Falcon Heavy - 7&8 Reuse - Elon's Roadster Demo - LC-39A

[mongo]

Final burn though? That time is just over a minute away from reaching the drone ship.

The side cores do a burn just under 90 seconds before their final landing burn...

Should be final. Re-entry happened previously (edit 28:55) and the landing legs deploy during the shot.

I'm also not seeing any movement from the grid fins (which are deployed).
Any reason to think the camera is rotated 90 degrees? Smoke off legs near the end seems to match video up with world up.

 

[scaesare]

True. Just trying to reconcile why so far ahead of landing... Even the event bar at bottom shows some time to go.

60 second final burns aren't typical, are they?

 

[macpacheco]

TEA/TEB doesn't boil.
Not my theory, but it makes perfect sense.
TEA/TEB isn't dispensed in discrete shots, but rather dispensed until some parameters are hit, indicating combustion.
The center core was going about Mach 1 faster than every previous recovery that worked.
The re-entry burn used more TEA/TEB because of the rare atmosphere going against the rocket rear (at much higher speeds).
The 3 engine landing burn starts one engine then quickly starts the other two. But there was only enough TEA/TEB left for the center one to start, which even at full throttle is hopelessly too late to stop the rocket.
If that was the problem, the solution should be easy, just increase TEA/TEB capacity for center cores or for all Falcon cores.
Perhaps if a boostback wasn't used there would have been enough TEA/TEB to land safely.

 

[mongo]

True. Just trying to reconcile why so far ahead of landing... Even the event bar at bottom shows some time to go.

60 second final burns aren't typical, are they?

I see what you are saying, engine ignition at 7:49 to 8:40 drone camera impact. Side booster finals about 15 seconds long. Perhaps core had more speed to negate? The 8:40 impact shot looked to have occurred earlier than projected landing (makes sense).
Be helpful/ interesting to know if it was under or overshoot...

 

[mongo]

TEA/TEB doesn't boil.
Not my theory, but it makes perfect sense.
TEA/TEB isn't dispensed in discrete shots, but rather dispensed until some parameters are hit, indicating combustion.
The center core was going about Mach 1 faster than every previous recovery that worked.
The re-entry burn used more TEA/TEB because of the rare atmosphere going against the rocket rear (at much higher speeds).
The 3 engine landing burn starts one engine then quickly starts the other two. But there was only enough TEA/TEB left for the center one to start, which even at full throttle is hopelessly too late to stop the rocket.
If that was the problem, the solution should be easy, just increase TEA/TEB capacity for center cores or for all Falcon cores.
Perhaps if a boostback wasn't used there would have been enough TEA/TEB to land safely.

Would a center core use a 3-1-3 burn on final? This shot shows all 3 were running (starting at 59 seconds before impact), but then it was down to one engine a few seconds later.

 

[Grendal]

The side cores did a standard one engine landing burn. The center core, because it was coming in so hot or SpaceX was pushing the envelope, was supposed to do a three engine hoverslam. SpaceX would know from data what went wrong and they say there was a shortage of TEA-TEB. They have no reason to lie about that. So the question is really what caused the shortage? I have full confidence they will know and correct whatever it was. I doubt that there just wasn't enough TEA-TEB loaded. Lots of interesting takes on it here.

What was different?
Probably the hottest reentry yet. You could see the camera get clogged with crud a lot earlier than ever before. That tells me it was very hot.
The center core had more bits on it than a standard F9 does. Maybe dealing with different aerodynamics had some factor in the shortage.
Three cores instead of one and doing different things. Maybe a software error prevented or purged excess TEA-TEB before the final landing burn.

Would a center core use a 3-1-3 burn on final? This shot shows all 3 were running (starting at 59 seconds before impact), but then it was down to one engine a few seconds later.

I went back and watched it. There was a single engine start, that expanded to three engines for maybe a second, and then it went back to a single engine for the landing.

I really like the corrected final FH launch video. You can see what they really wanted and where they went wrong originally. You can catch some of the original video in other people's livestream, now just a video.

Note that this is the first landing failure since June 15, 2016. The Eutelsat GTO hot landing where they just ran out of fuel just above the ASDS.

 

[macpacheco]

Look at the video and you will see the 1-3-1 landing sequence. The same one the center core was going to use.
Its the most fuel efficient/aggressive one.

 

[mongo]

So, am I now correct in understanding that the upper right feed is the side booster landing (with a rotated image), not the center core like I've been thinking for the last 2 hours?

 

[Grendal]

So, am I now correct in understanding that the upper right feed is the side booster landing (with a rotated image), not the center core like I've been thinking for the last 2 hours?

That would be a yes. A core landing on the ASDS is never seen with such clarity. The best we ever got was the CRS-8 (first) drone ship landing where SpaceX was allowed to borrow NASA's special chase plane with an incredible camera attached to it.

The center core would have done a burn similar to what we see during the standard entry burn. Rewatching it again, the side cores do a 17 second landing burn. The center core in a hoverslam situation is probably 7 to 10 seconds.

 

[mongo]

That would be a yes. A core landing on the ASDS is never seen with such clarity. The best we ever got was the CRS-8 (first) drone ship landing where SpaceX was allowed to borrow NASA's special chase plane with an incredible camera attached to it.

