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Hey_Ducky
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Homework Statement
A helicopter is hovering in a steady cross wind at a gross weight of 3,000lb. The helicopter has 275 hp delivered to the main rotor shaft. The tail rotor radius is 2.3 ft and has an induced power factor of 1.15. The tail rotor is located 15.3 ft away from the main rotor shaft. Determine the crosswind conditions (velocity and direction) in which tail rotor effectiveness may be reduced or lost. If the center of gravity is assumed to lie on the rotor shaft axis, determine the feasible yawing angular velocity that the pilot can demand that may also result in a loss of tail rotor effectiveness
Homework Equations
My understanding is that the torque of the tail rotor needs to counteract, ie, be equal to the torque created by the main rotor. For that reason, my first goal is to right down torque equation for each scenario. Leishman, my textbook, uses Q = Torque, T = Thrust (here, same as weight in hover).
Qrotor = T * Vinduced/(Vtip/R)
Qtail = r x f = |r| |f| sin(theta)
--> Figure out under what circumstances Qtail < Qrotor
I'm interested in exploring the angle of the crosswind, so theta is fine.
Known (or solvable): T, R, Vi, r
Vi = sqrt(T/ (2*A*rho))
Unknown: Vtip (how do I deal with this?)
Not sure: f ? and theta
F must be the thrust exerted by the tail rotor. So, call it Ttail ?
In rotorcraft P = T * Vi.
Here's where I'm stuck. How do I use the induced power factor to get Ptail? How do I get Vi,tail? I don't have area or disk loading or really any information about the tail?
Am I on the right track? Your help would be greatly appreciated.