Question

What is the flap frequency of a gimballed rotor?

(a) 1/rev

(b) 2/rev

(c) 0.5/rev

(d) 10/rev

The question was asked in unit test.

My enquiry is from Blades and Propellers topic in portion Helicopter Dynamics of Aerodynamics

Answer 1

Correct choice is (a) 1/rev

Explanation: Gimbaled rotor is a multi-blade helicopter rotor unlike teetering rotor which has only two blades. It is characterized by flap hinge which lies at exactly the rotational center which yields a flap frequency of 1/rev.