Author Topic: Dragon 2 or Starliner derived dedicated lunar lander?  (Read 66208 times)

Offline clongton

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #60 on: 03/01/2017 12:07 am »
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.
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.
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Offline Rocket Science

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #61 on: 03/01/2017 12:16 am »
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.
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...
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Offline clongton

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #62 on: 03/01/2017 12:27 am »
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.
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?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Rocket Science

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #63 on: 03/01/2017 12:38 am »
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.
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?
Reusable as a goal is the way to go as my thinking evolved about this 5 years back on my thread that I linked on the first page...
http://forum.nasaspaceflight.com/index.php?topic=30567.0
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Offline Rocket Science

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #64 on: 03/01/2017 01:08 am »
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.

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.
Since these suits would be exposed to space for prolonged periods a simple MMD collapsible cover would be useful...
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Offline Rocket Science

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #65 on: 03/01/2017 01:51 am »
How many crew members and for how long a stay ideally?
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Offline CameronD

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #66 on: 03/01/2017 02:19 am »
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.

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.

I realise Red Dragon is off-topic for this thread, but can't help thinking that if you're right, then from the 'artist concepts' we've seen they're going to have the same problems using a Dragon 2 variant on Mars.

Maybe mars-dust is better, but from what I've read, moon-dust is really nasty stuff and ingress into the cabin a non-trivial issue.
 
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline Lars-J

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Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #67 on: 03/01/2017 03:07 am »
Are the Super Dracos on the Dragon pressure or pump fed?

Pressure fed.

(And just to clarify a common misconception, they share tanks with the Draco's)
« Last Edit: 03/01/2017 03:08 am by Lars-J »

Offline Patchouli

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #68 on: 03/01/2017 06:07 am »
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.

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.

Actually the Apollo LEM hatch was only 32" square.
The Dragon hatch looks similar in size little more narrow but taller so a suited astronaut should fit esp since the door moves up and out of the way vs into the vehicle.
Widening it slightly would be one of the easier modifications Dragon would need to land on the moon.
Though I suspect they may have test fit a suit with backpack to arrive at the dimensions which BTW is how the LEM ended up with a square door in front.
Originally the LEM was supposed to have a second docking port in front but it was a tight squeeze with the PLSS.
« Last Edit: 03/01/2017 06:22 am by Patchouli »

Offline A_M_Swallow

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #69 on: 03/01/2017 06:55 am »
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 refuelling or the attachment of drop tanks.

Offline Proponent

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #70 on: 03/01/2017 09:16 am »
How does that work in zero-g? What keeps the liquid between the orifice and the pressure boundary?
Is the propellant in a bladder?

What about using a settling burn?

Offline russianhalo117

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #71 on: 03/01/2017 05:45 pm »
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.
There are provisions to allow for such transfers in International Docking System Standard (IDSS) Rev D release which were transferred from Mir's APAS-89 config to allow prop and oxidizer transfer via Progress, Soyuz, and the Buran system

Online Andy Smith

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #72 on: 03/02/2017 01:39 pm »
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 place

Ive 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.


Offline envy887

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #73 on: 03/02/2017 02:31 pm »
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 place

Ive 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.

Lunar escape is 2380 m/s, so an absolutely minimal budget for TLI>surface>TEI is twice that: 4670 m/s. So you lander Dragon can't get back to TEI, although it does look like it can make it to the surface and back to LLO

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.

Offline clongton

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #74 on: 03/02/2017 05:09 pm »
So asking for some help. I cannot locate any good numbers for the Dragon Pressure Vessel. Since my concept is based on using the pressure vessel sans all the exterior stuff I need the PV mass in order to calculate the mass ratio to compute the propellant requirements. Anyone have a source, or the actual (close) numbers?
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Offline Space Ghost 1962

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #75 on: 03/02/2017 05:56 pm »
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.

The original presumed architecture here was Orion/SLS for crew, and single launch under fairing with PAF of CC derived, dedicated lander to LLO. SLS in this case has considerable excess capacity, so it could also "carry the lunch" e.g. props for a lander (reuse). To replace Orion/SLS, likely one either needs more or a different architecture to add in capacity. Which could be as little as a F9US lofted by a F9R, assuming you have a means  to use that capacity creatively ...

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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.

IMHO the three biggest issues for Dragon 2 NOT being ideal as a lunar lander are a) underexpansion, b) lack of a pump driven engine, and c) tank weight due to increased volume of props needed. For a reusable lander, this issues become critical.

