totm nov 2023 SpaceX Discussion Thread

[Beccab]

 

[JoeSchmuckatelli]

8 hours ago, tater said:

I think it's something the military has thought was cool since Phil Bono in the 60s, but it has little actual utility

Correct me if I'm wrong - but even if launch cargo capacity = landing capacity on Earth, wouldn't the max cargo a SS could land at any one time be equivalent to three standard shipping containers worth of stuff? 

To me that seems militarily insignificant.  You are certainly not supplying much more than a Battalion with this. 

Also, given the proliferating shoulder fired AA missiles and theater denial vehicles out there... You don't want SS to land anywhere close to the hot zone.  It might be good for delivering critical shortfalls to a secure, rear area like @SunlitZelkova's AIM's for F-35s idea... But again for regular military logistics it's fairly insignificant, per load. 

Run a fleet like we do with C5 Galaxy and you might change those numbers. 

Edit - let me add that the PR / morale boost potential for using SS in the Disaster Relief scenario is far more likely...

But as I think about it - the news howling about 'The US landed a Freaking Starship full of weapons just outside of Dictatorstania!!!' would be a PR coup / morale boost, too. 

(one that could only be beaten by 'Dictatorstania shot the US Super Starship out of the sky!!!') 

[StrandedonEarth]

27 minutes ago, JoeSchmuckatelli said:

Run a fleet like we do with C5 Galaxy and you might change those numbers. 

The thing is, I see emergency Starship deliveries, whether for relief  or military purposes, as a strictly one-way trip, since refueling depots would either be non-exisitent or very tempting targets. Good for limited quantities of gotta-have-it-now supplies, but not much else. But it could  presumably land anywhere flat enough and safe enough. 

[JoeSchmuckatelli]

42 minutes ago, StrandedonEarth said:

The thing is, I see emergency Starship deliveries, whether for relief  or military purposes, as a strictly one-way trip, since refueling depots would either be non-exisitent or very tempting targets. Good for limited quantities of gotta-have-it-now supplies, but not much else. But it could  presumably land anywhere flat enough and safe enough. 

There's a high probability that, should SS be used for Relief missions, that a 'secured area' could (or would have to be) established for it.  Fairly simple to do with infantry - which is who most often gets sent in as the 'grunt labor' in bad situations (professional, disciplined and trained force, used to hardship living and capable of rapid deployment - with an inherent security ability).  Designate a sufficiently large enough area, clear it, secure it and then use it as a Log Hub.  Later on, Elon and Crew can come in with just enough juice to get a hop for a water landing/recovery... or just harvest the engines & electronics and leave the shell as a monument.

The military use situation?  Yeah; unlikely to get the right mix of fuel at a FARP to reuse; again, a special team can come in and do as mentioned above.  The caveat here, being, no Military Commander is going to want that big silver 'SHOOT ME HERE' sign sticking around for long - or blocking flight paths/landing areas/ etc.  In this case, SF is probably going to have to develop a forward deployable ISRU to send it home.

Edited June 21, 2022 by JoeSchmuckatelli

[tater]

1 hour ago, JoeSchmuckatelli said:

The military use situation?  Yeah; unlikely to get the right mix of fuel at a FARP to reuse; again, a special team can come in and do as mentioned above.  The caveat here, being, no Military Commander is going to want that big silver 'SHOOT ME HERE' sign sticking around for long - or blocking flight paths/landing areas/ etc.  In this case, SF is probably going to have to develop a forward deployable ISRU to send it home.

Yeah, exactly. SpaceX can't hire foreign nationals because of ITAR, but the US Gov would be fine with leaving one where some rando can take it? LOL.

(ignoring where we abandoned loads of sensitive hardware in the last year or so)

[GuessingEveryDay]

3 minutes ago, tater said:

Yeah, exactly. SpaceX can't hire foreign nationals because of ITAR, but the US Gov would be fine with leaving one where some rando can take it? LOL.

(ignoring where we abandoned loads of sensitive hardware in the last year or so)

Eh, leave out the tiles and just 2 engines (1 back-up), after it's empty, it can make another hop to smash the enemy's camp. Jolly good.

[RCgothic]

What's the suborbital range for a full starship, reserving enough fuel for a return trip?

[RealKerbal3x]

59 minutes ago, RCgothic said:

What's the suborbital range for a full starship, reserving enough fuel for a return trip?

Not sure this would work, for stability during descent the main tanks are almost empty, leaving only propellant in the header tanks for landing. Once the ship is landed, it's stuck there until a refuel is possible.

