Jeff Foust has the highlights of what Gwynne said at the conference yesterday (I flew back last night, got in about midnight).
Not covered: I asked her the status on crossfeeding Falcon Heavy. She said definitely not first flight — they want to get the thing flying first (which makes perfect sense), but want to get there, maybe in the next two years. She also said that they had no current customer for a “sixty-ton(ne) payload.” Parenthesis because I don’t know if she meant English or metric, but either way, that’s the first time I’ve heard that number. The original stated payload (with crossfeed) was fifty-three tonnes (I think, have to double check, might have been tons), but that was also in expendable mode. I can imagine with the improved performance of the new larger densified Falcon cores, it would go up, but it’s not clear what the flyback penalty is. I may follow up with her in email.
[Update a few minutes later]
30th Space Wing is planning for a Falcon landing at Vandenberg this year.
Maybe this is splitting hairs (splitting parallel stages), but if you cross feed from outer stages to drain their tanks to top off a center stage, maybe you want to land/reuse only the outer stages?
Those stages will be drained of propellant and separated sooner than with in a non-Heavy flight and will be more favorable for flyback and recovery?
“More favorable,” yes (and I pointed that out when the concept was first announced), but they plan to bring back all three. If they have the mission performance for it. People who want larger payloads that require the cores to be expended would obviously be charged more (and at some point, a lot more).
Depending on the mission, you have several options with a Falcon Heavy. From lightest payload to heaviest, here are the options:
1. Return all three cores to the launch site.
2. Return the outer cores to the launch site and the center core to a barge.
3. Land all three cores on barges (they’d need another barge).
4. Land the outer cores on barges and throw away the center core.
5. Throw away all of the cores.
Plus all those things with cross feed.
61 tons?!?!?!? Okay, I’m assuming that’s absolute max to LEO in total expendable mode. Also, SpaceX pretty much always uses metric, but I agree with not assuming that.
But still, 61 tons? Wow. For comparison, SLS block 1 is baselined at 70 tonnes, which is a very, very optimistic number which assumes performance specs the RS-25 E engines are rather unlikely to achieve (and the former Shuttle RS 25D’s they’ll use at first don’t have). But, even assuming they hit baseline, that puts FH is the same league for LEO payload (though not beyond LEO, due to the lower ISP of the FH upper stage).
What this does is give lots of excess performance that can be used for recoverability, including potentially of the upper stage.
Do “expendable” and “reusable” boosters differ solely in whether the 5% (or howevermuch) fuel is reserved for recovery? Or do they intend to strip the fins, landing gear, etc. off to save that smidge of weight? Pretty sure I’ve already heard they don’t intend to proceed with “two models”, where there are actual engineering changes. But simply stripping some parts would look like “weight saved” to me.
I don’t know, but the danger of having two different processes and vehicles is that you’ll mix them up.
I hope they have a good launch rate this year. Curious to see how ramping up production and reusability interact.
My understanding is that SpaceX intends for the FH center core to be identical to the F9 Full Thrust 1st stage and for the 2nd stages to be identical.
Given that FH is to have over 2.5 times the LEO throw weight of F9, that implies all the structural components of the shared F9-1st/FH-center stages and the common 2nd stage are to be built to the more demanding FH standard. That would have the, probably entirely intended, effect of making them better able to withstand the rigors of re-entry and reuse.
The FH side cores, as they have nothing atop them, can, and will be, built more lightly. That may mean they will have fewer launch-and-reuse cycles in them than the center cores, but, given that there will likely be fewer FH launches than F9 launches in any given future year, that shouldn’t matter. It may well be the case that the same beefier 1st stage cores will sometimes do duty alone, as F9 1st stages and at other times, be center cores on FH launches.
Going to this system of having two standard core designs might mean SpaceX no longer intends to ever implement cross-feed on the FH, but that would depend upon how much of the extra weight for such a capability would wind up resident in the center core. If most of the extra mass needed for cross-feed can be placed into the side cores, then cross-feed could still be a worthwhile enhancement. So it could be the initial flight version of FH will lack cross-feed hardware, but still provide improved LEO delivery stats, relative to the long-since announced 53 tonnes, based on use of cores of the F9 Upgrade type and the newly enhanced 2nd stage. Then, in due course, cross-feed could be implemented as a separate set of enhancements and boost FH’s LEO throw weight still more – conceivably up to or even beyond that of the putative SLS Block 1.
The first of these two FH “generations” will, one presumes, be the test article launched from LC-39A later this year. The second-generation FH, with cross-feed, could follow relatively quickly thereafter – quite possibly seeing an initial launch before that of the first Block 1 SLS.
Beyond these two possible versions of FH, of course, there is a possible third-generation version employing an enhanced 2nd stage based on a vacuum Raptor engine – per SpaceX’s recent development contract with the Air Force. This new 2nd stage, which might well also be recoverable and reusable, could put FH’s LEO throw weight well beyond that of SLS Block 1 and might get within spitting distance of the SLS Block 1B with the Exploration Upper Stage. This fully-evolved FH might have very competitive lunar, Mars and other cis-lunar and/or deep space mission throw weights relative to SLS Block 1B. It’s operating economics, of course, would be vastly superior.