totm nov 2023 SpaceX Discussion Thread

[sevenperforce]

I did a TikTok using the first NSF footage:

Link here in case it doesn't embed properly.

[tater]

 

[tater]

Putting this here for reference. Most of the engines in B7 are fairly early serials:

 

 

[Nuke]

starting to wonder if the engine that was aborted and the engine that "stopped on its own" were part of a safety test. perhaps they were simulating the 2 most likely failure modes and seeing if it could fail safe. 

Edited February 10, 2023 by Nuke

[sevenperforce]

19 minutes ago, Nuke said:

starting to wonder if the engine that was aborted and the engine that "stopped on its own" were part of a safety test. perhaps they were simulating the 2 most likely failure modes and seeing if it could fail safe. 

Doubtful; I think Elon would have characterized it differently if that were the case.

[StrandedonEarth]

23 minutes ago, Nuke said:

starting to wonder if the engine that was aborted and the engine that "stopped on its own" were part of a safety test. perhaps they were simulating the 2 most likely failure modes and seeing if it could fail safe. 

 

1 minute ago, sevenperforce said:

Doubtful; I think Elon would have characterized it differently if that were the case.

True, but I wonder if the engine that stopped on its own was on the opposite side, to balance thrust, as per flight software. At the same time, I wonder if it has enough gimbal authority to handle a single engine out. 

[sevenperforce]

33 minutes ago, StrandedonEarth said:

40 minutes ago, sevenperforce said:

Doubtful; I think Elon would have characterized it differently if that were the case.

True, but I wonder if the engine that stopped on its own was on the opposite side, to balance thrust, as per flight software. At the same time, I wonder if it has enough gimbal authority to handle a single engine out. 

Nope, not needed to balance thrust. Even Falcon 9 has enough gimbal authority to handle a single-engine-out anywhere in the outer ring without needing to shut down the opposite engine. With 33 engines, an odd engine out is barely felt against the mighty gimbal authority of the central core of 13 engines all gimbaling at 15 degrees.

[StrandedonEarth]

4 minutes ago, sevenperforce said:

Nope, not needed to balance thrust. Even Falcon 9 has enough gimbal authority to handle a single-engine-out anywhere in the outer ring without needing to shut down the opposite engine. With 33 engines, an odd engine out is barely felt against the mighty gimbal authority of the central core of 13 engines all gimbaling at 15 degrees.

Yeah, that's what i figured

 

Edited February 10, 2023 by StrandedonEarth

[CatastrophicFailure]

7 hours ago, sevenperforce said:

The billowing clouds were HUGE. Just absolutely huge. Way, way bigger than I could have anticipated.

The absolute lack of anything on fire, smoking, or apparently damaged on GSE is impressive. That's exactly what they need to have.

Of course.  Gwynne. Said. So. 
 

but having said that now the tank watchers will find some critical bit relocated to the next zip code…

[tater]

<Half thrust.

 

[JoeSchmuckatelli]

7 minutes ago, tater said:

<Half thrust.

 

So N1 still holds that record?

[tater]

3 minutes ago, JoeSchmuckatelli said:

So N1 still holds that record?

So far. Basically about the same as Saturn V

 

[sevenperforce]

50 minutes ago, tater said:

<Half thrust.

 

Came here to post that but as usual @tater is faster.

But wow. If this is only half thrust...good grief. Imagine what it will do at full thrust.

7.9 million pounds force is ~35.1 MN. In vacuum thrust (since that's what I shoved into my table yesterday) that's ~39 MN, putting it just ahead of Saturn V but just below STS-1. Thus it increased the world's power consumption by only 0.76% instead of the 1.54% I had previously calculated. In terms of sea level thrust, it was 3.8% higher than the Saturn V but 0.9% lower than STS (and of course significantly lower than SLS or N1).

35.1 MN divided by 31 engines comes to almost exactly 50% of each engine's 2.3-MN full thrust capability. So it's safe to say that they throttled to 50% but it was slightly less because of the two engines that didn't participate.

Given the lower throttle setting I wonder if they will do it again at full thrust or just go straight to launch.

Edited February 10, 2023 by sevenperforce
correction

[mikegarrison]

46 minutes ago, sevenperforce said:

Given the lower throttle setting I wonder if they will do it again at full thrust

I have my doubts that they can, without damaging the pad.

