Author Topic: Dragon 2 or Starliner derived dedicated lunar lander?  (Read 24131 times)

Online MATTBLAK

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #20 on: 02/23/2017 09:42 PM »
Yes, though since I've already talked about Dragon and Starliner as prospective Lunar Landers, I don't have much to add. Though, I would ask if anyone knows much about their crew life support systems? And therefore, what about performing EVAs from them?
« Last Edit: 02/23/2017 09:43 PM by MATTBLAK »
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Offline Lars-J

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #21 on: 02/24/2017 06:24 PM »
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.

I just wanted to respond to this to clear up this - but in the interest of keeping the thread on topic, we should continue this elsewhere.

Yes, looks like I didn't have that right, I guess I transposed CxP issues on to J-2X. But as far as budget issues, the scope of the engine significantly increased when the project morphed from being a J-2 upgrade to a virtually new engine. I have a recollection (which could be mistaken) that the project was sold as being a mush faster/cheaper than it turned out to be. That is all.

Offline GWH

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 dV
Delta 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 dV
Dragon II lander (1750kg prop burn) 0.54 km/s dV (1.87 dV total)
Landed Lunar payload: 1000 kg

Same 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 kg
In 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.

Offline Negan

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #23 on: 02/25/2017 10:43 PM »
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 dV
Delta 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 dV
Dragon II lander (1750kg prop burn) 0.54 km/s dV (1.87 dV total)
Landed Lunar payload: 1000 kg

Same 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 kg
In 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.

Offline Space Ghost 1962

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #24 on: 02/25/2017 11:37 PM »
Keep in mind you can have as long a trunk as you like, and integrate within that trunk propulsion.

And no, you don't integrate anything off Earth. You dock with Orion, do the mission to the surface and back, and discard.

After you've built a mission architecture and vehicle off that, then we'll talk about refueling from excess capacity and storage on other vehicle.

Aestus is still current, and there are stages available with it. There are a few others also in and outside of the US that also can be used.

Here's the difficulty with trunk based propulsion integration - staying within the bounds of what you can and can't do.

You can integrate and fuel a pallet/stage separately. Then you encapsulate it in the trunk while integrating "Dragon 2 Lander" derivative vehicle. Then you encapsulate in fairing. Then you integrate payload on LV. Launch to LLO and await Orion. On landing, you can burn coaxially for descent and braking, then jettison BEFORE landing.

Similar for Starliner.

Anything that breaks this CONOPS won't work for this thread. And could never operate/test/be flown.

Oh, and for checkout with ISS, the pallet/stage is safed. It will be jettisioned/disposed after test and before redocking with ISS.

Another thing. Look at Apollo 9's checkout for the LM. Note the spacewalk back in the event of a docking malfunction. That is a test that can also be done at the station.

Also, one could perform the equivalent of the Apollo 10 by having two landers on LLO - one to simulate landing, then  at the last moment abort and return on ascent engines. Following that, one could take the second and complete the landing. Then you'd have flight history before the initial landing.


Offline GWH


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.

No. Single launch on expendable Falcon Heavy.  But its a one way trip without on surface refuel.
« Last Edit: 02/26/2017 04:48 AM by GWH »

Offline GWH


And 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

Offline Patchouli

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #27 on: 02/26/2017 05:19 PM »

And 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
A Dragon V2 made to land on the lunar surface with enough fuel to get back to LLO would likely come in at 45 metric tons.

Interestingly if you made a separate lunar vehicle with composites you probably could make a landing vehicle both lighter and roomier than the original LM.

SS1 minus it's wings probably could make lunar orbit and had a loaded mass of 3600kg with some extra propellant reserves I'd say 4000kg which means the entire lander would be 12,000kg.
Which shows why they choose lunar orbit rendezvous in the first place.

Though for a lunar lander I'd use something like Xcor's 5M12 for landing and the XR-5K18 for the ascent propulsion.

Might be be able to make the lander single stage if the Falcon Heavy US is used as a crasher.
« Last Edit: 02/28/2017 07:13 AM by Patchouli »

Offline Space Ghost 1962

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #28 on: 02/26/2017 07:18 PM »
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.

