Request Artemis landers

[gattispilot]

Thanks. That will be a help. I just got the array mesh done. I think I might add the solar tracking to it also.
Press a key and the array rotate up and expands and then rotates toward the sun.
Press a key it goes to the back to the start. collapse and tilt back down

 

[Gargantua2024]

So I searched with the official specifications of the ALPACA on the web, but not found anything (yet) on its specific mass, fuel, and propulsion. Maybe it is not released publicly yet.

Not going to specify the power of its engines at the moment...I'll just focus more on the position of its rocket exhausts and landing legs tomorrow

 

[gattispilot]

I can make the arrays into a vessel and just attach to the VB lander. I will try to get a new mesh later today or tomorrow. It will have new HGA and NO arrays on top

I wonder what that structure under the door is?

What to do about the ladder? Maybe the ladder is rotated into the hull?

 

[francisdrake]

Gargantua2024 wrote:
"So I searched with the official specifications of the ALPACA on the web, but not found anything (yet) "

Indeed nothing usable is published on the performance of the Dynetics lander, or even on the mission profile.
The type of fuel is in discussion, either being LH2/LOX or CH4/LOX. The best data I found is an educated guess on https://forum.nasaspaceflight.com/index.php?topic=50843.280

-- quote: --
Main ALPACA (launched dry, no drop tanks):
Payload (which is the crew module): 3.1t
Dry mass: 2.4t
...
Isp: 350s
Prop for descent (sub-LLO to surface: 1100 m/s): 4.7t
Prop for ascent (surface to NRHO: 2810 m/s): 6.9t

Single drop tank:
Dry mass: 0.4t (tankage, batteries, COPVs, RCS, docking and methalox lines)
Prop (pre-docking, one tank): 11.6t
Prop (start of descent, one tank): 5.8t
RCS prop (Isp=300s): 0.2t (40 m/s TLI to BLT NRHO)

Both drop tanks, after transferring prop to main ALPACA:
Dry mass: 0.8t
Prop: 11.6t (1730 m/s, NRHO to sub-LLO)
--end quote --

For the thrusters - if you find nothing better - you might use Morpheus-type thrusters
at 24 kN each. This gives an initial acceleration of ~10 m/s², which gives plenty
of engine-out capability in case one thrusters fails and the opposite one has to be shut down as well.

 

[Gargantua2024]

Gargantua2024 wrote:
"So I searched with the official specifications of the ALPACA on the web, but not found anything (yet) "

Indeed nothing usable is published on the performance of the Dynetics lander, or even on the mission profile.
The type of fuel is in discussion, either being LH2/LOX or CH4/LOX. The best data I found is an educated guess on https://forum.nasaspaceflight.com/index.php?topic=50843.280

-- quote: --
Main ALPACA (launched dry, no drop tanks):
Payload (which is the crew module): 3.1t
Dry mass: 2.4t
...
Isp: 350s
Prop for descent (sub-LLO to surface: 1100 m/s): 4.7t
Prop for ascent (surface to NRHO: 2810 m/s): 6.9t

Single drop tank:
Dry mass: 0.4t (tankage, batteries, COPVs, RCS, docking and methalox lines)
Prop (pre-docking, one tank): 11.6t
Prop (start of descent, one tank): 5.8t
RCS prop (Isp=300s): 0.2t (40 m/s TLI to BLT NRHO)

Both drop tanks, after transferring prop to main ALPACA:
Dry mass: 0.8t
Prop: 11.6t (1730 m/s, NRHO to sub-LLO)
--end quote --

Thanks! At first I thought they are going to use hypergolic N²O⁴/UDMH fuel just like the Apollo LEM, but it makes sense because it could not be used in reusable landers because of its corrosive nature.

For the thrusters - if you find nothing better - you might use Morpheus-type thrusters
at 24 kN each. This gives an initial acceleration of ~10 m/s², which gives plenty
of engine-out capability in case one thrusters fails and the opposite one has to be shut down as well.

