Here is my latest Reusable Dragon Horizontal lander
Quote from: Rocket Science on 03/08/2017 03:13 PM Here is my latest Reusable Dragon Horizontal landerThat's a beautiful design! But what allows the MVac to restart successfully after a days-long cold soak during trans-lunar coast? Because ... kerolox doesn't do that?
Dragon2 Lander Concept:Nested in the original SuperDraco mounts are new Vac SuperDracos.
Dragon2 Lander Concept:Nested in the original SuperDraco mounts are new Vac SuperDracos. All pressure fed tanks have been removed, utilizing the primary propellant tanks with electric turbo pumps. Draco engine mounted arrangement is maintained in the conformal pods on the side of the pressure vessel. 4xSuper Draco Vacs, 345s ISP. Double engine SD packs modified to single engine & actuators added for gimballing at landing + vac nozzle. Dragon 2 Dry Mass: 6750 kg-chutes + heatshield: -780 kg+ turbo pump batteries: 164 kg+ electric turbo pumps: +40 kg*- D2 pressurized tanks: -100kg*- Helium tanks: -20kg*- nose cone, ascent thermal shield & misc weight savings: -351kg*+ carbon fiber prop tanks: +300kg**+ legs and ladder: +200kg*Total Lunar Lander Dry mass: 5800kg*Numbers marked as asterisk are guesses and need further research of confirmation, based off 10% prop mass of Dragon 2 for removed tanks.**Does anyone have any reference info on what I could expect Carbon fibre tanks to weigh?Total Required Prop Mass for 1000 kg payload: 14000 kgLLO to Lunar Surface: 8900 kg prop for 1.9 km/s dVLunar Surface to LLO: 5100 kg prop for 1.9 km/s dVAt launch a Falcon Heavy could launch into a GTO transfer the D2 Lunar Lander without payload and a full prop load of 15,500 kg for a combined mass of 21,100kg. Arriving in LLO the lander would have 7500kg prop remaining with the remaining 6500kg to be transferred in orbit by Orion stack or separate transfer vehicle.Tanks for a 15,500kg prop load are 1xN2O4 2m dia x 2.3m long & 4xMMH 0.87m dia x 2.3m longAn alternative to the cluster tanks would be a 2.1m dia and 3.7m long tank with common bulkheadNot shown in the model are solar panels & ladder (among many other small details).
1000 kg payload is included (meat bags + suits), transfered on orbit during docking.If operated as a 1 way lander launched by Falcon Heavy expendable cargo to surface would be 2100kg.With the superdraco thrust 3 engines is plenty but more losses due to gimballing would be incurred if one is lost.As for impingement of exhaust, I was under the impression that with a very high expansion ratio to achieve the desired isp that this wouldnt be an issue. The F9 pictured is of sea level optomized engines at altitude. I wil read up more on that. However the engines can be gimballed out to 10 degrees without cosine losses becoming too significant. The 0 degree cant is required to fit in a faring during launch.
The intent is that the dracos are in identical locations as D2 capsule
Quote from: GWH on 03/10/2017 01:43 PMThe intent is that the dracos are in identical locations as D2 capsule Each location is a pair of SDs, do the single nozzles service both engines?
OK. Please look at OP of this thread. The focus is very narrow. Lets keep to it.Yes it might enable more. Fine. But that isn't this thread. This thread is about doing something ... hard.It's a hard, disciplined thing to take a CC vehicle, which we don't know much about (highly granular specs), and turn it into a dedicated lunar lander, in a few years (and I mean it) that could be used by a planned EM 1/2 mission (perhaps other/later). You get something around a billion or so to do this with. That's the challenge.It does not need to be reusable. LM and LK certainly weren't. You get a bonus for a reusable lander or a plan leading to such. You can't burden dissimilar vehicles with co-integration, that's a no-no.Here's the simplest expendable system - a Dragon for up, a Dragon for down, outfitted/integrated differently. Both require props/and engine enhancement. Requires precision landing. Requires LLO/direct descent props/pallet/stage (please note that Falcon 9/H had an optional third stage as PAM-D). You can mission plan it if you like. You'll find you'll need about 2k/sec delta-v addition for contingencies, which you can get in a variety of ways.Like some of the additions this thread has come up with. Drop tanks - inside trunk, outside trunk, on capsule. Be careful you don't want to shade the PV panels. Or have plume impingement. The possibility of using electric pumps in place of pressurized tanks to a)lower tank mass, b) increase thrust/iSP, and c)reduce/reuse consumable pressurant. However, what would be the development time to make that as reliable as a pressurized escape system?I've let things go a bit wider on this thread so you can gain involvement and promote some. Don't go too far.The hard part here is coloring withing the outline. Think small and tight. Can this be done in a few years at all?If so, can it be done better? Can it lead to something ... where an aggressive follow-on program might develop its ambitions ...