[sevenperforce]

Just now, mikegarrison said:

I have my doubts that they can, without damaging the pad.

Yeah, once they light'em all up I'm guessing they'll want to get away from the pad as quickly as possible.

It's so large that despite having the same T/W ratio as SLS and STS, it'll probably look like it's lifting off slower. Will definitely look faster than the similarly-sized Saturn V, though.

[mikegarrison]

Maybe it will be like this:

 

[magnemoe]

39 minutes ago, sevenperforce said:

Came here to post that but as usual @tater is faster.

But wow. If this is only half thrust...good grief. Imagine what it will do at full thrust.

7.9 million pounds force is ~35.1 MN. In vacuum thrust (since that's what I shoved into my table yesterday) that's ~39 MN, putting it just ahead of Saturn V but just below STS-1. Thus it increased the world's power consumption by only 0.76% instead of the 1.54% I had previously calculated. In terms of sea level thrust, it was 3.8% higher than the Saturn V but 0.9% lower than STS (and of course significantly lower than SLS or N1).

35.1 MN divided by 31 engines comes to almost exactly 50% of each engine's 2.3-MN full thrust capability. So it's safe to say that they throttled to 50% but it was slightly less because of the two engines that didn't participate.

Given the lower throttle setting I wonder if they will do it again at full thrust or just go straight to launch.

Good question, one option is full throttle burn if all is green release the launch clamps if not: its an static fire not an abort. 
Now  it might be bureaucratic, as in they have an limiter number of launches they can do but static tests are less limited. 
Also why not put an layers of steel slabs underneath, the you coming out of the foundries. 
You don't need armor just an layer who act as ah heat sink and don't throw fragments into you engines, who I imagine is hard to get from thick steel plates heating it. 

[tater]

 

[sevenperforce]

2 hours ago, magnemoe said:

Good question, one option is full throttle burn if all is green release the launch clamps if not: its an static fire not an abort. 
Now  it might be bureaucratic, as in they have an limiter number of launches they can do but static tests are less limited. 

Given that this will be a launch license for an experimental flight and not an operational launch license, the window constraints will likely be tighter, and so I’m guessing they will be less likely to abort as long as they are still reasonably assured of clearing the pad.

2 hours ago, magnemoe said:

Also why not put an layers of steel slabs underneath, the you coming out of the foundries. 
You don't need armor just an layer who act as ah heat sink and don't throw fragments into you engines, who I imagine is hard to get from thick steel plates heating it. 

Spalling will ruin your day. With the raw energy coming off 33 raptors, steel would melt and be sprayed away faster than it could conduct heat away. A copper plate would be able to conduct heat faster, but it is soft and would be absolutely shredded by the exhaust coming out of the engine at nearly Mach 10. You’d need a 10” tungsten plate to be able to handle the heat and forces, and even then you might have problems.

Then again a 10” tungsten plate 10 meters in diameter would only cost about $3 million scrap cost. 

[tater]

Not sure if they fly then add the new deluge system, or add it first.

[darthgently]

1 hour ago, sevenperforce said:

Given that this will be a launch license for an experimental flight and not an operational launch license, the window constraints will likely be tighter, and so I’m guessing they will be less likely to abort as long as they are still reasonably assured of clearing the pad.

Spalling will ruin your day. With the raw energy coming off 33 raptors, steel would melt and be sprayed away faster than it could conduct heat away. A copper plate would be able to conduct heat faster, but it is soft and would be absolutely shredded by the exhaust coming out of the engine at nearly Mach 10. You’d need a 10” tungsten plate to be able to handle the heat and forces, and even then you might have problems.

Then again a 10” tungsten plate 10 meters in diameter would only cost about $3 million scrap cost. 

What about actively cooled plating, steel or otherwise?  I suppose a deluge would be simpler and easier really

[tater]

 

[AVaughan]

Quote

Each bridge crane can lift 150t, so due to the increased mass of the completed Superheavy Booster, they must conduct a tandem lift in order to lift it.

Any idea why it is heavier?  Or is it simply heavier than an incomplete booster?  (Also was a dual lift always the plan, or did SpaceX somehow underestimate how much a booster would weigh?) 

[snkiz]

On 2/9/2023 at 5:53 PM, tater said:

 

Is it just me or does the booster look like a MK3 tank from above?

[tater]