- D2 + trunk + MUS take off from moon on a direct flight to Earth.
Quote from: MikeAtkinson on 02/20/2017 09:49 pm- D2 + trunk + MUS take off from moon on a direct flight to Earth.Taking the TEI propellant from LLO all the way to the Lunar surface and back to LLO is a huge penalty since it requires 4 km/s of delta-V. Better to leave the TEI propellant in your tanker and have the D2+trunk+MUS dock with the tanker after liftoff from the Lunar surface.
1. Fuel rich ...
Why place all the dV requirements for ascent/descent on the lander, and in doing so drive up the requirements on the lander significantly when an upper stage can do the work here?
A Xeus-Centaur is at least partly off the shelf, IVF is scheduled to be demo'd in 2018. Investment in that area would have a much greater return IMO then trying to make a capsule perform a 2-way trip. Also meets criteria of a future, reusable lander.
The canted engines on Dragon 2 might not be so disadvantageous if they are providing the final landing control of the stack. Trunk mounted engines for the caspule/return would still be required.
- Instead heavily modify the 2nd stage (still using Merlin 1D vac)--- Add landing legs--- Add refueling capability--- Add long duration capability ----- keep the LOX cold----- keep the kero warm----- power from the trunk
- Tanker version of second stage- Tanker 1 launched into LEO on FH- Tanker 2 launched into LEO on FH, refueled by tanker 1.- Tanker 2 does TLI and inserts into LLO (uses modified trunk for power).- Tanker 3 launched into LEO on FH.- Tanker 4 launches into LEO on FH, refueled by tanker 3
- D2 + trunk + modified upper stage (MUS) launches into LEO on FH, refueled by Tanker 4.- D2 + trunk + MUS does TLI and inserts into LLO- D2 + trunk + MUS refueled from tanker 2- D2 + trunk + MUS land on moon- D2 + trunk + MUS take off from moon on a direct flight to Earth.
- D2 + trunk separate from MUS- D2 and trunk separate shortly before landing. - modified versions of this can place heavy cargo payloads on the lunar surface.- modified versions of this can use other launchers for the tankers.- modified versions of this can use other means to get fuel into LEO.- future version could produce LOX on the lunar surface.
- the tankers could be launched by SLS, in which case we have 1 launched to LEO to refuel the D2 stack there and/or another launched to LLO for the second refueling (I don't see how this could be cost effective).- Alternatively, the D2 + trunk + MUS could be launched by SLS to LLO (MUS does insertion burn) and then refueled from a tanker launched on a second SLS (again I don't see how this could be cost effective).
- This develops refueling capability, could use a shakedown mission in Earth orbit and/or lunar flyby, not much point in sending the stack to ISS (and probably would not be allowed anyway). Crew stays with D2 the entire time, and can use D2 abort capability at launch and retropropulsion landing.
This would I think have a low development cost (well under $2B) and per mission costs in the order of $700M. Using SLS would increase per mission costs to at least $1500M
Unfortunately, it does not quite meet the brief. Fuel rich architectures really hurt SLS because it costs so much to launch. To make this architecture work a high flight rate for FH would be required, and ideally from 2 launch sites, IF SpaceX could demonstrate 2 week turnarounds and use 2 launch pads. A design like this would place the D2 a long way above the ground, not exactly easy for egress.
Perhaps the Trunk could have a ‘Propulsion Pallet mounted within it – 2x fuel, 2x oxidizer and 2x helium pressurization tanks; supplying a cluster of Draco thrusters (6 or 8?) mounted in the center of the Pallet, or 1x Super Draco, throttled down and with or without a nozzle extension.
Would it need about 2km/s delta v to insert into Lunar orbit and leave on an Earth transfer orbit X days later, or a bit more?The Dragon meets the LM Dragon waiting in lunar orbit, the crew transfers and then it’s time for P.D.I. (Powered Descent Initiation).
My concern is that SX/Boeing are not up to the task of appropriate lunar lander propulsion here. Convince me otherwise please.
Quote from: Space Ghost 1962 on 02/21/2017 03:12 pmMy concern is that SX/Boeing are not up to the task of appropriate lunar lander propulsion here. Convince me otherwise please.How about using spare Aerojet OMS leftover from the Shuttle program? SX/Boeing could incorporate it in their designs.
Outside of the AJ10 and derivatives, there is a need for qualified hypergolic engines for both concepts.My concern is that SX/Boeing are not up to the task of appropriate lunar lander propulsion here. Convince me otherwise please.
AeroJet Rocketdyne is more of a caretaker of older technology at the moment. (RS-68 being their last real development, 15 years ago)
Quote from: Lars-J on 02/21/2017 11:33 pmAeroJet Rocketdyne is more of a caretaker of older technology at the moment. (RS-68 being their last real development, 15 years ago)What about J-2X? They have also been given the contract to develop RS-25E and are developing the AR-1.
J-2X didn't go so well, did it? Over budget/schedule, underperforming, and shelved.
Quote from: Lars-J on 02/22/2017 03:41 pmJ-2X didn't go so well, did it? Over budget/schedule, underperforming, and shelved.Please provide a reference showing that J-2X was over budget/schedule and underperforming. That was not my impression.