There is no way one gets a rapidly developed lander here except with off the shelf engines, either integrated in pallet, or ... using the feeds/mounts for the SuperDracos but from different, larger tankage (certain issues here).

Getting to 340 iSP on a hypergolic engine is not easy. Also, the nozzle rides the vehicle CG up high.

Also, any non SLS lunar exploration mission architecture ... only becomes economic with a reusable lander at a minimum.

PS. Watch out - Musk convince Amber Heard to go on another of their "weird dates" once again. Usually coincides with something unexpected coming out of SX ...  ::) ... actors are good at "pretend" ...

Offline Rocket Science

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #76 on: 03/02/2017 06:15 pm »
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.
Thinking about this a bit more... Leave the standard hatch as is and on the opposite side cut out an opening and weld in a flange for the "suit-port airlock"...
« Last Edit: 03/02/2017 06:16 pm by Rocket Science »
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Offline CJ

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #77 on: 03/03/2017 06:50 am »
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.

It's a fine post. On topic and relevant. I'll attempt to give you feedback.

Thank you!

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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.

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.

The need for in-space duration is why I stuck with hypergolics, in spite of the awful ISP. A cryo-fueled lander would, IMHO, be a monumental development project, which huge mission duration issues. 
The docking issue... I'm thinking a simple-as-possible drogue and shroud capture system (Perhaps modeled on Gemini-Agena), because the crew lander doesn't have a hatch or an airlock (there's no crew cabin on the crew lander)Rather pointless without a crew cabin on the lander). I went with crew-piloted docking because I did not know if the autodocking systems used for ISS docking could work in low lunar orbit. I guessed they could, but wasn't sure. I'd much prefer automated rendezvous/docking.   

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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.

Good point; it's a jettison-able propulsion assist pallet. I need it to fit within the trunk, not be part of the trunk, due to abort requirements. I used it as the basis of a lander for cost reasons - comonality. 

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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.
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.

Sorry, but while I agree in general, I disagree in this particular instance. For this concept of mine to be even remotely plausible, the JPAP has to fit within the trunk - not be part of the trunk, and the trunk can't be redesigned (far too costly). If it won't fit, my concept is kaput - so I looked at making it fit first, as it's an instant deal-killer if it does not.  The good news IMHO is the Dragon 2 trunk looks like it has ample volume (though that's a SWAG on my part - I can't find figures to support it - yet).


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The 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

First, thanks for the LM delta/v specs and the 5kps spec.  I could not find those. That's a higher delta/v from LLO to the surface than I thought - and pretty much blows my concept of a single stage return crew lander with a 1000kg dry mass or superdracos. 

The entering/leaving LLO was for the Dragon2, not the landers. Bad wording on my part. 

Given the delta/v requirements from LLO to the surface and back, it does not make economic sense to me to push mass that's not needed on the surface through 5 kps. Heat shield, structure, etc. What's really needed, IMHO, is to leave as much as possible on the lunar surface - sent by a one-way lander. What needs to come back up to LLO is, really, crew and space suits. No need for a crew cabin, etc. However, suits can fail (leaks, etc) prior to ascent, so a backup would be required. I was thinking of the shuttle "Rescue ball", which went as far as a prototype. Or, a spare spacesuit.   

Hrmmm.. However... if 5 kps is what's needed from LLO to the surface and back, and the lander had a mass fraction close to that of the F9 second stage... it's still doable, but marginal. Depends on ISP. I'll get to that later in this post. A further issue; approaching the mass fraction of the F9 S2 is probably implausible for any stage using pressure-fed engines, because the tankage will be a lot heavier if it has to withstand pressurization. Perhaps the F1 upper stage (Kestral was pressure fed) would be a better guide as to a plausible mass fraction?     

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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.
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.

I love the AJ-10. It's got a long history, very reliable, and great ISP for a storable. It also has available specs, including mass. I went with Superdraco, originally, because I assumed it's cheaper, but I flat out don't know (nor was I able to find out the price of either). I also wanted redundancy if practical. I was also trying to stay within the Dragon/Starliner derived rules, so I tried to use Dragon components. The AJ-10 DeltaII upper stage would actually have made a near ideal JPAP, almost off the shelf, because it's low dry mass (950kg), higher ISP, and *might* fit inside a Dragon 2 trunk (the stage is 2.6 meters diameter, 6 meters long) as well as being the basis for a lander - but it's not a Dragon or Starliner component, so I didn't try that route. 

However, because the AJ-10 has a great ISP, plus has things like a known mass, I'll use that for now - if you're okay with that on this thread.. However, due to size constraints plus reuse potential, I'd prefer the Shuttle OMS version (with its smaller, non-ablative, engine bell) in spite of its lower ISP of 316.     

