GURPS Spaceships Design Spreadsheet

[vierasmarius]

Originally Posted by DaltonS

As for "Crush Depth" calculations, since this thread is supposed to be about a Spaceships spreadsheet, shouldn't it measured in atmospheres by default? (While some spacecraft may float, few will dive.) An "Aquatic Vehicle" switch could be used to add Aquatic performance statistics (surface/submerged acceleration/speed, floation, crush depth, etc.) to the sheet.

That's definitely what I'd do. Armored probes dropping into the depths of a gas giant are an old trope of science fiction. It would also be cool if an Aquatic switch could be applied to Reactionless Thrusters (and maybe fusion ramscoops? Hmm...) to let them serve dual function as air and water propulsion, like they could in 3e. The difficulty there, of course, is translating Gs of thrust into surface and underwater speed.

[Humabout]

Originally Posted by Flyndaran

Except the bathyscaphe was from 1960, not TL 8.

Oops. Still much improved. So 16 armor systems....

[Flyndaran]

Originally Posted by DaltonS

As for "Crush Depth" calculations, since this thread is supposed to be about a Spaceships spreadsheet, shouldn't it measured in atmospheres by default? (While some spacecraft may float, few will dive.) ...

Listing feet for crush depth only works for earth oceans. I was making my submarine as an scientific exploration vehicle for non earth oceans.
So while it isn't that hard to translate numbers for atmospheres, it would make is aesthetically cleaner and more generic in my opinion.

[Flyndaran]

Originally Posted by vierasmarius

That's definitely what I'd do. Armored probes dropping into the depths of a gas giant are an old trope of science fiction. It would also be cool if an Aquatic switch could be applied to Reactionless Thrusters (and maybe fusion ramscoops? Hmm...) to let them serve dual function as air and water propulsion, like they could in 3e. The difficulty there, of course, is translating Gs of thrust into surface and underwater speed.

That would require knowing the viscosity of the fluid I would imagine.

[ericthered]

Originally Posted by Flyndaran

That would require knowing the viscosity of the fluid I would imagine.

well, its a terminal velocity problem turned sideways: G's vs. drag.

The terminal velocity problem is: ((2ma)/(pAC))^.5

m is mass. This I believe is given in spaceships.
a is acceleration, This is definitively given.

p is not viscosity, as I expected, but density. hmmm. not terribly difficult, though there are some pitfalls (what is the density of the hydrogen 100k below jupiters liquid surface?), this is still strait forward.

A is area. for a simple shape, this is the area of the maximum cross section going forward. For a more complicated shape, inflate that number a little bit.

C is the Drag coefficient. this would be a pain without the wonderful charts of the internet. Enjoy.

The nice thing about this equation is that almost all of it can be figured out only once and then left. The bad thing is it leaves out viscosity, which means we're working with spherical cows.

[panton41]

I think I found another bug. When you change the type of missile warhead the damage entry doesn't change back to standard if you switch back to that.

Edit: Apparently it even holds onto it if you change the weapon in the mount.

[Lamech]

Originally Posted by ciaran_skye

I think I found another bug. When you change the type of missile warhead the damage entry doesn't change back to standard if you switch back to that.

Edit: Apparently it even holds onto it if you change the weapon in the mount.

Use a new weapon line! That's what I do.

[ericbsmith]

Originally Posted by ciaran_skye

I think I found another bug. When you change the type of missile warhead the damage entry doesn't change back to standard if you switch back to that.

Edit: Apparently it even holds onto it if you change the weapon in the mount.

Is that in Excel? I'm guessing a sheet recalc isn't being triggered, probably due to one of my macros (recalcs are often bypassed in macros to speed up the sheet). Try pressing F9 to force a recalc, that should clear things up.

I may have used similar code in the OpenOffice version too, and forcing a recalc there should also work (don't remember exactly how in Ooo). I'll have to look it over later.

[ericbsmith]

Originally Posted by ciaran_skye

I think I found another bug. When you change the type of missile warhead the damage entry doesn't change back to standard if you switch back to that.

Edit: Apparently it even holds onto it if you change the weapon in the mount.

OK, finally got around to checking this out. The error happens when you chose the "blank" entry from the drop-down menu; it's odd, but the sheet is treating this blank differently than an empty cell. The fix for now is to delete the contents of the cell rather than selecting the empty entry. I'll fix this in the future, but I have no idea how long it'll be before I release another update.

[panton41]

Originally Posted by ericbsmith

OK, finally got around to checking this out. The error happens when you chose the "blank" entry from the drop-down menu; it's odd, but the sheet is treating this blank differently than an empty cell. The fix for now is to delete the contents of the cell rather than selecting the empty entry. I'll fix this in the future, but I have no idea how long it'll be before I release another update.

Maybe "blank" is different from a named cell? I dunno, but stranger things have happened.