Quote from: Dudely on 01/08/2015 04:10 pmAnd just to be a pedant, the residual fuel is listed as being 15 gal LOX and up to 150 gal RP-1. 15 gal of LOX is not very much.That really is a tiny amount. At full thrust a single Merlin 1D uses something like 200 kg/s of propellant.Perhaps they plan to vent the lox tank just before touchdown? idk, it doesn't make much sense to me.
And just to be a pedant, the residual fuel is listed as being 15 gal LOX and up to 150 gal RP-1. 15 gal of LOX is not very much.
Does the potential ability to "boost" the first stage for BFR from construction site to the launch facility come into play at all?
Quote from: sghill on 01/08/2015 05:25 pmI seem to recall you being vociferously in the "refurbishment-costs-may-make-reusability-unfeasible" camp when we were discussing all this last summer and now you're in the "it'll-be-ok" camp? The McGregor boosters never flew backwards at hypersonic speeds. We don't know what the returning stage is going to look like beyond the grainy video of that charred booster landing in the ocean the airplane took during the last landing.The point is that the booster may either need a complete tear down (and component replacements) requiring the abilities they have back at the CA factory- and I expect they will do this for the first few returns, or the booster may be good to go after an inspection, air in the tires, and fluid top-off, which allows them to use their existing HIF facilities, or get a new one (build or lease) for refurbishment in FL instead of CA. The EA for LC-13 indicates that SpaceX believes the latter is true- which is what Dudely pointed out in his post. I also pointed out that if the latter is indeed true, then we can also begin to put boundaries on questions about the economics of reusability because the refurbishment costs will likely be small.My point is McGregor would be the likely site for any tear down vs Hawthorne. They have replaced engines, attached engine structure to tanks before and fixed up stages from static fire. Also, component replacements can be done at the launch site, since this happens prelaunch when failures are found. If "teardown" doesn't include thrust structure or tank demates, any facility that can hold the stage on the access stands with roll rings can be used.
I seem to recall you being vociferously in the "refurbishment-costs-may-make-reusability-unfeasible" camp when we were discussing all this last summer and now you're in the "it'll-be-ok" camp? The McGregor boosters never flew backwards at hypersonic speeds. We don't know what the returning stage is going to look like beyond the grainy video of that charred booster landing in the ocean the airplane took during the last landing.The point is that the booster may either need a complete tear down (and component replacements) requiring the abilities they have back at the CA factory- and I expect they will do this for the first few returns, or the booster may be good to go after an inspection, air in the tires, and fluid top-off, which allows them to use their existing HIF facilities, or get a new one (build or lease) for refurbishment in FL instead of CA. The EA for LC-13 indicates that SpaceX believes the latter is true- which is what Dudely pointed out in his post. I also pointed out that if the latter is indeed true, then we can also begin to put boundaries on questions about the economics of reusability because the refurbishment costs will likely be small.
Quote from: Jim on 01/08/2015 05:37 pmQuote from: sghill on 01/08/2015 05:25 pmI seem to recall you being vociferously in the "refurbishment-costs-may-make-reusability-unfeasible" camp when we were discussing all this last summer and now you're in the "it'll-be-ok" camp? The McGregor boosters never flew backwards at hypersonic speeds. We don't know what the returning stage is going to look like beyond the grainy video of that charred booster landing in the ocean the airplane took during the last landing.The point is that the booster may either need a complete tear down (and component replacements) requiring the abilities they have back at the CA factory- and I expect they will do this for the first few returns, or the booster may be good to go after an inspection, air in the tires, and fluid top-off, which allows them to use their existing HIF facilities, or get a new one (build or lease) for refurbishment in FL instead of CA. The EA for LC-13 indicates that SpaceX believes the latter is true- which is what Dudely pointed out in his post. I also pointed out that if the latter is indeed true, then we can also begin to put boundaries on questions about the economics of reusability because the refurbishment costs will likely be small.My point is McGregor would be the likely site for any tear down vs Hawthorne. They have replaced engines, attached engine structure to tanks before and fixed up stages from static fire. Also, component replacements can be done at the launch site, since this happens prelaunch when failures are found. If "teardown" doesn't include thrust structure or tank demates, any facility that can hold the stage on the access stands with roll rings can be used.Fair enough statement, but we know now from the EA that SpaceX rejected KSC for landing sites in part because it was too far from a TBD refurbishment location. Normal post-flight refurbishment won't be happening in TX even if tear-downs and major work does occur there.It also gives some insight into Musk's "self-contained space center" comment recently....
While difficult to calculate, there may be a slight positive impact on traffic since the re-landed vehicle would be transported to a local SpaceX facility, rather than transporting a new Falcon first stage vehicle from Texas to CCAFS.(emphasis added)
http://www.patrick.af.mil/shared/media/document/AFD-141107-004.pdf
Quote from: pericynthion on 01/08/2015 06:50 pmQuote from: Dudely on 01/08/2015 04:10 pmAnd just to be a pedant, the residual fuel is listed as being 15 gal LOX and up to 150 gal RP-1. 15 gal of LOX is not very much.That really is a tiny amount. At full thrust a single Merlin 1D uses something like 200 kg/s of propellant.Perhaps they plan to vent the lox tank just before touchdown? idk, it doesn't make much sense to me.The number of residual propellant is very small, which gives some ideas:1. Why 10x less LOX than RP? IMHO they have long thin tube with LOX, but not with RP, so the precision of measuring remaining LOX may be much higher. Or there could be uncertainty in heat flux into LOX tank, so they load a bit more RP for the worst case LOX vaporization during flight, so there may be a bit of excess RP.2. They know terminal velocity very well and so how much fuel is required, as the steering is by grid fins it does not ue propellant, so they will just extend the atmosperic entrance burn (the one before landing burn) to expend excess propellant leaving just required amount plus uncertainty.
...Is it possible there's room within the LC39 area for a landing pad, nearer to shore?
If they couldn't find room for the HIB other than on the crawlway, there will also be no room for a landing pad.
Quote from: meekGee on 01/09/2015 04:18 pm...Is it possible there's room within the LC39 area for a landing pad, nearer to shore?If they couldn't find room for the HIB other than on the crawlway, there will also be no room for a landing pad.
Quote from: Zed_Noir on 01/09/2015 05:33 pmQuote from: meekGee on 01/09/2015 04:18 pm...Is it possible there's room within the LC39 area for a landing pad, nearer to shore?If they couldn't find room for the HIB other than on the crawlway, there will also be no room for a landing pad.?? The requirements for both structures are almost completely opposite.(Though I agree it's not very likely, I'm just trying to find out where the second core will land)
Quote from: meekGee on 01/09/2015 05:55 pmQuote from: Zed_Noir on 01/09/2015 05:33 pmQuote from: meekGee on 01/09/2015 04:18 pm...Is it possible there's room within the LC39 area for a landing pad, nearer to shore?If they couldn't find room for the HIB other than on the crawlway, there will also be no room for a landing pad.?? The requirements for both structures are almost completely opposite.(Though I agree it's not very likely, I'm just trying to find out where the second core will land)The ground surface area require for both structures seems similar.
Hey maybe this doubles as a landing pad for a *really* large rocket with asymmetric leg placement.Honestly, I'm stumped by the contingency pads.