totm nov 2023 SpaceX Discussion Thread

[Geonovast]

The lightning was a nice touch.

That and the second stage engine lighting up the gridfins as they deployed.  I love the night launches.

[tater]

Wait, they are going to show deploy in an hour... After the primary payload I imagine.

 

 

[Beccab]

Interesting details on the secret secondary payload:

We know that the starlink bus was selected to develop missile-warning satellites a year and a half ago; maybe it's related to that?

https://spacenews.com/spacex-l3harris-win-space-development-agency-contracts-to-build-missile-warning-satellites/

[Beccab]

 

Edit: with the recent launches, SpaceX is now three launches ahead of their weekly launch target for this year, since we're at the 23rd week of the year with 26 successful launches/landings and no failures

Edited June 19, 2022 by Beccab

[Beccab]

https://theintercept.com/2022/06/19/spacex-pentagon-elon-musk-space-defense/


A fantastic work redacting that pic US Transportation Command 

[magnemoe]

31 minutes ago, Beccab said:

https://theintercept.com/2022/06/19/spacex-pentagon-elon-musk-space-defense/


A fantastic work redacting that pic US Transportation Command 

I think that the time to arrange the launch will take longer than flying something in. More so as in you will probably have closer bases you can fly from.  Part of the reason for the V-22 was to do  this without an airstrip faster than an helicopter and you have the option to fly the V-22 ahead perhaps with some supplies then fly the rest on an transport to an forward base and then use the V-22 to insert stuff. 

[SunlitZelkova]

On 6/18/2022 at 5:03 PM, tater said:

More like contemporary Apollo coverage mentioning landing men on the Moon, since that was the goal (regardless of the underlying geopolitical rationale).

That's the entire purpose of SpaceX, making life/humanity/consciousness multiplanetary.

To the extent Musk mentions business WRT space, he always talks about reducing the cost to space by orders of magnitude.

Fair point, but it still feels meme-like because of the scale.

Landing men on the Moon was quite a challenge, but certainly doable, as multiple studies had indicated prior to 1961. If it wasn’t the US government would not have funded it in the first place.

”Making life multi-planetary”? This raises a huge amount of issues. It doesn’t help that SpaceX’s plan in that regard (and to a certain extent in the “end game” cost reduction levels they claim too) is basically 1970s Space Shuttle flight cadence and cost level vague.

To be clear, I am not trying to deny that Starship will be groundbreaking or cheap at some point, has potential for cost reduction, or can land humans on Mars. And they certainly have the right to pursue “making life multi-planetary” with maximum effort. It’s even completely fine to hold as an official ultimate goal. But stating it so often feels odd. One doesn’t proclaim they are working towards living an enriched and fulfilling life full of family and friendship when they buy a new car, after all, even if the purchase of that car is technically, in the end, a step as part of that effort which the average human takes part in.

9 hours ago, magnemoe said:

I think that the time to arrange the launch will take longer than flying something in. More so as in you will probably have closer bases you can fly from.  Part of the reason for the V-22 was to do  this without an airstrip faster than an helicopter and you have the option to fly the V-22 ahead perhaps with some supplies then fly the rest on an transport to an forward base and then use the V-22 to insert stuff. 

I personally disagree. Although I would need to research some more, I am certain that the military has the ability to do launches rapidly and without warning in the event of an emergency- and if they can’t, they probably will work to gain that ability.

Was not the Shuttle’s special satellite retrieval mission intended for wartime? They wouldn’t be waiting weeks or months for bureaucratic approval in such an instance.

Starship’s real military potential comes in a rapid resupply role in the event of a major war. Forward bases capable of accommodating big transport aircraft like the C-17 will be knocked out by ballistic missiles early, while the Osprey is not a good option if air space is contested, not to mention its poor range for somewhere like the Pacific.

Example- While flying in a C-130 or getting transport ships to a Pacific island airfield (like in some of the distributed ops concepts studied by the USMC) might be problematic, Starship could deliver a fresh supply of AIM-120s for an F-35B squadron basically unopposed and in very short time.