Playing around with Dragon2 and Falcon Heavy Capabilities some more, and looking at cargo or empty lander came up with the following:Dragon 2 with same 5570kg dry mass and 1815 kg prop:Fully expendable FH 54,400 kg to LEO (partial kerelox prop mass, delta II stage + Dragon 2)FH US partial burn to LLO 3.47 km/s dVDelta II US remainder 1600 kg burn to LLO 0.57 km/s dV (4.04 dV total)Delta II crasher stage 1.33 km/s dVDragon II lander (1750kg prop burn) 0.54 km/s dV (1.87 dV total)Landed Lunar payload: 1000 kgSame scenario as above but taking the Delta II US based crasher lander to all the way to the surface to be refueled, saving some Dragon 2 prop for initial ascent, landed lunar payload: 300 kgIn this scenario availability of more efficient but non man-rated cargo landers could deliver the necessary 6000kg of prop for a man-rated Dragon2 + ascent vehicle to return to Lunar orbit. A overall cost reduction could be seen here as a lunar base evolves.Another option instead of using the AJ-10 (ISP=319s) is the Aestus upper stage engine, a pressure fed N2O4/MMH engine used in the Ariane 5G upper stage with an ISP of 324s. The big advantage here being common prop to the Dragon 2 lander to support refueling in a reusable lander. The turbo pump fed but not yet in operation Aestus II could further enhance capabilities of the system with an ISP of 340s.
So in this scenario the multistage lander is still pieced together in LLO? Seems a bit of a stretch to what has been done to date.
And no, you don't integrate anything off Earth. You dock with Orion, do the mission to the surface and back, and discard.
Quote from: Space Ghost 1962 on 02/25/2017 11:37 pmAnd no, you don't integrate anything off Earth. You dock with Orion, do the mission to the surface and back, and discard.What launch vehicles would be allowed? Just commercial or a second SLS?Without docking to a crasher stage in orbit, or some in space prop transfer, or high ISP cryogen propulsion I just don't see how a Dragon 2 (nevermind the heavier Starliner) could possibly work.The Apollo Lunar Module was 15200kg total mass in Lunar orbit. The ascent vehicle was 2150 kg dry. That is about what a single FH can place in lunar orbit, meaning a crew dragon would need to lose 2/3 its mass operating as a 2 stage Lander/Ascent vehicle to fit those constraints
The price of a "crasher stage" is to eliminate reuse as a possibility, for the benefit of accelerating a development program. As both LEM/LM and LK-1 (derived from Soyuz and using a crasher descent stage) attest to.
Quote from: Space Ghost 1962 on 02/26/2017 07:18 pmThe price of a "crasher stage" is to eliminate reuse as a possibility, for the benefit of accelerating a development program. As both LEM/LM and LK-1 (derived from Soyuz and using a crasher descent stage) attest to.Not necessarily. The crasher stage in the scenarios I listed is only to provide for a two way trip, and could be eliminated by refueling the stacked Dragon capsule and ascent stage in LLO and lunar surface.
So reuse could be phased in as more capable vehicles get developed, but the concept listed gets the ball rolling on manned landers with minimal development cost. -Start with a single Dragon 2 and crasher trunk integrated stage to land a cargo/surface "lab" type of mission.
-Initial manned missions use a LLO docked crasher descent stage to land a Dragon 2 & trunk integrated ascent stage this doesn't need to separate.
- Follow up missions can refuel the D2 & ascent stage, along with a new crasher stage.
Shouldn't landers/ascent vehicles be minimal for safety and cost? Like the size of the Soyuz descent module, maybe with more seats. A pre-landed uncrewed habitat (never to be launched from the Moon) within walking range could support them while on the surface. And another habitat in Lunar orbit for the transfers.For sustainable presence on the Moon one should not launch more stuff than necessary from it, but accumulate landed useful mass there.
Pressure fed.
Quote from: GWH on 02/28/2017 07:08 pmPressure fed. How does that work in zero-g? What keeps the liquid between the orifice and the pressure boundary?Is the propellant in a bladder?
This would be a reusable lander: The lander consists of a stripped-down version of Dragon's pressure hull permanently mounted into a structural frame at the bottom. Set the lower part of the cabin into a frame that contains 2 banks of hypergolic propellant tanks (upper and lower banks) and lander legs. The lower bank of tanks provide propellant to Dragon's SDs for the descent and are dropped onto the lunar surface before ascent. The upper bank of tanks provide propellant to Dragon's SDs for the ascent burn and are dropped off in LLO after reaching it. Crew transfers back to Orion and goes home. Returning Orion for next mission brings fresh (full) tanks that are mated to the lander frame that was left in the stable LLO. Crew descends to lunar surface in this reusable lander and executes next mission. Will have to decide how many missions the lander is good for before it needs to be replaced.Everything happens in a vacuum so we don't need clean lines. This will be ugly as hell but should work beautifully.There would be no separate ascent or descent stage. Dragon IS the lander with a structural frame to contain and connect propellant tanks to her SDs. The frame is permanent. Only the emptied tanks are discarded. There would be no propellant "transfer" as brand new completely full tanks, brought along by the returning Orion would simply be connected to the plumbing.
Threw this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.
Quote from: clongton on 02/28/2017 08:34 pmThrew this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.I always like reusable! You are going to need to replace the drop tanks after ever mission then?
Quote from: Rocket Science on 02/28/2017 08:36 pmQuote from: clongton on 02/28/2017 08:34 pmThrew this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.I always like reusable! You are going to need to replace the drop tanks after ever mission then?Yes. Every arriving Orion crew would bring new (full) tanks that they would connect to the lander, plus whatever else they needed for the surface mission. No messy propellant transfer. Just connect the tanks and go.
Quote from: clongton on 02/28/2017 08:47 pmQuote from: Rocket Science on 02/28/2017 08:36 pmQuote from: clongton on 02/28/2017 08:34 pmThrew this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.I always like reusable! You are going to need to replace the drop tanks after ever mission then?Yes. Every arriving Orion crew would bring new (full) tanks that they would connect to the lander, plus whatever else they needed for the surface mission. No messy propellant transfer. Just connect the tanks and go.Perhaps toroidal tanks could be mated without having to go EVA...
