Greg Arehart
Well Known Member
I am building a 9A primarily for cross-country use and need to make some engine choices (well, at least choose ONE engine). Three questions:
1) presuming identical airplanes (including weight) with identical fixed-pitch propellers, am I correct in assuming that no matter the engine, if it is running the same RPM, I will be traveling at the same speed in both planes? If this is true, then wouldn?t the fuel burn be higher on a larger-displacement engine (more cylinder volume, therefore more fuel used), and therefore my dollars/gallons per mile would be higher for say, a 180 vs 160 Lycoming?
2) starting with identical airplanes in terms of drag issues, if I were to put a constant-speed prop plus the larger engine on one, would/could the fuel burn be the same or better than the fuel burn on the smaller engine (that is, would they have the same efficiency)? I realize that this would probably mean a weight increase because of the larger engine and CS prop.
3) can anyone comment on the gain in efficiency from electronic ignition systems? Lightspeed Engineering claims a 10-15% gain depending on whether one or two mags are replaced. What has been the experience of the group?
Thanks,
Greg Arehart
1) presuming identical airplanes (including weight) with identical fixed-pitch propellers, am I correct in assuming that no matter the engine, if it is running the same RPM, I will be traveling at the same speed in both planes? If this is true, then wouldn?t the fuel burn be higher on a larger-displacement engine (more cylinder volume, therefore more fuel used), and therefore my dollars/gallons per mile would be higher for say, a 180 vs 160 Lycoming?
2) starting with identical airplanes in terms of drag issues, if I were to put a constant-speed prop plus the larger engine on one, would/could the fuel burn be the same or better than the fuel burn on the smaller engine (that is, would they have the same efficiency)? I realize that this would probably mean a weight increase because of the larger engine and CS prop.
3) can anyone comment on the gain in efficiency from electronic ignition systems? Lightspeed Engineering claims a 10-15% gain depending on whether one or two mags are replaced. What has been the experience of the group?
Thanks,
Greg Arehart