Spacecraft average densities

[T.Neo]

Not sure if this should go here or in one of the Orbiter forums, please move it if you feel it would be better suited there.

As detailed here, a really quick and dirty way to figure out the mass of a spacecraft is to multiply it's volume by it's average density. Some of the example densities given are 0.28 ton/m^3 for commercial airliners, 0.35 ton/m^3 for fighter aircraft, 0.5-0.6 ton/m^3 for modern warships, and 0.9 ton/m^3 for submarines.

So if you lack a more in-depth study on what your spacecraft's mass would be, you can always do that. If not to the entire spacecraft, even to just a part of it.

However, I didn't see any actual spacecraft on the list, but Orbiter provides an easy platform to find out several values, since it contains meshes (from which volume can be deduced), a tool to measure the volume of the mesh, and multiple examples.

So;

STS orbiter- 0.088 ton/m^3

ISS- 0.074 ton/m^3

Mir- 0.175 ton/m^3

HST- 0.061 ton/m^3

STS ET- 0.011 ton/m^3*

STS SRB- 0.206 ton/m^3*

Leonardo MPLM- 0.058 ton/m^3

LDEF - 0.049 ton/m^3

S-IC - 0.05 ton/m^3*

And some fictional examples:

DeltaGlider- 0.049 ton/m^3

ShuttleA- 0.045 ton/m^3

Dragonfly- 0.101 ton/m^3

Carina- 1.666 ton/m^3

*Large portion of volume is dedicated to propellant.

Which yields some interestingly low numbers (except for Carina, which is denser than a submarine). Of course, I was a little less patient with Mesh Wizard, so the numbers aren't as accurate as they could be.

 

[N_Molson]

I'm amazed by the fact that Mir had more than twice the density of the ISS. Maybe because it was smaller ? Anyway it's well over the average of the other spacecraft.

 

[T.Neo]

Because it was an older and more primitive design, maybe?

 

[jinglesassy]

The orbiter is older then mir and it weighs less and it has to reenter and land.

 

[statickid]

Maybe the solar panels were heavier. I'm thinking about those images of the ISS having those really thin ones that somebody posted.

 

[francisdrake]

Some time ago I did a comparision table of rocket stages in fueled condition, looking on fuel types, engines, ISP, thrust, etc. The densities are to the right hand side of the table.

The 'apparent density' is the total mass divided by the cylindrical volume of the rocket stage. The 'prop. density' is the chemical propellant density, with fuel and oxidizer mixed in the required ratio.

The table is quite handy when designing fictional (but realistic) spacecrafts.

 

[Schimz]

Holy cow ! The DGex miss some weight. With fuel, I have the Shuttle's density.

Ok... I can haul 180t, it give me a lot of margin. The fatty will be more fatty...

... and I can hear whinings around the globe :lol: