centrifuged the propellant away from the piping connection to the tank, and then started the engine on residual fuel in the piping. Why would we think that the stage remained stable all the way until the last few seconds, and then try to come up with some unusual mechanism of spinning up the stage?
Musk said it was aero, and they ran out of roll control authority. Doesn't it make more sense that slight aerodynamic proturbances at 300km/hr spun it up after running out of cold gas for the thrusters?
This discussion about torques on the stage in the final approach are confusing to me. My bet is the video will show a rapidly-spinning stage dropping into view, a short burn of the single engine in the last seconds, and the stage hitting the water at a pretty good velocity.
Still an amazing feat.
Apart from the 1st stage restart video (which was blown up unnecessarily, cropping the 4:3 aspect to fit 16:9 in the process), the mission overview video was pretty disappointing.
Seriously, no tracking camera shots?
Apart from the 1st stage restart video (which was blown up unnecessarily, cropping the 4:3 aspect to fit 16:9 in the process), the mission overview video was pretty disappointing.
Seriously, no tracking camera shots?
There weren't any cameras.
Apart from the 1st stage restart video (which was blown up unnecessarily, cropping the 4:3 aspect to fit 16:9 in the process), the mission overview video was pretty disappointing.
Seriously, no tracking camera shots?
There weren't any cameras.
What's this, then? www.youtube.com/watch?v=WX0Gnid2E0E&t=72
Cameras weren't disabled. What Helodriver reported in another thread was that the antenna that SpaceX apparently used for forwarding camera video was knocked off alignment because it was too close to the pad. The western range obviously had their own links and range recorders.
I'm a little surprised that we haven't seen photos of some major rocket parts recovered. I guess they broke up and sank.
Someone with a better explanation than a mistake for those two frames showing exactly the same speed?
Someone with a better explanation than a mistake for those two frames showing exactly the same speed?
Possibility:
The first overlay is shown right as the "first stage is relighting..." - so it is continuing to accelerate. By 10 seconds later, the stage has begun to decelerate. The stage's peak speed is somewhere just above 6814 km/hr and occurred between the two screengrabs.
The explanation offered by "space our soul" is the most likely imho.
Zoe
Just for fun, I did a few BOTE calcs re that 6,814 km/hr speed number.
Over the 10 second interval from 7:40 to 7:50:
Altitude loss = 11.4 km, which would result in speed gain of 58 m/sec if no retro burn
Assume 20% propellant load
3 engine burn at 100% thrust results in approximately 2 g retro burn
Over 10 seconds, delta V retro is approximately 200 m/sec
Then speed change is approximately 58-200=negative 140 m/sec= negative 504 km/hr
6,814-504=6,310 km hr.
So unless my math and or physics are way off (entirely possible, I admit!) we should see a significant speed decrease after 10 seconds of retro burn, despite the energy gain due to altitude loss.
Ergo, I continue to posit that the speed cannot be 6,814 km/hr both before and after 10 seconds of retro burn, and that the difference is far greater than measurement resolution/precision granularity.
Not that empty with 20% fuel. It would still be about 200 tons of thrust for 20 tons of booster and 80? tons of fuel?Just for fun, I did a few BOTE calcs re that 6,814 km/hr speed number.
Over the 10 second interval from 7:40 to 7:50:
Altitude loss = 11.4 km, which would result in speed gain of 58 m/sec if no retro burn
Assume 20% propellant load
3 engine burn at 100% thrust results in approximately 2 g retro burn
Over 10 seconds, delta V retro is approximately 200 m/sec
Then speed change is approximately 58-200=negative 140 m/sec= negative 504 km/hr
6,814-504=6,310 km hr.
So unless my math and or physics are way off (entirely possible, I admit!) we should see a significant speed decrease after 10 seconds of retro burn, despite the energy gain due to altitude loss.
Ergo, I continue to posit that the speed cannot be 6,814 km/hr both before and after 10 seconds of retro burn, and that the difference is far greater than measurement resolution/precision granularity.
How did you get 2 g acceleration for the retro burn? I think it would be a lot higher with an almost-empty stage.
Just for fun, I did a few BOTE calcs re that 6,814 km/hr speed number.
Over the 10 second interval from 7:40 to 7:50:
Altitude loss = 11.4 km, which would result in speed gain of 58 m/sec if no retro burn
Assume 20% propellant load
3 engine burn at 100% thrust results in approximately 2 g retro burn
Over 10 seconds, delta V retro is approximately 200 m/sec
Then speed change is approximately 58-200=negative 140 m/sec= negative 504 km/hr
6,814-504=6,310 km hr.
