SpaceX News

[GIThruster]

I think too, it will matter much if they're launching 53T to LEO or a lighter payload much higher. The higher the first stage goes, the more trouble flying it back unless of course they fly around once.

[hanelyp]

With an underweight payload some flexibility in the launch trajectory opens up. The first stage flying a more vertical trajectory, leaving more horizontal velocity for the second stage, makes first stage return to launch site easier.

[ogiw]

Maybe I'm a bit dense here, but it seems to me that the first requirement met in Falcon 9 v1.1 was to loft pretty much the same level of payload but add enough margin in the first stage to permit adding the structures needed for controlled reentry and landing of the first stage. This marks the first time outside of the Shuttle that somebody's radically departed from ICBM groupthink: maximize throw-weight.

With that in mind, everything in their RLV program makes sense. The more powerful Merlin 1D, increased fuel and oxidizer etc. only costs more if you keep throwing it away.

They're close to completion on first stage reuse; I'm curious about Dragon Mk II and a reusable second stage: will the stack weigh too much at that point?

[ladajo]

Maybe they can run the existing tanks with mods for higher pressure. Get a little more stuff stuffed in them.

Elon once mentioned prechilling the fuel a bit to make it more dense would be possible with the falcon 9, which would increase its capabilities further. The engines are currently also only operating at a limited thrust. They still have some 15% (IIRC) of headroom there as well. I guess that all that combined could make up for the losses for the reuse of the second stage (which will be about 30% that need to be subtracted from the 13.1 tonnes of payload the F9 with first stage reuse has.
Not sure what plans they have for the methane powered rocket (the so called mars colonial transport) and whether any of this will be applicable there as well. It is still too early to tell. They are only just beginning to test components of the new methane engine at Stennis.

Too bad I don't work at Stennis any more, I could check out how they are doing.

[GIThruster]

This marks the first time outside of the Shuttle that somebody's radically departed from ICBM groupthink: maximize throw-weight.

I think Gary Hudson was thinking this way back with DC-X. Had he had access to throttleable engines we might have seen this 2 decades ago. But of course X-33 got the money instead.

I'm curious about Dragon Mk II and a reusable second stage: will the stack weigh too much at that point?

What Musk really needs to reuse the second stage is something that will make it able to withstand the process of reentry. . .something I happen to have a solution to. Not really sure how to tell him though.

[Betruger]

Reportedly something remarkable happened WRT this last mission, going by rumours at NSF. It kinda sounds like either first or second stage boost-back again went beyond expected performance.

[GIThruster]

Well, Musk says the remarkable thing was they were able to control the roll rate that had destroyed all the previous stages:

http://www.spaceflightnow.com/falcon9/0 ... 1lRxSgmz_s


I haven't heard a peep about the condition of what they recovered. If the second landing burn worked right it may still be in one piece.

[Skipjack]

Maybe I'm a bit dense here, but it seems to me that the first requirement met in Falcon 9 v1.1 was to loft pretty much the same level of payload but add enough margin in the first stage to permit adding the structures needed for controlled reentry and landing of the first stage. This marks the first time outside of the Shuttle that somebody's radically departed from ICBM groupthink: maximize throw-weight.
With that in mind, everything in their RLV program makes sense. The more powerful Merlin 1D, increased fuel and oxidizer etc. only costs more if you keep throwing it away.
They're close to completion on first stage reuse; I'm curious about Dragon Mk II and a reusable second stage: will the stack weigh too much at that point?

Yes, they are doing a really good job at staying in the sweet spot of reusability margin and ideal payload size for the class of the F9.
One thing to note is (and few people are aware of that) that the 13,150 kg of payload to LEO listed for the F9 on the SpaceX website, already include the margins needed for first stage reuse. So reusing the first stage wont reduce the payload from the current 13.1 tonnes at all. That in itself is already quite an achievement considering that this is quite a bit more payload than the F9 1.0 had.
Now, second stage reuse is more costly than first stage reuse, because one kg more weight on that stage will directly reduce the payload by one kg. It will be very interesting to see how SpaceX plans to solve that part. The good news is that the F9 1.1 still has some extra margins that SpaceX has not used yet. The engines are currently only running at 85% (I think that was the number) of their potential (I presume that means thrust). So they still have some margin for improvement there. Note though that increasing the thrust by 15% does not increase the payload by 15% because it could mean that the rocket needs more fuel when the thrust increases (unless the sweet spot for Isp is 15% higher than the current thrust setting). Still, there may be some extra % of payload that can come from that. All together this could mean that a F9 1.1. with both stages reused could still have a higher payload than F9 1.0 had. This is quite astounding, if you think about it.
The other cool thing is that SpaceX can always decide to launch an F9 in expendable or semi expendable mode (throw away both stages or only the second stage) and get more performance out of it, should a customer require it. Then they can just use an older stage that has already reflown a few times.

Edit: Should also add that Musk said they can also prechill the RP1 for even more performance. So there are still plenty of margins and little knobs they can turn to get more performance out of the thing.

[Skipjack]

This marks the first time outside of the Shuttle that somebody's radically departed from ICBM groupthink: maximize throw-weight.

I think Gary Hudson was thinking this way back with DC-X. Had he had access to throttleable engines we might have seen this 2 decades ago. But of course X-33 got the money instead.

Gary has been an advocate for VTOL and he has been one of the people that paved the way for the DC-X with his work, but from all I know, he was not directly involved with the DC-X.
You are right about the unfortunate fact that the DC-X was discontinued in favor of the X33, which never flew and was doomed from the start.
TSTO VTOL is very different from SSTO VTOL and has its own challenges. I quietly deep down still hope that one day SpaceX will try to do SSTO.
Well, we will see.

[GIThruster]

Gary was one of the team who did DC-X. This is no surprise with his previous interest in VTOL SSTO. I'm sure there were others who are more often mentioned for their work on DC-X but you can rest assured, Hudson was indeed very involved.

[Skipjack]

Gary was one of the team who did DC-X. This is no surprise with his previous interest in VTOL SSTO. I'm sure there were others who are more often mentioned for their work on DC-X but you can rest assured, Hudson was indeed very involved.

Gary was definitely not on the MDAC team. He was a contractor for the competing Boeing and General Dynamics team. But he was among the people that got the project kicked off (along with Max Hunter) and his work on the Phoenix and other VTOL designs was the basis for the DC-X design. This got him mentioned in the DC-X team lists (and rightfully so). I still dream of a day, when I see a Phoenix rise to the sky.

[Skipjack]

Reportedly something remarkable happened WRT this last mission, going by rumours at NSF. It kinda sounds like either first or second stage boost-back again went beyond expected performance.

There will be a press conference today at 1 pm CST:
http://press.org/events/spacex-press-conference

[KitemanSA]

Launch from Baker Island, land on Jarvis. Both very near the equator, both US possessions
.

[Maui]

There will be a press conference today at 1 pm CST:
http://press.org/events/spacex-press-conference

I missed the beginning. Doesn't seem to be saying anything new from where I picked up. Was there any news?

[ladajo]

Besides launching a law suit against the Government about Sole Source contracting of space launches, not so much.

He did confirm they had a soft touchdown with the 1st stage. But that was already out there given his tweets on status.
He had previously (launch day) tweeted that the telemtry showed roll control, and a vertical landing. After wet touchdown the telemetry showed it went from vertical to horizontal (kept transmitting). All good signs of a controlled profile that he confirmed at the press conference.
He also added that they could not recover the stage, as the vessel on hand was not capable. The stage later broke up and sank due to wave action.

What I still don' t know was how far out at sea it was when it made the touchdown.