Is there a preliminary Spacex Dragon XL addon yet?

[llarian]

Just wondering if someone is working on one now that NASA has made the announcement of using only SpaceX to supply Gateway.

 

[PhantomCruiser]

No solid information is available yet, but I'd be willing to bet the cost of a soft drink to say that someone is already working on a mesh.

 

[francisdrake]

I think it is a little early for this. There is very little information published, basically only one picture and a short NASA announcement.
Looked into a few forums, like NasaSpaceflight.com.

Then I tried to figure out the size, possible mass and performance figures.
I ended up with guessing this:

- Diameter 3.7 m, length 8.6 m
- The pressurized section is about the size of the F9 2nd stage oxygen tank, dia 3.7 x 3.6 m long.
- Dry mass estimated 6.8 ton, payload 6 ton (requirement is > 5 ton), fuel mass 5 ton.
- This gives a dV of 900 m/s, consisting of 100 m/s midcourse correction, 400 m LOI capture and additional arbitrary 400 m/s for orbital maneuvering or pushing the gateway around.
- Then I launched a boilerplate model with this data on a FalconHeavy. In the all-expendable configuration it achieved TLI with 4 ton fuel left in the 2nd stage.
- Lunar capture burn into a highly elliptical orbit took about 1 hour with 4 Draco thrusters.

Feel free to have a look into the attached calculation sheet and give your comments. Some (or all) of my estimated values may be wrong.

 

[francisdrake]

Meanwhile I read the NASA requirement paper.

The minimum payload requirements is 3400 kg pressurized + 1000 kg unpressurized cargo. The maximum allowed docking mass to the Gateway is 15 ton. There is no trunk, external payloads are stored on the underside of the pressurized section.

So I scaled everything down a little, but keeping the pressure vessel size The total mass came down to 16 ton, which will be below 15 ton after the Lunar Orbit Insertion burn. As shown in the attached sketch a tunnel leads from the docking port through the engine and tank section to the pressurized storage.

It looks like this vessel will be very much different from other Dragon capsules. It may inherit some systems like engines, tanks, parts of the structure and the solar panels, but its design may be closer to other cargo vessels like the Cygnus or ATV.

 

[francisdrake]

I put together the meshes and data to a kind of 'boilerplate DragonXL' addon.
Feel free to try it. The launch scenario requires BrianJ's FalconHeavy rocket.

There is a Gateway station in Lunar orbit as a docking target. It is a nightmare to chase it.