SpaceX Falcon 9 historic landing thread (1st landing attempt & most recent missions)
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RocketGeekInFL
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RocketGeekInFL
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If you are not following the Mr. Steven Twitter feed you are missing out on comedy gold.
I have been saying that since day one in this thread. I don't blame them, I would do the same thing if I were Musk. But it is pretty obvious to me that is what they do. Okay bring it on now.
Is the landing attempt video somewhere? I went to the main feed just now and it was only second stage. I wanted to watch the failure just to see what happened...
I hope they caught some on-shore video of the soft landing.
RocketGeekInFL
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I wonder if they will ever release the final onboard video as it apparently splashes down then pitches over.
Of course, this is the first landing failure in a long time, and even so the payload and mice with non-moldy food were safely lofted, and this "failed landing" was soft compared to all booster landings pre-SpaceX, so while unfortunate, it's really more of a learning opportunity.
Of course, this is the first landing failure in a long time, and even so the payload and mice with non-moldy food were safely lofted, and this "failed landing" was soft compared to all booster landings pre-SpaceX, so while unfortunate, it's really more of a learning opportunity.
RocketGeekInFL
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Final onboard video. Watch the the RCS thruster go full time to stabilize the spin.
https://twitter.com/elonmusk/status/1070399755526656000
https://twitter.com/elonmusk/status/1070399755526656000
Hard to tell from the video but it appeared to be a hard over in shallow water. If so I wonder what the side that landed on the grid fin looks like.
Too bad as this was a brand new booster, but at least they should recover most of not all of the hardware for a thorough postmortem.
F9's attitude control system was fighting like crazy to control that bird on her way down. It seemed to actually regain control for a second or two then went really crazy, then came back again then video cut. The algorithms and overall firmware that control that stuff are next level type sh$t. Absolutely unreal. It would be really interesting to see the command and response telemetry from those last 20 seconds.
I would imagine that SpaceX firmware engineers have though of this all and have some type of secondary or tertiary code for responding to and controlling the F9 in the event of sluggish control surfaces or even the failure of a surface. Maybe I'm putting them on too high of a pedestal though.... Either way....ultra-impressive!!!
I would imagine that SpaceX firmware engineers have though of this all and have some type of secondary or tertiary code for responding to and controlling the F9 in the event of sluggish control surfaces or even the failure of a surface. Maybe I'm putting them on too high of a pedestal though.... Either way....ultra-impressive!!!
ThirstyBarbarian
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Latest report is that the failure was caused when the grid fin hydraulics were gnawed through by 40 hungry mice.
It was neat the the CG thrusters were able to cancel the roll eventually. I suspect that happened as the booster slowed down and the control authority of the gridfins waned. Maybe a little luck involved with the timing there. Slightly clever code is possiblity, but I suspect they would have just deliberately ignored that corner case due to low expected probability. Great it turned out so well for them.
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Yeah, I gotta temper my earlier comment now that I've seen more footage. It's really remarkable how it fought the problem and very nearly had it zeroed out just as it met the water. All while a major control system was not only offline but was probably making things worse! Well done.
Also, they sure released the video fast this time. Some earlier flights with trouble took longer.
Also, they sure released the video fast this time. Some earlier flights with trouble took longer.
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Onboard video of the descent all the way to touchdown in the water and subsequent tip over on spaceflightnow.com. https://spaceflightnow.com/2018/12/05/falcon-9-dragon-crs-16-mission-status-center/ Interesting that the engine (just one for landing burn?) managed to stop the spin just before the landing legs deployed.
Oh... I see George and beat me to it....with a commentary over it.
And, cvanc. Color me late to the party (again).
Oh... I see George and beat me to it....with a commentary over it.
And, cvanc. Color me late to the party (again).
That commentary video is a brilliant bit of PR. Getting it out so fast, and having it be so definitive about the redundant safety mechanisms to avoid potential human/property damage, is really a coup.
I had some back of the mind concerns about the RTLS recoveries thinking "gosh, what if there were a control failure? Will it crash through buildings?" And this video shows how the various scenarios are pre-thought-out and worked together for a safe landing, even if the booster is toast.
Well done, SpaceX. Of course the news -if they take notice at all- will be all about the crash landing, rather than the safety stuff. And will probably not mention that despite loss of booster, the actual launch was successful....
I had some back of the mind concerns about the RTLS recoveries thinking "gosh, what if there were a control failure? Will it crash through buildings?" And this video shows how the various scenarios are pre-thought-out and worked together for a safe landing, even if the booster is toast.
Well done, SpaceX. Of course the news -if they take notice at all- will be all about the crash landing, rather than the safety stuff. And will probably not mention that despite loss of booster, the actual launch was successful....
Not a pedestal, I suspect, but just good engineering. What you're describing is an FMEA (Failure Mode Engineering Analysis) and is common practice for many engineering practices. It's where you look at what would happen if various components failed or misbehaved in one way or another (loss of control, failure to respond to commands, etc). I would expect SpaceX to have an EXTREMELY thorough and detailed FMEA given the high risks (both physical and monetary) of launching a rocket, not to mention landing one.