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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.
See above. You don't have delta-v budget to surface and back.

That's because the Dragon 2 does not go to the surface. It stays in LLO. Only the landers actually land. 

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It'll need a few mods; add legs plus draco thrusters and Dragon avionics.
Unneeded. Use existing Dragons.

Not viable for my concept; you'd be pushing a lot of superfluous mass through 5kps if you try to land a Dragon on the moon and take off again. Very prop-rich architecture, and needing a large dedicated landing stage and ascent stage.  I'm trying for something lower-cost.

A lander using Dragon components (SuperDraco, avionics, dracos) that's largely the same as the  jettison-able propulsion assist pallet I outlined. It's a squat cylinder. Add legs, and Dracos for maneuvering. On the flat upper surface, put four light collapsible canvas (or similar) seats, and a deployable control console, (could be cable-connected, strapped to a crewmember's lap). No cabin, just seats. They'll meet up with supplies/inflatable hab on the surface. This gets rid of a heck of a lot of mass and engineering cost.   

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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.

I got the delta/v for LLO to lunar surface from looking up several delta/v maps. Apparently, that's a bad method, because your numbers (including for the LEM) are considerably higher. I'll use yours.

I assumed a dry mass of 1000kg for the lander - which is nothing more than a cylinder (containing fuel tanks) and (originally) two superdracos. I'll go with a single AJ-10 instead. Still 1000kg dry mass (Which I think is a poor mass ratio and could be reduced a little... though not a lot.). The mass of the crew plus spacesuits: I'm guessing 200kg per person (person plus spacesuit) based on the following: the Apollo suits weighed around 81kg including backpack. I have no idea what a modern space suit (Such as SpaceX and Boeing are working on), modified as a lunar EVA suit, would weigh, so I'm wild-guessing (with, yes, plenty of handwaving) 100kg. I'm guessing the same for the occupant, so 200kg per crew, 800kg if we're landing 4. The only remaining mass is the seats plus small control console... the latter would be akin to a laptop in mass - call it 5kg. The seats? 5kg each?. So, payload plus dry mass, 1825 kg. ISP 316 (Shuttle AJ10). Delta/v potential, 4883.9 m/s, not enough.

However, if the lander could achieve a better mass fraction, closer to the F9 1st stage, , to get the dry mass down to 600kg, delta/v goes up to 5506 m/s with the same 825kg payload. Enough for a round trip from LLO to the surface and back, with higher-than-speced margins. Or, more plausibly, reduce the number of crew by one.       

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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;
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.

Okay. Hrmmm. My concept needs a hab of some sort on the surface (Due to no crew cabin on either lander). So... existing hardware (well, almost existing); A Dragon 2 - perhaps used. Strip it of superfluous mass (Heat shield, parachutes, seats). Put the proposed JPAP (or a a Delta II AJ-10 upper stage) in the trunk (if it'll fit - if not, won't work) and launch it on course for a direct-decent to the lunar surface - with as close to zero velocity at the earth-moon gravity threshold as possible (Though I suspect Apollo is a good guide for that, even though heading for LLO). For landing, drop the trunk, burn the JPAP dry, then drop the JPAP. Use Dragon's SuperDracos to land. Okay, the math; delta/v needed for this, bare minimum, is (if my delta/v maps are accurate) about 2.5 KPS to land with no margins at all. So, call it 2.6 (It's unmanned, so margins aren't as important). That JPAP had the ability to push Dragon and trunk through 1.4 kps. Dragon 2's internal delta/v capacity was calculated to be (sans trunk) 742 M/S doing a hoverslam-mode landing in vacuum. I didn't do the calc, but the person who did looks to have done a good job, his work is here;
https://www.reddit.com/r/spacex/comments/4qwpdz/dragon_2_landing_calculations_analysis_for/   

1.4 + .742 is 2.142 kps. Not enough, but that's without factoring for dropping the trunk or increasing the fuel capacity of the JPAP. Seeing as I can't find the mass of the trunk, I have no clue how to go further... but *IF* this would work, there's the Dragon-derived surface hab. (It'd need solar cells, due to not having a trunk on the surface). And if that's the route, we can dispense with the one-way (LLO to surface) cargo version of the JPAP based crew lander.   

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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.
If you mean prove that a stretched version could land a stowed expandable hab along with crew, I can't because I was wrong. It'd need to be a very light hab, 1000kg or so, plus there's nowhere safe to put it (the crew would need to sit on top of it...). Not plausible.     
 
