Author Topic: Dragon 2 or Starliner derived dedicated lunar lander?  (Read 24238 times)

Offline Space Ghost 1962

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Have been asked by three different groups about dedicated lunar landers that could be developed leveraging a qualified crew vehicle.

Obviously one could include Orion and/or Dreamchaser into this as well, but those don't seem like likely candidates due to cost, weight, applicability.

This gets back to an early sixties study on deriving from Apollo, Gemini, and Mercury landable vehicles - the idea is to reuse the qualified systems that so much work went into for HSF. And, remember, the Apollo CSM had the propulsion to lift both off the surface for a direct return!

So, consider if one were to "piggyback" existing programs with say a $2B funding each optionally to increase to accelerate a) CCP completion such that crews are actually accumulating flight history on the vehicle, and b) derive an expendable lander, launched to LLO by commercial launch services, meant to dock with say Block 1/1B SLS launched Orion? Would also involve a checkout flight within two years - perhaps launched to the ISS autonomously, where a qualified pair of astros would undock, checkout the vehicle extensively, and then redock.

So we're talking of omitting the top aeroshell, just thin metal like the LM, converting the abort engines into descent/ascent engines, no heat shield, join SM/trunk to capsule and use volume as tanks/storage as with the LM, and add/reposition legs. And adding high-gain comm, and high visibility landing capability to piloting positions.

Oh, and you'd need a trainer. Cannabalize DragonFly?

In doing my sims, you'd have to significantly reduce mass, like with LM, to make this work. Oh, and the entry doors are too small for lunar egress/ingress. And I doubt the avionics are setup to allow depressurization/repressurization.

Is this a plausible program "option" to add?

Recap - for this thread, you can only do Dragon 2/Starliner, only launched to LLO, only launched on non-SLS, and largely(70-80%) of CCP qualified components. Optional points if you get a lander that could be evolved into a refuelable from SLS-launched "added" payload.

add:
Oh and for the SuperDraco's let's assume either fixed pointing down launched in shroud or that tilt out for zero cosine losses. Optional higher expansion nozzle for more iSP.

add:
Now that Musk has let the cat out of the bag, you can see that there is a place for this thread as one CC provider is announced as doing missions around the Moon.

The same propulsion pallet for Dragon/Starliner lander, discussed in this thread,  could also be used as a means to enter/exit LLO, the next step past a free return.

So yes, I really mean it that this is about real hardware for real missions in the immediate future.

add:

Some additions. Regarding meaning of expendable or reuse:

For expendable, single use:

Surface access for multiple, suited astros for a 1-4 day access. Fully expendable single sortie.

And for reuse:

Same CC derived vehicle used for at least two sorties - LLO to surface to LLO is a sortie, even to the same place.
Likely replenishment between sorties, replenishment from another vehicle than the lander.

add:
No discussion of non-LLO mission architectures at all, take them elsewhere.

For this thread we'll focus only on a favorable to landers/surface exploration polar frozen LLO that is difficult  to enter/leave/maintain - discussed mid thread. There are multiple variations within the margin of this mission architecture. The point is to put the burden on the earth crew vehicles for LOR (Orion/SLS has this already, CC vehciles could add it with multiple launch), we want to minimize lander operational burden (props, trip time, comm to surface, vehicle turnover,...), and allow an option for rapidly reusable lander with mission lifetime of around a month (focus on concentrating surface access capability through reuse).

So expendable lander can happen soonest, and reusable lander can demonstrate  enhanced exploration as immediate benefit, besides increasing mission safety/contingencies through reflight. Later duration and/or concentration of reuse through performance enhancement can increase scope of use either to a single or multiple sites.
« Last Edit: 03/03/2017 05:09 PM by Space Ghost 1962 »

Offline Rocket Science

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #1 on: 02/20/2017 01:26 AM »
I toyed with this several years back and haven't thought about it since. I offer it as a starting point...
http://forum.nasaspaceflight.com/index.php?topic=30567.0
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Offline A_M_Swallow

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #2 on: 02/20/2017 04:19 AM »
A lander has 3 main parts - the descent stage, the ascent stage and the cabin. They can be from different manufacturers. The ascent and descent stages can be merged if the lander has big fuel tanks.

