Max speed versus Weight R44
A while ago, I stumbled over a weird condition/prediction of my R44-simulator.
When very light (f.ex. little fuel, 1POB), it takes more power to achieve high speeds.
Could be an error, but I can't seem to find it, so I tried to explain it.
I came up with the following possible explanation:
At light weight the trust vector is smaller. To achieve a speed, the drag forces are relatively unsensitive to weight, resulting in essentially the same needed forward force to achieve a speed.
In the case of light weight, and the resulting lower trust vector this requires the rotor disk to be tillted more forward than when heavy. At some point the forward tilt gets so great that it reduces rotor efficiency because transversal flow increases too much, requiring a lot of power to achieve this smaller trust. The rotary wing becomes an inefficient propeller so to speak.
I tried this out on a R44-I and II, and feel that with 2 POB, little fuel it is indeed faster than with 1 POB. Anyone care to comment ?
d3