So assume got this Vulcan ACES as Horizontal Lander and want to ship 800 tons of LOX from lunar surface to L-2.How much rocket fuel in addition to the 800 tons of LOX being shipped is needed at lunar surface, assuming Vulcan ACES as Horizontal Lander starts at lunar surface and is empty?And in comparison how much rocket fuel is required if instead one ship 800 metric tons of LOX to Low lunar orbit?I tend to think shipping rocket fuel to Low lunar orbit is better. One reason is one could use SEP or chemical/SEP as tug between LLO and L-2. And another reason [or if just using chemical rockets rather than involving SEP] then one does not need lunar landing capability as part of mass of the tug which goes from low lunar orbit to L-2.
The answer to how much prop at Lunar surface is needed is full tank of 150mt of prop for delivery of 118mt of cargo/lox/water/etc which also is enough prop to be able to return the vehicle empty back to Lunar surface requiring no refueling at L2. So If you want 800mt of something delivered from Lunar surface to L2 say, it would take 7/8 trips.Number of trips brings up total burn duration capability for the engines. A round trip involves about 500 seconds of burn time. So 10 round trips may be the max number of trips per engine before major overhaul/replacement. It is a matter of how robust are the engines used.
The answer to how much prop at Lunar surface is needed is full tank of 150mt of prop for delivery of 118mt of cargo/lox/water/etc which also is enough prop to be able to return the vehicle empty back to Lunar surface requiring no refueling at L2. So If you want 800mt of something delivered from Lunar surface to L2 say, it would take 7/8 trips.
Quote from: oldAtlas_Eguy on 11/10/2015 04:19 amThe answer to how much prop at Lunar surface is needed is full tank of 150mt of prop for delivery of 118mt of cargo/lox/water/etc which also is enough prop to be able to return the vehicle empty back to Lunar surface requiring no refueling at L2. So If you want 800mt of something delivered from Lunar surface to L2 say, it would take 7/8 trips.Shouldn't there be three numbers here?A = mass of propellant expended for ACES to deliver its cargo from the lunar surface to EML2B = mass of cargo delivered to EML2C = mass of propellant expended for ACES with no cargo to return from EML2 to the lunar surface
Why waste precious fuel you just dragged up the gravity well from the Earth of the Moon instead of taking advantage of that?
Propulsive braking into LEO is such a silly waste compared to aerocapture/braking. Especially if something like Magnetoshell Aerocapture works out. Earth has this wonderful atmosphere that can be used as free reaction mass for slowing down. Why waste precious fuel you just dragged up the gravity well from the Earth of the Moon instead of taking advantage of that?~Jon
Propulsive return to LEO is expensive on fuel but that is a know cost and is likely to get cheaper with RLV. Of the 12km/s round trip from LEO- moon- LEO, 9km/s has to be done with propulsion. Only the last 3km/s would benefit from an expensive and heavy BLEO capsule.Any reusable lander operating from EML1 would need to be able support a crew in deep space environment so it is more than capable of keeping crew safe for LEO-EML1-LEO trip. A reduced weight OTV version could be used for LEO-EML1 section. For commercial/tourism operations the development costs of this capsule would easily cover the EML1 - LEO fuel costs of quite a few missions. A 7t OTV would require 9t fuel for EML1-LEO trip. Using Vulcan only for fuel launches this should be <$150m, RLV fuel tankers should bring this well under $100m.