[Spaceships] TL10^ multipurpose orbital shuttle

[Agemegos]

Originally Posted by thtraveller

I still get 4.36. Wings?

Arithmetic. I've fixed it now.

The big issue is this: over half the cost of the vehicle is an air intake and compressor to make one engine into a ram-rocket. Incredulity aside, you have to wonder whether the air cruise capability is worth the cost.

[thtraveller]

Originally Posted by Agemegos

The big issue is this: over half the cost of the vehicle is an air intake and compressor to make one engine into a ram-rocket. Incredulity aside, you have to wonder whether the air cruise capability is worth the cost.

Another instance where it makes you want to go to fractional modules. A one-third air ram (of any kind) somewhere would be OK. Swap round the desalination plant and a cargo hold and replace the cargo hold with 2 small fuel tanks and a small air-ram in a single module perhaps?

[Agemegos]

Originally Posted by thtraveller

Another instance where it makes you want to go to fractional modules.

Actually, it's an instance that makes me want to rule that cost multiple of a ram-rocket is 1.5, not 5. In fact, I think that this instance makes the issue stick out far enough to be considered an erratum. We have an air intake, a compressor, and some bypass conduit of negligible mass that cost as much as a 30-ton spaceplane.

[Pomphis]

Originally Posted by Agemegos

The big issue is this: over half the cost of the vehicle is an air intake and compressor to make one engine into a ram-rocket. Incredulity aside, you have to wonder whether the air cruise capability is worth the cost.

IIRC one reason to for the US to build the B-1B instead of the B-1A was the cost of the variable air intakes needed for mach 2. VE2 gives x10 cost multiplier for winged designs. Brute force vertols are significantly cheaper in VE2 than those flying with aerodynamic lift. Designing and building for aerodynamic flight can apparently be seriously expensive.

And is it really that costly ? I mean, in today´s money we are talking a small plane or helicopter, not even a mid-size business jet. On board of a ship that´s apparently not mass produced like liberty ships, but not much more common than a USCG cutter. The USCG spends more on it´s on board helicopters.

[Pomphis]

Originally Posted by Agemegos

We have an air intake, a compressor, and some bypass conduit of negligible mass that cost as much as a 30-ton spaceplane.

Plus presumably a redesign of the entire surface of the shuttle for the air intake to work properly at a great range of speeds and atmospheric pressures.

[Agemegos]

Originally Posted by Pomphis

Plus presumably a redesign of the entire surface of the shuttle for the air intake to work properly at a great range of speeds and atmospheric pressures.

Yes, but if you install a jet engine in your space plane it also has an air intake that has to work through the same range of conditions, but you get the whole job done for $300K instead of $2.4M, and a jet engine into the bargain. And a similar airframe design, air intake, compressor, and bypass conduit cost only $600k on an NERVA nuclear thermal rocket.

[Peter Knutsen]

Originally Posted by Agemegos

Actually, it's an instance that makes me want to rule that cost multiple of a ram-rocket is 1.5, not 5. In fact, I think that this instance makes the issue stick out far enough to be considered an erratum. We have an air intake, a compressor, and some bypass conduit of negligible mass that cost as much as a 30-ton spaceplane.

You could rule that the ship's (or boat's) designer gets a choice of a very efficient ram-rocket if he uses the x5 cost multiplier, or a somewhat nerfed ram-rocket for the x1.5 (or perhaps more reasonably x2) multiplier. The nerfed version has full performance in space or when otherwise using its own fuel, but when it uses the ram function performance is somewhat reduced. Perhaps acceleration halved, or reduced to 2/3?

[thtraveller]

For atmospheric craft you also want air-rams that only operate in fuel-less mode. So you should be able to save yourself a chunk of cash on those too.

[Adina]

Originally Posted by Agemegos

Type 64 MkI orbital shuttle (TL10^ limited-superscience)



The manufacturer offered "fuselage tanks" that could be fitted in the cargo hold to carry an extra eight tons of water, but in practice these only ever used for conveying cargoes of fuel to the mother ship.

You might want to put a few of these in the hanger bay of the

Necho if you only carry two shuttles.

Jeff