Author Topic: Dragon XL Derived Lunar Lander or Surface Hab  (Read 5342 times)

Offline Rocket Science

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Dragon XL Derived Lunar Lander or Surface Hab
« on: 04/05/2020 11:53 pm »
We performed some thought experiments on the use of CST-100 and Dragon as a Lunar Lander  a while back, so I'm throwing Dragon XL out for some ideas....

Edit: typo

https://forum.nasaspaceflight.com/index.php?topic=42363.0
« Last Edit: 04/06/2020 03:42 pm by Rocket Science »
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Offline Robotbeat

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #1 on: 04/06/2020 02:44 am »
We performed some thought experiments on the use of CST-100 and Dragon as a Lunar Lander  a while back, so I throwing Dragon XL out for some ideas....
I definitely think SpaceX probably proposed something similar to Dragon XL for their Lunar lander ascent stage for HLS.
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Offline su27k

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #2 on: 04/06/2020 03:34 am »
Doesn't the ascent stage need a lot of thrust? Dragon XL doesn't seem to a good fit for that.

Maybe a common chassis for both ascent and descent stage, since the two have a lot more in common, then a transfer stage based on Dragon XL?

This is assuming SpaceX wanted to bid Dragon/Falcon architecture for HLS instead of using Starship. If they do this, I think the key would be to reduce the # of unique elements, I don't think SpaceX would be willing to design 3 unique elements for HLS no matter how much NASA is paying them.

Offline Rocket Science

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #3 on: 04/06/2020 03:39 am »
We performed some thought experiments on the use of CST-100 and Dragon as a Lunar Lander  a while back, so I throwing Dragon XL out for some ideas....
I definitely think SpaceX probably proposed something similar to Dragon XL for their Lunar lander ascent stage for HLS.
Thanks Chris, I don't recall it... Must be the after effects of COVID-Brain+ age... If you have any links I would appreciate it as a starting point...
~Rob
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Offline yg1968

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #4 on: 04/06/2020 04:06 am »
Here is the link to the information that we have on the SpaceX Moon lander:
https://forum.nasaspaceflight.com/index.php?topic=48178.msg1947006#msg1947006
« Last Edit: 04/06/2020 01:28 pm by yg1968 »

Offline Rocket Science

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #5 on: 04/06/2020 04:43 am »
Here is the link to the SpaceX Moon lander:
https://forum.nasaspaceflight.com/index.php?topic=48178.msg1947006#msg1947006
Thanks yg, I'm thinking something smaller in scale and hypergolic at this point...
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Offline GWH

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #6 on: 04/06/2020 06:39 am »
I've been thinking on that. Take the port/fuel tank assembly of Dragon XL and stretch it, add canted super dragons on top, keep the same F9 tank derived pressure vessel below. Basically like a Dragon 2 with an under slung Dragon XL PV. Whether or not those cosine losses could be kept manageable would need to be drawn out.
If not feasible then base mounted engine would be used.

Utilize an expendable landing cradle that gets left behind, and a "super tug" crasher stage in place of a true descent stage. A NASA paper had some pretty reasonable scenarios where this could be done as a 2 stage architecture.

The idea would be a lander that could evolve into Starship and full reuse without scaring away the customer initially. First use a dedicated crasher stage, then a Starship unleashed stage, before finally doing away with the landing leg cradle and simply sitting on top of Starship as a lifeboat/abort system for a fully reusable lunar transport that meets all the NASA criteria.




Offline Rocket Science

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #7 on: 04/06/2020 08:21 am »
I've been thinking on that. Take the port/fuel tank assembly of Dragon XL and stretch it, add canted super dragons on top, keep the same F9 tank derived pressure vessel below. Basically like a Dragon 2 with an under slung Dragon XL PV. Whether or not those cosine losses could be kept manageable would need to be drawn out.
If not feasible then base mounted engine would be used.

