ORIGINAL: Eugoogoly
what is the relationship between RPM and speed? Also what part does the prop size play in this?
if i have a 11x4 spinning at say 15000 Rpm and a 11x6 spinning at 13500, which would give me more speed, which would give more pull?
Eugoogoly,
It is not quite valid to distiguish between speed and pull. The distinction that makes more sense is between pull at low airspeed and pull at high airspeed. What we frequently think of as pull ( thrust ) is pull at low airspeed, and what we frequently think of as speed is pull at high airspeed. Going fast requires high thrust just at hovering requires high thrust. The difference is that hovering requires thrust with virtually no airspeed, while speed requires as much thrust as you can get at high airspeed. Generally, thrust at low airspeed requires a low pitch prop, and thrust at high airspeed requires a high pitch prop. Often, the quest for maximum airspeed requires that the high pitch prop have a fairly small diameter, so that the engine can turn it fast enough.
banktoturn