[tater]

3 minutes ago, SunlitZelkova said:

To be clear, I am not trying to deny that Starship will be groundbreaking or cheap at some point, has potential for cost reduction, or can land humans on Mars. And they certainly have the right to pursue “making life multi-planetary” with maximum effort. It’s even completely fine to hold as an official ultimate goal. But stating it so often feels odd. One doesn’t proclaim they are working towards living an enriched and fulfilling life full of family and friendship when they buy a new car, after all, even if the purchase of that car is technically, in the end, a step as part of that effort which the average human takes part in.

There are people that look at Starship and say, "They should do reuse, but make it smaller, SS is just too large" etc. 4-6X Shuttle payload mass, and a few orders of magnitude lower cost...

Or that is should land like Shuttle, etc. Or that he's trying to make some place for rich people to escape to (as if living underground on a barren world is an "escape").

Instead, he states the goal.

[Beccab]

Just now, SunlitZelkova said:

I personally disagree. Although I would need to research some more, I am certain that the military has the ability to do launches rapidly and without warning in the event of an emergency- and if they can’t, they probably will work to gain that ability.

Was not the Shuttle’s special satellite retrieval mission intended for wartime? They wouldn’t be waiting weeks or months for bureaucratic approval in such an instance.

Starship’s real military potential comes in a rapid resupply role in the event of a major war. Forward bases capable of accommodating big transport aircraft like the C-17 will be knocked out by ballistic missiles early, while the Osprey is not a good option if air space is contested, not to mention its poor range for somewhere like the Pacific.

Example- While flying in a C-130 or getting transport ships to a Pacific island airfield (like in some of the distributed ops concepts studied by the USMC) might be problematic, Starship could deliver a fresh supply of AIM-120s for an F-35B squadron basically unopposed and in very short time.

It's possible it could work similar to DEFCON levels - if an embassy is at high risk of needing additional military support or a temporary base may need to be landed somewhere soon, you fuel a starship or two and keep them ready to reach the target in a hour or so until the danger is over, like an Atlas ICBM

[RCgothic]

Rockets are extremely damage intolerant. You do not want to send something like Starship anywhere remotely unsecured.

3.5mm stainless steel tank walls are at risk from .22 rounds, never mind actual military calibre munitions.

Edited June 20, 2022 by RCgothic

[Flying dutchman]

17 minutes ago, RCgothic said:

Rockets are extremely damage intolerant. You do not want to send something like Starship anywhere remotely unsecured.

3.5mm stainless steel tank walls are at risk from .22 rounds, never mind actual military calibres munitions.

Would that lead to an explosion?

[RCgothic]

6 hours ago, Flying dutchman said:

Would that lead to an explosion?

Could do. A methane tank leak probably won't end well.

If it's hit on approach and the tanks depress then the engines will go engine-rich and the landing won't be pretty either.

If it's on the ground, then it won't be taking off again without pressurised tanks. And the tanks depressurising through a hole could itself cause catastrophic failure.

And if hit by an explosive munition it's basically game over.

Edited June 20, 2022 by RCgothic

[zolotiyeruki]

56 minutes ago, RCgothic said:

Could do. A methane tank leak probably won't end well.

If it's hit on approach and the tanks depress then the engines will go engine-rich and the landing won't be pretty either.

If it's on the ground, then it won't be taking off again without pressurised tanks. And the tanks depressurising through a hole could itself cause catastrophic failure.

And if hit by an explosive munition it's basically game over.

I'm skeptical that a 0.22" hole in a tank the size of Starship's would cause any huge issues by itself.  The fuel and oxidizer flow is waaaaay higher than what you could squeeze out that hole, and the pressure isn't that high anyway--under 100 psi.  Reentry is short enough that the volume you'd lose through such a hole wouldn't accumulate to an appreciable quantity, compared to the total amount in the tank.  Even if the hole was in the vapor space, the volume in that tank is huge by comparison.

I'd be more concerned about the bullet getting stopped by the liquid fuel,  sucked into a turbopump, and blowing up an engine.

[RCgothic]

5 minutes ago, zolotiyeruki said:

I'm skeptical that a 0.22" hole in a tank the size of Starship's would cause any huge issues by itself.  The fuel and oxidizer flow is waaaaay higher than what you could squeeze out that hole, and the pressure isn't that high anyway--under 100 psi.  Reentry is short enough that the volume you'd lose through such a hole wouldn't accumulate to an appreciable quantity, compared to the total amount in the tank.  Even if the hole was in the vapor space, the volume in that tank is huge by comparison.

