totm nov 2023 SpaceX Discussion Thread

[JoeSchmuckatelli]

Has there been anything about differential curing of the concrete due to the engine testing? 

Not that there necessarily would be - but I do know that foundations exposed to a house fire often need replacing. 

[tater]

3 hours ago, AckSed said:

I see how it is, you have to advance the tech tree to "Armoured Launch Platform" before "Reusable Heavy Lift".

We know they are pretty far along—they have ladders.

 

[FleshJeb]

7 hours ago, JoeSchmuckatelli said:

Has there been anything about differential curing of the concrete due to the engine testing? 

Not that there necessarily would be - but I do know that foundations exposed to a house fire often need replacing. 

They'll be using "refractory concrete" anywhere exposed to high temperatures. Very different cement (and possibly aggregate) mix and performance than standard Portland cement concrete.

You're right though. I've inspected several bridge abutments that were exposed to wildfires, and they lost almost all strength for a depth of about 2 inches. The field test for that is tapping it with a hammer--big flat chunks come off. I speculate that for concrete that was still curing, all the water would flash to steam and just detonate/spall it.

[JoeSchmuckatelli]

1 hour ago, FleshJeb said:

for concrete that was still curing

Yeah - and the old rule of thumb was that concrete was forever curing. 

Not to mention that most of it is vapor permiable and... 

Let's just say I'd be interested in the tech specifications.  It's been a long time since I looked into this! 

[FleshJeb]

5 minutes ago, JoeSchmuckatelli said:

Let's just say I'd be interested in the tech specifications.

I only knew the term before I googled it and spent a few minutes reading (which I'm sure you've done by now). I've only dealt with 2 or 3 standard grades of PCC. The one time I had to specify something with custom performance, I called a PhD at the concrete mixing plant. Concrete and asphalt can be deeply technical subjects.

[JoeSchmuckatelli]

1 hour ago, FleshJeb said:

Concrete and asphalt can be deeply technical subjects

Preach! 

FWIW I recently got into a discussion with an artist and an engineer about clay and ceramics.  Thank god I'm a science nerd! 

Edited March 6, 2023 by JoeSchmuckatelli

[tater]

Tomorrow afternoon:

 

 

[Exoscientist]

Updated discussion of the topic:

SuperHeavy+Starship have the thermal energy of the Hiroshima bomb. UPDATED, 3/8/2023.

https://exoscientist.blogspot.com/2023/03/superheavystarship-have-thermal-energy.html

  Key points:

1.)While the explosive force of the SuperHeavy/Starship (SH/ST) is not likely to reach that of its full thermal content of 13.3 kilotons of TNT, comparable to the Hiroshima bomb, it is still likely to be in the range of 3 to 5 kilotons of TNT.

2.)The Halifax and Texas City disasters of comparable explosive force suggests damage can extend kilometers away.

3.)The hazard or exclusion zones of only 2 miles, 3 km, for SH/ST is likely inadequate based on the Halifax and Texas City disasters.

4.)SpaceX ignored FAA warnings not to launch SN8 due to weather conditions exacerbating the effects of a possible blast wave from an explosion.

5.)The Starship SN11 explosion in midair may have been a BLEVE, which introduces an additional detonation mode for cryogenic fuels.

6.)At least one Raptor leaked methane and caught fire on multiple test flights of the Starship.

7.)Since the SuperHeavy static test lasted little more than 5 seconds, a strong possibility exists that multiple engines will fail during a full burn of an actual flight.

Recommendations.

1.)It should be revealed to the public the SH/ST has the thermal energy content of the Hiroshima bomb.

2.)Experts on launch vehicle explosions and fuel-air detonations should present a report to the public explaining what the likely explosive force would be if the vehicle exploded.

3.)SpaceX should not be granted a launch license for the SH/ST until SpaceX constructs a separate engine test stand sufficient to test all 33 Superheavy engines at the same time time, at full power, and at full flight duration, and for such tests to complete successfully for multiple tests.

Edited March 13, 2023 by Exoscientist

[tater]

1 hour ago, Exoscientist said:

3.)SpaceX should not be granted a launch license for the SH/ST until SpaceX constructs a separate engine test stand sufficient to test all 33 Superheavy engines at the same time at full power and at full flight duration, and for such tests to complete successfully for multiple tests.

The entire point of the licenses that they have already been granted was that they knew all this. So no.

https://nuclearsecrecy.com/nukemap/?&kt=5&lat=25.9961227&lng=-97.154417&airburst=0&hob_ft=0&psi=20,5,1&zm=15

Pad alt 5kT explosion:

 

480m alt 5kT explosion (maxes the 5 psi radius, higher alt reduces impact):

Note that evac is past Stargate facility for launch.

Outer circle is 1 psi overpressure.

Also, a 13.3kT detonation on the pad doesn't have 1 psi overpressure reach the middle of the old village. It kisses the closest side (all SpaceX at this point I think—regardless launch evac is farther away).

Not that this explodes at that level vs deflagration.

Edited March 9, 2023 by tater

[RCgothic]

Blast Danger area is specifically delineated in Figure 2-4 of the draft Programatic Environmental Assessment. It roughly corresponds with the outer circle in Tater's second pic.

The FAA is aware.

