[Spacships] SS7: Extradimensional Interface and Force Screens
 

An “Extradimensional Interface” system (SS7 p.8) reduces the external volume (and thus the surface area) of a vehicle by 4 or 8 SM. A “Force Screen” (SS1 p.16) is projected outside the vehicle’s hull and its dDR is determined by its “thickness” which increases with the vehicle’s surface area/internal volume ratio. Therefore, to find the strength of a screen on a vessel using EI systems, find its strength for the reduced external volume and multiply it by 100 for one EI system or 10,000 for two. Discuss?

Re: [Spacships] SS7: Extradimensional Interface and Force Screens
 

LxW... Yep. The math is basically right.

Re: [Spacships] SS7: Extradimensional Interface and Force Screens
 

No. There are a lot of problems with the force screen rules, but in this case it's not hard to justify it not working that way, since you can presumably have losses for projecting the screen across a dimensional boundary.

Re: [Spacships] SS7: Extradimensional Interface and Force Screens
 

It also doesn't really work from a balance point of view. 100x the dDR will make it almost impossible to damage the ship; 10000x the dDR will make it effectively impervious to anything that doesn't completely bypass Force Screens.

Re: [Spacships] SS7: Extradimensional Interface and Force Screens
 

As Force Screens are superscience, you can pretty much justify them working however you'd like. Maybe they can't function across the barrier, maybe they do so at a loss, maybe they create a shape-able sphere with initial radius entirely dependent on the mass of the generator, or maybe they can be compressed down and see the very increases you're suggesting.

Re: [Spacships] SS7: Extradimensional Interface and Force Screens
 

Wait...there's a space ship that's bigger on the inside than on the outside, and the forcefield is the superscience we're concerned over?

Re: [Spacships] SS7: Extradimensional Interface and Force Screens
 

The net effect is actually 20× and 400× dDR respectively if you work from the Force Screen dDR for the original expanded volume. Not quite as bad for play balance, and it does fit in with TARDIS level toughness.

Re: [Spacships] SS7: Extradimensional Interface and Force Screens
 

I work very hard to ignore impulses like that but I often have to specifically mention "leaving that aside, here's how I respond to the issue"

Re: [Spacships] SS7: Extradimensional Interface and Force Screens
 

As it weighs 5% of the craft's total weight, it does indeed effect inertial/gravitational mass in real space, just like every other system.

As for if it affects this, that's up to the GM, but I'd go with "no." A 300,000 ton spaceship has the mass of a 300,000 ton spaceship, regardless of if it's the size of an ocean liner or a police box. You may need contragravity lifters or similar if you don't want the pressure exerted by said 300,000 ton police box to break through the ground, however.

Re: [Spacships] SS7: Extradimensional Interface and Force Screens
 

But the TARDIS isn't actually the size of a police box, that's its perception filter working (or not working, as the case may be).