Franky

Space enthusiast, F1 fan, The Warning fan⚡, rock 'n' roll all the way 🤟

[Franky @_FrankyPi]

@nickaramaOG @NASAJohnson @FreddyLA7 @NASA @AstroAnnimal https://t.co/xXtIIOtgMF

[Taylor @TaylorHose]

@FreddyLA7 @NASA @AstroAnnimal This is not the Orion capsule that flew around the Moon, that capsule is currently at the MPPF in Florida. This is the medium fidelity Orion mockup at the SVMF at JSC. Still super cool! We do a ton of training there to get ready for launch!

[Franky @_FrankyPi]

@chan_lambda @guy_eats_twit3r @jackywacky_3 This isn't just about acceleration, which has to be kept below 1g at all times, it's about the result of not having all 6 engines at 100% for entire TLI burn and not for LOI burn at all. Throttling and shutting down tanks overall propulsion efficiency, especially without Rvacs.

[Franky @_FrankyPi]

@chan_lambda @guy_eats_twit3r @jackywacky_3 I don't see what S-IVB has to do with any of this. The issue with partially using available propulsion is degrading efficiency which means degrading dV performance which shrinks margins to unacceptable levels or worse.

[Franky @_FrankyPi]

@Sir_Benedict_S @NASAAdmin I also wanna know whether they even did any kind of feasibility study for this or are they yet to do so and find out there are problems, even if structural load concern can be mitigated, the result of that would compromise HLS performance required to complete the mission profile.

[Franky @_FrankyPi]

@Sir_Benedict_S @luke_leisher_ I'm pretty sure you're off by a factor of 100, acceleration under all 6 engines at full throttle would be ~0.875g on the system, or in other words, ~24.5 tf (240 kN) imparted on Orion. Would only increase as propellant drains and engines would need throttling and shutting down.

[Franky @_FrankyPi]

@Sir_Benedict_S @luke_leisher_ Even with 1g limit for SAWs, and SADMs bending moment limit of 220 Nm, brake torque limit greater than 1200 Nm, the compounded efficiency losses from degraded propulsion result in inadequate performance to complete the mission profile, accounting for all factors I could think of.

[Franky @_FrankyPi]

@chan_lambda @guy_eats_twit3r @jackywacky_3 The issue with that is the efficiency losses compounded from degraded ISP, increased gravity losses, and degraded Oberth effect would result in eviscerating propellant margins and not having enough to even complete the mission profile, even with fairly conservative estimates.

[Franky @_FrankyPi]

@Sir_Benedict_S @luke_leisher_ With thin margins it matters, you're ignoring gravity losses and underutilizing Oberth effect. Even with 1 Raptor running on minimum throttle would be too much because NDS compressive load limit is several times lower than the minimal force that can be produced, around 300kN.

[Franky @_FrankyPi]

@Sir_Benedict_S @luke_leisher_ That's one engine firing off center the whole time and for much longer, it can only be a SL Raptor which ruins the stage propulsion efficiency, other engines not firing and being dead weight further ruins the efficiency, 100% throttle with TVC is questionable (R2 couldn't do it).

[Franky @_FrankyPi]

@squeaky2031 @AeroBigMike @Donald4Munro The original post I was replying to has Musk claiming Starship would do the entire mission, that's why I said "it can't happen" and why.

[Franky @_FrankyPi]

@squeaky2031 @AeroBigMike @Donald4Munro A4 and A5 Orion are being assembled right now, especially A4 which is already at KSC being integrated, too late to change their designs to this degree.

[Franky @_FrankyPi]

@squeaky2031 @AeroBigMike @Donald4Munro That's not "Starship doing the whole mission" is it?

[Franky @_FrankyPi]

@Donald4Munro @AeroBigMike Only in fantasyland.

[Franky @_FrankyPi]

@AeroBigMike @Donald4Munro It still can't happen because Starship HLS can't return from the Moon.

[Franky @_FrankyPi]

@luke_leisher_ Not to mention the solar arrays would also break because they're not rated for such high loads.

[Franky @_FrankyPi]

@luke_leisher_ Assuming this is permanent and not a one-off for SpaceX, Blue Origin architecture still depends on Orion being launched by SLS. You should be asking how do they think to do this when Orion docking structure isn't rated for such loads, while A4 and A5 Orion are being assembled rn.

[Franky @_FrankyPi]

@_Booster9 @mcrs987 @ThePrimalDino Whatever you call it, it has key systems the actual lander will have and they're getting their hands on that, even the actual lander if previously reported info is confirmed (surprisingly wasn't now), is the so called Initial Lander in their accelerated plan without refueling.

[Franky @_FrankyPi]

@User132165 @jackywacky_3 The big difference is Apollo spacecraft had this in plan from the start and hardware was designed and built to handle required loads, not the case here. Docking structure and solar arrays will break under these loads. It's a non starter. A4 and A5 units are in assembly right now.

[Franky @_FrankyPi]

@TheJordan276 @jackywacky_3 Its docking structure and solar arrays aren't rated for such loads.

[Franky @_FrankyPi]

@guy_eats_twit3r @jackywacky_3 It would, also the solar array joints as well. They're out of their minds.

[Franky @_FrankyPi]

@Cosmic_Andrew1 Well they're actually doing Apollo 9 with BM MK2, just not with Starship.