[Spaceships] Is This Legal?

[MatthewVilter]

Originally Posted by scc

OK, I'm kicking around the idea of a flyback booster, specifically a winged spaceplane.

Cool!

Originally Posted by scc

2) I'm thinking of using Jet Engines to get a better price per mps to orbit, the question is do I count the tank of jet fuel (Which I assume will be empty or nearly so) when calculating the Delta-V increase for chemical rockets?

Keep in mind that you will want some fuel in that tank for return and landing. Unless you plan to just glide in. In that case you can probably get away with a partially filled small tank at launch and dump whatever you haven't used by the time you run out of air.

Originally Posted by Ulzgoroth

Yes, no control room means no control. You could omit it if it uses a soft landing system, probably.

A small control room might suffice, though for atmospheric flight it might not.

It should be fine as long as you don't plan on any fancy flying, I would think. But yeah you do need a control room system for controlled flight (more for the RCS and control surfaces than for the room itself).

Originally Posted by Ulzgoroth

Definitely not.

If you want to account for those emptied tanks, you can multiply the number of tanks or rocket fuel by 20/(20-jet fuel tanks) and using that to calculate dleta-V. This isn't given in RAW, but it whoulc be correct.

And if you want to get really accurate numbers even for a rocket that still has partially full jet fuel tanks it is really not that hard to break out your slide rule. (Although doing that with a system where fuel tanks are 100% fuel and wings are a massless body feature might be overkill...)

Originally Posted by Ulzgoroth

It seems a bit questionable to allow a vessel that has a hughe hole in the front from where its forward parts flew away on their own to be streamlined at all.

Theoretically SpaceX will be doing this. But that is a conventional (non-winged) design that will be doing a vertical landing so in scc's case I think you're right. I mean I guess it would be possible to build an inline lift stage with wings that is aerodynamic after separation but...it would be hard.

For a piggyback configuration I would use an External Clamp. And if the spacecraft is also winged that is probably the way to go; stacking something with wings on the top of a rocket introduces a lot of instability.

An alternative is a Soft Landing System. I would be tempted to let something with wings use a smaller Soft Landing System...but that just brings us back to the streamlining problem.

Originally Posted by RogerBW

I think the "a ship one SM smaller as the front six systems of the big ship" approach is not necessarily appropriate for ships where the back section can operate autonomously. For the big plane with a spaceship on top, I'd be more inclined to have six systems of Hangar Bay or even Cargo in the midsection, or just a huge External Clamp (and change performance accordingly for the payload craft).

Agreed, as far as the clamp goes. I don't think that a Hangar Bay or Cargo Hold would represent this particularly well but I guess it does make things a lot easier...

Originally Posted by schmeelke

"A streamlined spacecraft must have at least one Armor system for its front hull or central hull (if a multi-stage design, only the uppermost section need be armored)." (p. 9)

I think this rule assumes the booster stage is discarded, rather than reused. I would assume that yes, it should be armored.

Originally Posted by RogerBW

If you do still want to use the Upper Stage approach, then armouring one of the central systems will be vital for a fly-back booster.

Agreed.