So unless my math and or physics are way off (entirely possible, I admit!) we should see a significant speed decrease after 10 seconds of retro burn, despite the energy gain due to altitude loss.
Ergo, I continue to posit that the speed cannot be 6,814 km/hr both before and after 10 seconds of retro burn, and that the difference is far greater than measurement resolution/precision granularity.
How did you get 2 g acceleration for the retro burn? I think it would be a lot higher with an almost-empty stage.
Just for fun, I did a few BOTE calcs re that 6,814 km/hr speed number.
Over the 10 second interval from 7:40 to 7:50:
Altitude loss = 11.4 km, which would result in speed gain of 58 m/sec if no retro burn
Assume 20% propellant load
3 engine burn at 100% thrust results in approximately 2 g retro burn
Over 10 seconds, delta V retro is approximately 200 m/sec
Then speed change is approximately 58-200=negative 140 m/sec= negative 504 km/hr
6,814-504=6,310 km hr.
So unless my math and or physics are way off (entirely possible, I admit!) we should see a significant speed decrease after 10 seconds of retro burn, despite the energy gain due to altitude loss.
Ergo, I continue to posit that the speed cannot be 6,814 km/hr both before and after 10 seconds of retro burn, and that the difference is far greater than measurement resolution/precision granularity.
How did you get 2 g acceleration for the retro burn? I think it would be a lot higher with an almost-empty stage.
Assuming 20% residual propellant the acceleration should be about 2g.
I agree with you (Jason1701) that the residual propellant should be much less (around 5%), but in this particular case, commenting the labels of some frames, the BOTE calculation of Kabloona is OK (if anything, strenghtened by a lower propellant residue).
20% residual would let three engines burn for over 100 seconds. The actual residual is probably about 3-5%.
yes - I calculate that 20 % fuel would boost the stage 1 by over 14,000 km/hr. so I think 20 % fuel reserve is excessive.
dry mass = 28 tonnes
fuel load = 411 tonnes, 20 % = 82.2 tonnes
reserve for final soft touchdown burn= ~ 2 tonnes, for terminal velocity =200 m/s, from the rocket equation and sea level Isp.
so with vacuum Isp, the rocket equation gives delta V = 3051 m/s* ln(110/30) and that's a lot.
yes - I calculate that 20 % fuel would boost the stage 1 by over 14,000 km/hr. so I think 20 % fuel reserve is excessive.
dry mass = 28 tonnes
fuel load = 411 tonnes, 20 % = 82.2 tonnes
reserve for final soft touchdown burn= ~ 2 tonnes, for terminal velocity =200 m/s, from the rocket equation and sea level Isp.
so with vacuum Isp, the rocket equation gives delta V = 3051 m/s* ln(110/30) and that's a lot.
Sorry for the confusion. I was merely trying to prove that it would be virtually impossible for the speed to be 6,814 km/hr at both 7:40 and at 7:50, ten seconds into a retro burn. Earlier in this thread I posited that there must have been an error in the video editing, where someone put the same number (6,814 km/hr) on the screen at two different points in the video.
But some forumites here wondered if, perhaps, that number could be correct at both times, by coincidence, that the gain in speed due to altitude loss might cancel the thrust delta V over that small time interval.
So I pulled some numbers out of the air (e.g. the 20% fuel load) and did the calcs to show that, even with a relatively large (assumed) residual fuel load, there should be a quite significant difference in speed at those two points.
If in fact the correct number is closer to 5% residual propellant load, the change in speed from 7:40 to 7:50 will be even greater...reinforcing my original point that the 6,814 km/hr figure cannot be correct at *both* the 7:40 and 7:50 time marks, and is likely a mere video editing error.
So if the real number is more like 5% residual propellant, I apologize for muddying the waters with the 20% assumed figure I used for my BOTE calcs. But as a limiting case, it proved my point.
How many times does it need to be said... it was an obvious error in the video. Let it go.
How many times does it need to be said... it was an obvious error in the video. Let it go.
Yes - your point is proven. Your argument brings up some interesting points though.
Like-
how much fuel did S1 actually use to reach staging altitude and velocity?
Which begs the question of whether of not CASSIOPE launched with a full fuel load.
What was the lift-off mass?
With a little more data we could calculate the actual average thrust of the v1.1.