[RCgothic]

That's not insurmountable. Just include extra baffles or subdivide the main tanks to keep the remaining propellant stable. Recharge the header tanks from the mains once landed.

[AVaughan]

Personally I think the interest in Starship is some of the military wanting a new toy.  

For moving cargo to a forward zone, in general I think they would be better off either para-dropping supplies from a transport aircraft or using helicopters/v-22 osprey.   One possible exception is if a large isolated base (eg an island) was surrounded and cut-off from normal aircraft approach and in need of resupply.  Even then I think that Starship would just be too vulnerable to interception.  (I guess it is possible that no existing air to air missile is able to target something like Starship.  But I'm sure that won't last if the military actually acquired some).  

Obviously that all changes if we have bases on the Moon or in space.

The other exception is if they think they can use Starship as a giant fuel air bomb.  

2 hours ago, RCgothic said:

What's the suborbital range for a full starship, reserving enough fuel for a return trip?

From memory a while ago Elon said that a full fuelled Starship (without any payload) had almost enough dV for orbital.  So lets say about 9000 m/s.  I think the Booster adds something like 2500 extra.  So all up lets hypothetically say something like 12,000 m/s.  When playing in RO/RP-1 the 3000km down-range contract needs roughly 6000 m/s of dV.  So from those figures you might think that 2 sub-orbital hops of up to 3000 km each might work.

But that is neglecting that Starship is designed to re-enter and land with a limited amount of fuel + cargo onboard.  I don't know what Starship's re-entry mass limits are but lets guess at 100 tons dry mass, plus 100 tons cargo, plus 20 tons of fuel for landing.  So a total mass at re-entry of about 220 tons.  However the fuel needed for the return trip (6000 m/s + 300 m/s for landing) is roughly 450 tons.  So to be able to fly that return trip Starship's total mass when landed on target needs to be about 550 tons.    Fuel for landing would be another 45 tons or so.  (Probably more like 50 tons, since a heavier Starship with the same cross-sectional area would have a higher terminal velocity, and would need more landing fuel).   So mass at re-entry is probably about 600 tons.   

Note that all of this is with a zero ton payload, and without any allowance for landing legs. 

You might also need more mass to strengthen the flaps and their actuating mechanisms.  Higher re-entry mass also means more energy to bleed off, however this is offset by lower re-entry velocity.  Higher re-entry mass with the same cross-sectional area probably has some effect on altitude of peak heating and peak deceleration loads.  Centre of mass is likely different as well.  (Rotational inertia would definitely be larger, requiring either a longer flip or more engines for the flip, and hence even more landing propellant).  I've got no idea what that the net effect of all of that would be other than to say you would need a new design study and probably significant design changes before a Starship optimised for a 220 ton re-entry wants to attempt a 600 ton re-entry.  

So even if a Starship has theoretically could have enough range for a return trip I don't think it is practical to land with that much fuel.   (At least not without significant design changes).

 

 

 

[tater]

 

[Beccab]

 

[Beccab]

I know I already said it a few days ago, but B7's rollout should be imminent - featuring two new strakes in addition to the two original chines, aerocovers for a lot of stuff and a large number of Raptor 2s (possibly all of them)

[RealKerbal3x]

4 minutes ago, Beccab said:

I know I already said it a few days ago, but B7's rollout should be imminent - featuring two new strakes in addition to the two original chines, aerocovers for a lot of stuff and a large number of Raptor 2s (possibly all of them)

We already know it has all 33:

 

[JoeSchmuckatelli]

15 minutes ago, RealKerbal3x said:

We already know it has all 33

But does it need all 33?  

(which - btw - I cannot escape the sense of absurdity whenever I think about a ship having a 33-rocket cluster.  It's bonkers) 

[RealKerbal3x]

8 minutes ago, JoeSchmuckatelli said:

But does it need all 33? 

Yes, they want it to leave the pad with ~1.5 TWR.

[Beccab]

 

[tater]

 

 

[Beccab]

15 minutes ago, tater said:

 

 

The chopsticks are moving up!

[Beccab]

 

[RCgothic]

 

 

[magnemoe]

8 hours ago, RealKerbal3x said:

Yes, they want it to leave the pad with ~1.5 TWR.

True, and you want high TWR for an reusable rocket, more so for RTLS as faster acceleration let you drop second stage faster. 
Now this is just static fire and I guess they start with 2 engines as in an landing burn, move up to 7 or boostback then finally all. 

[StrandedonEarth]

That is one L of a cherry-picker!

[CatastrophicFailure]

[CatastrophicFailure]

I’ll take one SciFi plz, with extra shiny.