Quote from: Rocket Science on 02/28/2017 08:51 pmQuote from: clongton on 02/28/2017 08:47 pmQuote from: Rocket Science on 02/28/2017 08:36 pmQuote from: clongton on 02/28/2017 08:34 pmThrew this sketch together a couple of minutes ago to show what I mean.It's really, really rough but I hope you get the idea.FH should be able to drop this into LLO as long as it doesn't carry any propellant tanks with it.Just the dry mass lander.I always like reusable! You are going to need to replace the drop tanks after ever mission then?Yes. Every arriving Orion crew would bring new (full) tanks that they would connect to the lander, plus whatever else they needed for the surface mission. No messy propellant transfer. Just connect the tanks and go.Perhaps toroidal tanks could be mated without having to go EVA...That works, but not 360 degrees all around. Hemispherical; 1/2 each of the required hypergol. One pair for the upper bank and 1 pair for the lower bank. Remember there's nothing in the middle. We can completely fill the space under the lander.On second thought go all around with a single tank with a common bulkhead separating the 2 propellants. One for the upper load and one for the lower load.
Dragon seats could be on a semi-circular track for take-off and landing and the display on a pivot if one wishes eyeballs out the window...
Quote from: Rocket Science on 02/28/2017 09:24 pmDragon seats could be on a semi-circular track for take-off and landing and the display on a pivot if one wishes eyeballs out the window...Apollo LM didn't have seats at all. The astronauts stood up. If mass is an issue they could do the same. Interior would not resemble the crew dragon very much. Very different mission profile, very different ergonomics.
I may be pushing the boundaries of Dragon or Starliner-derived lander here - so, SpaceGhost, if you feel I have, let me know and I'll delete my post.
Operating premise; keep costs down, including R&D. Use existing tech (Dragon2, in this case) as much as possible. That means, in part, keep it as simple as possible. It also means avoiding unneeded mass. It would require lunar orbit rendezvous like Apollo.
First, Dragon 2 needs a propulsion service module to enter and leave lunar orbit. (please bear with me here, as this is directly relevant to the lander design).
Essentially, a cylinder, slightly smaller in diameter than the F9 (to fit within the Dragon trunk), containing Superdracos (2, for redundancy) and fuel. Theoretically, you should be able to make this with about the same mass ratio as the upper stage. It'll be a short cylinder, mounted behind the trunk, size dictated by needed delta/v and thus tankage capacity.
Needed Delta/v is entering low lunar orbit and departing. So, what length and mass? To the rocket equation! A Dragon 2, plus trunk, plus crew, etc, reportedly (?) wet masses about 7385 kg. (In this scenario, the Dragon2 plays the role of the Apollo CSM stack).
The math. It takes about 680 m/s to enter low lunar orbit. About the same for the TEI burn. So, 1360MS.
Round up for margins, 1500 m/s. ISP of a SuperDraco is about 240 at sea level. But, the fuel is MMH/NTO, which has a theoretical max of 336, so a superdraco with a vacuum expander bell (with electric actuators for steering) should do a lot better than 240. I'll ballpark it at 275, which I think is conservative.
The dry mass of this upper stage should be, using a mass fraction of the S2 (again, I'm being conservative - this service module is just tankage and superdracos, and does not need to support Dragon and Trunk launch loads the way S2 does).
Annnnd, ack, I can't find a mass figure, even a ballpark, for a superdraco. So, I'm going to totally ballpark it and take a SWAG, so basically my proposed service module for inside the trunk is a scaled down Stage 2 in mass fraction. S2 Dry mass (?) is 3900 kg. I'll scale that down, as the service module is a lot smaller, with fewer structural demands.
Dragon2 plus internal SD fuel, etc, has reported mass of 7385kg. I'll add 1000kg for crew plus non-life-support consumables, putting it as 8385kg. That, plus dry service module (I've rounded that up to 1000kg - a very poor mass ratio compared to either F9 stages), 9385kg. So, per the rocket equation, we have a fuel mass for the service module (to get 1500 m/s delta/v) of 7000kg. That's about 1555 gallons. Even assuming the same density as water, it should therefor fit in a cylindrical unit within the trunk.
So, the service module is a cylinder, 1000kg dry mass (It's far smaller than Stage 2, and I'm taking a wild guess as to SuperDraco mass), using 2 Dragon Superdraco engines. Here's where it finally gets relevant to this thread; It's also a baseline lander, derived in part from Dragon 2 components.
It'll need a few mods; add legs plus draco thrusters and Dragon avionics.
Without cargo, by itself, it has a delta/v of 5.5 kps, more than enough to land on the moon and take off again (you need 4.4 kps for that.)
It can carry 600kg of payload and still do the job (low lunar orbit, land, and come back). Crew accommodations would consist of lightweight aluminum tube Apollo style couches atop the cylinder (They're in space suits - no need for walls, life support, etc.).
That same lander type, in one-way cargo mode, could land 2500 kg of cargo on the moon - for example a BEAM type module (With a dragon-based life support) for a short term hab, and other supplies. If added capacity is needed on the crew and cargo versions, it could be attained by stretching the tanks;
it could land and take off with one superdraco even with an additional couple of tons of fuel, due to the low lunar G. (The stretched version could thus include a stowed expandable hab on the crew lander).
A mission might look like this; a FH launches with a lander plus cargo and a crew lander, either stacked or side by side in a shroud.
These go to low lunar orbit.