Utilize an expendable landing cradle that gets left behind, and a "super tug" crasher stage in place of a true descent stage. A NASA paper had some pretty reasonable scenarios where this could be done as a 2 stage architecture.

The idea would be a lander that could evolve into Starship and full reuse without scaring away the customer initially. First use a dedicated crasher stage, then a Starship unleashed stage, before finally doing away with the landing leg cradle and simply sitting on top of Starship as a lifeboat/abort system for a fully reusable lunar transport that meets all the NASA criteria.
Sounds like were in the same ballpark...
"The laws of physics are unforgiving"
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Offline Robotbeat

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #8 on: 04/06/2020 02:02 pm »
I've been thinking on that. Take the port/fuel tank assembly of Dragon XL and stretch it, add canted super dragons on top, keep the same F9 tank derived pressure vessel below. Basically like a Dragon 2 with an under slung Dragon XL PV. Whether or not those cosine losses could be kept manageable would need to be drawn out.
If not feasible then base mounted engine would be used.

Utilize an expendable landing cradle that gets left behind, and a "super tug" crasher stage in place of a true descent stage. A NASA paper had some pretty reasonable scenarios where this could be done as a 2 stage architecture.

The idea would be a lander that could evolve into Starship and full reuse without scaring away the customer initially. First use a dedicated crasher stage, then a Starship unleashed stage, before finally doing away with the landing leg cradle and simply sitting on top of Starship as a lifeboat/abort system for a fully reusable lunar transport that meets all the NASA criteria.
I kind of wonder if SpaceX wants a Falcon 9/Heavy upper stage as a kerolox crasher stage like the Sovietsí plan. Pretty ambitious from a boiloff perspective, but a big performance boost.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Robotbeat

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #9 on: 04/06/2020 02:03 pm »
We performed some thought experiments on the use of CST-100 and Dragon as a Lunar Lander  a while back, so I throwing Dragon XL out for some ideas....
I definitely think SpaceX probably proposed something similar to Dragon XL for their Lunar lander ascent stage for HLS.
Thanks Chris, I don't recall it... Must be the after effects of COVID-Brain+ age... If you have any links I would appreciate it as a starting point...
~Rob
My guess, no links. But I think we know they didnít bid Starship.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline DreamyPickle

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #10 on: 04/06/2020 03:09 pm »
The dragon XL does not yet exist so it's premature to talk of "deriving" anything from it, at most it would be "related". Any project starting right now would be a derivation of Dragon 2.

There is not much information on Dragon XL but the only render appears to show it using only Draco thrusters. A lander would need a lot more delta-V and the obvious choice would be something based on SuperDraco but the changes would be very large.

Do you think SpaceX should invest in a vacuum-optimized hypergolic engine?

Offline Rocket Science

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #11 on: 04/06/2020 03:40 pm »
The dragon XL does not yet exist so it's premature to talk of "deriving" anything from it, at most it would be "related". Any project starting right now would be a derivation of Dragon 2.

There is not much information on Dragon XL but the only render appears to show it using only Draco thrusters. A lander would need a lot more delta-V and the obvious choice would be something based on SuperDraco but the changes would be very large.

Do you think SpaceX should invest in a vacuum-optimized hypergolic engine?
Nothing else exists as a lander either so what's your point...
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Offline Paul451

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #12 on: 04/08/2020 07:16 pm »
We performed some thought experiments on the use of CST-100 and Dragon as a Lunar Lander  a while back, so I'm throwing Dragon XL out for some ideas....

Given how little there is in common between "Dragon" XL and either of the actual Dragon capsules, I would think that XL shows the pointlessness in trying to derive a lander from existing capsules. If your brief was "what would a large volume cargo-Dragon look like for supplying Gateway?" would you have ended up with an expendable cylinder launched entirely inside a payload shroud, with the engines around the hatch, hatch at the bottom, unpressurised payload perched on top...etc...?