Yes. Any aviation related craft is required by federal regulations. It is called the system safety process. Each potential failure mode is analyzed for its effect on the aircraft function. Whether it’s failure is catastrophic, hazardous, major, minor, or no safety effect. In the case of a SpaceX booster they apparently have the additional analysis for damage to the public and buildings so they design in additional control to eliminate that. For transport airplanes the regulation is 14 CFR 25.1309 for system safety.
I reckon you're right. Death or severe injury usually score a 10 and bad outcomes for a company financially usually a 9 (varies a little between different instances) for severity so they usually result in having to take some sort of action to mitigate the outcome. Fantastic information to have when you are designing a system. When a safety event crops up you can say "We designed for that and it worked as designed. Nobody was likely to be injured". Everyone then breathes a sigh of relief
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This Twitter post has a very clear video of landing on the water, and tipping over.
https://twitter.com/twitter/statuses/1070446975642812416
I was away for the afternoon, so didn't see the launch live. During the descent when the onboard camera view started to roll more than usual, figured it was trouble. And then several rotations, that NEVER happens, so it was out of control, at least for aerodynamic steering. The GOOD thing about the way the boosters come in for RTLS landings, is that the ballistic path is always over the water. To make it stretch the path out to the landing zone, the aerodynamic steering needs to "glide" it (albeit crudely at a high diagonal angle). So if the aerodynamic steering or guidance goes out, it won't "glide" across the coastline. So when it was rolling around, that's why it landed into the water. One reason why it rotated more slowly as it got close to landing, is that the engine thrust was reducing the velocity, so the aerodynamic roll from the stuck grid fins had less and less force. So, the RCS thrusters were able to be more effective. In any case though, once it lost aerodynamic steering control for say 10 seconds, it was too low and too far out of position from shore to get back on course for LZ-1 even if the grid fin system had come back to 100%
In theory, fixing this might cause a slip in upcoming launch scheduling. But it's not an issue for the paying customers, no effect on the launch part, but in re-using the boosters. So it might depend on how long the customers might be willing to wait for a fix before their scheduled launch (Say, perhaps SpaceX give them a $1 to 2 million discount for waiting, plus expenses incurred due to delay). Most likely there's some conditions on the contacts for things like this, where issues about reusability sometimes conflict with launching payloads in a timely manner. Such as weather perfectly fine for launch, but too bad at sea for booster recovery.... what's in it for the customer to agree to wait a few days for better landing weather? Of course there was at least one planned landing around 2-3 years ago where the booster was flown expendably to launch the customer's satellite on time, when the weather was too bad at sea for landing. But those were boosters that they never flew more than twice, not the Block-5 that they claim can fly 10 times before overhaul. So they do have better reason than ever to have some clauses for "reasonable" delay related to re-use, such as a few days for weather.
BTW - there is a totally false perception that the Sea landings are less reliable. It's BS. Every failed landing (which by coincidence was a planned sea landing, until today) was due to an onboard problem with the rocket - like running out of hydraulic fluid, leg lock not locking which allowed a leg to fold up, running out of fuel (risky "hot" landings with very little fuel left), sticky throttle valve, running out of TEA/TEB to reignite all three engines (why Falcon Heavy Core crashed). Had nothing to do with landing on the ASDS barge at sea. Blaming those crashes as "risky sea landings" would be like blaming today's Hydrauiic pump failure on "risky RTLS landings". Where it was trying to land had nothing to do with the cause. To be sure, it is riskier to land at sea, due to issues like high winds and rough seas. But none of the crashes that I can think of were attributed to that, they were all problems with the rocket. And it has been impressive how well the F9 has been able to land in some pretty high wind at times, and rough seas. Eventually, some day, wind will be too strong or sea swells too much and cause a loss of a Falcon, unless indeed they have some contract clauses to allow delays when landing weather is too poor.
So, anyway, it'll be interesting to see how fast they can solve this. And whether or not it affects scheduling since it's not a launch risk or a payload risk.
UPDATE - Here's a youtube video of the ocean landing in the tweet above, followed by onboard camera view.
And an excellent update by Tim Dodd, the Everyday Astronaut, with some more info, how SpaceX plans to fix this and some other nuggets.
