[Spaceships] Is This Legal?

[scc]

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

1) Does the booster stage need a Control Room so that it can glide or possibly even fly to a landing once the orbiter has separated?

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?

3) The booster needs to be streamlined, normally as this has an Upper Stage it doesn't need armor in it's forward section, but this one isn't discarded, so does that rule still apply?

[Ulzgoroth]

Originally Posted by scc

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

1) Does the booster stage need a Control Room so that it can glide or possibly even fly to a landing once the orbiter has separated?

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.

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?

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.

Originally Posted by scc

3) The booster needs to be streamlined, normally as this has an Upper Stage it doesn't need armor in it's forward section, but this one isn't discarded, so does that rule still apply?

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.

[schmeelke]

Originally Posted by scc

1) Does the booster stage need a Control Room so that it can glide or possibly even fly to a landing once the orbiter has separated?

"All spacecraft capable of maneuvering require a control room; multi-stage spacecraft only need this in the uppermost stage. […] You may install fewer control stations: it’s possible to have an autonomous vessel with no control stations at all if the vessel is run by sapient AIs instead." (p. 14)

So that's a yes, you need a control room, but don't need any control stations if it's flown by remote or AI.

Originally Posted by scc

3) The booster needs to be streamlined, normally as this has an Upper Stage it doesn't need armor in it's forward section, but this one isn't discarded, so does that rule still apply?

"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.

[munin]

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.

There doesn't need to be a "huge hole". A mult-stage design could be, for example, a plane with a small spaceship attached to it (like WhiteKnightTwo or that thing from "Superman Returns"). For both craft to be streamlined the front and central hulls would both require armor.

[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).

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.

[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.

[Flyndaran]

Originally Posted by MatthewVilter

...
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.
...


Agreed.

Wasn't that what the shuttle "on top" of booster rockets was?
Size-wise it was boosters with a smaller ship attached.

[MatthewVilter]

Originally Posted by Flyndaran

Wasn't that what the shuttle "on top" of booster rockets was?
Size-wise it was boosters with a smaller ship attached.

The shuttle actually works as example of my point. A conventional rocket has each stage stacked on top of the last. The shuttle on the other hand had a drop tank mounted along side and booters mounted on the sides of that. If the shuttle had been stacked on top of the external tank (like the Orion on top of the Space Launch System) the drag from its wings would make it want to flip over and the more it turned over the more drag the wings would cause.

(Of course, the other reason the drop tank was on the side was because the shuttle needed to carry the expansive main engines into space so that it could bring them home safe.)

[Flyndaran]

Okay, I failed my reading comprehension roll.
An A.I. piloted booster rocket ship attached via an external clamp onto the manned ship works, right?
I'm under the weather today, and am not comprehending things I otherwise would.

[scc]

And it looks like I don't need a booster after all. By playing some games using Large Systems on a SM+7 hull I can cram 265 tons of fuel into only 16 spaces, that equal to 17 and 2/3 spaces of fuel, this gives me 5.83 mps from standard chemical rockets. A Large System cargo bay lets me carry 50 tons into orbit, and 3 small systems, a chemical rocket, control room and METALLIC LAMINATE Armor round out the design