Vehicles doesn't say that there is a minimum weight for submersible craft, but it doesn't require a house rule to make your craft heavy enough. The displacement is 62.5 lbs. times 'non-fake' volume, and the ballast tanks are 20% of that. The 'fake' volume are all those multipliers which are due to shape -- slopes, streamlining, etc.
Say I've got a plane with 80 cf component volume in the body and two 10 cf wings. With a submersible hull, very fine lines, and very good streamlining, the body becomes 162.5 cf, but 62.5 cf of that are due to the streamlining and lines. Components plus ballast tanks are 100 cf in the body, and 2*10 cf in the wings. The remaining 62.5 cf are 'virtual volume' to account for the sleek shape. So the plane will displace 7,500 lbs., and the ballast tanks can hold about 1,250 lbs. of water. That means Ewt has to be about 6,250 lbs. and crew/fuel/ammo should be less than 1,250 lbs. to make sure it can sink with full ballast tanks and float with empty ballast tanks, no matter how much fuel is left. I can afford roughly 400 kW of engine, which gives 1,200 lbs. of thrust. Hydrodynamic drag is 19 and top water speed is 24 mph. Stall speed will be about 95 or so. It won't work that way ... A submersible helicopter or autogyro? Jet engines for extra thrust? More wings, less body? But that would reduce the dive volume. Regards, Onno _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