https://twitter.com/twitter/statuses/1070446975642812416
I was away for the afternoon, so didn't see the launch live. During the descent when the onboard camera view started to roll more than usual, figured it was trouble. And then several rotations, that NEVER happens, so it was out of control, at least for aerodynamic steering. The GOOD thing about the way the boosters come in for RTLS landings, is that the ballistic path is always over the water. To make it stretch the path out to the landing zone, the aerodynamic steering needs to "glide" it (albeit crudely at a high diagonal angle). So if the aerodynamic steering or guidance goes out, it won't "glide" across the coastline. So when it was rolling around, that's why it landed into the water. One reason why it rotated more slowly as it got close to landing, is that the engine thrust was reducing the velocity, so the aerodynamic roll from the stuck grid fins had less and less force. So, the RCS thrusters were able to be more effective. In any case though, once it lost aerodynamic steering control for say 10 seconds, it was too low and too far out of position from shore to get back on course for LZ-1 even if the grid fin system had come back to 100%
In theory, fixing this might cause a slip in upcoming launch scheduling. But it's not an issue for the paying customers, no effect on the launch part, but in re-using the boosters. So it might depend on how long the customers might be willing to wait for a fix before their scheduled launch (Say, perhaps SpaceX give them a $1 to 2 million discount for waiting, plus expenses incurred due to delay). Most likely there's some conditions on the contacts for things like this, where issues about reusability sometimes conflict with launching payloads in a timely manner. Such as weather perfectly fine for launch, but too bad at sea for booster recovery.... what's in it for the customer to agree to wait a few days for better landing weather? Of course there was at least one planned landing around 2-3 years ago where the booster was flown expendably to launch the customer's satellite on time, when the weather was too bad at sea for landing. But those were boosters that they never flew more than twice, not the Block-5 that they claim can fly 10 times before overhaul. So they do have better reason than ever to have some clauses for "reasonable" delay related to re-use, such as a few days for weather.
BTW - there is a totally false perception that the Sea landings are less reliable. It's BS. Every failed landing (which by coincidence was a planned sea landing, until today) was due to an onboard problem with the rocket - like running out of hydraulic fluid, leg lock not locking which allowed a leg to fold up, running out of fuel (risky "hot" landings with very little fuel left), sticky throttle valve, running out of TEA/TEB to reignite all three engines (why Falcon Heavy Core crashed). Had nothing to do with landing on the ASDS barge at sea. Blaming those crashes as "risky sea landings" would be like blaming today's Hydrauiic pump failure on "risky RTLS landings". Where it was trying to land had nothing to do with the cause. To be sure, it is riskier to land at sea, due to issues like high winds and rough seas. But none of the crashes that I can think of were attributed to that, they were all problems with the rocket. And it has been impressive how well the F9 has been able to land in some pretty high wind at times, and rough seas. Eventually, some day, wind will be too strong or sea swells too much and cause a loss of a Falcon, unless indeed they have some contract clauses to allow delays when landing weather is too poor.
So, anyway, it'll be interesting to see how fast they can solve this. And whether or not it affects scheduling since it's not a launch risk or a payload risk.
UPDATE - Here's a youtube video of the ocean landing in the tweet above, followed by onboard camera view.
And an excellent update by Tim Dodd, the Everyday Astronaut, with some more info, how SpaceX plans to fix this and some other nuggets.
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Do we think the legs deploying helped slow the spin? A bit of "yo-yo-despin" effect might be in play when the legs come out, right?
Yes, the legs lower increased the moment of inertia of the booster, created more drag, and a few other factors that dramatically slowed down the roll.
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"SpaceX landing mishap won’t affect upcoming launches"
https://spacenews.com/spacex-landin...I6OREQLANSyLcp-bvMf_nEqyo-leo-0r_xyFHVjq9IQEs
https://spacenews.com/spacex-landin...I6OREQLANSyLcp-bvMf_nEqyo-leo-0r_xyFHVjq9IQEs
I suspect the legs coming out will not help from an angular momentum point of view. The overall rotation rate will drop due to the higher moment of inertia with the legs extended, but the angular momentum will be the same. The CG thrusters will still be applying force (torque) from their same location on the airframe, working against a higher moment of inertia, but from a lower spin rate. I think the net outcome will be the same. Somebody correct me if I am wrong.
Increased drag yes, decreased control authority on the gridfins due to lower airspeed yes.
Increased drag yes, decreased control authority on the gridfins due to lower airspeed yes.
The RCS thrusters are very inefficient and weak at surface level. Gridfins were locked up so they did not have any effect on the rotation of the rocket the entire way down (besides their stuck position). As seen in the video Elon released, the rate of rotation DRAMATICALLY dropped once the landing gear went down. This is due to the higher moment of inertia as you stated coupled with a few other factors such as horizontal aerodynamic drag. The engine had nothing to do with the cancellation of the rotation since a single gimballing engine cannot dictate roll.
I never said it did
.The gridfins were the entire cause of the rotation due to being locked off to one side.
The legs are what "saved" it. Just wanted to point out the engine's lack of effect on the rotation since many assume the gimbal on a single engine can control roll. Certainly was an impressive failure.I never said it did
The gridfins were the entire cause of the rotation due to being locked off to one side.
OverTheTop said:I never said it did
Yeah, but I kinda did - even though it didn't make sense. That the stuck grid fins' effect decreased with speed and maybe the rotational moment of inertia change (and probably the thrusters, inefficient as they may have been) seemed to do the trick (almost). I need to watch the Everyday Astronaut link George provided.
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I'm talking in the actual sense of the gimbal changing the roll, not the engine itself reducing the speed of the booster and thereby reducing the effect of the gridfins. The RCS thrusters helped a bit, but they were certainly not the only factor due to their lack of power at sea level. Looking at the video, the roll substantially decreased when the legs were deployed.
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