Dragon 2 or Starliner derived dedicated lunar lander?

[Negan]

Don't use heavy suit ports. Setup a temporary light plastic barrier inside the lander. You still use the same concept as the suit ports, but still only one hatch out of Dragon. You can collapse it around the dusty suits when not in use.

Maybe, yes. I had a similar idea but didn't use it because I thought no one would like it.

I really like the suit ports too, but since they are basically airlocks in of themselves I'm assuming they are heavy. IMO the best lander would be built around the SEV cab if it's abilities are to be believed, but the other's might leave room for growth beyond a two person crew.

[Rocket Science]

Don't use heavy suit ports. Setup a temporary light plastic barrier inside the lander. You still use the same concept as the suit ports, but still only one hatch out of Dragon. You can collapse it around the dusty suits when not in use.

Maybe, yes. I had a similar idea but didn't use it because I thought no one would like it.

I really like the suit ports too, but since they are basically airlocks in of themselves I'm assuming they are heavy. IMO the best lander would be built around the SEV cab if it's abilities are to be believed, but the other's might leave room for growth beyond a two person crew.

Yes, a few year back we toyed around with an idea with that, but we are constrained on this thread by Dragon or Starliner...

[Negan]

Yes, a few year back we toyed around with an idea with that, but we are constrained on this thread by Dragon or Starliner...

Suit ports are the optimal solution for moon dust. Pairing with a suboptimal solution for a lander just doesn't seem right to me. I see a suboptimal solution like a collapsible mud room with a vacuum hose and filtration system for the dust as a better fit. We already know the dust won't kill you so going with experimental and cheap shouldn't be an issue.

[Space Ghost 1962]

Do the research on the suit ports, find the weight. Since the vehicle will fly under a fairing, you don't have to stow/clean/enter/exit the suits, which also takes weight - so it's not all added weight.

The suit ports also mean you have more surface time. And, if the suits are lower to the surface, less weight/trouble to to EVA, operations can be automated to prepair/consumables/integrity check.

You could also have shorter, multiple sorties or hops. If you were planning surface ops following stratigraphy, layout of a base perimeter/line runs, or charting/sampling lunar ice in crater shadows, you could cover a lot of ground in a short space of time that way.

So for a refuelable, reusable, multi-sortie mission design ... you might be able to gather enough "results" in a single month LLO mission, that your next mission in 6-12 months might be able to deploy to the same locations visited, instruments/mining equipment/base components. Or have independently flown cargo landed at those sites in the intervening time.

A powerful mission architecture built out of existing developed componentry.

Enough "blue sky". Propulsion? Weight? Mission planning? Logistics? Get off your hands.

[Rocket Science]

Yes, a few year back we toyed around with an idea with that, but we are constrained on this thread by Dragon or Starliner...

Suit ports are the optimal solution for moon dust. Pairing with a suboptimal solution for a lander just doesn't seem right to me. I see a suboptimal solution like a collapsible mud room with a vacuum hose and filtration system for the dust as a better fit. We already know the dust won't kill you so going with experimental and cheap shouldn't be an issue.

Hard to get any "less sub-optimal" than having no lander at all...

[Negan]

Do the research on the suit ports, find the weight. Since the vehicle will fly under a fairing, you don't have to stow/clean/enter/exit the suits, which also takes weight - so it's not all added weight.

So the only available suits are outside of the spacecraft and only available through the suit ports. I didn't know the technology was that far along for that to be acceptable, but I'm glad it is.

Edit: Have to wonder why the Altair design utilized an airlock instead of suit ports though.

[Negan]

Do the research on the suit ports, find the weight.

1,904 kg

http://www.spacearchitect.org/pubs/AIAA-95-1062.pdf

[Space Ghost 1962]

Do the research on the suit ports, find the weight.

1,904 kg

http://www.spacearchitect.org/pubs/AIAA-95-1062.pdf

Good - you did the first step for evaluating a "trade".

Next step is to find the weight of everything the suit port would displace. So, find the suit weights, and all of the suit related equipment/brackets/lockers/replenishment/hoses/volume/etc. Hint: you can find in Orion/Apollo manifests some of this, and SWAG the rest.

So you create a total weight/cost/volume/... of w/ and w/o suit ports. Now you know the trade. My bet is that the suit lock will be slightly better due to tighter integration having less mass growth. Also, realize that the suit lock is a true airlock, unlike LM/CSM evacuating/re-pressurizing entire volume - which means cost of replenishment is part of the trade ...

If "flags and footprints", you are doing 1-2 of these a sortie. If you are actively working on a work site, you might be doing 10-20 of these a sortie. Now we get into mission planning and mission operations details - granularly.

You might be surprised by how much the totals are here.

[clongton]

Edit: Have to wonder why the Altair design utilized an airlock instead of suit ports though.

Because the designers were constrained to what had already been done.
Innovate only where absolutely necessary.

[Negan]

If "flags and footprints", you are doing 1-2 of these a sortie. If you are actively working on a work site, you might be doing 10-20 of these a sortie. Now we get into mission planning and mission operations details - granularly.

You might be surprised by how much the totals are here.

I'm surprised that you would do 10-20 sorties in a max 4 day mission with only a expendable Dragon or Starliner derived lander.

[Negan]

Edit: Have to wonder why the Altair design utilized an airlock instead of suit ports though.

Because the designers were constrained to what had already been done.
Innovate only where absolutely necessary.