NASA has been paying the vertical lander firms to test avionics like the ALHAT lidar and guidance systems. These can form part of the cabin or descent stage.
https://en.wikipedia.org/wiki/Autonomous_Landing_Hazard_Avoidance_Technology

As well as avionics and controls the cabin will need life support. The ISS life support is too big and using Russian life support too controversial. Within 2-3 years test life support will be in the Dragon 2, Starliner and NextSTEP-2 Deep Space Habitats from Bigelow, Boeing, Lockheed Martin and Orbital ATK. One of these could be used as the cabin's life support.

Offline GWH

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.

I'd like to make a more thorough post with some analysis but don't have the time at the moment.

For discussion on Dragon 2 cV capabilities, this reddit post may be useful for the conversation:
https://www.reddit.com/r/spacex/comments/4qwpdz/dragon_2_landing_calculations_analysis_for/

Online MikeAtkinson

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #4 on: 02/20/2017 09:49 PM »
For Dragon I think there are two main options:

1. Fuel rich
- Keep D2 as it is
- 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.



2. Component reuse, new engine

- Don't reuse any structure from D2 or the trunk
- Instead reuse components and subsystems.
--- avionics
--- ECLSS
--- power and cooling
- optimise design for mass.
- use storable propellants and a new engine in the Draco family optimised for the mission.
--- optimised engine probably cost effective as it makes the rest of the design easier.
- two stage
--- descent stage
--- ascent stage, includes trunk functionality

- descent stage could be used as a cargo lander
- ascent stage + crew compartment could be reused
- storable propellants could be transferred to LLO on a commercial contract.

Once you decide to do away with most of the D2 structure, you might as well get rid of it all and start from scratch. It is difficult to reuse components and subsystems as is, there will be a constant pressure to modify them for performance, but that would almost certainly blow the budget. A tanker spacecraft would still be required, this time holding storable propellants. It is going to be difficult to do the development in the $2B budget. Development schedule just about impossible to get anything flying in 2 years. Missions will cost ~2B because of SLS+Orion+lunar lander+tanker+commercial launch.

I'll let someone else discuss Xeus-Centaur, IVF, acceleration of ACES, etc.

Offline Steven Pietrobon

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #5 on: 02/21/2017 07:02 AM »
- 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.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Online MikeAtkinson

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #6 on: 02/21/2017 07:10 AM »
- 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.

Sure, but it avoids a rendezvous, docking and fuel transfer. Refueling the stack totally in LEO is also not optimum, better to send a full load of fuel on the tanker. So we might have:

- Tanker version of second stage
- Tanker 1 launched into LEO on FH
- Tanker 2 launched into LEO on FH, refueled by tanker 1.
- Tanker 3 launched into LEO on FH, refuels tanker 2.
- Tanker 2 does TLI and inserts into LLO (uses modified trunk for power).
- Tanker 4 launches into LEO on FH
- 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 to LLO.
- D2 + trunk + MUS refueled from tanker 2
- D2 + trunk + MUS do TEI
- D2 + trunk separate from MUS
- D2 and trunk separate shortly before landing.

Online MikeAtkinson

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #7 on: 02/21/2017 07:36 AM »
1. Fuel rich
...

Development program could have a Grasshopper like demonstrator. Showing the Modified Upper Stage (MUS) with trunk and D2 on top, performing various hops, harzard avoidance (not necessary in my opinion when landing on a prepared site). I think this could be done within 18 months of program start.

Development program would also need a fuel transfer in LEO demo and a long duration fuel storage demo. These could be done within 2 years of program start and be combined into one two launch demo (uncrewed). After 6 months in orbit the MUS could then perform a TLI.

A crewed Apollo 8 redux. could happen about 3 years into the program, with a cargo landing also in year 3 and then a crewed landing in year 4.