The engines that are going to be used on the Nova-C? We'll go ahead with it then

 

[Gargantua2024]

Isp: 350s
Prop for descent (sub-LLO to surface: 1100 m/s): 4.7t
Prop for ascent (surface to NRHO: 2810 m/s): 6.9t

So without the drop tanks, the total propellant load of ALPACA is also 11.6 tons? If it is, this makes the total propellant load (with tanks) is 34.8 tons?

 

[gattispilot]

Redid the hatch. I might just make a simple interior. But looking at this image There seems to be platform around the top edge?

On the ladder what if I just make it so it extends out and then rotates down from the habitat module.

 

[francisdrake]

Good question. I will try to come up with a calculation sheet over the weekend.
Could you maybe give the main dimensions of the tanks from the model?
Diameter and height of internal and drop tanks would be interesting.

 

[Gargantua2024]

Main engines test...

 

[gattispilot]

main tanks are about 2.4 length x 1.77diameter. There are curved on both ends.
drop off tanks are: about 3.2 length and 2.1665 dia

 

[Gargantua2024]

I have an idea about how to implement the drop-tank effect on ALPACA:
Since VesselBuilder does not support asparagus staging yet (transfer fuel to the main tanks while firing), I'll set the main tank to its maximum propellant load (34.8 tons instead of 11.6 tons, until francisdrake came up with a better figure). Then, when it reaches 11.6 tons left, then the "depleted" tanks will be jettisoned automatically by using the "Events+Child Spawn+Type (Main Fuel Tank Lvl)" command

Will set the drop tanks as dummy payloads on VesselBuilder. However, the empty mass of each tank could not be set in this approach

 

[francisdrake]

Ok, here is the next iteration on the figures. It seems the lander is smaller than I expected. On the photos of the mockup, the interior looks quite spacious, but when comparing the tanks to the hab, it does not look so big. I assumed here a hab diameter of 2.4 m. Is that correct?

If the tanks are sized as mentioned above, their capacity is small if Methane / LOX is used. This has an average density of 573 kg/m³ only. I flew a few tests with this figures in a simple cfg-vessel. On descent the drop-tank fuel just ran out before landing. On ascent the onboard fuel is good for reaching an orbit with 3000 km apoapsis, which is still low for an NRHO orbit. I guess the figures will still need some tweaking.

 

[gattispilot]

Yes hab is 2.4. New meshes. droptank and main body witha VERY simple interior. No mfd,.....

https://drive.google.com/file/d/19gjdUNSsTshvYVVuwaoAxx3kmlOgshlL/view?usp=sharing

 

[francisdrake]

With the new meshes I was able to import them into my 3D modeller. Thanks!

When looking at the docking port used for scaling, I think the model is a little bit too small.
I used the "petal base diameter" as reference, as shown in the sketch below.
It should be 1200 mm, but was 954 mm.
The factor to increase the dimensions would be to 126%.

Assuming this scale-up, I revised the data sheet with the mass figures.
The masses increase slightly, the ratio of fuel/dry mass gets better.

 

[gattispilot]

Ok. So I should increase the scale by 1.26?

On the array: The best I can get it this. The animation has an issue. The 2 outside rods are scaled the rest is rotation.

 

[francisdrake]

Ok. So I should increase the scale by 1.26?

Yes, if that is ok for you.
This will also increase the width of the front hatch to 0.9 m, which is good when passing through wearing a space suit.

 

[gattispilot]

No problem. I will rescale the mesh.

 

[gattispilot]

nEW MESHES:

https://drive.google.com/file/d/1GQOZaza1GOv06mb5snkUAoIx8uPMEA37/view?usp=sharing

 

[Gargantua2024]

View attachment 22983 View attachment 22984

May I ask: does the propellant load stated applies to a single tank only or both two tanks?

 

[Gargantua2024]

Gateway test...

Even in its early concepts, the Artemis architecture looks magnificent already! (Note that the Dynetics HLS can only dock on the front port with its two drop tanks still in place)

EDIT: I can't command the two drop tanks to jettison automatically at 3800 kg propellant left for some reason. Temporarily made it a manual command instead