METHOD OF DETERMINING AND INDICATING ROTOR APPROXIMATION TO VORTEX RING CONDITIONS AT SINGLE-ROTOR HELICOPTER PRE-LANDING MANEUVERS Russian patent published in 2013 - IPC G08B21/00 B64C27/00 

FIELD: aircraft engineering.

SUBSTANCE: method comprises measuring incident air flow nearby rotor by air pressure receiver fitted at blade tip. Helicopter vertical speed, pitch and wobble plate lengthwise deflection are measured. Rotor angle of attack, tangential and normal components of incident airflow velocity in real time are computed. Measured also are incident airflow velocity nearby rotor at its decrease due to oncoming inductive velocities created by helicopter vortex trace and axial velocity are measured. Measured magnitudes are compared to limiting parameters of cortex ring zone. At helicopter descent at the rate over 3 m/s and tangential velocity nearby rotor lower than 45-50 km/h, pilot is warned about approach to said rig zone by light and voice signals. Besides, instruction on decrease in pitch to landing magnitude is sent to control system and, at a time, vertical rate of helicopter descent is stabilised to not over 2.0 m/s.

EFFECT: higher accuracy.

2 cl, 4 dwg, 1 ex