D2 would probably need a few modifications, but all relatively small. The communication system probably would need enhancement, software would need enhancement for controlling the D2 + trunk + MUS stack, hatch is probably too small (would need determination of what lunar suits would be used to be sure).

A major problem is landing on the moon using the Merlin 1D vac is likely to damage the engine due to flying regolith. There are three potential solutions I can think of:

1. Shut down the Merlin 1D vac early, then descend the last few hundred meters on Super Dracro.
2. Prepare a landing pad in advance using sintering or perhaps laying a membrane.
3. Protect the nozzle in some manner (or perhaps carry a replacement nozzle extension ?!).

I like option 2 the best as it would allow several landings in close proximity. It is more appropriate to a base, rather than a series of exploration missions to various landing sites.

Offline MATTBLAK

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #8 on: 02/21/2017 07:54 AM »
To turn a Dragon spacecraft into a Command & Service Module:

Perhaps the Trunk could have a ‘Propulsion Pallet'tm 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).

A Dragon Lunar Module: The trunk contains another Propulsion Pallet, but one with enough propellants and thrust to act as a virtual ‘Crasher Stage’ that is jettisoned before the ‘High Gate’ of the powered descent, allowing a Dragon LM – with no weighty Earth heatshield or parachutes – augmented with 4x strap-on or ‘saddlebag’ propellant drop tanks to descend to the landing site. After landing, 2x of the drop tanks are depleted and removed to discard dead weight. After the surface mission, the Dragon LM ascends via the remaining drop tanks prop supplies, plus internal propellants to the waiting Dragon CSM.

This is a variation of what I’ve proposed before with Space X-based launchers and spacecraft. Although, it could be a little more launcher agnostic. The two spacecraft could be orbited by Falcon 9 ‘Full Thrust’ expendables. Then, either Falcon Heavy reusable could send up a LOX/Kerosene second stage for the space craft to dock with and perform Trans-Lunar Injection, or Atlas V-552 could place a dual-engined Centaur into orbit near the spacecraft for the same procedure.

A variation of all the above could be done with a heavily modified Boeing Starliner as the CSM and the LM could be a bare-bones, clean sheet Commercial Space craft.
« Last Edit: 02/28/2017 02:55 AM by MATTBLAK »
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Offline Nilof

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #9 on: 02/21/2017 11:45 AM »
Another option for a bare-bones lunar mission with Dragon, would be to carry an unpressurized lander like this one into the trunk. Possibly derived from the Morpheus lander that was tested a few years ago.

The nice thing about unpressurized landers is that they don't really become obsolete if you come back with something bigger. With a moon base they are a viable emergency evacuation vehicle or backup, and they have a useful niche as hoppers to explore places that are a nontrivial distance away from the base or difficult to reach because of cliffs. Double the thrust and they could be useful on Mars as well.

Alternatively, if you had an ITS in orbit around the moon that could refuel a small unpressurized methalox lander, you could do something like a hundred sorties before having to refuel. Great for surveying a wide number of sites quickly.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline Space Ghost 1962

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #10 on: 02/21/2017 03:12 PM »
First, please carefully read OP. Many are assuming the content of an old thread.

This is a very different approach, and is attempting to NOT follow the same pattern, but instead leverage the history of the original LEM/LM in the form of  qualified CC vehicles.

And we are seriously talking 1-3 years for the total program, including ISS test program (NB - it has to be a VV, because it must dock with the ISS, hello?).

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?

Capability. Dragon 2 / Starliner unmodified can't even make ascent to LLO with margin, so you already know you'll need to significantly improve propulsion, even if you were to use 1 vehicle to land and a different vehicle to ascend (assumes precision landing capability) - the absolutely simplest approach possible!

But even for that, at a minimum, you need an area ratio increase on engine nozzles of >10x, burn duration >1.5x, and tankage increase of 3x. The 2.5x more allows you to reach efficiencies  near that of a single vehicle w/o modifying capsule systems/CG.

However, to do this, you must, like the LM, reduce mass and launch under a fairing (in this case a standard PAF). Which is off the shelf.

