[Spaceships] TL10 Space RV

[DataPacRat]

Originally Posted by Michael Thayne

This won't let you take off from Titan—Titan's surface gravity is 0.14G.

Yes, but it also has an atmosphere denser than Earth's; if the RV can fly into orbit from Earth, it should be able to fly up from Titan.

Originally Posted by Michael Thayne

The "extra large" habitat seems fine and I don't think it breaks anything even if it isn't RAW. I might consider more armor, even just for purposes of dealing with micrometeor impacts (IIRC Spaceships 5 has them doing 1d dDamage per 10 mps of velocity).

We're a bit squeezed for space; even upgrading to best-in-setting diamondoid armor, 2 spaces provides a total of 10 dDR to spread across 3 hull sections. ... Probably still a good idea.

Originally Posted by Michael Thayne

If the laser is solely for micrometeor / missile defense you might make it very rapid fire—point defense is a major area where Spaceships can give odd or at least-counter intuitive results.

I looked at that, and the trouble with a VRF beam seems to be that its kJ goes down so far it only does 1d-2 dDamage, which runs a 1-in-3 risk of not being able to vaporize a micrometeor even if it hits.

Hm... re-reading attack rolls, though, it looks like going from RF to VRF adds +5 to the attack roll, so any attack that would hit with a RF shot would like hit with at least 5 VRF shots, and there's more than a 99% chance of getting at least 1 damage with at least 1 of 5 shots. Looks like another change worth making.

Originally Posted by ericthered

If you've got a reaction-less drive, a power source that doesn't run out, and you can make it to the extreme upper atmosphere? you probably can get into orbit, and once in orbit the size of the acceleration doesn't matter.


I think your bird can fly, but not strongly. The power to weight ratio on a jet liner is about 0.3, and you've got a third of that.

By SS's RAW, the RV should be able to hit 790 mph, rounded up; I'm not worried about relatively poor in-atmosphere performance, as long as it's got at least some.

Originally Posted by ericthered

I've got some concerns about the play between air resistance, lift, velocity, and heating. You need to be in atmosphere to generate lift until you reach orbital velocity. atmosphere is going to slow you down as long as you're in it, and eventually create massive heating around your ship, not to mention drag. You can reduce drag by flying higher, but that also reduces your lift.

Originally Posted by Michael Thayne

Yeah, I don't think there's any way you can make it to orbit with 0.1G thrust. Even doing it with 1G would be tricky. If you want a rigorous answer though you'd need to play around with a program like Orbiter or perhaps a heavily modded Kerbal Space Program.

I suppose another reality check might be to try to recreate the RV in 3e's Vehicles, and see it it still works. Let's see, that's Vp164's sidebar; if the craft's aerial top speed is below orbital velocity, it should be able to reach Earth orbit, though the sAccel is reduced by whatever portion is required to keep the craft aloft. However, SS doesn't get fine-grained enough to describe stall speeds; that's in VXii p30, and if I guesstimate a lift area of 70 sf and "good" streamlining, that's a stall speed of 250 mph. With SS's airspeed of 800 mph, then less than half of the craft's thrust is needed to keep it airborne, so the other half can still be applied as sAccel to get into orbit.

Though I've probably made all sorts of math errors in that paragraph, so somebody with more experience with GURPS vehicle-building should feel free to correct me. :)