CompuServe Messages

Actually, realistic RPM for non-jet (i.e. piston powered) props is in the 2100-2500 rpm depending on whether you are in cruise, climb or decent mode. Most normally aspirated and fuel injected AC engines are close to an over-speed condition at 2800. It is also somewhat dependant on the prop and whether it is fixed pitch, climb or cruise optimised or variable pitch (aka constant speed) prop. If you want realistic speeds for different flight conditions, the following are good for most general aviation prop planes: Climb-out 2700; Cruise (economy) 65% power: 2100; Cruise (pushing it) 75% power (which is about all you can get at altitude) 2400; Cruise climb (gradual ascent that is a compomise between rapid altitude gain and cross-country travel) 2500; Cruise decent 1700; approach to landing (on final, essentially with the power nearly off, and gliding in) 1100. Now, for the lightwave part: 2400 is bad because it is evenly divisible by 30 and 60. In order to not get an "interference pattern" or an apparent no motion condition with interlace, I would use 2350 or 2300 or 2450. Then try a run with field rendering without motion blur. Then up the motion blur percentage until it looked satisfactory. It could also be faked with a highly transparent disk, two slightly less transparent blade shadows (solid, like maybe an elliptical cylinder with its axis along the line of the prop blade) with high edge transparency that vibrates back and forth quickly in a very short arc (like maybe +/- 5 deg) and the transparency quickly alternating between say, 100 and 93%, but not at a rate evenly divisible by the vibration rate. Unless absolute mechnical accuracy is demanded, it seems one should rather think in terms of the animation realities involved. No matter what rate you spin it you'll only see at most 60 discreet positions per second. With a 2 blade prop this is the same as 30 unique positions of the blades due to the symmetry of the blade. So something even as low as .9-1.1 RPM with field rendering and motion blur might do. wmc – via Autopilot!