If SpaceX built a non-Starship lander for NASA's Artemis program, it would be a clean-sheet design that derived from the skills they've developed from Dragon/Falcon/etc/etc, not by trying to Lego the specific hardware. (A few subsystems, like engines, sure. But there'd be no large scale semblance.)
« Last Edit: 04/08/2020 07:17 pm by Paul451 »

Offline Robotbeat

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #13 on: 04/08/2020 07:25 pm »
The dragon XL does not yet exist so it's premature to talk of ...
Welcome to the forum!

Always glad to greet new members.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline TrevorMonty

Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #14 on: 04/08/2020 07:36 pm »
SpaceX don't have published engines for either descent or ascent stage. SuperDraco can handle landing  and ascent stage but aren't very efficient. Maybe case of buying somebody elses engines unless they have small methane engine we don't know about, which may well be case as I doubt Raptor was their first attempt at methane engine.

Offline GWH

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #15 on: 04/08/2020 08:35 pm »
SuperDraco's are really under expanded, limiting the efficiency. Chamber pressure is really quite high, with a proper vacuum nozzle they should be a high performing engine - albeit high overall mass due to their pressure fed nature and heavy tanks.

Offline Paul451

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #16 on: 04/10/2020 02:51 am »
SuperDraco's are really under expanded, limiting the efficiency. Chamber pressure is really quite high, with a proper vacuum nozzle they should be a high performing engine - albeit high overall mass due to their pressure fed nature and heavy tanks.

Theoretical NTO/MMH Isp in a vacuum is 336s, so if you could get anything close to that, you've drastically improved their fuel efficiency. The Apollo LM decent engine achieved 311s with a similar propellant mix.

Offline Zed_Noir

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #17 on: 04/10/2020 04:13 pm »
SuperDraco's are really under expanded, limiting the efficiency. Chamber pressure is really quite high, with a proper vacuum nozzle they should be a high performing engine - albeit high overall mass due to their pressure fed nature and heavy tanks.

Theoretical NTO/MMH Isp in a vacuum is 336s, so if you could get anything close to that, you've drastically improved their fuel efficiency. The Apollo LM decent engine achieved 311s with a similar propellant mix.

IIRC the Apollo LM engines runs on the denser Aerozine 50 fuel.

Offline Rocket Science

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #18 on: 04/10/2020 04:24 pm »
We performed some thought experiments on the use of CST-100 and Dragon as a Lunar Lander  a while back, so I'm throwing Dragon XL out for some ideas....

Given how little there is in common between "Dragon" XL and either of the actual Dragon capsules, I would think that XL shows the pointlessness in trying to derive a lander from existing capsules. If your brief was "what would a large volume cargo-Dragon look like for supplying Gateway?" would you have ended up with an expendable cylinder launched entirely inside a payload shroud, with the engines around the hatch, hatch at the bottom, unpressurised payload perched on top...etc...?

If SpaceX built a non-Starship lander for NASA's Artemis program, it would be a clean-sheet design that derived from the skills they've developed from Dragon/Falcon/etc/etc, not by trying to Lego the specific hardware. (A few subsystems, like engines, sure. But there'd be no large scale semblance.)
You're misunderstanding the thread OP. This has nothing to do with the other thread regarding CST-100 or Dragon2 capsules. Only derived from "XL" as a possibility for a Lunar lander or Hab...
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Offline ulm_atms

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Re: Dragon XL Derived Lunar Lander or Surface Hab
« Reply #19 on: 04/13/2020 12:21 am »
SuperDraco's are really under expanded, limiting the efficiency. Chamber pressure is really quite high, with a proper vacuum nozzle they should be a high performing engine - albeit high overall mass due to their pressure fed nature and heavy tanks.

SuperDracos could always use electric pumps instead of being pressure fed..shouldn't be as heavy tank wise and should be a lot more throttleable that way too I would think?  I looked everywhere but couldn't find it...what is the throttle range for them?

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