I'd be more concerned about the bullet getting stopped by the liquid fuel,  sucked into a turbopump, and blowing up an engine.

Which is why I said "at risk from".

I don't think every .22 round would necessarily penetrate, but a weakening, gouging, or ragged entry hole on the side of the tank could easily lead to catastrophic failure. You don't really want to test it.

Larger munitions pose exponentially more risk. 5.56mm would easily penetrate 3.5mm of stainless and nobody wants to find out what a tracer, incendiary or explosive round might do.

[RealKerbal3x]

I think the takeaway from this should be "if you fire a bullet at a rocket, you and/or the rocket will probably have a bad time".

[Vanamonde]

Some unrelated discussion removed. Please stick to the subject of the thread. 

[Pthigrivi]

Yeah starship itself doesn't make much sense as a military platform. Reusability is the whole point and that still takes a lot of ground infrastructure. Like you could use it to deliver a few dozen armed drones that deploy seconds after landing to secure a perimeter, but then it's basically stuck there. It's also going to be hugely vulnerable to SAM fire during belly flop. 

[RCgothic]

12 minutes ago, Pthigrivi said:

Yeah starship itself doesn't make much sense as a military platform. Reusability is the whole point and that still takes a lot of ground infrastructure. Like you could use it to deliver a few dozen armed drones that deploy seconds after landing to secure a perimeter, but then it's basically stuck there. It's also going to be hugely vulnerable to SAM fire during belly flop. 

I suppose it could Adama-manoeuvre a load of drones at a height above conventional SAM ceiling and then additionally pancake on a target, but that's kind of ICBM-adjacent. I suspect other nations are unlikely to approve.

[RCgothic]

 

 

[tomf]

Do we know what the rentry timings will be line? If starships  profile is anything like the f9 first stage you have two minutes between rentry burn and landing which doesn't seem a lot of time to target it with heavy weaponry. And it spends most of that time hypersonic so good luck trying to hit it with small arms fire.

[sevenperforce]

8 hours ago, RCgothic said:

I don't think every .22 round would necessarily penetrate, but a weakening, gouging, or ragged entry hole on the side of the tank could easily lead to catastrophic failure. You don't really want to test it.

Larger munitions pose exponentially more risk. 5.56mm would easily penetrate 3.5mm of stainless and nobody wants to find out what a tracer, incendiary or explosive round might do.

Anything above .22LR will certainly penetrate, but I don’t imagine a tracer or incendiary would make much of a difference compared to standard ball ammunition. It’s not as if the tanks are filled with an explosive mixture, after all; both oxygen and methane are quite safe as long as they aren’t mixed with each other. Obviously if the round punctured the common bulkhead or the downcomer it would be a different matter.

As others have pointed out, the size of a bullet hole puncture is pretty insignificant compared to the size of Starship and the amount of propellant on board. Bernoulli’s equations tell us that to a first order, the flow rate at a 2-bar differential through a 5.56-mm hole is on the order of 1.1 gallons per minute. Won’t be missed.

The more likely failure mode from a ballistic impact, imo, would be pressure-driven tensile failure propagation from the puncture point. I don’t know enough about metallurgy to hazard a guess about whether 304 stainless (or whatever alloy they’re using) is resistant to failure propagation. 

[Ultimate Steve]

I forget exactly what it was, but stress concentrations around part defects matter significantly. A bullet hole might be too big for that math to apply, I'm not sure, but given how borderline the fuel tanks are (see: all the fuel tanks they have blown up in testing) it wouldn't take much.

[CatastrophicFailure]

Shhhhh…. 
 

 

 

[SunlitZelkova]

@RCgothic @Pthigrivi I think the real intention is for fast resupply to a rear support area, which would not face such threats. Any talk of employment in or near a combat zone is just “trumped up icing” on the “proposal cake” to help gain traction with others who might object to its development.

[tater]

7 hours ago, SunlitZelkova said:

@RCgothic @Pthigrivi I think the real intention is for fast resupply to a rear support area, which would not face such threats. Any talk of employment in or near a combat zone is just “trumped up icing” on the “proposal cake” to help gain traction with others who might object to its development.

I think it's something the military has thought was cool since Phil Bono in the 60s, but it has little actual utility. But it gives Space Force something cool to crow about. Seems... unlikely.

 

Meanwhile: