On Tuesday 25 December 2007 13:57, GWMobile wrote: [snip...] > Setting a crash default is silly. It forces people to not be able > to do what they want and it isn't realistic. > > 2. In reality all water is in fact landable even in > a non float plane. It simply acts like extremely mushy ground. It > should be treated like land and have a large drag component. In > fact all ground should have a drag componenet so pavement, grass, > snow, and muddy runways can be modeled - water should just have a > very large drag component. This would more properly simulate > takeoffs and landings on ground on water or snow or hard ground > etc..
I'm sorry but this just seems silly to me. You cannot land on water if you are not in an aircraft with a planing hull or floats. A transitional planing phase, where the hull or floats change from being _on_ the water to being _in_ the water, or visa-versa for takeoffs, is necessary both for takeoff and landing. You can't plane on water with wheels, at least not at any sort of speed that could be attained with fixed gear or with retractable gear extended, even if the water was perfectly flat and undisturbed. Also, water doesn't act just like mushy ground. Ditching a land-plane into water does a lot more damage to the aircraft than belly landing it on any sort of ground. Even if you hit the water at a low vertical descent rate you won't plane on the surface because the fuselage will not have been designed and built for the stresses, unlike the planing hulls and floats on a seaplane/floatplane. The outer non-structural fuselage panelling will be quickly torn away leaving just the structural frames and members and once these are exposed the drag will shoot through the roof. This, in turn, results in a much higher decceleration rate than you would get in a ground belly-landing. Just the decceleration forces on their own would cause severe stress and structural damage to the airframe, quite apart from the impact damage, but in addition to this water is forced in to every opening and vent, at very high 'pressure', causing even more 'internal' damage to the aircraft and it's systems. I'm afraid that I can't agree with all that you say about ground drag components either. While it's certainly true that paved, grass, snowy, icy or muddy runways will have different co-efficients of friction, this only really applies to objects that are sliding across the surface - not rolling upon it. Sure, a grass strip will have a greater rolling-resistance than a paved strip but the power levels in anything but the earliest aircraft are more than sufficient to compensate for it. In any event, I know that YASim allows you to specify both the dynamic and static friction for wheeled landing gear, so it is possible to simulate low or high pressure tyres, which is what really dictates what sort of surfaces you can operate from and the corresponding ground characteristics are implicit in that. I'm not familiar with JSBSim but I expect it has similar capabilities. I just can't see how you describe the default crash result from landing in the water in a land plane as unrealistic. Once you've ditched in a land plane you're certainly not going to be flying it anywhere else because it will no longer function as an aircraft and that, to all intents and purposes, is a crash. LeeE ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
