# Helicopter vertical rate of descent and what it depends on

Answer 1. The vertical rate of descent is the altitude which the heli­copter loses per second, i. e., V^es = V^eg ^ sin 0. It depends on the

velocity along the trajectory and the descent angle. The flight velocity along the trajectory depends on the main rotor thrust force component +P^, directed parallel to the flight trajectory. The descent angle depends on the lift force Y, i. e., on the magnitude of the main rotor pitch.

The larger the main rotor pitch for the same rpm and the larger the back­ward tilt of the cone axis, the smaller the descent angle, velocity along the trajectory, and helicopter vertical rate of descent.

Answer 2. The vertical rate of descent is the altitude which the heli­copter loses per second sin 0. This rate depends on the velocity

along the trajectory V and the descent angle. The velocity along the

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trajectory will be the larger, the larger the propulsive force G^, which is a part of the helicopter weight force (G^ = G sin 0).

This means that the larger the descent angle, the larger the propulsive force G^, the larger the flight velocity V^eg, and the higher the vertical rate of descent.

Answer 3. The vertical rate of descent is the altitude which the heli­

copter loses per second (Vjeg = sin 0). It is larger, the higher ;her

the velocity along the trajectory and the larger the descent angle. The vertical velocity along the trajectory depends on the propulsive force G^ and the parasite drag force X. propulsive force G^ = G sin 0.

The larger the angle between the fuselage longitudinal axis and the flight trajectory, the larger the parasite drag force and the lower the velo­city along the trajectory. This means that, by altering the position of the helicopter fuselage relative to the flight trajectory and by altering the descent angle, we can alter the flight velocity along the trajectory and the vertical rate of descent.