Quote
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.

Not suggesting returning capsule to earth, just to LLO. Again, the point here is proven systems, in this case hypers as potential refueling is already proven, and one can incrementally work up such a system to long duration, multiple sortie/mission reuse/disposal incrementally, deployable in a few years.

Hydrolox fuel transfer is still low TRL, (hope to see Altius coupler today - Hi Jon), and  IVF is in the 1-3 years before first flight (still not committed to).  Masten is tied up with XS-1, Xeus is to test with a discarded RL-10 for cost reasons and is a long way to flight test, let alone HR. Bridge too far.

ULA's long term vision is interesting. But at current rate of program speed (even with 0.5B of that $1B per vehicle in OP), it's still more than a decade away by my watch.

Quote
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.

The benefits for keeping the side mounts are  a) keeps vehicle CG as designed, meaning that it does not need to be seen as a differently operating vehicle, b) lower to ground - you could build access into the trunk side as a fixed ladder etc.

- 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

5 year development program to do so, out of scope. Not enough power from trunk. Requires cryogen refuel too low TRL.

Quote
- 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

Too costly to support multiple versions, no reuse with existing sat launch business.

Quote
- 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.
See Steven's comment. Very complex CONOPS - would make SLS blush.

Quote
- 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.

Now we're getting to your agenda - to bootstrap prop depots for larger scale exploration.

Quote
- 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).
Any time you mess with SLS, you slow down both programs. Don't do it!

Quote
- 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.
Way more than even SX ambitious. It's really a way to avoid the big rocket.

Quote
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
And ... out of scope. And your test program alone would be about $6B.

Quote
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.

I'll given you points for attempting to build a lunar exploration program out of F9US taken to the max.

But that wasn't the OP. And the reason why the OP was written so, was to translate BOTH CC VEHICLES into a DEDICATED LUNAR LANDER w/o requiring integration with SLS/Orion - they all fly using own systems to LLO, dock, and complete mission segments separately. Optional long duration/refueling transfer much later.

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.
Not a bad idea.

It could be used in place of either extending tankage into the trunk (to shorten dev time and maintain commonality with Dragon 2. Could be jettisoned using the same cargo payload brackets before landing, like a "crasher stage".

Then you could use  over-expanded, verticalized SuperDracos  on the capsule to orbit.

A similar arrangement using stacked SM's on the Starliner, launched also in a fairing with a mass reduced outer skin and thrust structures might also give the same capability.

The advantage of launch under a fairing for both approaches is that you can have things like fixed landing legs, additional PV panels, high gain antenna's, and other booms. This greatly improves both development time and lander performance on LLO.

Quote
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).

You're again forgetting that this is a dedicated lunar lander. See thread title. Read OP!

All the derived CC vehicle is doing is functioning as the LM did for Apollo. Orion is still the crew's ride!

add:

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.
« Last Edit: 02/21/2017 07:32 PM by Space Ghost 1962 »

Offline MATTBLAK

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #11 on: 02/21/2017 08:07 PM »
You post above is epic and covers all the details - thank you. I too think a dedicated Lander is needed. Starliner under most any circumstances is not going to 'cut the mustard'. I only mentioned a Dragon Lunar Lander because I'd used those details in a couple other threads and included the details here, mainly for comparison.

I know that Northrop-Grumman was tapped by Golden Spike to design a basic, 2x person Lunar Lander. Some sort of derivative of this design might still be fairly close to what's required.

http://www.americaspace.com/2013/05/09/northrop-grumman-completes-golden-spike-lunar-lander-study/
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Offline RonM

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #12 on: 02/21/2017 08:39 PM »
My 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.

Offline russianhalo117

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #13 on: 02/21/2017 08:51 PM »
My 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.
All shuttle programme OMS engines were transferred to the SLS program for use as the SM Main engine be it an American or European SM.
« Last Edit: 02/21/2017 08:58 PM by russianhalo117 »

Offline Lars-J

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #14 on: 02/21/2017 11:33 PM »
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.