A third launch is a fuel depot - not technically hard, as the fuel is storeable hypergolic.
4th launch, crew Dragon plus service module.
Rendezvous in lunar orbit. Crew handles docking plus topping up the two stages.
Cargo lander lands the cargo - if successful, a crew descends on the crew lander, stays a few days, then ascends to rejoin Dragon for a return to Earth.
Crew lander remains in low lunar orbit, to be refueled from the depot for the next mission. This architecture is flexible; could be used to set up a base, or have a standby emergency ascent vehicle.
Is this a bit far fetched, and relying on a lot of assumptions and guesses? Yup.
I tried to be conservative, but I'm sure I missed some big things. I tried to keep it as cheap as possible, to make it viable for tourism. As part of this, I tried to keep it efficient (such as just couches on the lander, no structure or shell, and no staging, plus possibly reusable.)
A few huge technical challenges/issues; Can a FH push 16385kg (Dragon plus service module) through TLI? If they can, as claimed, throw 10 tons at mars, maybe, but my guess is probably not. If they do stretch the second stage, then I'd feel better about it being plausible.
Another hard point is Lunar orbital rendezvous; hard to do. Can't use the GPS based system they use for ISS; GPS won't work in lunar orbit.
The DragonEye laser docking system would - but navigation to close proximity will probably require either crew or a lot of work on the automated navigation system. Further problem, the fuel depot; storable fuel has been transferred in orbit before (such as to ISS) but I have no idea how hard it would be to accomplish for this.
I'm sure there are major flaws I didn't see - and I'd appreciate criticism and correction.
I'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.
Quote from: MATTBLAK on 02/28/2017 10:30 pmI'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.I like these when multiple EVA's are planned or sustained surface ops. Might be different if you are looking at the requirements for a minimum basic lander...
Quote from: Rocket Science on 02/28/2017 11:45 pmQuote from: MATTBLAK on 02/28/2017 10:30 pmI'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.I like these when multiple EVA's are planned or sustained surface ops. Might be different if you are looking at the requirements for a minimum basic lander...But if it's a reusable lander what's the effectual difference? Even if it is only 2 EVAs per mission if the Lander is used 10 times then that's 20 EVA's. Better to keep the interior clean for the next mission, plus negates the need to vent the cabin, which requires replenishment supplies.
Quote from: clongton on 03/01/2017 12:07 amQuote from: Rocket Science on 02/28/2017 11:45 pmQuote from: MATTBLAK on 02/28/2017 10:30 pmI'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.I like these when multiple EVA's are planned or sustained surface ops. Might be different if you are looking at the requirements for a minimum basic lander...But if it's a reusable lander what's the effectual difference? Even if it is only 2 EVAs per mission if the Lander is used 10 times then that's 20 EVA's. Better to keep the interior clean for the next mission, plus negates the need to vent the cabin, which requires replenishment supplies.Agreed for a reusable lander. I just didn't see the value of the additional complexity on a single use short stay along the lines of a Golden Spike proposal...
Quote from: Rocket Science on 03/01/2017 12:16 amQuote from: clongton on 03/01/2017 12:07 amQuote from: Rocket Science on 02/28/2017 11:45 pmQuote from: MATTBLAK on 02/28/2017 10:30 pmI'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.I like these when multiple EVA's are planned or sustained surface ops. Might be different if you are looking at the requirements for a minimum basic lander...But if it's a reusable lander what's the effectual difference? Even if it is only 2 EVAs per mission if the Lander is used 10 times then that's 20 EVA's. Better to keep the interior clean for the next mission, plus negates the need to vent the cabin, which requires replenishment supplies.Agreed for a reusable lander. I just didn't see the value of the additional complexity on a single use short stay along the lines of a Golden Spike proposal... Ghost said extra points for a reusable lander so why not go for that?
Quote from: MATTBLAK on 02/28/2017 10:30 pmI'd like to see how the Dragon 2 hatch could be adapted to work with a porch/ladder for EVA egress. And would it be a good idea to have the suits able to join with the hatch or hull as external 'suit locks' after the first EVA? I've become a bit of a fan of suit locks - keeps the dust out of the Lander interior, which was always strongly advocated by John Young and Gene Cernan in particular.Because you are flying under a fairing, these are quite possible (you'll at least need a minimal cover to reduce exposure in transit). Also, one of the troubles with Dragon as a lander is that the side hatch is insufficient in size for suited access. This would deal with that.
Are the Super Dracos on the Dragon pressure or pump fed?
How does that work in zero-g? What keeps the liquid between the orifice and the pressure boundary?Is the propellant in a bladder?
Dragon V2 has a NASA Docking System port on its roof. This allows the transferase of power and air. Can the water, fuel and LOX tanks be connected to the port? This would allow either refueling or the attachment of drop tanks.
I may have come up with a solution using the Dragon V2 as a lunar lander. Which avoids new technology developments, refuelling, drop tanks and other low TRL items.Launch dragon (wet 7400kg) on FH with a trunk pallet consisting of 19,600 kg of hypergolic fuel, a properly expanded engine, tank, trunk mounting and stubby legs - I estimated 1000kg for hardware.The dragon would get to LEO + 1670 m/s, now that abort capability is no longer needed - separate from the second stage then burn the superdraco's to bring the dragon mass down to 5000kg and add a small amount more of delta V.Launch a second FH with a payload of just an IDA (500kg) - no fairing or minimal nosecone. Rendezvous with the dragon and dock. At this point dragon is facing the second stage (rather than being mounted in the way it launched).If docking fails then dragon can drop the trunk pallet and return home.If docking succeeds then at this point the new second stage should still have 20,350kg of fuel, sufficient to push the lightened dragon (with its trunk fuel and engine) into TLI (3150 m/s above LEO).Separate from the second second stage once translunar and the dragon has enough fuel for LOI, to meet the Orion etc then to land on the lunar surface. Later it can launch back to LLO then the dragon can TEI for a parachute landing (total 4560 m/s).It appears to meet the requirements of the OP at the cost of two FH launches and requires no new technology. The dragon is returned to earth each mission, so learning and development can take placeIve based all this on the figures I've been able to find for delta V budgets, weights and capacities etc - I'm happy to share the numbers.
