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Realistic space concept doodles
http://www.shipbucket.com/forums/viewtopic.php?f=19&t=6916		 Page 2 of 3
Author:  Colosseum [ May 17th, 2016, 1:19 am ]
Post subject:  Re: Realistic space concept doodles
Classic comment re: "less beer".
Author:  Skyder2598 [ May 20th, 2016, 8:59 am ]
Post subject:  Re: Realistic space concept doodles
Nice work ;-)
Author:  erik_t [ July 10th, 2016, 6:57 pm ]
Post subject:  Re: Realistic space concept doodles
Restructuring everything around the TR-106, and reverting to the 8.4m heritage, gave me a much more pleasing vehicle family. The spaceplane is unchanged aside from a relocation of the abort solid motors, but pretty much everything else is redraw from scratch (GLACIESFIRE's Ares V drawing is attractive but not really to scale). Most tanks are generally Shuttle-derived SLWTs, with an additional barrel segment in the LH2 tank and an appropriate-length LOX tank ahead of it.

The TR-106's deep throttling ability allows us to play some games with the number and size of RSRM-derived solid motors (two-segment, three-segment, and five-segment) while still having all engines start on the pad (which is desirable for a variety of reasons). There's a very reasonable capability between 60MT and 125MT (130klb to 275klb), with a short 20MT (50klb) no-booster option on the very low end and a rather absurd 260MT (575klb) triple-stack on the high end.

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For comparison, Saturn V put 140MT into LEO. Proton-M achieves 23MT. The largest version of the Space Launch System promises, I think, 130MT.

In every case, the only disposable part of the system is the payload fairing and the LH2/LOX fuel tank -- it is every bit as reusable as the Shuttle. The solids fall off as with the real thing, and the tank and engine pod are put fully into LEO, for later deorbit once the engine pod thinks it has a good reentry window to glide home. All notional payloads are given 9800m/s of total dV, which is on the high end of what's necessary for a real-life launch vehicle. All weights are relatively conservative estimates and derivations from the real thing. Conveniently, all but the biggest variant could share the same launch facilities.

I don't really see much utility in the 20MT variant. It seems rather wasteful, but I don't care to study the economics too much. Also I suspect the 260MT drawing here would be badly volume-limited and would have few practical applications, which is a downside of the 8.4m heritage. We're just a very long, low-density rocket, and there's only so much space up at the top. All of the taller variants are essentially the same height as a bog-standard Saturn V, and although the VAB doors are somewhat taller, I don't know how much more height could be allowed for a big payload fairing. I've seen some images floating around that suggest up to a 410' vehicle would be possible without undue modification to facilities, which would allow for something like a 100' barrel on the 10m fairing.
Author:  eswube [ July 10th, 2016, 9:51 pm ]
Post subject:  Re: Realistic space concept doodles
Very interesting design.
Author:  erik_t [ July 12th, 2016, 6:27 am ]
Post subject:  Re: Realistic space concept doodles
This is a much better "span" of vehicles. A quartet of GEM-60 on the smallest vehicle, now featuring the same lengthened stage, takes us up to 35MT. The GEM-60 don't do much for total dV, but their thrust is required to get us up and moving off of the pad, TR-106 still being a little anemic for rockets of this scale. All liquid service masts and whatnot are identical across the lineup (although obviously the triple-stack would need three of everything). The VAB had a 410' max, so now the giant vehicle makes a bit more sense, with a full 100' 10m barrel section fairing.

[ img ]
Author:  eswube [ July 13th, 2016, 8:05 pm ]
Post subject:  Re: Realistic space concept doodles
Very impressive.
Author:  erik_t [ July 13th, 2016, 8:58 pm ]
Post subject:  Re: Realistic space concept doodles
Thanks! These have been a lot of fun.
Author:  Colosseum [ July 14th, 2016, 5:34 pm ]
Post subject:  Re: Realistic space concept doodles
Very, very cool stuff.
Author:  sebu [ July 21st, 2016, 10:27 am ]
Post subject:  Re: Realistic space concept doodles
Really cool stuff, I'd say. With a proper "rocket science for dummies"-text...
Author:  erik_t [ December 24th, 2016, 12:40 am ]
Post subject:  Re: Realistic space concept doodles
I didn't really get a lot of work done at work today, but I drew more big dumb rockets!

Two things had bothered me. First, these are all huge vehicles. If you can't scale down to less than 150% of a Delta IV Heavy, you're probably not going to end up flying many vehicles. Second, it wasn't obvious how the 34MT variant could use the same launch facilities as the other single-bore variants. Shuttle did all hold-down through the solid motors, and our solids are too damn small. If you can't share facilities, what's the point? But if you get rid of the 34MT, then things get even sillier.

No, what we REALLY need, clearly, is a half-brother family using as much of the same technology and facilities as possible. I wondered about Ares I, and what similar solution we might explore here. Two Shuttle-derived solids of various lengths, with a liquid stage on top. For no particular reason I elected to go with 6.5m diameter, which it turns out is the Saturn V third stage. This certainly aided calculations.

A single J-2X was selected, in lieu of more TR-106, because the Isp is great and it's already certified for vacuum start/restart.

We end up with a pleasing family of launchers that could use all of the same facilities as the 8.4m reusable set I posted previously, all with a single throwaway liquid engine and recoverable solid first stage. The set spans the range of 18MT (about 20% bigger than the smallest common Delta IV variant) to 34MT (about 20% bigger than a D-IV-Heavy, and big enough to launch HL-42). If desired, we could probably launch entire without ullage thrusters, since the space directly beneath the J-2X is clear and open, but that's left as an exercise for the reader.

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