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Skylon

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Falcon startup.

Liftoff.

Lots of clouds west of the cape, but clear out over the ocean.

Stage 2 is good. Fairing jettison,

Booster entry burn start…

Entry burn shutdown.

SECO.

Booster landed successfully.

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Great first article in a series of 2 about Falcon 9 refurb process (free with registration). Seriously, read it.

https://aviationweek.com/defense-space/space/spacex-building-airline-type-flight-ops-launch

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We got to 10 [flights] and the vehicles were still looking really good, so we started the effort to qualify for 15,” Jon Edwards, SpaceX vice president of Falcon launch vehicles and Falcon engineering, told Aviation Week during a series of interviews with top company managers.

 

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“We’re not going into a 12th or 13th flight crossing our fingers,” she adds. “We have confidence based on all the testing we’ve done on every piece of hardware that it’s going to survive.”

 

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SpaceX has three classes of inspections: A class is performed for every mission; B class involves periodic maintenance, which is now performed every sixth or seventh flight; and C class, the most thorough maintenance process, is used for the fleet life-leaders and for all crewed missions.

 

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“If there is something we don’t fully understand, we will test it off-line to understand the risk, fly it on a Starlink flight to gain real test data and then apply that learning to our other customers,” Gerstenmaier says. “Pushing the envelope from a performance standpoint actually makes us more reliable for crew and other missions because we’ve been able to kind of experiment with our hardware a little bit.”

52099933760_2198dfb3cf_b.jpg

 

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14 minutes ago, JoeSchmuckatelli said:

The fact that humans can fly and land something the size of a building will never cease to amaze me 

Never gets old. Will be astounding to see SS/SH do that.

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Ok, dumb question:  Is it worth it to push the engines that far, rather than just slapping a few more engines on?  Musk is talking about an 8% increase in thrust from each engine, which is nothing to sniff at.  But a few extra tons of engine mass on a launch vehicle weighing thousands of tons makes me wonder if it wouldn't be more prudent to baby the engines in order to improve reliability.

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If you read the article above SpaceX has the habbit of actually changing flight parameters constantly to find the optimal ones.  Having engines max thrust increase certainly gives them more room to experiment with. Although quite likely it doesn't mean they will use the maximum thrust or duration of maximum thrust might be more limited than for falcon 9. Actually starship has already a pretty decent TWR, so efficency gains from using more thrust will propably be weighted against wear and tear.

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5 minutes ago, zolotiyeruki said:

Ok, dumb question:  Is it worth it to push the engines that far, rather than just slapping a few more engines on?  Musk is talking about an 8% increase in thrust from each engine, which is nothing to sniff at.  But a few extra tons of engine mass on a launch vehicle weighing thousands of tons makes me wonder if it wouldn't be more prudent to baby the engines in order to improve reliability.

Well, maybe, but he's also previously talked about how TWR is everything for a reusable launcher - especially a huge one like Starship. It seems to make sense why - if your TWR is lower, you're using more propellant to do the same amount of work accelerating up until stage separation, which cuts into landing reserves, so you have to carry more. And of course, the longer period of slower acceleration means that stage sep happens later, meaning you're further downrange and need even more propellant to boostback for landing.

I haven't done the maths to figure out how much of an effect it would actually have, but I imagine they're working pretty hard to optimise the booster's mass. If they can figure out how to get more thrust from a single engine, that's (almost) 'free' from a mass perspective - as opposed to just adding more engines, which probably adds up pretty fast (the booster is pretty tail-heavy when empty, because the engines are some of the most massive single components).

'Slapping a few more engines on' might end up being more difficult than it sounds as well, because they've almost run out of space on the bottom of the booster as it is already. So to get the equivalent thrust of 33x 250t-thrust Raptors by adding more 230t-thrust engines, you'd probably end up having to rearrange the engine configuration, or possibly even flare the base of the booster a little. That opens the door to all kinds of extra structural and aerodynamic considerations which might be more trouble than they're worth.

So for now at least, just increasing per-engine thrust is probably the way to go. It's worth noting that Merlin is one of the highest-performing modern rocket engines, while also being one of the most reliable. There are lessons there that can be (and probably already are) applied to Raptor development. Reliability improvements will go hand in hand with performance improvements as they continue to develop and test the engine.

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