# How would you determine the Lift(thrust) force of a Helicopter in hover

by fujifilm6502002
Tags: determine, force, helicopter, hover, liftthrust
 P: 9 I know the lift force equation is .5*rho*V^2*Area*Coefficient. But I was wondering in the real world how would you measure the lift force? I hope they don't just plug the values for the equations.
 PF Gold P: 8,964 The easiest way is to weigh the helicopter. If it's hovering, the lift force equals the weight.
 P: 9 I was wondering like if you are building your own helicopter what would someone use to test the amount of thrust produced by the rotor?
 P: 183 How would you determine the Lift(thrust) force of a Helicopter in hover i wonder if bernouilli's equation can be put to use in this case. i know that it can be used when there is wind driving a wind turbine. it should work here
 P: 9 I guess you can use Bernoulli to calculate the change in pressure helicopter.
 P: 183 i think u can find the maximum power yield by zeroing the velocity at the exit
 P: 21 yeah we can find the maximum power yield by zeroing the velocity at the exit if smbody interested , i caN upload a book on the aerodynamic of the helicopter. tel me if interested regards
 P: 9 That would be great. Thanks
 P: 21 I will try tmrow , i willl send u a link on rapidshare or mhid.net; ur welcome and hope that will be helpful
 P: 183 definitely interested in that:)
P: 5,095
 Quote by fujifilm6502002 I was wondering like if you are building your own helicopter what would someone use to test the amount of thrust produced by the rotor?
You could do this simply with a spring scale and something to constrain the rotor group to the scale and something to drive it. It is even easier if you have a strain gauge based force transducer because then there would be no axial movement due to the thrust.

In regards to the original question, the airfoils and rotors are well known throughout the flight envelope from wind tunnel testing. The calculations involve effects of trailing blades, etc... Of course, the calculations are always compared to actual testing.
Mentor
P: 22,312
 Quote by fujifilm6502002 I was wondering like if you are building your own helicopter what would someone use to test the amount of thrust produced by the rotor?
To test it, you mount it on a test rig and measure the forces.
 P: 53 scale down models and wind tunnels are to measure the force.
P: 21