SRBs = Atlas V SRMs=F9 N/AET/Orbiter = Atlas V core= F9 coreSSME's = RD-180= 9 MerlinsOMS system = Centaur= F9 second stage
(Not an expert)SSME and M1D have huge fundamental differences- propellant being an obvious one, but also a completely different engine cycle. So the actual components are doing different jobs, a bit like the difference between a petrol and a diesel engine. SSME was also designed in the 70s, Merlin can draw on another three decades of development (perhaps not as big an advantage as it should be)I don't personally know what refurbishing each of these engines entails, but a few points to consider:1) where do you draw the line between refurb and inspection? You might not replace a component, but you might still want to whip it out and check e.g. tolerance on a bearing seal.2) There will be a trade between the hassle and cost if inspection/refurb, and the hassle and cost of engine failure. That scale will be weighted massively in favour of not losing the vehicle.3) There may also (and I'm starting to speculate a little here) be a trade between cost, performance, and service intervals. Is it worth building a no-refurb engine if it comes at the cost of performance loss? Would you buy a car that didn't need refuelled until the next service interval- of course not, that would mean driving around lugging 20,000 miles worth of fuel with you. Absurd example but I hope it illustrates the point.
What's a Merlin these days? About $2m apiece? Well worth the costs of recovery and refurb.
Returning to Shuttle for a moment - STS-1 was a narrow thing, with lots of learning for the launch system, orbiter, and recovery of vehicle. It was a laboratory experiment, where we learned more of "what not to do".Would not begrudge SX/BO on early reuse here. NS/F9 are the smallest reusable booster systems ever, and the margins are the smallest they'll ever be. Flight history here tells you much in the puzzle of "how you thought it would work" vs "how it works"."Waterfall" and "agile" play this quite differently from my direct observation. Typically waterfall is looking for adequate margins against design validation. Agile on the other hand has a bunch of stochastic guesses where they were under/over margin.What I like about the first is adherence to schedule/pressure (some may say "hide bound") . What I like about the second is that you get more exposure to pushing the bounds beyond the firsts implied "safe limits" (some may say "reckless").So those four months of reprocessing ... does it result in a vehicle that achieves rapid reuse (e.g. less than a week) ... or just three months of reprocessing? The former is likely economic, the latter is not. And why Shuttle taught us all to doubt economic reuse.That's how to "grade" effectiveness IMHO.
Quote from: vanoord on 03/13/2017 09:08 pmWhat's a Merlin these days? About $2m apiece? Well worth the costs of recovery and refurb.And since you seem to have insight into SpaceX's cost structure: how much of these 2mil are fixed costs (tooling, minimum staff,...) that you don't save on if you build one less?
Quote from: pippin on 03/14/2017 03:02 amQuote from: vanoord on 03/13/2017 09:08 pmWhat's a Merlin these days? About $2m apiece? Well worth the costs of recovery and refurb.And since you seem to have insight into SpaceX's cost structure: how much of these 2mil are fixed costs (tooling, minimum staff,...) that you don't save on if you build one less?No idea Given that the engines appear able to be re-used with minimal work - the JCSAT-14 core has (apparently) had 8 (?) full-duration firings since recovery - that *suggests* there is value in recovered engines?The proposed Vulcan recovery method also suggests that engines are the driving force behind recovery and re-use.From a personal - and yes, uninformed - point of view, I suspect we may see re-use of stages a lot fewer times than is currently being touted, e.g. two or three uses in Recovery mode, then a final flight in Expendable configuration. That means there's still going to be a need to build new engines; and the fixed costs will still keep being covered.
Quote from: vanoord on 03/14/2017 11:35 amQuote from: pippin on 03/14/2017 03:02 amQuote from: vanoord on 03/13/2017 09:08 pmWhat's a Merlin these days? About $2m apiece? Well worth the costs of recovery and refurb.And since you seem to have insight into SpaceX's cost structure: how much of these 2mil are fixed costs (tooling, minimum staff,...) that you don't save on if you build one less?No idea Given that the engines appear able to be re-used with minimal work - the JCSAT-14 core has (apparently) had 8 (?) full-duration firings since recovery - that *suggests* there is value in recovered engines?The proposed Vulcan recovery method also suggests that engines are the driving force behind recovery and re-use.From a personal - and yes, uninformed - point of view, I suspect we may see re-use of stages a lot fewer times than is currently being touted, e.g. two or three uses in Recovery mode, then a final flight in Expendable configuration. That means there's still going to be a need to build new engines; and the fixed costs will still keep being covered.Rocket = aluminium alloy tube with Things bolted on to it.Things = Engines, grid fins, hydraulics, legs, plus some electronics and connectors, some pipes 'n stuff.Really Expensive things subset = engines, legs.To me, the cost of the engines is the major component of the cost of the stage. Recovering them seems a no brainer, however you do it.
SRBs = Falcon 9 first stageET = Falcon 9 second stage tankSSME's = MVACOMS system (and orbiter) = Dragon.
... So those four months of reprocessing ...
Quote from: Space Ghost 1962 on 03/13/2017 07:31 pm... So those four months of reprocessing ...Where does this reference to four months of processing come from? Did SpaceX tell us how much time went into 'processing' and how long the stage was just sitting there?
Quote from: mn on 03/14/2017 01:54 pmQuote from: Space Ghost 1962 on 03/13/2017 07:31 pm... So those four months of reprocessing ...Where does this reference to four months of processing come from? Did SpaceX tell us how much time went into 'processing' and how long the stage was just sitting there?Peter B. de Selding of Space Intel Report:Shotwell: Took us 4 months to refurbish the stage that we'll refly at end of this month. Going forward, it'll be sub that.
Peter B. de Selding of Space Intel Report:Shotwell: Took us 4 months to refurbish the stage that we'll refly at end of this month. Going forward, it'll be sub that.https://twitter.com/pbdes/status/839598801375608832
That means there's still going to be a need to build new engines; and the fixed costs will still keep being covered.