Then who is? AeroJet Rocketdyne?  :) I would argue that the primary american rocket engine development expertise now *firmly* resides at SpaceX and Blue Origin. For both cryo and hypergolic engines. Both have developed several high performance engines in the last decade, and on a small budget.

AeroJet Rocketdyne is more of a caretaker of older technology at the moment. (RS-68 being their last real development, 15 years ago) And to get them to do anything, you need to back up a truck with hundreds of millions of $ at a minimum.
« Last Edit: 02/21/2017 11:38 PM by Lars-J »

Offline GWH

OK let's try this, off the shelf rocket stages, assumption would be that a minimal spacecraft bus is added in for orbital maneuvers.
Minimally modified Dragon 2, heatshield & parachutes stripped out:
- Dry mass 5570 kg
- Prop mass 1815 kg
- Total mass 7385 kg
- Additional Payload 1000 kg
- LLO injected mass 8485 kg

Descent Crasher Stage: Castor 30A
- Dry mass 1220 kg
- Prop mass 12815 kg
- Sat bus mass 200 kg
- Total mass 14235 kg

Ascent Stage: Delta II Upper Stage (this could be stuffed partially in a D2 trunk)
- Dry mass 950 kg
- Prop mass 6000 kg
- Total mass 6950 kg

Dragon 2, Delta II US, and Castor 30A are all injected into LLO by 3 separate Falcon Heavy's.  Complicated in orbit rendezvous of all 3 components would be required.
Castor 30A would be an expendable FH flight, both D2 & DeltaII stage could see maybe side booster reuse.

Sequence:
Castor 30A burns to depletion slowing complete stack from LLO - dV 1.68 km/s
Castor falls away
Dragon landing engines consume 1250 kg prop to land the stack on surface - dV 0.2 km/s (1.88 km/s total)
Dragon lifts off with landing engines consumes 400 kg prop - dV 0.07 km/s
Delta II US's AJ-10 burns to completion and falls away - dV 1.81 km/s (1.87 km/s total)

I think here my dV numbers are probably not totally right as I don't have any allowance for orbital maneuvers.
*Assuming of course my ad-hoc spreadsheet isn't totally flawed.

3 flights of FH with at least 3 center cores and 2 boosters being expended is probably getting pretty expensive (3 x $135M?) but I'm sure a lot of missions could be bought with money saved by developing a multi-billion dedicated lander.  The Dragon 2 and Delta II Upper stage stack with payload mass 15,355 kg which is either at the limit or just barely above what a FH can do expendable.  Might be possible to do in 2 flights.

** A Centaur with around 8,500 kg prop in LLO could get a D2 down and back again with the D2 performing the necessary landing and lift off burns, cutting the required flights down but a single Atlas 551 couldn't lift it there (max payload to escape = 6109kg, lunar would be lower).  This actually works out to very similar prop load as would be required for a centaur crasher + delta II ascent stage.
*** A Raptor powered Falcon Heavy Upper stage could probably also perform the task on FH with various levels of expendable cores depending on prop load.  Just sayin'.

« Last Edit: 02/22/2017 05:33 AM by GWH »

Offline Steven Pietrobon

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #16 on: 02/22/2017 07:22 AM »
AeroJet 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.
« Last Edit: 02/22/2017 07:23 AM by Steven Pietrobon »
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Offline Lars-J

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #17 on: 02/22/2017 03:41 PM »
AeroJet 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. As for AR-1, they are spending minimal amounts while waiting for that truck of cash to arrive. I'm skeptical.

Obviously they CAN do engines, just not as well as others these days. They bought up and merged with every traditional liquid propulsion maker and have a culture of expecting to be the default engine choice.

Offline Steven Pietrobon

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #18 on: 02/23/2017 04:27 AM »
J-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.
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Offline MATTBLAK

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #19 on: 02/23/2017 04:58 AM »
That's what I was thinking! It's a real pity this engine isn't being used. But then again; some of the products of Project Constellation often get slammed, even when it's not entirely rational to do so.
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