Since Musk explicitly said that they're trying to make f9 and FH redundant, I think if anything we can now categorically put this to bed. There will be no raptor US for any Falcon rocket. Their focus now is FH and dragon 2, then straight on to BFR/BFS
At the risk of a barrage of rotten fruit: How close to orbit could a Falcon Heavy throw a semi-boilerplate (some engines, at least the inner landing tanks, TPS, but otherwise empty of ECLSS and the like) BFS, likely with the core stage expended? It would enable an EDL test at higher velocities than BFS could achieve in SSTO mode, and with a simpler to produce BFS analog ('main' tanks don't need to hold propellants, TWR can potentially be below 1 allowing fewer engines to be fitted). BFS dry mass from IAC was 85t, but that's for the all-up crew transporter variant.
Quote from: edzieba on 04/04/2018 03:25 pmAt the risk of a barrage of rotten fruit: How close to orbit could a Falcon Heavy throw a semi-boilerplate (some engines, at least the inner landing tanks, TPS, but otherwise empty of ECLSS and the like) BFS, likely with the core stage expended? It would enable an EDL test at higher velocities than BFS could achieve in SSTO mode, and with a simpler to produce BFS analog ('main' tanks don't need to hold propellants, TWR can potentially be below 1 allowing fewer engines to be fitted). BFS dry mass from IAC was 85t, but that's for the all-up crew transporter variant.Putting a 9m ship on top of a 3.6m rocket body seems super problematic for a host of reasons completely independent of what lifting capability FH would have.
Quote from: cppetrie on 04/04/2018 03:32 pmQuote from: edzieba on 04/04/2018 03:25 pmAt the risk of a barrage of rotten fruit: How close to orbit could a Falcon Heavy throw a semi-boilerplate (some engines, at least the inner landing tanks, TPS, but otherwise empty of ECLSS and the like) BFS, likely with the core stage expended? It would enable an EDL test at higher velocities than BFS could achieve in SSTO mode, and with a simpler to produce BFS analog ('main' tanks don't need to hold propellants, TWR can potentially be below 1 allowing fewer engines to be fitted). BFS dry mass from IAC was 85t, but that's for the all-up crew transporter variant.Putting a 9m ship on top of a 3.6m rocket body seems super problematic for a host of reasons completely independent of what lifting capability FH would have.Given the already skinny fineness ratio of Falcon with a huge blob on top, Max Q (like it would ever get that far) would be Must See TV!
Having twice the mass of full Falcon 9 as a second stage also makes for an interesting first staging point somewhere very near the launchpad.
It'd need one heck of a payload adapter though!
Putting a BFS on top of a Falcon Heavy is a little too Kerbal. That said, strapping a couple Falcon Heavy boosters to the sides of the BFS would probably give it a pretty big payload boost over flying it in an SSTO configuration.
Since this is the Thread for Raptor Upper Stage:Could Raptor be used as Kickstage from BFS "Chomper Launcher" from L2 with a slingshot around Earth? Could it be filled with propellent from BFS before launching?
Quote from: Tomness on 08/14/2018 11:06 pmSince this is the Thread for Raptor Upper Stage:Could Raptor be used as Kickstage from BFS "Chomper Launcher" from L2 with a slingshot around Earth? Could it be filled with propellent from BFS before launching?It would require quite heavy redesign of BFS. Unless they design in the capability to fuel a third stage from the beginning. Which would be nice but I am not sure they bother.Edit: The third stage would reasonably be fueled in orbit when BFS gets refueled. No reason to fuel it on the ground. The propellant would only get unnecessarily warm while waiting for refueling in orbit.
>A RapVac-based BFS-refuelable orbital tug (launched in a chomper) makes a lot of sense. Something that can can be disposed of for multiple years (say, to Europa or Titan) without significantly affecting earth launch, or has better optimized VacTWR for Lunar (or Ceres, Calisto, or Mercury) surface shuttling, or can make multiple plane changes for intercepting space junk in earth orbit...
It would require quite heavy redesign of BFS. Unless they design in the capability to fuel a third stage from the beginning. Which would be nice but I am not sure they bother.Edit: The third stage would reasonably be fueled in orbit when BFS gets refueled. No reason to fuel it on the ground. The propellant would only get unnecessarily warm while waiting for refueling in orbit.
Quote from: rakaydos on 08/15/2018 06:55 am>A RapVac-based BFS-refuelable orbital tug (launched in a chomper) makes a lot of sense. Something that can can be disposed of for multiple years (say, to Europa or Titan) without significantly affecting earth launch, or has better optimized VacTWR for Lunar (or Ceres, Calisto, or Mercury) surface shuttling, or can make multiple plane changes for intercepting space junk in earth orbit...If you look closely at the Chomper graphic a case could be made it's there...
Quote from: docmordrid on 08/15/2018 08:24 amQuote from: rakaydos on 08/15/2018 06:55 am>A RapVac-based BFS-refuelable orbital tug (launched in a chomper) makes a lot of sense. Something that can can be disposed of for multiple years (say, to Europa or Titan) without significantly affecting earth launch, or has better optimized VacTWR for Lunar (or Ceres, Calisto, or Mercury) surface shuttling, or can make multiple plane changes for intercepting space junk in earth orbit...If you look closely at the Chomper graphic a case could be made it's there...Nozzle is WAY too small to be a Raptor. Compare it to the "can be used at sea level, but not advised" Raptorvacs of the Ship in those pics, and compare to that nozzle.If anything, a Raptor Tug should have an even larger nozzle, to elk out every last point of ISP from vacuum operations.
Hard to imagine any current known version of Raptor being on a tug. Once in orbit why use a large engine that weighs more. Use a smaller, lighter engine that you burn longer. May as well ask about going to LH2 instead of Methane as well, BFR is not going to be volume limited for almost any payload.