Author Topic: F9 Second Stage Reusability  (Read 190438 times)

Offline wannamoonbase

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Re: F9 Second Stage Reusability
« Reply #460 on: 06/04/2017 07:41 PM »
NASA Considering Using Pre-flown SpaceX Rockets for Cargo Flights - Space.com
https://apple.news/AL8bTtgpdOg6Hgm1ELziJ3g

'Falcon 9 second stage apparently splashed down softly in the ocean southwest of Australia'

Ex-squeeze me, soft landed second stage?  Is this poor reporting or the biggest development since landing a first stage?
« Last Edit: 06/04/2017 08:00 PM by wannamoonbase »
SpaceX, just a few things planned for 2018: FH, Starlink Prototypes, Block 5, Dragon 2, Increased launch rate.

Re: F9 Second Stage Reusability
« Reply #461 on: 06/04/2017 08:00 PM »
NASA Considering Using Pre-flown SpaceX Rockets for Cargo Flights - Space.com
https://apple.news/AL8bTtgpdOg6Hgm1ELziJ3g

'Falcon 9 second stage apparently splashed down softly in the ocean southwest of Australia'

Ex-squeeze me, soft landed second stage?  Is this poor reporter or the biggest development since landing a first stage?

Poor reporting, per Chris G:

I noticed this:
Quote
After its work was done on Saturday, for example, the Falcon 9 second stage apparently splashed down softly in the ocean southwest of Australia, Hans Koenigsmann, SpaceX's vice president of build and flight reliability, said during Saturday's press conference.
in this article.

Anyone know if that's true, or rubbish?  I spotted at least one other factual error in the article, so the latter wouldn't surprise me.

He said it was deorbited and reentered SW of Australia.  He said nothing about it splashing down softly, which is most likely complete rubbish.  You can find links to the press conference in the CRS-11 threads.

Thanks, I sort of figured.  I missed the presser due to hosting an (unrelated) party, but figured NSF crowd would be all over it already if Hans had actually said that.

Yeah, Hans said it "deorbited and landed"... but everyone took that to mean it reentered and broke up, not that it actually landed in one piece.

Offline Rocket Science

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Re: F9 Second Stage Reusability
« Reply #462 on: 06/04/2017 08:01 PM »
NASA Considering Using Pre-flown SpaceX Rockets for Cargo Flights - Space.com
https://apple.news/AL8bTtgpdOg6Hgm1ELziJ3g

'Falcon 9 second stage apparently splashed down softly in the ocean southwest of Australia'

Ex-squeeze me, soft landed second stage?  Is this poor reporter or the biggest development since landing a first stage?
I don't recall anything being said by Hans during the presser yesterday as mentioned in your link. Definitely worth checking out!
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Offline TrevorMonty

Re: F9 Second Stage Reusability
« Reply #463 on: 06/04/2017 09:48 PM »
For US to do soft landing it would need landing engines and heatshield both should be visible.

Offline punder

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Re: F9 Second Stage Reusability
« Reply #464 on: 06/04/2017 10:18 PM »
He just said it landed in the Pacific. Nothing about "soft."

Just like most meteorites do...   :D

Offline wannamoonbase

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Re: F9 Second Stage Reusability
« Reply #465 on: 06/04/2017 11:07 PM »
For US to do soft landing it would need landing engines and heatshield both should be visible.

A incremental first step might just be control surfaces for atmospheric entry, then a heat Shield, then landing engines.

LEO missions may have margin for second stage development.
SpaceX, just a few things planned for 2018: FH, Starlink Prototypes, Block 5, Dragon 2, Increased launch rate.

Offline ChrisWilson68

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Re: F9 Second Stage Reusability
« Reply #466 on: 06/04/2017 11:48 PM »
For US to do soft landing it would need landing engines and heatshield both should be visible.

A incremental first step might just be control surfaces for atmospheric entry, then a heat Shield, then landing engines.

LEO missions may have margin for second stage development.

But the point is that this mission definitely didn't have a heat shield and definitely didn't do a "soft landing" as the article claims.

Offline Robotbeat

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Re: F9 Second Stage Reusability
« Reply #467 on: 06/04/2017 11:52 PM »
The article is based on a misinterpretation BUT we don't actually know the full extent of SpaceX's upper stage experiments. Could include some TPS.
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Offline macpacheco

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Re: F9 Second Stage Reusability
« Reply #468 on: 06/05/2017 03:54 AM »
What kind of payload capability is expected to be left on the CRS11 mission considering its RTLS profile ?
Could that be enough to try some 2nd stage re-entry tests, if NASA had concurred ?
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Offline spacenut

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Re: F9 Second Stage Reusability
« Reply #469 on: 06/05/2017 01:25 PM »
Reusability may work with a FH, but wouldn't the extra weight bring down the F9 capabilities too much? 

Offline TrevorMonty

Re: F9 Second Stage Reusability
« Reply #470 on: 06/05/2017 02:02 PM »
Reusability may work with a FH, but wouldn't the extra weight bring down the F9 capabilities too much?
I think F9 can still launch crew dragon and do RTLS with booster while recovering 2nd stage. GTO missions are probably to much but LEO broadband satellites shouldn't be problem.

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Offline ChrisWilson68

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Re: F9 Second Stage Reusability
« Reply #471 on: 06/05/2017 03:33 PM »
Reusability may work with a FH, but wouldn't the extra weight bring down the F9 capabilities too much?

