Question

Which of the following is false with respect to rotating anemometer?

(a) Used in low speeds

(b) High sensitivity

(c) Airspeed is measured in forward direction

(d) Can be used within the rotor blade

I have been asked this question in an online interview.

This key question is from Helicopter, Optical and Hyper Sonic Air Data in section Air Data Systems, Altitude and Heading Reference of Avionics

Answer 1

Right choice is (c) Airspeed is measured in forward direction

Easiest explanation: Rotating anemometer is like a pitot tube for helicopters to measure low velocities below 40 knots. In addition to obtaining improved sensitivity at low speeds, the rotating probe measures omnidirectional airspeed, including backward velocities.