And how long was the deceleration burn actually?
Did we ever find out what the real value of terminal velocity is?
Answers it would be fun to know.
I think Jim has said that all they have are indicators that the fuel and oxidizer are full or empty. It would not be possible to fuel it partially with precision. The logical result is that SpaceX launched with a full fuel load, throttled down based on measured acceleration, and cut the engines upon achieving the proper velocity for staging.
QuoteI think Jim has said that all they have are indicators that the fuel and oxidizer are full or empty. It would not be possible to fuel it partially with precision. The logical result is that SpaceX launched with a full fuel load, throttled down based on measured acceleration, and cut the engines upon achieving the proper velocity for staging.
Most of the aero and gravity drag was incurred before staging though, so we can't use the rocket equation to accurately calculate the fuel burned to reach 6,814 m/sec.
Anyone want to try that calculation? (Or supply numerical inputs?)
Looking at the last photos in the recent SpaceX.com article about this flight...the side-by side photos, where the one on the left shows the first stage descending with 3 engines running...
Exactly what are we seeing in the right photo? It's obviously long-range, with rather low resolution. Is the stage in mid-air, at some significant altitude, and, if so, what is the white "donut" of water vapor? Or, is the stage just above the ocean surface with the "donut" being spray kicked up off the water by the exhaust plume?
I apologize in advance if this is already being discussed, or has already been discussed, elsewhere.
I'm guessing that the blue background field is sky, not water, and my first possibility is the case. From earlier reports, AIUI, the second, one-engine relight wasn't of sufficient duration and stability to get them that close to a "successful" simulated landing.
Is the stage in mid-air, at some significant altitudeNo its near the ocean, 3 meters above.
Or, is the stage just above the ocean surface with the "donut" being spray kicked up off the water by the exhaust plume?Near the ocean yes, unclear how the spray was kicked up or if the engine was firing at or shortly before the picture was taken.
QuoteI think Jim has said that all they have are indicators that the fuel and oxidizer are full or empty. It would not be possible to fuel it partially with precision. The logical result is that SpaceX launched with a full fuel load, throttled down based on measured acceleration, and cut the engines upon achieving the proper velocity for staging.
That makes sense. We know that they top-up to replace LOX boil off, which would be very hard to control with a partial LOX load. Full LOX implies full RP-1, so the tanks were full.
Most of the aero and gravity drag was incurred before staging though, so we can't use the rocket equation to accurately calculate the fuel burned to reach 6,814 m/sec.
QuoteI think Jim has said that all they have are indicators that the fuel and oxidizer are full or empty. It would not be possible to fuel it partially with precision. The logical result is that SpaceX launched with a full fuel load, throttled down based on measured acceleration, and cut the engines upon achieving the proper velocity for staging.
That makes sense. We know that they top-up to replace LOX boil off, which would be very hard to control with a partial LOX load. Full LOX implies full RP-1, so the tanks were full.
Most of the aero and gravity drag was incurred before staging though, so we can't use the rocket equation to accurately calculate the fuel burned to reach 6,814 m/sec.
We know SpaceX uses a propellant utilization system, where they try to burn out both propellants at the same time. You can't do that (very well, at least) without knowing how much propellant is left in the tanks during the burn, which implies that they have more than just full/empty sensors.
They use differential pressure transducers, the standard way of measuring propellant levels.So I was wrong about the sensors, but does anyone think the rocket flew with less than a full load of fuel and oxidizer?
QuoteI think Jim has said that all they have are indicators that the fuel and oxidizer are full or empty. It would not be possible to fuel it partially with precision. The logical result is that SpaceX launched with a full fuel load, throttled down based on measured acceleration, and cut the engines upon achieving the proper velocity for staging.
That makes sense. We know that they top-up to replace LOX boil off, which would be very hard to control with a partial LOX load. Full LOX implies full RP-1, so the tanks were full.
Most of the aero and gravity drag was incurred before staging though, so we can't use the rocket equation to accurately calculate the fuel burned to reach 6,814 m/sec.
We know SpaceX uses a propellant utilization system, where they try to burn out both propellants at the same time. You can't do that (very well, at least) without knowing how much propellant is left in the tanks during the burn, which implies that they have more than just full/empty sensors.
They use differential pressure transducers, the standard way of measuring propellant levels.
How much did the chutes on 1.0 weigh?
