Quote from: envy887 on 03/07/2017 04:28 pmAbout 340-345 seconds with a highly expanded nozzle extension. This is consistent with other pump-fed NTO-MMH vacuum engines that operate at similar chamber pressures (e.g. Aestus II).The SuperDraco is designed for short duration burns, but it is regeneratively cooled and designed for reuse so longer duration burns are probably feasible. The nozzle extension would probably need to be radiatively cooled.What nozzle diameter would be required? I'd like to put a rendering together for discussion purposes based off the known pressure vessel dimensions.Also, what happens to the ISP if the SD's are ran at a lower throttle setting to allow for adequate expansion with smaller nozzles? At 71kN max thrust per engine even 4 SD's would be more than enough rather than 8.
About 340-345 seconds with a highly expanded nozzle extension. This is consistent with other pump-fed NTO-MMH vacuum engines that operate at similar chamber pressures (e.g. Aestus II).The SuperDraco is designed for short duration burns, but it is regeneratively cooled and designed for reuse so longer duration burns are probably feasible. The nozzle extension would probably need to be radiatively cooled.
If you are running sets of engines on both sides anyway why not launch the lander on its side and make it more rectangular? The cabin (or capsule) is in the middle and everything is disbursed to the sides including the equipment that would normally be under it that is part of the trunk. Hatch would be closer to the ground also. You would have do something creative to take the some of the load off of the side of the lander during launch.Edit: Maybe even use two trunks for the side structures on each side.
53 tonnes maxed out tanker and lander.Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?
Quote from: lamontagne on 03/07/2017 11:50 pm53 tonnes maxed out tanker and lander.Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?SuperDraco is pressure-fed. Will those tanks hold 1000+ psi?
Quote from: lamontagne on 03/07/2017 11:50 pm53 tonnes maxed out tanker and lander.Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?Small note: you have 3 engines shown in all the TWR calcs.What material did you assume for the tanks? SuperDraco mass?
Quote from: lamontagne on 03/07/2017 11:50 pm53 tonnes maxed out tanker and lander.Just barely does all the required performances. But it makes for an awfully tall stack on the moon.I guess we could launch the whole thing inside a fairing as well, with the crew launches separately in a falcon 9?Yes - which is why a Crasher Stage has been mentioned a couple times, in part so as to not make the Lander too tall.
Perhaps a turbine fed equivalent for the engine?
Quote from: Negan on 03/07/2017 07:11 pmIf you are running sets of engines on both sides anyway why not launch the lander on its side and make it more rectangular? The cabin (or capsule) is in the middle and everything is disbursed to the sides including the equipment that would normally be under it that is part of the trunk. Hatch would be closer to the ground also. You would have do something creative to take the some of the load off of the side of the lander during launch.Edit: Maybe even use two trunks for the side structures on each side.Use an sheet metal cylinder sidewall similar to F9 stage tank construction with no cant. Use the additional volume to allow more lower tankage w/o affecting crew volume. Isolate lines externally with MLI.
Why are you launching 51 tonnes of hypergols? The Falcon upper stage is more efficient for TLI, and you don't need that much fuel after TLI.