Lift rotor - underestimated power

[Radimir]

Dear SUAVE Team,

I'm trying to use Matthew's approach for design of a lift rotor (and proprotor).

My first step is to replicate his results excluding the noise constraints - pure maximization of aero performance. I used simple slsqp optimization (not the nexus one), XFOIL NACA 4412 airfoil polars (Ncrit 9 or NCrit 0.1 Mach 0.0). I can get similar chord and twist distributions for the given design thrust BUT the torque / power were too low - FoM was quite high respectively (0.85 and above).

Then, I tried to spin the lift rotor from the thesis in hover (3-bladed, T=2200 N, chord, twist, tip Mach matching and the above NACA 4412 polars), but power is still around 30% lower than the one in thesis - I get around 42kW, real value is around 58kW.

What do you think I am missing?

Best regards,
Radimir

[Emilio]

I would suggest contacting Matthew directly. Ask, if he can to respond here for the benefits of everyone.