If this was able to get through the worst of the atmosphere without ripping apart, couldn't a drogue have gotten rid of low-rpm procession (precession?) and possibly whatever roll messed with the fuel? Then a Soyuz-style soft landing to ensure bigger pieces recovered.
Or, would bigger RCS tanks solve some of the problems instead?
What's important is that the design be extendible, so that adding optimizations doesn't require a major rework. If it's tweakable, the F9 could become the next DC-3.
I would expect them to continue to upgrade F9 of course. It's what all other launch providers do, after all.
What's important is that the design be extendible, so that adding optimizations doesn't require a major rework. If it's tweakable, the F9 could become the next DC-3.
I would expect them to continue to upgrade F9 of course. It's what all other launch providers do, after all. But the main priority is to prove the reliability of the new design and fly the manifest. I wouldn't expect them to make large design changes while establishing v1.1.
I remember the Shuttle being compared with the DC-3 in the early days. I think F9R has a good chance of being commercially successful, but comparing it to the DC-3 is not useful. Spaceflight and aviation are too different.
I would expect them to continue to upgrade F9 of course. It's what all other launch providers do, after all.
Careful. That needs to be conditional. Experience needs to be developed. Repeatability and consistency is important to customers. That the flight hardware has worked and done so together many times before is important. Several major changes bundled together doesn't make customers happy. It tends to reset the counter on the number of successful launches of a type.
...I remember the Shuttle being compared with the DC-3 in the early days. I think F9R has a good chance of being commercially successful, but comparing it to the DC-3 is not useful. Spaceflight and aviation are too different.
Sure it's useful. It's not a comparison of propellers and rocket engines, it's a matter of simplicity, economy, reliability, robustness, and longevity. These are valid comparison points, within their respective domains.
...I am pretty much convinced that the only true customer of SpaceX is SpaceX self.
All other customers are indeed very important but merely the means to get to their goal...
I would expect them to continue to upgrade F9 of course. It's what all other launch providers do, after all.
...However, the company should seek to avoid regular complete model upgrades similar to the recent v.1.0/v.1.1 transition. Such things will only increase backlogs and reduce confidence in the reliability of the current product.
Just keep in mind that they are not done with the full roll-out / upgrade path of F9V1.1. (F9R) They still need to incorporate those legs and that's not a small thing. And after that they'll start 2nd stage re-design for boost back. Point being that, although it seems they are over the proverbial hump with 1.1, I do not get the sense they'll be slowing down upgrades. However, they have probably bought themselves enough time and stability to do so in a less disruptive way even if they do decide to radically alter F9 again within the next few years. Which I think they will. But by that time, they'll be able to cycle in a new design without disrupting their current manifest. IMO.
...However, the company should seek to avoid regular complete model upgrades similar to the recent v.1.0/v.1.1 transition. Such things will only increase backlogs and reduce confidence in the reliability of the current product.
Agree. I meant (and should have said) small upgrades. Antares made a similar point.
We're talking about v1.1 generally here. Maybe this discussion belongs on another thread.
Just keep in mind that they are not done with the full roll-out / upgrade path of F9V1.1. (F9R) They still need to incorporate those legs and that's not a small thing. And after that they'll start 2nd stage re-design for boost back. Point being that, although it seems they are over the proverbial hump with 1.1, I do not get the sense they'll be slowing down upgrades. However, they have probably bought themselves enough time and stability to do so in a less disruptive way even if they do decide to radically alter F9 again within the next few years. Which I think they will. But by that time, they'll be able to cycle in a new design without disrupting their current manifest. IMO.
...However, the company should seek to avoid regular complete model upgrades similar to the recent v.1.0/v.1.1 transition. Such things will only increase backlogs and reduce confidence in the reliability of the current product.
Agree. I meant (and should have said) small upgrades. Antares made a similar point.
We're talking about v1.1 generally here. Maybe this discussion belongs on another thread.
And after that they'll start 2nd stage re-design for boost back.
Ha, ha, very good.And after that they'll start 2nd stage re-design for boost back.
The 2nd stage will not be doing any boost back to the launch site. Since it will be doing at least one orbit it would be boost forward to the launch site. :)
They might choose not to attempt recovery of the second stage.
They might choose not to attempt recovery of the second stage.
Perhaps. I think they will certainly focus on fully implementing 1st stage return and Cargo Dragon V2 first. But I fully suspect they will transition into 2nd stage return after. Perhaps sometime in late 2014 after they have completed some pad abort tests using the Super Dracos on Crewed Dragon. As I believe they will use the same configuration on a redesigned 2nd stage. It fits with their philosophy of using common systems. Ok, off topic...