Yeah, I should have known better. It was also time aligned with the landings. Hadn't realized (or forgot) that even the single engine landing uses three briefly. The whole rotated camera didn't help either, what's the deal with that? Did they post process to fit in the frame better?

 

[TEG]

Here's a video taken from "Feel the Heat" and I can see what you're commenting about. I suppose you need to get some press credentials. Someone from Teslarati was even in the post launch conference and asked a question.

I'll bet the people took this video from SLC-17. They seem to be up high. Maybe they are on one of the old launch towers from the Delta II.

Cape Canaveral Air Force Station Space Launch Complex 17 - Wikipedia

Can you tell where I was in 1994 when I did this video of a space shuttle launch?:

I had some kind of press credential, but they said I arrived too late to go to the press area so they sent me to some grandstand area they said was for friends/family of the astronauts in the shuttle...

 

[dhanson865]

Check out latest video from SpaceX.
At 29:50 all three engines are lit. A few seconds later the bottom one is out and the top is weak.

So it looks like TEA-TEB was not the issue (all three running). Possible turbo pump failure on one causing SW to shut down the other to balance?

are you talking about the top right video at 29:50? If so that is a close up of one of the side boosters not the center core.

If you are talking about the top left video just before 29:50 they call out at 29:15 center core entry burn shut down. That's the last we see of that core with an engine on.

 

[Mike1080i]

Can you tell where I was in 1994 when I did this video of a space shuttle launch?:
View attachment 278788
View attachment 278789

I had some kind of press credential, but they said I arrived too late to go to the press area so they sent me to some grandstand area they said was for friends/family of the astronauts in the shuttle...

Hmm, may have been the NASA causeway, since it looks like you were almost due South of the pad and that's where some of the crew friends and family and congressional pass viewing was. There was also the Static Test Road viewing site a little North of the causeway but I don't recall any grandstands the one time I was there, STS-65 in July 1994.

 

[dhanson865]

Look at the video and you will see the 1-3-1 landing sequence. The same one the center core was going to use.
Its the most fuel efficient/aggressive one.

1-3-1 is the most common one but not the most fuel efficient

1 only would use the most fuel
1-3-1 uses less
1-3 uses less than that
3 uses the least
theoretically if they could time it perfectly using all 9 engines would use the least fuel. But 3 is the most they have every used. No reason to push fate any further than that.

The 1 signifies a longer burn, the 3 signifies a shorter burn. Shorter equal less fuel used but also less margin for error.

To be clear it also signifies the number of engines burning during that time but using 3 allows for a shorter burn than using 1.

 

[Grendal]

Last pic of Starman in Roadster enroute to Mars orbit and then the Asteroid Belt.
Elon Musk on Instagram: “Last pic of Starman in Roadster enroute to Mars orbit and then the Asteroid Belt”

 

[macpacheco]

Correct, but AFAIK 1-3-1 is the most aggressive in use.

1-3-1 is the most common one but not the most fuel efficient

1 only would use the most fuel
1-3-1 uses less
1-3 uses less than that
3 uses the least
theoretically if they could time it perfectly using all 9 engines would use the least fuel. But 3 is the most they have every used. No reason to push fate any further than that.

The 1 signifies a longer burn, the 3 signifies a shorter burn. Shorter equal less fuel used but also less margin for error.

To be clear it also signifies the number of engines burning during that time but using 3 allows for a shorter burn than using 1.

To my knowledge the 1-3-1 sequence is the most aggressive in use. The spacing between events is quite short. Little benefit to a pure 3 engine landing. And plenty of risks. Of course I'm not qualified to know if it actually makes sense at all. We can see less than 1 second between 0 to 1 to 3 and from 3 to 1 to landing.

 

[dhanson865]

Correct, but AFAIK 1-3-1 is the most aggressive in use.

To my knowledge the 1-3-1 sequence is the most aggressive in use. The spacing between events is quite short. Little benefit to a pure 3 engine landing. And plenty of risks. Of course I'm not qualified to know if it actually makes sense at all. We can see less than 1 second between 0 to 1 to 3 and from 3 to 1 to landing.

They do the pure 3 engine landing when they do GTO missions and don't have enough fuel left for a 1-3-1. As a percentage of flights its low but it happens several times a year.

I don't know what you mean by "most aggressive in use" since they do actually use 3 only and it is more aggressive.

By the way the term most commonly used for this is "hoverslam" but some prefer the term "suicide burn". That applies to 1 or 3 engine final landing burn as even one engine at minimum thrust has more power than needed to stop. It's basically impossible for Falcon 9 to not be aggressive in landing.

 

[SMAlset]

We got SO many great images from Starman's voyage but have to say I really do love the parting shot Elon posted on Instagram. I was wondering how long they were able to get transmissions from the car and actually was disappointed when they cut the feed before the orbit path was changed. What a great ride.

 

[dpeilow]

Can you tell where I was in 1994 when I did this video of a space shuttle launch?:

Which launch was that @TEG ?

 

[TEG]

Which launch was that @TEG ?

STS-66 Atlantis