I think to fully close the mass budgets here you need a 3rd FH launch, which launches a crew Dragon with a similar trunk pallet (with less fuel) and vac engine directly to TLI. The crew rides the crew Dragon to LLO, then transfers to the lander Dragon for the the ride to the surface and back to LLO. This eliminates the need for the lander Dragon to have SuperDracos or parachutes or a heatshield, saving ~1000 kg, and it can be discarded on return to LLO.
Which engine are you proposing? SuperDraco fully expanded would get 340 - 345 sec I_sp at 90 kN, but will not hit your mass budget since it needs heavy tanks that can be pressurized to 1000 psi. You probably need a pump-fed engine like Aestus 2/RS-72, which gets 340 sec I_sp at 60 kN.
Quote from: CJ on 02/28/2017 06:30 amI may be pushing the boundaries of Dragon or Starliner-derived lander here - so, SpaceGhost, if you feel I have, let me know and I'll delete my post. It's a fine post. On topic and relevant. I'll attempt to give you feedback.
QuoteOperating premise; keep costs down, including R&D. Use existing tech (Dragon2, in this case) as much as possible. That means, in part, keep it as simple as possible. It also means avoiding unneeded mass. It would require lunar orbit rendezvous like Apollo. Correct. And the existing tech also includes associated mission systems. Since docking is standardized, other vehicles that may be used like Orion have systems as well, but outside of such standardized interfaces, you don't "mix and match". You do LOR because of the limitations of the combined systems. Each has a means to arrive on LLO. Adding complexity to share the ride slows things down. And you can use the excess performance margin for extended capabilities later. But it introduces risk, contingencies, and variables. Likely you want the CC derived lander on LLO ahead of crew launch, and thus it must last significantly longer.
Wouldn't call it a SM. Dragon has an integral SM.Would call it a jettison-able propulsion assist pallet (JPAP). Use the Dragon's trunk/radiator/other systems to keep PMF low, might construct CF tanks with integral thrust structure and membranes to get below F9US PMF.
QuoteEssentially, a cylinder, slightly smaller in diameter than the F9 (to fit within the Dragon trunk), containing Superdracos (2, for redundancy) and fuel. Theoretically, you should be able to make this with about the same mass ratio as the upper stage. It'll be a short cylinder, mounted behind the trunk, size dictated by needed delta/v and thus tankage capacity.Not how you do it.You calculate your mission's needs, including contingencies venting etc, the length of engines/nozzles/gimbal freedom/recontact margin/jettison compliance/other. From these you get the overall tanks/pallet dimensions, size the trunk from that. Not the other way round. Oh, and I forgot, you need to add mission growth margin.Then you can call it short, medium or long.
QuoteThe math. It takes about 680 m/s to enter low lunar orbit. About the same for the TEI burn. So, 1360MS.Why leave LLO? That's the crew mission segment, an entirely different vehicle.You only need to enter LLO. And, if Dragon was just used as a cargo vehicle to surface, it doesn't even need that, could do a direct landing. If the point was instrument/cargo on the Moon's surface at lowest delta v, one can use the mascons and the cancellation of angular momentum to land at even less delta v budget (very limited number of locations for this).Now, for a mission planning POV, lets assume we choose an optimum LLO polar access orbit (10km periapsis, 200km apoapsis, longitude 32 degrees) - this is about as low as you'll go, and it will require deft care with small thrusters to maintain such for a month. You could eventually work up to a number of repeat sorties from a single Orion mission, perhaps as many as ten (this would be a logistical challenge requiring multiple "lunar CRS" vehicles/resupply, likely all of them, thus a mission worth doing not EM 1/2). It will cost more to enter this orbit then you've budgeted above - close to 800 m/s given optimal timing. Also, altitude will greatly vary, dropping to 8km and exceeding 200 km as the mascons retard/accelerate the combined SC, not to mention the dispersions either.Each descent, hover, landing, ascent will require 5 km/sec delta v budget because the sites visited won't be as "easy" as the Apollo ones. So on orbit props will need to support 50 km/sec of props eventually for such a mission.For comparison - LM two stage system delta-v: DPS 2.5 km/sec, APS 2.2 km/sec
QuoteRound up for margins, 1500 m/s. ISP of a SuperDraco is about 240 at sea level. But, the fuel is MMH/NTO, which has a theoretical max of 336, so a superdraco with a vacuum expander bell (with electric actuators for steering) should do a lot better than 240. I'll ballpark it at 275, which I think is conservative.No I wouldn't - its not so easy to get, and not enough.By my measure you'll need to exceed 300 sec-1 (APS/DPS 311). Delta II's AJ10-118K is 319 for reference. No slouches here.What I would do is work backwards from the mass flow needed to get the thrust/iSP for the pumps/nozzle, and then you'd deal with the engine/tankage weight as part of the total vehicle's PMF.