I wonder if this is showing MVac throttling down near the end of the burn? It doesn't seem to me to be related to camera exposure variation as seen earlier in the burn. Once the bright Earth exited the frame, nozzle glow was roughly constant between T+8:00 and T+8:30 and then it starts slowly dropping off.
I'd look not on the brightness, but on the nozzle color. :) There should not be mixture change, so most likely throttling.I wonder if this is showing MVac throttling down near the end of the burn? It doesn't seem to me to be related to camera exposure variation as seen earlier in the burn. Once the bright Earth exited the frame, nozzle glow was roughly constant between T+8:00 and T+8:30 and then it starts slowly dropping off.
Its actually dimming a lot more than the eyeball sees, towards the end.
Note how the apparent illumination level of the structure is rapidly brightening, while the nozzle seems to dim just a bit. That nozzle is actually dimming a lot faster, but the camera is adjusting its exposure to mostly compensate.
Cause.. Throttling? Mixture change? Both?
Using this stage 1 trajectory I conclude that the F9.1 could not reach LEO with 13,150 kg though it can with other trajectories.
Using this stage 1 trajectory I conclude that the F9.1 could not reach LEO with 13,150 kg though it can with other trajectories.
How did you reach that conclusion, given the lack of specifics about the upper stage performance?
Does anyone know what the actual payload mass was for the Cassiope launch? what was it?Cassiope went to a 300 x 1,500 km x 80 deg orbit from Vandenberg AFB. The 13.15 tonne figure is given for a 185 km x 28.5 deg orbit from Cape Canaveral, where extra delta-v is provided by the Earth's rotation. Payload from Vandenberg toward a near-polar orbit will be much less - and the higher altitude will take away even more lifting capability. Falcon 9 v1.1 is probably only able to lift 9 tonnes or less to the Cassiope orbit, assuming that the advertised capabilities are accurate.
If not, I've searched and found the satellite masses but not the mass of any ancillary parts.
Cassiope - 481 kg
CU Sat - 40.82 kg
DANDE - 50 kg
DOPACS - 4.5 kg
Does anyone know what the mass of the payload adapter? What was it?
I know the trajectory of the first stage up to MECO pretty well from repeatedly viewing the launch (available on livestream), pausing and recording the data as it is given. Using this stage 1 trajectory I conclude that the F9.1 could not reach LEO with 13,150 kg though it can with other trajectories. I'm trying to simulate the boost-back so knowing the payload would help determine the fuel available for that function.
Does anyone know what the actual payload mass was for the Cassiope launch? what was it?Cassiope went to a 300 x 1,500 km x 80 deg orbit from Vandenberg AFB. The 13.15 tonne figure is given for a 185 km x 28.5 deg orbit from Cape Canaveral, where extra delta-v is provided by the Earth's rotation. Payload from Vandenberg toward a near-polar orbit will be much less - and the higher altitude will take away even more lifting capability. Falcon 9 v1.1 is probably only able to lift 9 tonnes or less to the Cassiope orbit, assuming that the advertised capabilities are accurate.
If not, I've searched and found the satellite masses but not the mass of any ancillary parts.
Cassiope - 481 kg
CU Sat - 40.82 kg
DANDE - 50 kg
DOPACS - 4.5 kg
Does anyone know what the mass of the payload adapter? What was it?
I know the trajectory of the first stage up to MECO pretty well from repeatedly viewing the launch (available on livestream), pausing and recording the data as it is given. Using this stage 1 trajectory I conclude that the F9.1 could not reach LEO with 13,150 kg though it can with other trajectories. I'm trying to simulate the boost-back so knowing the payload would help determine the fuel available for that function.
- Ed Kyle
Don't you also incur a penalty for Cassiope's use of a single upper stage burn vs. double upper stage burn trajectory.The problem with having the Falcon second stage do three burns (LEO injection, raise apogee to GEO, raise perigee to GEO also) is the 5-6 hours spent between the second and third orbit. Some of the engine lines froze in the CASSIOPE mission in less than an hour. The SES launch handled the half-hour wait fine, but 5-6 hours is a lot longer. On top of that is the issue of keeping the LOX tank stable during that time.
Though to be fair, if the payload needs the extra boost, there is no reason they would not use a two burn profile.