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These go to low lunar orbit.
You need an LOI burn.

That has to be provided by the landers, which is unfortunately why this concept needs a fuel depot in LLO. The latter, though, has the benefit of making the crew lander reusable. 

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A 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?

I don't like the need for the depot, but I couldn't see a way around it.
For the fuel transfer, I was thinking something similar to the system the Progress tankers use to refuel ISS's propulsion module. Simple connectors within the docking mechanism (If what I've read is correct). In my proposal, there's no atmosphere-containing passage as part of the docking mechanism, so less risk and complexity (should be easier - theoretically.).

As for where the crew would be during lunar orbit refueling of the lander... my preference is doing their last few days of launch prep at the Cape. No point in launching them unless the landers are refueled, and the cargo one has landed their supplies and accommodations on the moon.   
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4th 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?

No Orion; Dragon 2 with the JPAP serves that role (Same as the Apollo CSM stack). Your OP post isn't written so as to require Orion. It said,  "meant to dock with say Block 1/1B SLS launched Orion?" I read the "say" and question mark as indicative of suggestion, not specification. 

The Dragon 2, with the  jettison-able propulsion assist pallet, should have the delta/v margin to handle a lander takeoff shortfall - assuming the lander actually makes orbit. Does Dragon have all of Orion's capabilities? No. But does it have (with the JPAP) enough? I think so (but I may well be wrong).

In any case, I couldn't see a way to make Orion part of this (Even if we overlook the huge cost) because I couldn't see a way, off-the-shelf, to get Orion and its SM through TLI that does not involve the letters "SLS" and it's even more astronomical cost (and thus implausible for my concept.) A further issue: slow launch cadence.     

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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?

If you're right that the docking can be automated, then the crew will be safely on Earth during lunar orbit refueling of the landers. They'd launch after that, assuming all went well. If the crew can't, for some reason, transfer from the dragon to the crew lander (which is a simple EVA of leaning out the open Dragon hatch, clipping a tether to the lander, climbing into the seats, and buckling in) then mission aborted, and back to Earth they go. If, on the other hand, they can't get off the lander and into the Dragon, it's a very bad day - but wouldn't that be the case with any lander that isn't also the return vehicle?   

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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.
Is this the fuel vehicle or another?

The fuel depot remains in lunar orbit, it does not land (it can't). It's just there to top up the cargo lander and the crew lander/ascent. However, now that you mention it... it'd be nice if there was also the ability to top up (in case of emergency need) the Dragon's jettison-able propulsion assist pallet.

I don't like the need for a fuel depot. Its complexity and cost makes this even harder. But, refueling is needed to make reuse possible - and also due to the need to get the landers into LLO on their own power. 

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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.
Autonomous fueling? Autonomous landing? Lifetime? Other consumables replenishment? Means?

If you're right that autonomous docking is feasible, then autonomous docking, and autonomous landing . However, pilot override ability during landing would be a must IMHO for the manned lander.   

Lifetime? I have no idea how to begin to calculate that. Other consumables replenishment - food, O2. water, lithium dioxide, etc... would have to come in the Dragon along with crew. (Perhaps I'm way overoptimistic saying a crew of 4... two would make this a lot easier).

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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.)
To be fair you handwaived.

Sure - try taking the feedback and do some more homework.

I'm trying, but I'm so out of my depth that that in many cases I don't even know what I don't know. :)

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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.

A larger F9US would decrease landed mass. They've sized F9US appropriately. Raptor US, if built, would increase landed mass.

Unless FH (non-expendable mode) can push 16 tons (Dragon2 plus the jettison-able propulsion assist pallet)  through TLI, I'm flat out sunk - the concept just isn't viable. Raptor US might make it possible, but that's ifs on top of ifs with a unicorn for a side booster at this point in time as far as my concept is concerned. 
IMHO, my first step should be figuring out what, exactly, FH can push through TLI. SpaceX's figures keep changing. In 2011, it 19 tons to GTO and 16 tons to TLI. In 2013, they upped that to 21.2 tons to GTO, but didn't mention TLI. Even if that's a commensurate increase, I don't think it's enough to allow FH to do the job in anything but expandable mode. And if so, that makes my concept preposterous in an of itself; it's only plausible costwise if FH is in recoverable mode. The reason is this architecture is going to take (once the pieces are in place) two FH launches per landing, and if one is expendable mode, that's 150 million right there - for just the one launch, not counting payloads.   
 
