sevenperforce

I would argue that the SLS is designed to use STS hardware for, uh, whatever.

Methalox upper stage would make a HUGE difference, especially if the upper stage was stretched (as it would be). Multiple launches are no problem when you have a reusable vehicle and rapid pad turn-around. Anything SLS can launch beyond LEO, FH can launch to LEO (most likely with side-booster reuse) and use a second launch to dock a BLEO stage to it. A methalox upper stage for Falcon Heavy, all expendable, would be very close to what SLS can do.

Do we see B5 FH or B5 F9 first?

BFR launches next to the water and does its ascent over water. BFS lands on a pad next to water. Any abort puts the escape capsule in the water. If the capsule needs to be used as an orbital lifeboat, then it can choose where to do its deorbit burn, which again will put it in the water. It has plenty of dV for a deorbit burn since it doesn't need to do an escape burn. Chutes, splashdown, low center of gravity, wide footprint. No possibility of rollover. No, it won't be a cone-cylinder; it will be biconic. Forward CoM, wide entry area, aft CoP. Think less D2, more Dream Chaser. But bigger. Passively aerodynamically stable on abort (all regimes), entry, and landing. Chute placement designed for splash down with a low forward velocity.

Ares IV was the proposed evolution of Ares V, where an Ares I upper stage would be placed on the Ares V base to make a man-rated SHLV comanifesting crew and cargo.

You don't need an dragon 2 its an fully fledged spaceship able to dock, do orbital burns and reenter. The trunk only hold cargo, solar panels and radiators. That makes sense if you reuse it not for an escape pod, think blue Shepard capsule but larger, more cramped and no windows. I would put the solid fuel engine below, it would give you more room, inside and an way to give aerodynamic stability. Also an crumble zone if you land on land because landing fail Agreed, you don't need a full spaceship; I was just giving a worst-case-scenario where you do separate Dragon 2 capsules for each set of 7 passengers. Having a few more capabilities (like a little on-orbit maneuvering) comes in handy if you have a major problem in space (think docking mishap or MMOD/debris strike to the main LOX tank). Sure, you could launch a rescue mission, but if you already have an escape capsule, you might as well be able to use it. Why would placing a solid LES motor underneath be better? I mean, I get not putting a launch tower on top, but you could as easily put them on the sides. I would say to use a bank of hot-gas methane-ox thrusters (RCS thrusters for the BFS/BFR) for the escape engines, with pressurized tanks inside the escape capsule. You're overcomplicating. Soyuz lands on land, with retrorockets, because they have no large body of water near their launch sites. US-based capsules always splashdown. Plus, you don't need a D2 shape. You can go biconic. Your heat shield can be part of the main vehicle heat shield; the escape capsule is placed at the very tip of the BFS and uses pneumatic or pyrotechnic breakaway from the main body. The biconic entry vehicle has some degree of body lift, which avoids nasty ballistic entry, and splashes down, belly-first, with chutes. The passengers can egress using the same door used to move into the main hab area, and you can throw on some airbags for flotation if you like.

Unrelated: Ares IV is weird nomenclature. It should be Ares VI; it's the combination of Ares I plus Ares V, not one-less-than-V.

Fixed it, thanks!

A separate escape capsule for BFS is certainly challenging, but it's doable. Dragon 2, fully fueled, masses 7800 kg; you can probably budget 800 kg more for a crew of 7 but let's just round up to 9 tonnes. If, as a super-simple approach, all the passengers were placed in separate Dragon 2 escape capsules and nothing more, you could pack in 70 passengers and still have 40% of BFS's payload available for a common hab, airlocks, support structure, and additional cargo. A monolithic crew escape capsule built into the BFS airframe would probably be able to do much better.

The BFR/BFS can put 150 tonnes into LEO, reusable. I'm sure you can build an escape capsule big enough to hold more than 8 passengers if your mass budget is 150 tonnes.

