Energy efficiency and electric propellers.

[Pds314]

So, I've been working on some reaction wheel-powered stock propeller aircraft in FAR, and I've come to the conclusion that at high speed, they are quite wasteful in converting rotational power to thrust.

Examples:

A many-bladed fin-based prop gets 2.1 kN at 204 m/s on 8 small reaction wheels. According to the wiki, the reaction wheels have 5 kN of torque, and they were spinning at around 45 Radians/second.

Rotational power: 1.8 MW

Thrust power: 0.43 MW

A prop gets 8.6 kN at 45 Rads/s and 110 m/s with 8 reaction wheels.

Rotational power: 1.8 MW

Thrust power: 0.95 MW

A prop gets 3.6 kN at 48 Rads/s and 138 m/s with 3 reaction wheels.

Rotational power: 720 kW

Thrust power: 497 kW

 

Has anyone looked at this before in terms of efficiencies of stock propellers? What has been found?

Edited February 26, 2018 by Pds314

[suicidejunkie]

Reaction wheels are well known to be physically unrealistic in many ways.  It should also be pointed out that kN are force, not torque.  Electricity units are never going to convert properly into movement.

From what I've seen and read here, the practical problems with turning rotation into thrust mostly comes down to blade physics limitations.