HRMMM... maybe there is a way. Have the JPAP only partially fueled (enough to enter LLO and reach the fuel depot) for launch - but that'd mean the refueling of it would be both manned, and also life-or-death (no way home without it).  And, without knowing what the FH can actually push through TLI in reusable mode, there's no way (That I can see) to figure out if this is even plausible from a mass perspective. (on the other hand, if FH can't do it, it's 100% implausible).     

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I'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.

All I can say is I'll try. You've made me realize I have a vast amount of homework to do. Thank you for your help and feedback.

My take at the moment; my concept has too many flaws, and also too many unknowns. I'm also very dubious that it would fit this thread, due to switching from Superdraco to AJ-10 for the lander.

Yet another flaw just occurred to me; use of GPS for docking or, especially, landing, is problematic even if possible; you're going to have no GPS for around 40% of each orbit (Depending where periapis is) and it also places anything not on the earthside of the moon off limits (but the lack of a comms relay pretty much does that anyway).   

I'll start with the homework.

Offline MATTBLAK

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #78 on: 03/03/2017 01:25 pm »
A lot of good thoughts in the post above, and reasoned speculations. I think, though that the only way to get this to close is by a 2x launch (1.5 launch CXP) that sends an approximately 22 ton spacecraft up on an expendable Falcon 9 and an Earth Departure Stage (EDS) up on a Falcon Heavy expendable. Apollo needed more than 70 tons of LOX/LH2 to send about 50 tons on TLI. With the lower quantity and Isp of LOX/RP-1 on a Falcon upper stage - 22 tons to TLI sounds about right. I'm assuming that both Lunar vehicles are Dragon-derived.

Dragon 'Command Module' - Adapted Dragon 2 with Propulsion pallet in it's Trunk (an idea first touted by me; but based on a Golden Spike requirement) The Prop Pallet's delta-v is intended to be enough for LOI and other plane-change and circularization manuevers, and also Trans-Earth Injection later. Dragon CM also has a high-gain comms antenna. Target mass injected into LEO on an expendable Falcon 9 Block 5 is 20-to-22 tons.

Dragon 'Lunar Module' - Launch weight on Falcon 9 expendable; 22 tons is the goal. Adapted Dragon 2 with no heatshield or Earth recovery systems. Pressure shell is from Dragon 2, but is surrounded by MMOD shielding and insulation - matching the form factor of a standard Dragon outer 'cone' backshell, but a bit 'bulgier'. This is based on Chuck's Dragon LM suggestions. Trunk contains Propulsion Pallet that acts as a Powered Descent Initiation stage - this is ejected before the 'High Gate' point in 'crasher mode' and the Dragon Lander uses conformal propellant tanks to finish the descent. The Lander has a small detachable porch and ladder beyond the main hatch that has the Astronauts emerging from it for the first EVA. At the rear of the cabin - opposite side to the hatch and windows - is a dual suitport station. Before ending the EVA, the crew detach the ladder and porch and replace it to the rear where the suitports are. This is their ingress/egress point for the rest of the EVAs. Surface stay time for two Astronauts is to be 7 Earth days with 6 or 7 EVAs. A micrometeroid shield to protect the suits between EVAs could be roller-curtain assembly.

However: The main hatch on one side and the suitports on the opposite side might be too complex - a suitport to either side of the main hatch instead of the two windows might be a better place for them; with a shared porch and small ladder to the surface. The landing and ascent would be largely automatic - if the crew had to manually take over from a malfunctioning Autopilot, they could 'see' with a pair of ultra hi-def 3D TV screens.

Ascent could be from onboard propellant supplies in the 'bulged', conformal tanks. And in all the above details - this Dragon Lander concept is not meant to be reusable. But it could be, if we took Chuck's earlier idea in the thread a step further: the Cabin Stage could be mounted upon a new structure of leg/prop tank set each time - brought fresh from Earth by the Dragon or Orion Command Module. No need to physically plug and unplug the prop tanks alone each time - make the tanks and legs a single, integrated structure able to be mated to the previously used Cabin Stage again and again. This would be a little bit like using an Apollo Ascent Stage over and over, with a fresh Descent Stage each time. But make the connections and prop transfer lines for the Dragon Cabin Stage and Prop/Legs far easier than that idea that I just made a crude analogy of. :)

EDIT: I'd draw a sketch of what I meant above, but I don't currently own a working scanner.
« Last Edit: 04/06/2020 06:43 am by MATTBLAK »
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Offline Rocket Science

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #79 on: 03/03/2017 01:49 pm »
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=30567.0

Could 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...
« Last Edit: 03/03/2017 02:00 pm by Rocket Science »
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