Or they decided that leaving the suit ports on the SEV was the better choice.

[Rocket Science]

Edit: Have to wonder why the Altair design utilized an airlock instead of suit ports though.

Because the designers were constrained to what had already been done.
Innovate only where absolutely necessary.

Or they decided that leaving the suit ports on the SEV was the better choice.

You might try to read through some of the older threads... Here I have a rover driving up to dock with a reusable  horizontal lander. Your suits would be on it... But that takes us OT again...
https://forum.nasaspaceflight.com/index.php?topic=27449.60

[Space Ghost 1962]

If "flags and footprints", you are doing 1-2 of these a sortie. If you are actively working on a work site, you might be doing 10-20 of these a sortie. Now we get into mission planning and mission operations details - granularly.

You might be surprised by how much the totals are here.

I'm surprised that you would do 10-20 sorties in a max 4 day mission with only a expendable Dragon or Starliner derived lander.

Upthread is described a reference orbit with a maximum mission (month LLO). This would be a topmost goal for a reusable lander. The point is to be able to rank missions/architectures/vehicles/devtime/... against each other, by figure of merit.

By necessity of the CC derived base, whose abort capability represents a base propulsion for orbital ascent, one chooses a reference orbit that can a) be achieved/maintained, b) puts the burden on the earth transit crew vehicle, and c) allows the largest number of surface access opportunities to visit.

This allows an expendable, minimal mission (likely few days) to be flown with margin/contingencies. If it is flown, follow-on reflights w/option for reuse, incrementally uprated to the maximum suggested, represent a compelling goal that far exceeds Apollo program. Perhaps a reason to be considered, and worth the effort?

And it lets others decide what the surface objective(s) might be? The same architecture could build a base, prospect/mine/produce/launch propellant/ISRU/other, learn the story of lunar formation/processes/resource/access, ...

An excuse to get serious. Back on topic of "Dragon 2 or Starliner derived dedicated lunar lander?".
Propulsion? Mass? Concept? Trades?

[A_M_Swallow]

Would the cabin be an Earth reentry capsule or a simpler structure?
The life support (ECLSS) and control systems could be the same ones used in a CST-100 or Dragon V2 and put in say a square box. The appropriate sized fuel tanks for lunar gravity can then be fitted along with landing lidars.

[lamontagne]

How about a Dragon 2 with an extended trunk, as discussed in NSF, and a tanker stage in moon orbit?

Two launches, one for the tanker, and one for the Dragon2 with an extended trunk.  The tanker is launched first into moon orbit. The Dragon 2 is launched, and uses a propulsion module fitted into the extended trunk to reach moon orbit.  It refuels and lands.  It takes off, refuels again, and returns to Earth.

Does this violate the terms of the challenge?

[TomH]

Originally the LEM was supposed to have a second docking port in front but it was a tight squeeze with the PLSS.

It was eliminated to reduce mass.

[sdsds]

This is a great thread. Rendezvous in LLO seems like a highly logical way to decompose the overall problem and allow two different efforts (perhaps one public and one private) to cooperate on the endeavor.

It leads to both halves of the solution (the crew capsule and the lander) addressing a shared propulsion challenge: lunar orbit insertion. It's a challenge because the propulsion system needs to function days after launch and with current technology that pretty much means hypergolic propellants which pretty much mean comparatively low Isp and thus higher (IMLEO) mass.

From Apollo we tend to think an AJ10 or similar engine is appropriate for this: 43.7 kN thrust; 319 s vac. Isp; 6 minute LOI burn duration. And gosh, Orion uses pretty much the same engine as Apollo. Could someone review what's expected for SuperDraco rated thrust, vacuum Isp, and rated burn duration?

[GWH]

T Could someone review what's expected for SuperDraco rated thrust, vacuum Isp, and rated burn duration?

According to the Wikipedia entry the stated chamber pressure of the SuperDraco is 6900 kpa, which seems to suggest it would have a pretty high ISP with a much larger nozzle.  I've been meaning to figure out what that might be but have a lot of "homework" to do on the matter to get an answer.

[envy887]

T Could someone review what's expected for SuperDraco rated thrust, vacuum Isp, and rated burn duration?

According to the Wikipedia entry the stated chamber pressure of the SuperDraco is 6900 kpa, which seems to suggest it would have a pretty high ISP with a much larger nozzle.  I've been meaning to figure out what that might be but have a lot of "homework" to do on the matter to get an answer.

About 340-345 seconds with a highly expanded nozzle extension. This is consistent with other pump-fed NTO-MMH vacuum engines that operate at similar chamber pressures (e.g. Aestus II).

The SuperDraco is designed for short duration burns, but it is regeneratively cooled and designed for reuse so longer duration burns are probably feasible. The nozzle extension would probably need to be radiatively cooled.

[GWH]

About 340-345 seconds with a highly expanded nozzle extension. This is consistent with other pump-fed NTO-MMH vacuum engines that operate at similar chamber pressures (e.g. Aestus II).

The SuperDraco is designed for short duration burns, but it is regeneratively cooled and designed for reuse so longer duration burns are probably feasible. The nozzle extension would probably need to be radiatively cooled.

What nozzle diameter would be required?  I'd like to put a rendering together for discussion purposes based off the known pressure vessel dimensions.

Also, what happens to the ISP if the SD's are ran at a lower throttle setting to allow for adequate expansion with smaller nozzles?  At 71kN max thrust per engine even 4 SD's would be more than enough rather than 8.