There are studies for refuelable lander concepts. These combine ascent/descent phases with the same vehicle/engines and rely on more delta-v and high iSP engines/nozzles/propellant/tank volume that both Dragon 2 and Starliner don't possess with SuperDraco and Bantam engines used for abort. Which gets back to my "neither is up to the propulsion task" post above.

So you have two "rapid development" options - separate ascent/descent vehicles with precision landing, and ascent vehicle with crasher stage. Neither directly yields a reusable lander in LLO.

For that, you'd need larger delta-v, and because of the weight growth, more iSP to make it useful. Playing with a kerolox environment like SX has in abundance is a no-go, as they have not demonstrated the long lived and ultra reliable needs that traditional stored propellant already have.

However, if you design your mission architecture such that you can "phase in" moving to a reusable architecture, then you can prove with an expendible component for speed and then migrate to the reusable.

The key advantage of that approach is to flight prove ascent engine capability soonest, with the capability for descent as well, and then revise the ascent configuration to provide enough to allow both ascent and descent. Followed by a means to refuel  from excess SLS capability, tanker, or other cargo capability.

The lack is in propulsion with storable props and long duration SC.

Offline GWH

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.

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.
-If regular lunar missions and a base were happening a more mass efficient cargo delivery system would need to be developed, and cargo would probably be far more frequent than crew.  Long duration cryogenic stages like ACES would be ideal for this + ISRU.
-With something like the ACES in operation the 6-7 mt of hypergol prop per ascent stage can be delivered to LLO lunar surface for cycling landers.  Although an alternative would be to use an ACES as a "braking tug" from LLO. 
-After this point a cost/benefit analysis would need to be done to decide whether a new all cryo fuel manned lander would be worth the added cost of development. 


I think that by tweaking the scenarios I proposed previously can probably get a single FH launch to place a Dragon 2 w/ fueled ascent stage in LLO.  Such as: full N2O4/MMH architechure, rely on a little more cargo transfer from Orion,  varying prop loads so the Dragon 2 does less of a landing burn at the Superdraco ISP (also include a small boost to ISP by larger nozzles) and perhaps using the Aestus II.

Offline Zed_Noir

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #30 on: 02/27/2017 03:39 AM »
@Space Ghost 1962

Does for this thread. That a proposal for a single crew fully automated and very austere lander is allow?

Offline Space Ghost 1962

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #31 on: 02/27/2017 06:55 AM »
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.

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. 

Definitions here. A "crasher" stage is depleted on descent, has no props to land, and you discard/"crash" it well away from where you land, outside of debris cone (large due to low lunar gravity). It's sole purpose is to preserve the lander's props/engine for ascent.

So no, you don't reuse it. That's the whole point.

Secondarily as to "docking" or integrating on orbit a stage with the vehicle (I'm assuming something like Gemini/Agena) - integrating a stage is nontrivial, as well as docking it. The whole point of this is to minimize the complexity of the lander from a known, qualified crew vehicle.

Where it will get exciting is on precisely two fronts - propulsion and mass reduction. Like exactly with the LM.

Which is what I thought all the discussion would center on here.

Essentially, with modern materials that Dragon/Starliner use/can use - can we drastically reduce the weight even more than Grumman did with LM - which was the limiting factor in how soon the LM could "fly". Remember - neither Dragon nor Starliner need to have the same thrust structures and mass distributions, because they would be used entirely in space, in the lunar environment, for a short time with human occupants, and launched under a fairing.

For this, the LM had practically a metal foil for walls, it was basically a balloon.

Quote
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.


Dragon can already land on the moon. Ask Musk. No crasher stage needed.

I think you could also do this with Starliner if repurposed. Yes it would need to be lighter.

Quote
-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.

Nope. A nonstarter because of the need for multiple dockings with Orion, the fact that the stage could not arrive, or arrive and not be usable, or in the intervening time if autonomously "docked" lose capability before Orion arrives. Too many things to go wrong and too few contingencies.

