BeechTalk - BT

Username Protected · **Posted:** 14 Mar 2024, 12:56

Username Protected wrote:

I'm guessing that they have the data that they need.

The booster had a problem restarting the engines for the landing burn. If the graphic was correct, among other things it was trying to light engines that weren't supposed to light, and of the three that were supposed to light they got one. I don't have a guess as to what went wrong there, but starting a rocket motor with several hundred kph of wind up the pipe is probably not that easy.

The ship loss on re-entry I think was the result of an unchecked rotation of the vehicle. You can see that in all of the video, which cuts out as the antennae rotate toward the planet and then is restored as they rotate back upward. I think the rotation was intentional as part of the orbital fuel transfer experiment, but it was supposed to stop before re-entry. Since it did not, instead of a heat shielded rocket, you had a sort of rotisserie effect that eventually claimed the vehicle.

Fix the engine re-light issue and whatever caused the unstable re-entry and we're good to go.

IFT4!!!

Thought I heard them say the Booster landing burn was to initially be 13 engines and then scaling back to fewer.

Got to rewatch tonight.

Tj

Username Protected · **Posted:** 14 Mar 2024, 13:42

Username Protected wrote:

Thought I heard them say the Booster landing burn was to initially be 13 engines and then scaling back to fewer.

That would make more sense. In that case they started to light a scattered few and then lost all but one in a matter of a second or two. I don't know what vertical speed is at that point, but since they didn't use an Entry Burn to decelerate before the Landing Burn, it might have been as simple as they blew the candles out.

Username Protected · **Posted:** 14 Mar 2024, 17:58

Username Protected wrote:

Nice job so far, 15 mins. into the mission.

From a post I made earlier, around 8:40 EDT (just after initial 8:30 scheduled launch):

The YouTube live feed from SpaceX via NASA TV went down to T-5 seconds or so around 8:30 EDT, with a cheering throng as liftoff was only seconds away, then switched before liftoff to a video of Elon hawking his new venture into cryptocurrency (really?!) and encouraging clicking on a QR code. I see on the NYT site that at least 30 mins. previous Space X had actually pushed the lunch back to 9:30 or so EDT. Terrible coverage. Elon sounds like the Pillow Guy.

There were multiple fake streams on YouTube purporting to be from SpaceX and Elon. All were scams. The official stream is always on X (Twitter) not YouTube. I prefer YouTube and so watched Tim Dodd’s (EverydayAstronaut) stream.

Username Protected · **Posted:** 14 Mar 2024, 18:20

Username Protected wrote:

The YouTube live feed from SpaceX via NASA TV went down to T-5 seconds or so around 8:30 EDT, with a cheering throng as liftoff was only seconds away, then switched before liftoff to a video of Elon hawking his new venture into cryptocurrency (really?!) and encouraging clicking on a QR code. Terrible coverage. Elon sounds like the Pillow Guy.

SpaceX do not stream launches on YouTube - they stopped quite a while ago. Quite a few frankly very obvious scams have sprung up pretending to be them. You were watching one of those.

Username Protected · **Posted:** 14 Mar 2024, 22:40

They even had the same names for the presenters as on the SpaceX site. Hmmm. Quite the spoof.

Username Protected · **Posted:** 14 Mar 2024, 23:00

Username Protected wrote:

The YouTube live feed from SpaceX via NASA TV went down to T-5 seconds or so around 8:30 EDT, with a cheering throng as liftoff was only seconds away, then switched before liftoff to a video of Elon hawking his new venture into cryptocurrency (really?!) and encouraging clicking on a QR code. Terrible coverage. Elon sounds like the Pillow Guy.

SpaceX do not stream launches on YouTube - they stopped quite a while ago. Quite a few frankly very obvious scams have sprung up pretending to be them. You were watching one of those.

Username Protected · **Posted:** 15 Mar 2024, 11:49

They did a retro burn to near zero velocity at ~100km altitude then dropped, They were at about 1100 km/h according to the video, pretty close to sonic. I could easily imagine the ~sonic wind causing relight issues in the engines. These are different engines than are used in falcon and I assume this was the first attempt at relight with that high airflow

Username Protected wrote:

Thought I heard them say the Booster landing burn was to initially be 13 engines and then scaling back to fewer.

That would make more sense. In that case they started to light a scattered few and then lost all but one in a matter of a second or two. I don't know what vertical speed is at that point, but since they didn't use an Entry Burn to decelerate before the Landing Burn, it might have been as simple as they blew the candles out.

Username Protected · **Posted:** 15 Mar 2024, 11:50

Friend of mine from NASA thought they were not able to maintain the correct attitude on reentry and so exposed some of the non shielded area.

This version apparently has very low thrust attitude jets - something they could change pretty easily. Also the hypersonic aerodynamics may not have been quite right and the center of pressure could have been off a bit - can fix by moving the fins.

Username Protected · **Posted:** 15 Mar 2024, 16:48

Username Protected wrote:

Friend of mine from NASA thought they were not able to maintain the correct attitude on reentry and so exposed some of the non shielded area.

That is a very polite way of saying "tumbling". I agree. It's clear from the video that the ship is rotating slowly about its roll axis and later adds some motion in the pitch axis, all of which is unchecked for the duration of the video.

Username Protected · **Posted:** 15 Mar 2024, 16:56

Horizon stabilized view

https://www.instagram.com/reel/C4iMWR0t ... 3580678311

Username Protected · **Posted:** 15 Mar 2024, 17:44

welp, there's your problem, lol.

Chip-

Username Protected · **Posted:** 15 Mar 2024, 18:55

Yes, unable to maintain correct attitude, followed by a thermal event, followed by rapid unintended disassembly.

Booster engines may have had a hard start due to the aerodynamics.

I guess NASA doesn't like to say "tumbled out of control, caught fire and exploded".

All seems fixable. It will be an interesting test when they get a controlled reentry to see how the tiles survive.

Username Protected wrote:

Friend of mine from NASA thought they were not able to maintain the correct attitude on reentry and so exposed some of the non shielded area.

That is a very polite way of saying "tumbling". I agree. It's clear from the video that the ship is rotating slowly about its roll axis and later adds some motion in the pitch axis, all of which is unchecked for the duration of the video.