--- On Fri, 7/22/11, Onno Meyer <[email protected]> wrote: > 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.
MA Lloyd addressed this in his unofficial vehicle expansions after VE2 came out. IIRC, a sub need to be at least 80% maximum displacement or it couldn't sink. > 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. This may be where the planes of Sky Captain start becoming impossible while the Russian project remains vaguely plausible -- the Russian fyling boat, as best I could tell, only flooded the pontoons, with wings, budy and engine pods sealed. The conning tower may or may not have taken on water to improve submerged performance. > 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. A lot depends on how far you want it to go down. While the planes in Sky Captain were fairly deep-diving, the Russian sub was not really intended to go below periscope depth. You may want to look at how Graham Hawkes _Deep Flight_ submersible works as an alternative. http://www.gizmag.com/hawkes-explains-how-deep-flight-flies-underwater/17275/ > 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 > ... Bigger wings, STOL wings! > A submersible helicopter or autogyro? Jet engines for extra > > thrust? More wings, less body? But that would reduce the > dive > volume. The biggest problem I see with the Sky Captain planes is the transition between land and water. Brandon _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