 

Edited March 9, 2023 by RCgothic

[Cuky]

 

[darthgently]

53 minutes ago, Cuky said:

 

Action speaks so much louder than words, lol

[JoeSchmuckatelli]

2 hours ago, Cuky said:

 

That is the most awesome thing I've seen in a while!

11 hours ago, Exoscientist said:

Updated discussion of the topic:

SuperHeavy+Starship have the thermal energy of the Hiroshima bomb. UPDATED, 3/8/2023.

https://exoscientist.blogspot.com/2023/03/superheavystarship-have-thermal-energy.html

  Key points:

1.)While the explosive force of the SuperHeavy/Starship (SH/ST) is not likely to reach that of its full thermal content of 13.3 kilotons of TNT, comparable to the Hiroshima bomb, it is still likely to be in the range of 3 to 5 kilotons of TNT.

2.)The Halifax and Texas City disasters of comparable explosive force suggests damage can extend kilometers away.

3.)The hazard or exclusion zones of only 2 miles, 3 km, for SH/ST is likely inadequate based on the Halifax and Texas City disasters.

4.)SpaceX ignored FAA warnings not to launch SN8 due to weather conditions exacerbating the effects of a possible blast wave from an explosion.

5.)The Starship SN11 explosion in midair may have been a BLEVE, which introduces an additional detonation mode for cryogenic fuels.

6.)At least one Raptor leaked methane and caught fire on multiple test flights of the Starship.

7.)Since the SuperHeavy static test lasted little more than 5 seconds, a strong possibility exists that multiple engines will fail during a full burn of an actual flight.

Recommendations.

1.)It should be revealed to the public the SH/ST has the thermal energy content of the Hiroshima bomb.

2.)Experts on launch vehicle explosions and fuel-air detonations should present a report to the public explaining what the likely explosive force would be if the vehicle exploded.

3.)SpaceX should not be granted a launch license for the SH/ST until SpaceX constructs a separate engine test stand sufficient to test all 33 Superheavy engines at the same time at full power and at full flight duration, and for such tests to complete successfully for multiple tests.

Do you mind adjusting the font size?  This is interesting info, but it comes across as really alarmist (and not quite believable because of that.  On the other hand the site you link to is normal looking and better presented).

Also - see below for more technical reasons why we should not panic.

Edited March 9, 2023 by JoeSchmuckatelli

[tater]

What's funny is that I did not follow the link, I read the post here, then pulled up the bomb map... just checked the link, and it references the same site.

[tater]

Launch today is RTLS.

BTW, should my son and I be down at Starbase March 20, I'm unsure where to drive to. If I can drive and stop at the side of the road as close as I could go where the roadblock is... I'd be perfectly happy to do so.

Edited March 9, 2023 by tater

[Nuke]

its not really fair to nukemap. i think precisely detonated nuclear weapons are completely different from chaotically detonated rocket fuel. the efficiency of conversion to energy is gonna be really low. not to say a huge detonation wont be bad. especially if it wipes starbase off the map. so i doubt spacex is being careless.

though im sure there are bureaucrats that want to spam space-x with so many regulations that they cant afford to launch anymore. as if they havent done so already.

Edited March 9, 2023 by Nuke

[sevenperforce]

7 minutes ago, Nuke said:

its not really fair to nukemap. i think precisely detonated nuclear weapons are completely different from chaotically detonated rocket fuel. the efficiency of conversion to energy is gonna be really low. 

For a worst-case-scenario pad explosion, where the common bulkhead fails and the LOX and CH4 mix into a gel before detonating, the difference wouldn't matter. The implosion and chain reaction in a nuke takes microseconds, while the detonation wave in a LOX+CH4 gel would take about 8 milliseconds to propagate from one end of the booster to the other. So even though a nuke would explode much faster from a physics standpoint, it would still happen fast enough that there's no real meaningful difference.

Nuclear weapons explode with a characteristic "double flash" that allows them to be confirmed as nukes. The x-ray emissions produced by the nuclear chain reactions superheat the air around the weapon into a plasma, which initially glows very brightly. However, because it becomes a plasma, it "traps" the x-rays inside it microseconds later, causing the plasma to start to dim as it cools while the heat inside builds up enormously. A few milliseconds later (or up to  a third of a second for very very large thermonuclear weapons), the outer layer of plasma has expanded enough that the much hotter plasma at the center (think: core-of-the-sun hot) can burst through and create the second flash.

But with a nuke comparable in size to the theoretical yield of a Superheavy RUD, that double-flash will take about the same amount of time as the actual detonation of Superheavy. So the resulting blast wave and aftereffects will be equivalent, sans radiation.

[RCgothic]

Presumably even in the case where the propellants in Superheavy were well-mixed, the propellants in Starship would not be.

[tater]

Bottom line is that if a nuke of equivalent total energy under the worst theoretical assumptions is not terribly concerning at a given distance, then the actual vehicle is even less concerning.

[Brotoro]

One minute to Falcon 9 launch

Oneweb Launch 17 .......Liftoff!

[Beccab]

Liftoff

Max Q

[Brotoro]

Tracking camera has lousy focus

 

[Beccab]

Stage sep, Mvac ignition, boostback

[Brotoro]

Always enjoy a nice boostback. RTLS launches are fun.

Nice landing of booster.

Excellent camera work. It seemed to have a little bounce on landing (or maybe I mis-saw... I'll have to rewatch).

[Beccab]