C2

Question 1

What is the difference between thrust and lift ?

Answer 1

Thrust is in the rotor axial direction, Lift is normal in the inflow direction

Question 2

Momentum theory assumptions ?

Answer 2

Incompressible flow, far away from disk the air is at rest, velocity imparted to the fluid is constant, existing a steam tube which is in an axiallly symmetric surface passing through the rotor disc perimeter which isolated flow through the rotor

Question 3

Induced velocity definition ?

Answer 3

The velocity increment due to the rotor

Question 4

Condition of momentum theory applicable to vertical descent flight?

Answer 4

Vd>2*Vhov

Question 5

What is a figure of merit used for ?

Answer 5

To evaluate rotor performance in hover

Question 6

What is the most reasonable pilot strategy to get rid of the vortex state ?

Answer 6

Increase forward speed by pushing longitudinal cyclic pitch

Question 7

What’s the use of pre-twist?

Answer 7

Allows most of blade element to be in optimal angle of attack

Question 8

What is the use of a pre-rotator ?

Answer 8

Reduce the take off distance of auto rotator and allow the autogiro to take off vertically

Question 9

What is the Mechanism of a pre-rotator ?

Answer 9

Engine disconnects with rotor after take-off