A better plan is to use the components of a stage that fit within the trunk, perhaps on a pallet, that is integrated with the Dragon's flight systems for SC integrity/GNC/jettison. Since it would be minimally used for (likely) two burns - Powered Descent Initiation and Braking Phase / "High Gate", these axial burns only require the CG of the combined vehicle to thrust through, as opposed to the 6DOF needs of an independent vehicle operation!

So you have little idea of how much more complex things can get.

Quote
- Follow up missions can refuel the D2 & ascent stage, along with a new crasher stage.

Nope - refueling architecture builds off of vehicle attachment and requires tankage in the supplying vehicle as well as excess payload mass. As an example of how this could work - Orion could dock with a module that would effectively be a docking tunnel of a minimal sort with a thrust structure to support tankage around it, and the CC derived lander would dock and accept fluids from ancillary docking extensions on the other end. Such would be extracted after LOI similar to the LM extraction of Saturn IVB, and initially docked with the CC derived lander vehicle for fluids transfer (note vehicle is unoccupied while fueling!), then undocked, discarded, and the CC derived lander would then redock for astro transfer.

This has the benefit of reusing all the capabilities already designed into the existing vehicles for later use unmodified.

And, note that it's a follow on. So scope doesn't creep.

Keep in mind this is meant as being entirely done and tested in a few years, not a few decades.

It is extremely hard to do HSF vehicles. Just minor mods require considerable work to be redone. This thread is an attempt to have extremely narrow scope to explore a real opportunity to do a real mission with real budget on a real time schedule.

So its a case of doing as little as possible, because even that could be too much.

Not playing rocket fabulist. There are plenty of threads for that here too.

Online TakeOff

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #32 on: 02/27/2017 01:17 PM »
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.
« Last Edit: 02/27/2017 01:18 PM by TakeOff »

Offline A_M_Swallow

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #33 on: 02/27/2017 02:47 PM »
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.

A ground vehicle like the MMSEV able to take astronauts from the landing site to the village would mass 5-6 tonne. This can also be pre-landed.

During landing and take off spacecraft throw up a considerable amount of dust that will sand blast anything in range. Consequently the landing site and the habitats are likely to be in different craters.

Offline CJ

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #34 on: 02/28/2017 06:30 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.

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. 

EDit: Here's one flaw  I just found; I used 4.4 kps as the needed delta/v to get from low lunar orbit to the surface and back. It's not, it's 1.78 kps each way, so, 3.56 kps. All that means is I understate the cargo capacities above, and/or have more margin. 
   
« Last Edit: 02/28/2017 06:33 AM by CJ »

Offline GWH

Let's work backwards here, starting point: single FH payload of Ascent/Descent stage and "Dragon Derived" crew capsule.
Assumptions:
- max FH payload to lunar orbit 15,000 kg 
- Delta V to lunar surface and back: 3.74 km/s (minimal)
- Payload: crew, space suits, supplies 1,00 kg

Requirements for total spacecraft dry mass and prop load for dV3.74 +0.02/-0:
Dry mass is for spacecraft only, the 1000kg payload is included in all calcs. 
ISP         Prop        Dry Mass   
275s       12.3mt      2.7mt      
320s     11.5mt   3.5mt
340s       11.15mt   3.85mt

Challenge is, starting from the Dragon 2, slimming down mass sufficiently to fit in those bounds.  Rocket stages are shown as reference only to compare general masses of propulsion stages.
Dragon 2 "stock" dry: 6,350 kg
Dragon 1 cargo dry: 4200 kg
Delta II US w/ AJ-10: 950 kg dry, 6000 kg prop
Ariane G US w/ Aestus: 1127 kg dry, 9700 kg prop

« Last Edit: 02/28/2017 07:07 PM by GWH »

Offline clongton

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #36 on: 02/28/2017 07:06 PM »
Are the Super Dracos on the Dragon pressure or pump fed?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline GWH

Pressure fed. 

Offline clongton

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Re: Dragon 2 or Starliner derived dedicated lunar lander?
« Reply #38 on: 02/28/2017 07:33 PM »
Pressure 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?
« Last Edit: 02/28/2017 07:34 PM by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline GWH

Pressure 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?

Are your questions specific to SpaceX's Dragon design or hypothetical ascent/descent stages based around the capsule? 

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