QuoteDragon2 plus internal SD fuel, etc, has reported mass of 7385kg. I'll add 1000kg for crew plus non-life-support consumables, putting it as 8385kg. That, plus dry service module (I've rounded that up to 1000kg - a very poor mass ratio compared to either F9 stages), 9385kg. So, per the rocket equation, we have a fuel mass for the service module (to get 1500 m/s delta/v) of 7000kg. That's about 1555 gallons. Even assuming the same density as water, it should therefor fit in a cylindrical unit within the trunk. See above. You don't have delta-v budget to surface and back.
QuoteIt'll need a few mods; add legs plus draco thrusters and Dragon avionics.Unneeded. Use existing Dragons.
Quote Without cargo, by itself, it has a delta/v of 5.5 kps, more than enough to land on the moon and take off again (you need 4.4 kps for that.)How do you get these numbers?One usually works from the mission architecture/profile and the desired orbit as a basis.Then you need to determine LLO entry weight, descent weight at PDI, ascent weight at launch to LLO.
QuoteThat same lander type, in one-way cargo mode, could land 2500 kg of cargo on the moon - for example a BEAM type module (With a dragon-based life support) for a short term hab, and other supplies. If added capacity is needed on the crew and cargo versions, it could be attained by stretching the tanks;Nope.BEAM is an experiment used to increase the TRL of an inflatable module. There is no "off the shelf" surface or orbital hab. Development of such is outside the scope of this thread.
Quote it could land and take off with one superdraco even with an additional couple of tons of fuel, due to the low lunar G. (The stretched version could thus include a stowed expandable hab on the crew lander). Prove this assumption.
QuoteThese go to low lunar orbit.You need an LOI burn.
QuoteA third launch is a fuel depot - not technically hard, as the fuel is storeable hypergolic.Another vehicle to be developed. How does the fuel get to the vehicle. Where is the crew when the vehicle is fueled?
Quote4th launch, crew Dragon plus service module.So no Orion as this thread is written? Does your crew Dragon have all of Orion's capabilities? Can it handle contingencies needed? What if the lander has a shortfall in performance and cannot reach crew vehicle?
Quote Rendezvous in lunar orbit. Crew handles docking plus topping up the two stages.What if crew can't transit vehicles? What happens if theres a fueling mishap?
QuoteCargo lander lands the cargo - if successful, a crew descends on the crew lander, stays a few days, then ascends to rejoin Dragon for a return to Earth.Is this the fuel vehicle or another?
QuoteCrew lander remains in low lunar orbit, to be refueled from the depot for the next mission. This architecture is flexible; could be used to set up a base, or have a standby emergency ascent vehicle. Autonomous fueling? Autonomous landing? Lifetime? Other consumables replenishment? Means?
QuoteI tried to be conservative, but I'm sure I missed some big things. I tried to keep it as cheap as possible, to make it viable for tourism. As part of this, I tried to keep it efficient (such as just couches on the lander, no structure or shell, and no staging, plus possibly reusable.)To be fair you handwaived.Sure - try taking the feedback and do some more homework.
QuoteA few huge technical challenges/issues; Can a FH push 16385kg (Dragon plus service module) through TLI? If they can, as claimed, throw 10 tons at mars, maybe, but my guess is probably not. If they do stretch the second stage, then I'd feel better about it being plausible.A larger F9US would decrease landed mass. They've sized F9US appropriately. Raptor US, if built, would increase landed mass.
QuoteI'm sure there are major flaws I didn't see - and I'd appreciate criticism and correction. Hope you make careful use of it.Many times one gives little here, because no one makes good use of the feedback.You want more critical feedback, you do the "homework", show your work, and you'll get more involvement.
EDIT: I'd draw a sketch of what I meant above, but I don't currently own a working scanner.
I don't think operating from LLO is practical, may make lander design easier but neither Orion or Dragon can operate in LLO.
Q: would electric pump fed super-draco be considered feasible for purpose of this discussion?Reason: Electron rocket mass fraction is better than pressure fed stages of similar prop loads (delta II US, Araine 5G US). In that case significant time and cost in development was saved by using electric pump fed over combustion cycle based pumps. I think the same case could be made for dragon derived lunar lander, fluid handling would be greatly simplified without transfer of pressurizing gases.
Quote from: GWH on 03/03/2017 05:03 pmQ: would electric pump fed super-draco be considered feasible for purpose of this discussion?Reason: Electron rocket mass fraction is better than pressure fed stages of similar prop loads (delta II US, Araine 5G US). In that case significant time and cost in development was saved by using electric pump fed over combustion cycle based pumps. I think the same case could be made for dragon derived lunar lander, fluid handling would be greatly simplified without transfer of pressurizing gases.Sure. Good idea - recharge via solar. Like Matt's pallet and clongton's drop tanks. Give me more. More homework. More detailed criticism. Diagrams.And to all others - please reread OP.Focus is on rapid development of CC-derived lander or optional reusable one (stretch goal for gifted engineers).Please also be critical on me if you see something wrong/missing. Still working on clongton's needs for Dragon 2 PV.
MATTBLAK, If you look at my link on the first page you will find both the horizontal and vertical lander have an engine at the end of the trunk. The horizontal lander has separate engines on the side for landing and ascent.http://forum.nasaspaceflight.com/index.php?topic=30567.0Could you please explain more about the ladder? I don't follow why you need to move the ladder which should only be needed under the suit location...
