totm nov 2023 SpaceX Discussion Thread

[tater]

Yeah, there were some explosions at the rear. Still, detonation looks at the common dome. Could be a RUD started, FTS then goes off as well. Still, it's probably as Manley suggests. It will be interesting if they can fix it with timing changes on the boostback.

[sevenperforce]

7 hours ago, tater said:

Yeah, there were some explosions at the rear. Still, detonation looks at the common dome. Could be a RUD started, FTS then goes off as well. Still, it's probably as Manley suggests. It will be interesting if they can fix it with timing changes on the boostback.

Cascading engine failure due to fuel starvation followed by commanded AFTS.

[tater]

Quote

A federal bankruptcy court in Florida approved an agreement Nov. 22 whereby SpaceX would acquire Pioneer Aerospace for $2.2 million.

 

[zolotiyeruki]

At stage separation, is there enough atmosphere left that the booster could flip and wait for drag to settle the propellants?

[AckSed]

Not saying you couldn't, but.

In RTLS, the timings are pretty strict. The sooner you flip and boostback burn to cancel out forward velocity, the closer you are to your landing site and the more reserve propellant you have to land. Or the less reserve propellant you need.

The booster is also going on a high trajectory so it's staging in a part of the atmosphere that's barely there. It is essentially a spaceship.

Figuring out when and how fast to flip this giant stick will have to be tested.

Edit: Batcrap idea - let it fly side-on for a bit to slow and then continue the flip a tad slower.

Edited November 30, 2023 by AckSed

[StrandedonEarth]

Best solution I can see is using header tanks to ensure the center three keep burning through the flip, once stabilized and ullage is restored in the main tanks then light the next ring of engines. 

[CBase]

The idea of SH central engines to fire was to keep positive acceleration. Instead of backing off from this: Could they increase thrust and keep acceleration high enough ? Maybe add some perforated sheet inside the tank bottom to reduce lateral movement as long as there is positive pressure.

[darthgently]

5 hours ago, CBase said:

The idea of SH central engines to fire was to keep positive acceleration. Instead of backing off from this: Could they increase thrust and keep acceleration high enough ? Maybe add some perforated sheet inside the tank bottom to reduce lateral movement as long as there is positive pressure.

Or switching to a small header tank specifically for stage sep and flip?  But that would incur a mass penalty whereas your idea would be a fuel use penalty I suppose.

But by implications you highlight the point that the booster's interaction with stage 2 plume was not well understood.

I'm thinking rather than more booster thrust at sep, maybe even less, and wait until booster is fully flipped via gridfin weathercocking and RCS before relight. 

But the key would be a very asymmetrical hot stage section such that stage 2 plume interaction kicks/pitches the booster around more to aid RCS and grid fins.  Basically utilize the underestimated plume force to help flip, not primarily brake, the booster.  Imagine hot stage section sloped with the slots only on one side , for example.  This might (probably) make control of the booster during boostback squirrelier though

[tater]

2 hours:

 

 

SpaceX is targeting Friday, December 1 at 10:19 a.m. PT for a Falcon 9 launch of the Korea 425 mission to low-Earth orbit from Space Launch Complex 4 East (SLC-4E) at Vandenberg Space Force Base in California.

 

[tater]

3 min

2 min

[tater]

 

[Cuky]

50 minutes ago, tater said:

 

I didn't know they launched for 250 times already, let alone landed that many times. Just wow!

[magnemoe]

On 11/30/2023 at 6:13 PM, zolotiyeruki said:

At stage separation, is there enough atmosphere left that the booster could flip and wait for drag to settle the propellants?

Not for an boost-back burn. The problem here was that the second stage pushed first so it got negative g force. Simplest solution is to adjust the trust,first trust harder. Another option is an higher grind section and a cone flame director so the sea level engine trust is deflected instead of pushing straight back. 
None had the problems with first stages after hot staging as they was just turned off. 

[tater]

 

[tater]

 

Also, tomorrow night:

 

 

[Geonovast]

5 hours ago, Cuky said:

I didn't know they launched for 250 times already, let alone landed that many times. Just wow!

They're on track for 100 this year.

[tater]

 

[tater]

https://twitter.com/i/broadcasts/1OwGWYZeOOexQ

4 min

 

[darthgently]

It would be interesting to have a fuel barge near the landing barge, put in just enough fuel into the landed booster to hop it back to Canaveral.  Super fast turnaround, bay-bee.

[tater]

 

[tater]

 

[tater]

 

[tater]

 

[SunlitZelkova]

21 minutes ago, tater said:

 

Is Bezos not involved with Kuiper anymore?

I feel like he would never allow this if he was involved.

4 hours ago, tater said:

This reminds me of when I built the Kerbal Space Center in Minecraft and then built infrastructure leading to it. The road leading to it was called The Road to the Cosmos, and the bridge over the valley in between it and the city had massive 2D glass sculptures fixed between the bridge supports.

It would be cool if they did more to make the surrounding area space themed.

[NFUN]

Amazon was getting sued for violating fiduciary responsibilities for not buying SpaceX launches for Kuiper, so Bezos wouldn't've'd much of a say either way