The honest answer is that nobody here actually knows how much second-stage reusability would reduce payload to different orbits.

I believe I heard the estimate of a 50% hit from Musk years ago, but that was likely only a very rough estimate.  SpaceX probably has better estimates now, and possibly very different ideas about how to do it than they did when the 50% payload hit estimate was made.  But it's likely even SpaceX only has a rough idea and won't really know better until they actually do more work on it.

Offline Space Ghost 1962

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Re: F9 Second Stage Reusability
« Reply #472 on: 06/05/2017 05:06 PM »
Suggest you think a lot about how SX has "evolved" its LV strategy as it has achieved success, as opposed to how their original roll out was supposed to go.

Originally F1, F5/9 and F9H were supposed to reuse engines (not terrifically differently than SMART reuse), and rollout successively with increasing payload to orbit (thus no need for much beyond M1C engine performance to cover Atlas/Delta families. Then factor in increased reuse.

F1/F5/F9H didn't work out, and one didn't have any reuse. SX also found limits to operations cadence, economics of the market (numerous), and limits to "agile" development (AMOS 6). Bright lights were the degree they could refine F9 into F9R-FT successively, so they stretched it into the "lower" payload range of FH, which is still to fly.

Along the way the flexible reusable/expendable approach (and M1D improvements) has meant that they could span a greater range of missions, while still retaining an economic advantage over rivals (high commonality components). Reuse is primarily a launch frequency rate improvement, as seen with this month's BulgariaSat, incrementally phasing in reuse economics (as well as inspiring rival's Quick Launch response).

SX always goes for the "good enough" solution, then evolves it. (Which, by the way, is why they *won't* do Raptor vehicles other than BFS/BFR BTW.) They will do experiments *after* mission success.

They need F9US largely unchanged - it is key to all F9/FH missions. So how do you factor in US reuse?

You do it above the payload adapter, as a secondary payload, with its own primary payload adapter.

You could either do this incrementally or "all up". Doesn't matter. It is excess payload, just like F9 reusable architecture on an expendable launch. As long as the mission risk isn't significant, you phase in such on various missions, as part of the launch bid process. As they have always done.

The "good enough" approach.

As to reuse economics, like with the booster, the key is to recover the US in a usable form for another mission, and to then see how the economics work to factor it in to your LV strategy, where then the entire LV "evolves" and the LV family takes on different roles to serve the market.

"Good enough" requires a non dogmatic approach. Which is why other providers find it so hard to do.


Offline spacenut

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Re: F9 Second Stage Reusability
« Reply #473 on: 06/05/2017 06:07 PM »
If SpaceX uses a lot of carbon fiber in the upgraded 2nd stage, would it not lighten the stage enough to offset some of the 50% drop in payload capability? 

Offline IRobot

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Re: F9 Second Stage Reusability
« Reply #474 on: 06/05/2017 06:21 PM »
Then they would end up with a duplicate of tooling for first and second stage. IMO either they remake the whole F9 in carbon (unlikely) or they do nothing.

Offline john smith 19

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Re: F9 Second Stage Reusability
« Reply #475 on: 06/05/2017 06:57 PM »
Then they would end up with a duplicate of tooling for first and second stage. IMO either they remake the whole F9 in carbon (unlikely) or they do nothing.
That would be very much in keeping with SX's way of doing things. That said they might shift to a CF upper stage if they mfg the big ITS LOX tank in house. Otherwise that would put an outside sub contractor in the critical path for all future upper stages. Something I'm pretty sure SX is very unwilling to do.
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Offline Rocket Science

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Re: F9 Second Stage Reusability
« Reply #476 on: 06/05/2017 07:57 PM »
The article is based on a misinterpretation BUT we don't actually know the full extent of SpaceX's upper stage experiments. Could include some TPS.
That and perhaps a different entry and burn profile...
« Last Edit: 06/06/2017 02:32 PM by Rocket Science »
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Offline ChrisWilson68

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Re: F9 Second Stage Reusability
« Reply #477 on: 06/05/2017 08:47 PM »
If SpaceX uses a lot of carbon fiber in the upgraded 2nd stage, would it not lighten the stage enough to offset some of the 50% drop in payload capability?

Carbon fiber isn't a magic bullet.  There are lots of costs and risks associated with changing to carbon fiber, and the upper stage already has a pretty low mass fraction.  There's a limit to how much you could improve payload by switching the main part of the stage to carbon fiber.

Offline IRobot

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Re: F9 Second Stage Reusability
« Reply #478 on: 06/05/2017 09:21 PM »
That said they might shift to a CF upper stage if they mfg the big ITS LOX tank in house. Otherwise that would put an outside sub contractor in the critical path for all future upper stages. Something I'm pretty sure SX is very unwilling to do.
I'm pretty sure they will not make the CF in house. CF is hugely difficult to do properly, especially big parts, high quality. You need experience, lots of it! If they want to control the process, the only way to do it is to buy the CF parts manufacturer.
Otherwise they could spend years perfecting that skill and still come short. This is not the same as machining aluminium or 3D printing superdracos. CF and other composite manufacturing is still some kind of an art.

Offline spacenut

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Re: F9 Second Stage Reusability
« Reply #479 on: 06/05/2017 09:58 PM »
So, would they stretch the stage for more fuel for orbiting and landing, or widen the stage? 

It would be nice if they could make a metholox upper stage with an upper stage Raptor for FH and F9 to not only get reusability, but be able to land it. 

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