Quote from: Rocket Science on 03/03/2017 01:49 pmMATTBLAK, If you look at my link on the first page you will find both the horizontal and vertical lander have an engine at the end of the trunk. The horizontal lander has separate engines on the side for landing and ascent.http://forum.nasaspaceflight.com/index.php?topic=30567.0Could you please explain more about the ladder? I don't follow why you need to move the ladder which should only be needed under the suit location...At the time I was writing and thinking this through, that I didn't want the suits to be launched and ride to the Moon, and then down to the surface on the outside of a Suit Lock. Though, off course this is entirely possible that they could, if they were protected by the payload shroud at launch and a MMOD shield the rest of the time. I thought that the crew could be wearing their clean suits within the Lunar Module during descent and landing; as the Apollo Astronauts did. But then the idea was to leave their dirty selves outside the Lander hatch after the first EVA; but I reasoned that they might need Suit Locks separate from the front, up-swinging Dragon hatch if that were so - hence my slightly clumsy idea of putting the Suit Locks around the back.I realize now - in the spirit of brainstorming at 2:30am (when I wrote it) that that was probably a weak idea. I think the best way to ensure inclusion of the Suit Lock idea is to make the main Dragon Hatch also a Suit Lock after the first EVA, where both Astronauts emerge from that hatch one by one, the first time. But also have a pure Suit lock station built into the hull alongside that hatch - just widen the porch a little so both Astros can back into their suit ports at the end of the EVA. A glorified 'roller blind' MMOD and thermal shield could be raised and lowered as needed over the suits between EVAs.Also: in using the Dragon 2 pressure shell idea; without the heavy, conic 'backshell' - taking a leaf out of the Apollo LM's book; that shell could be surrounded by thermal and MMOD shielding - covering propellant and helium tanks and radiators and other necessary plumbing. I imagine that a 'naked' Dragon pressure shell would look plenty odd with all the added protruding bumps and bulges then covered with gold mylar foil - but I'd love a talented scratch-building modeller to have a crack at building our Dragon Lunar Module!
Don't use heavy suit ports. Setup a temporary light plastic barrier inside the lander. You still use the same concept as the suit ports, but still only one hatch out of Dragon. You can collapse it around the dusty suits when not in use.
Remember this? http://www.nss.org/settlement/moon/ELA.html
Quote from: Rocket Science on 03/03/2017 11:16 pmRemember this? http://www.nss.org/settlement/moon/ELA.htmlSee the attached pdf. Change the idea to storable propellants and modern launchers and the principle is still basically sound.
Here's a derivative of that craft that I drew more carefully for a science fiction novel I was researching about 20 years ago. I didn't write that story - but I may still yet The story idea is sort of an update of an idea 'borrowed' from Martin Caidin's 'Marooned'.
Quote from: Negan on 03/03/2017 11:02 pmDon't use heavy suit ports. Setup a temporary light plastic barrier inside the lander. You still use the same concept as the suit ports, but still only one hatch out of Dragon. You can collapse it around the dusty suits when not in use.Maybe, yes. I had a similar idea but didn't use it because I thought no one would like it.
Quote from: MATTBLAK on 03/03/2017 11:23 pmQuote from: Negan on 03/03/2017 11:02 pmDon't use heavy suit ports. Setup a temporary light plastic barrier inside the lander. You still use the same concept as the suit ports, but still only one hatch out of Dragon. You can collapse it around the dusty suits when not in use.Maybe, yes. I had a similar idea but didn't use it because I thought no one would like it.I really like the suit ports too, but since they are basically airlocks in of themselves I'm assuming they are heavy. IMO the best lander would be built around the SEV cab if it's abilities are to be believed, but the other's might leave room for growth beyond a two person crew.
Yes, a few year back we toyed around with an idea with that, but we are constrained on this thread by Dragon or Starliner...
Quote from: Rocket Science on 03/04/2017 11:47 amYes, a few year back we toyed around with an idea with that, but we are constrained on this thread by Dragon or Starliner...Suit ports are the optimal solution for moon dust. Pairing with a suboptimal solution for a lander just doesn't seem right to me. I see a suboptimal solution like a collapsible mud room with a vacuum hose and filtration system for the dust as a better fit. We already know the dust won't kill you so going with experimental and cheap shouldn't be an issue.
Do the research on the suit ports, find the weight. Since the vehicle will fly under a fairing, you don't have to stow/clean/enter/exit the suits, which also takes weight - so it's not all added weight.
Do the research on the suit ports, find the weight.
Quote from: Space Ghost 1962 on 03/04/2017 07:57 pmDo the research on the suit ports, find the weight. 1,904 kghttp://www.spacearchitect.org/pubs/AIAA-95-1062.pdf
Edit: Have to wonder why the Altair design utilized an airlock instead of suit ports though.
If "flags and footprints", you are doing 1-2 of these a sortie. If you are actively working on a work site, you might be doing 10-20 of these a sortie. Now we get into mission planning and mission operations details - granularly. You might be surprised by how much the totals are here.
Quote from: Negan on 03/04/2017 09:36 pmEdit: Have to wonder why the Altair design utilized an airlock instead of suit ports though.Because the designers were constrained to what had already been done. Innovate only where absolutely necessary.
Quote from: clongton on 03/05/2017 06:28 pmQuote from: Negan on 03/04/2017 09:36 pmEdit: Have to wonder why the Altair design utilized an airlock instead of suit ports though.Because the designers were constrained to what had already been done. Innovate only where absolutely necessary.Or they decided that leaving the suit ports on the SEV was the better choice.
Quote from: Space Ghost 1962 on 03/05/2017 05:14 pmIf "flags and footprints", you are doing 1-2 of these a sortie. If you are actively working on a work site, you might be doing 10-20 of these a sortie. Now we get into mission planning and mission operations details - granularly. You might be surprised by how much the totals are here.I'm surprised that you would do 10-20 sorties in a max 4 day mission with only a expendable Dragon or Starliner derived lander.
Originally the LEM was supposed to have a second docking port in front but it was a tight squeeze with the PLSS.
