Quote from: hkultala on 11/27/2017 06:05 pmQuote from: aero on 11/27/2017 03:54 pmQuestion. Speaking of customizing a tanker for on orbit and deep space missions, would this customized tanker need to carry the mass of all of the engines? That is, once on orbit, would any significant mission capability be added by removing, say, six of the raptors?No. The engines weight only few tonnes, but removing them would worsen gravity losses considerably.I believe this was an on orbit modification, and this vessel then would never return to a gravity well but instead stay in orbit. So gravity losses might not apply, although maybe I am confused?
Quote from: aero on 11/27/2017 03:54 pmQuestion. Speaking of customizing a tanker for on orbit and deep space missions, would this customized tanker need to carry the mass of all of the engines? That is, once on orbit, would any significant mission capability be added by removing, say, six of the raptors?No. The engines weight only few tonnes, but removing them would worsen gravity losses considerably.
Question. Speaking of customizing a tanker for on orbit and deep space missions, would this customized tanker need to carry the mass of all of the engines? That is, once on orbit, would any significant mission capability be added by removing, say, six of the raptors?
Quote from: Lar on 11/29/2017 02:49 amQuote from: hkultala on 11/27/2017 06:05 pmQuote from: aero on 11/27/2017 03:54 pmQuestion. Speaking of customizing a tanker for on orbit and deep space missions, would this customized tanker need to carry the mass of all of the engines? That is, once on orbit, would any significant mission capability be added by removing, say, six of the raptors?No. The engines weight only few tonnes, but removing them would worsen gravity losses considerably.I believe this was an on orbit modification, and this vessel then would never return to a gravity well but instead stay in orbit. So gravity losses might not apply, although maybe I am confused?If I’m following this, the variant I was talking about was a BFS built on earth with propellant tanks completely filling its volume rather than the large cargo space left over. It could launch only with those extended tanks partially filled. It might however have utility as a fuel depot/deep space Booster. My notion was this would be an otherwise standard BFS with bigger tanks. I took the question about removing engines to be asking could it launch successfully and operate as an in space Booster if you left some engines off considering it wouldn’t land on earth again. I’m not sure what’s meant by gravity losses unless that’s assuming all the engines would be removed? I guess “propellant depot” sort of suggests it might have no engines but that’s not compatible with using it as a Booster too. It’s really more about function than any modification to the BFS. Assigning a BFS to the specialized function of collecting propellant from the Tanker flights so it can load it in one go to a mission. The same BFS could also dock nose to tail with a mission BFS and act as a Booster. A BFS that happened to be modified so it’s entire OML was occupied by propellant tanks would work better in this function. Unlike a Tanker it would remain in space rather than landing and repeatedly launching. Maybe it could get along without some of the ordinary BFS hardware.