*insert swears here*

They should have flown Orion Lite, using the Shuttle's OMS as a drop-in service module to provide LES, orbital insertion, and orbital maneuvering, with a smaller hydrolox tank and the SSMEs. If you're going to expend the SSMEs anyway, then just do an SSTO. They could have preserved US crewed flight capability to service the ISS, and built for BLEO by expanding that system.

You'd want four different BFS variants: SpaceX Earth Orbit Ferry (passengers are packed into a launch capsule with its own 0-0 abort, life support, chutes, and lifeboat capabilities; operates only in LEO; includes larger hab separate from escape capsule; can be used for P2P flights as a single stage) SpaceX Expedition Spaceship (no LES, includes longer-term ECLSS, includes solar storm shield chamber and crane assembly for egress) SpaceX Cargo Spaceship (clamshell cargo bay; can be used as a tanker in a pinch) SpaceX Tanker (cargo spaceship without additional propellant tanks in place of cargo bay) For flights to space stations and the like, the BFR launches the Earth Orbit Ferry, which does its thing and then returns. Flights BLEO are a bit more complicated. Steps: BFR launches the Expedition Spaceship into LEO unmanned. BFR launches repeated flights of the Tanker (or Cargo Spaceship, if need be) to refuel the Expedition Spaceship. BFR launches the Earth Orbit Ferry with passengers in the launch capsule. It does a rendezvous with the Expedition Spaceship and docks, and the crew transfers to the Expedition Spaceship. Earth Orbit Ferry returns to earth unmanned (or with only a few crew) while the Expedition Spaceship goes on to its BLEO mission. This way the crew has abort options at every point where abort would be possible but you don't drag unnecessary abort and lifeboat systems out beyond LEO.

Definitely.

I would argue that without very specific mixing conditions, you have deflagration at worst, not detonation. AMOS-6 was a rapid but entirely subsonic deflagration, and it had the nearly-perfect mixing conditions of a total pad RUD without FTS activation. CRS-7 didn't even ignite (at least not appreciably) and it was an in-air FTS.

I would definitely anticipate a Mars Transit flight article without LES that launches uncrewed, and an LEO operations flight article with LES for launching crew.

The requirement for use of Shuttle-derived hardware could have been satisfied if they had built DIRECT immediately. But nooooo.

Liquid rocket boosters use a pyrotechnic cord which fires along one side of the tank, essentially "unzipping" the tank walls along one side, immediately dumping the contents. BFR will have an AFTS but crewed BFS will not...at least, not unless they add a separate crew capsule and LES. Uncrewed BFS will have AFTS.

Does anyone know how many pyrotechnic bolts the Delta IV common booster core uses for stage separation?

I've gone to saving all my craft as subassemblies because I can put them in folders.

That would be H2, not O2, anyway, since the RL-10 is an expander cycle that uses fuel as coolant.

Cold gas thrusters (F9) are much nicer than the monoprop ullage thrusters used on Centaur, because you don't have to burn for ullage constantly during coast.

On that note -- I often see discussion of GTO insertions being quoted with a certain "-dV" value, like "-1800 m/s". I assume that is the dV which the payload will have to spend in order to circularize at GEO. For F9 launches, the upper stage sometimes burns to MRS to make that value as low as possible. In those cases, is the burn to MRS intended merely to raise apoapsis a little higher (decreasing the cost of the payload's plane change maneuver) or does it do a little bit of work to directly change inclination? Shoot! I suppose they can just do two burns but it will really shorten the lifespan of the sat. What's the oblong thing off-center next to the RL-10? Is that a helium bottle? My Centaur clone got the positions of the ullage thrusters and attitude thrusters exactly right, entirely by luck.

The RL-10 sure is a wimpy engine (REALLY long burn times) but it's got amazing specific impulse. Why is the third Centaur burn after a three-hour coast? The burn would be nowhere near periapsis, which is what I'd expect if you're going for a supersync. Does it raise periapsis or just apoapsis?