T Could someone review what's expected for SuperDraco rated thrust, vacuum Isp, and rated burn duration?
Quote from: sdsds on 03/07/2017 06:26 amT Could someone review what's expected for SuperDraco rated thrust, vacuum Isp, and rated burn duration?According to the Wikipedia entry the stated chamber pressure of the SuperDraco is 6900 kpa, which seems to suggest it would have a pretty high ISP with a much larger nozzle. I've been meaning to figure out what that might be but have a lot of "homework" to do on the matter to get an answer.
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.
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.
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.
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 ...
Could this be the simplest lander concept? Something that puts the entire burden of propulsion shortfall on a propulsive stage?
Why place all the dV requirements for ascent/descent on the lander, and in doing so drive up the requirements on the lander significantly when an upper stage can do the work here? A Xeus-Centaur is at least partly off the shelf, IVF is scheduled to be demo'd in 2018. Investment in that area would have a much greater return IMO then trying to make a capsule perform a 2-way trip.
...., and SX/BO have nothing on the board for this "distraction".
Quote from: Space Ghost 1962 on 03/29/2017 07:31 pmCould this be the simplest lander concept? Something that puts the entire burden of propulsion shortfall on a propulsive stage?Ahem.Quote from: GWH on 02/20/2017 03:14 pmWhy place all the dV requirements for ascent/descent on the lander, and in doing so drive up the requirements on the lander significantly when an upper stage can do the work here? A Xeus-Centaur is at least partly off the shelf, IVF is scheduled to be demo'd in 2018. Investment in that area would have a much greater return IMO then trying to make a capsule perform a 2-way trip. Xeus-ACES might be 5+ off, but Xeus-Centaur could be much sooner.
Gets the Lunar Dragon concept at least to the point where with moderate increases in ISP (canted, partially expanded nozzles) and a large increase in prop meet the ascent requirements.
Quote from: Space Ghost 1962 on 03/29/2017 07:31 pm...., and SX/BO have nothing on the board for this "distraction". Blue does have something on the board, bould be a fit:http://spacenews.com/bezos-and-blue-origin-reportedly-pitch-amazon-like-delivery-for-the-moon/
Nope. Masten is tied up with XS-1. ULA is at a point they can't afford any distractions.That's what I was getting at.And why I didn't remark about your earlier comment was that it was too desperate to be believed.It's not about being worthy, it's about having enough operational experience to bring this off. Masten doesn't.There are four US in active use on the globe that can be made to have on orbit lifetimes of weeks. Could be modified for the thermal environment. Can't take this further.
BO's plate is full for the next five years. Note also the game has gone up with the recycling of fairings. There's a few more things to come. And he doesn't have a orbital crew capsule yet. Or a orbital capsule recovery system with precision landing.
One of the simpler ways of dealing with this could be creative use of PAM's, but it is so ridiculous one hesitates to bring it up. No contingencies at all too. Hinted at it earlier because they are still flight qualified for F9/FH.
They all have full plates, so why draw the line at a crash program to modify an LEO capsule to a lunar lander vs a crash program to modify an US to a crasher stage?
Masten is probably too small I agree, however ULA is downsizing so one could argue that they have ALL the necessary resources other than funding.
Quote from: Space Ghost 1962 on 03/29/2017 07:31 pmBO's plate is full for the next five years. Note also the game has gone up with the recycling of fairings. There's a few more things to come. And he doesn't have a orbital crew capsule yet. Or a orbital capsule recovery system with precision landing.Blue Origin didn't have a lot visible for a suborbital rocket and capsule, then one day it was flying.Do you have any insider information on the progress of their biconic capsule?
I've tried researching that on the NASA CRS contracts and came up pretty empty, but that's typical for their level of secrecy. I know they want to use a composite PV that has had assistance but most other support went to New Shep.It isn't realistic to think that they have a complete crew vehicle all ready to go, however without knowing exact progress to date I don't think its fair for outright dismissal of something emerging in a 2-4 year time frame.
Quote from: Space Ghost 1962 on 03/29/2017 07:31 pmOne of the simpler ways of dealing with this could be creative use of PAM's, but it is so ridiculous one hesitates to bring it up. No contingencies at all too. Hinted at it earlier because they are still flight qualified for F9/FH.Please define PAM's? Payload Abort Motors?
Quote from: GWH on 04/01/2017 04:28 pmThey all have full plates, so why draw the line at a crash program to modify an LEO capsule to a lunar lander vs a crash program to modify an US to a crasher stage?Agreed.But the problem is ... what stages?...Payload Assist Module's. Things like Star-48B's. You can find them in the Orbital ATK Propulsion Products Catalog
Boeing released a nice picture at least of a lander
No windows! Bummer!
Quote from: TomH on 04/04/2017 10:29 pmNo windows! Bummer!The windows are on the other side.
Two more images of this lander can be viewed here: http://xp4d.com/gallery.htm#!prettyPhotoSelect the 'Cis-Lunar Missions' tab, 4th row down.
Great work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.
Of note...Having seen extended restart capability with FH, we can say an expendable Falcon Heavy should be able to deliver up to 15.2 tonnes direct to GEO.
Quote from: sevenperforce on 02/08/2018 12:53 pmOf note...Having seen extended restart capability with FH, we can say an expendable Falcon Heavy should be able to deliver up to 15.2 tonnes direct to GEO.I get more like 12-13 tons direct to GSO.
Quote from: Steven Pietrobon on 02/06/2018 06:08 amGreat work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.Another solution just include third stage using storable propellants which would remove the need for a lot of the design changes on the FH second stage.