The problem with having the Falcon second stage do three burns (LEO injection, raise apogee to GEO, raise perigee to GEO also) is the 5-6 hours spent between the second and third orbit. Some of the engine lines froze in the CASSIOPE mission in less than an hour. The SES launch handled the half-hour wait fine, but 5-6 hours is a lot longer. On top of that is the issue of keeping the LOX tank stable during that time.
If I'm not mistaken, those considerations were why they invented the current technique, the one used in the SES launch.
Don't you also incur a penalty for Cassiope's use of a single upper stage burn vs. double upper stage burn trajectory.In this case - a 300 x 1,500 km elliptical low earth orbit - the penalty isn't substantial assuming insertion is done at perigee. A two-burn mission would have a bigger advantage if the goal was a 1,500 km circular orbit.
Though to be fair, if the payload needs the extra boost, there is no reason they would not use a two burn profile.
I know they didn't invent this technique for this mission, and that the technique has been around for a very long time. But it wasn't there in the beginning (the 60s), and that was where I was coming from. I wasn't fully aware of the current technique until I saw it happening with the SES launch. It flew beneath my personal radar in the years since Apollo. I wasn't paying attention to the techniques of GEO satellite launching, being distracted by moon launches, space shuttles and interplanetary probes...
The "techniques of GEO satellite launching" were developed from "moon launches, space shuttles and interplanetary probes" in the 60's. The two burns were done for Surveyor in 1967 by Atlas Centaur and for Apollo 8 in 1968.That's not the same thing, and you know it. Both of those launches were translunar injection, which is not the same thing as coming up with a streamlined, efficient technique for launching a satellite to geosynchronous orbit. They didn't get really creative with trajectories and orbits until a few years later. The 70s saw a huge improvement in the imagination and capability of the trajectory designers, with the Voyager and Pioneer probes, and it hasn't stopped since. I don't know that anybody in the 60s would have ever dreamed of what they have been doing around Saturn these past ten years with the Cassini probe, or what they did in the 90s with the Galileo probe around Jupiter.
The "techniques of GEO satellite launching" were developed from "moon launches, space shuttles and interplanetary probes" in the 60's. The two burns were done for Surveyor in 1967 by Atlas Centaur and for Apollo 8 in 1968.That's not the same thing, and you know it. Both of those launches were translunar injection, which is not the same thing as coming up with a streamlined, efficient technique for launching a satellite to geosynchronous orbit.
I don't know that anybody in the 60s would have ever dreamed of what they have been doing around Saturn these past ten years with the Cassini probe, or what they did in the 90s with the Galileo probe around Jupiter.
Yes, they did. The sling shot maneuver was proposed in 1961 and used by Mariner 10 in 1973 (which means it was designed in the 60's).Slingshot after slingshot after slingshot, for years on end? They had many years, many dozens of orbits of the Cassini probe all laid out ahead of time. I remember seeing it on their web site in 2004. How many times to see Titan, how many to see Iapetus, etc, and exactly when. They had all the course corrections laid out already.
I don't know when somebody got the bright idea of having the final kick motor on the satellite itself, as a sort of final stage, using hypergolics or something else that keeps well. The satellite needed it anyway, for station-keeping. But I strongly suspect that they didn't think right away of starting off with an apogee 50% higher than GEO so that the essential energy level of the orbit starts off more or less the same as the target orbit.
Yes, they did. The sling shot maneuver was proposed in 1961 and used by Mariner 10 in 1973 (which means it was designed in the 60's).Slingshot after slingshot after slingshot, for years on end?
While I will agree that there is no essential difference between the second burn of Falcon and that of the other rockets you referred to, what I was originally referring to was the notion (long ago) that the final insertion into GTO would be handled by that last stage, making a third burn in total. That is the burn I was referring to as presenting the freezing or pressurization difficulties.
Since day 1 (going back to Syncom 1, the first GSO satellite). All the Delta and Atlas spacecraft going to GSO had the kick motor in them. All commercial comsats have kick motors or boost systems. Only the DOD spacecraft on Titan IIIC, 34D and IV using Transstage, IUS, and Centaur and Delta IV Heavy have relied on the launch vehicle for final injection into GSO, which is the exception vs the rule.Which begs the question: given that using a kick motor that is part of the satellite is more efficient and practical, why would the DOD use the final stage that way at all? Not arguing here. Just curious and learning stuff...
Which begs the question: given that using a kick motor that is part of the satellite is more efficient and practical, why would the DOD use the final stage that way at all? Not arguing here. Just curious and learning stuff...