HLSR—Heave Axis Response Criteria

Height response (HR) criterion: The HR criterion of heave axis response (HAR) is to evaluate the rotorcraft’s dynamic behavior following a step collective input in hover. While applying the collective input the pitch, roll, and heading excursions should be maintained essentially constant. According to ADS-33, the vertical rate response should have a quantitative first-order appearance for at least 5 s. The first-order TF can be fitted to this 5 s response:

h _ Ke-Ts d ~ 1 ± Ts,

where T is the equivalent time constant and t is the equivalent vertical axis time delay.

This criterion can also be evaluated in the frequency domain. For HQ Level 1 the max T is 5 s and max delay is 0.2 s, and for HQ Level 2 the max T is infinity and the delay is 0.3 s.

Torque response (TR) criterion: The torque displayed to the pilot is used as a measure of the maximum allowable power that can be commanded without exceed­ing the engine or transmission limits.

Some case study results of BW criterion for BO 105 helicopter data are given in Table 10.11.