How critical is the fore/aft location of the fuel tank? It would seem that the further the tank is fom the NVA the greater the change in fuel perssure between horizontal and "verticle" flight. The fuel has to be "lifted" up to the NVA. If having a short fuel feed distance does make for a more consistant run, why aren't rear intake engines more popular? That would also put the needle valve in a friendlier location. It would also seem that as tanks get larger in volume they must get longer because the verticle dimension is somewhat restricted by the height of the NVA.
fore/aft fuel tank placement?
Stuka Stunt Main Forum · 3 of 3 known posts recovered
Ron, was going to mention this in the R-M 40 corres, in "products". Yes, the further the tank from the engine the greater distance fuel has to be lifted in the climb, and the greater the pressure increase in the dive. All this encourages the engine to 2/4 more then if the tank is close to the engine.
Ian R.
Ron (and Ian)...
Fore and aft distance is not as critical as one would think. Sure, it has an effect, but only up to +/- 1 g. The "centrifugal" load on the fuel combines with the 1g of gravity. "Resultant" load is usually over 3g, and pointing out and down. Trig can get funny here...
More important than longitudinal length is the line loss of dragging fuel an extra distance, AND the relative height of the fuel's mass under the accelerated conditions.
Simple, unaccelerated gravity head would show more effect if the model were to fly straight, at steady speed and angle of climb or dive. But that doesn't describe control-line flight, does it? <G>
\BEST\LOU