In horizontal mode, how can the unit know its absolute angle of inclination even when drift occurs?
The HeliCommands integral artificial horizon responds to angular changes as well as to absolute neutral values. In the case of a standard heading-hold gyro the slightest deviations in the neutral point are cumulative, and the result would be a permanent angle of inclination. What is worse, control signals are also cumulative, with the result that the helicopter would maintain a deliberate inclination once initiated. However, the HeliCommand features an algorithm which is fundamentally different: the unit contains an artificial horizon which makes it capable of correcting such deviations. Compared to a normal triple-axis gyro, the difference can be explained as follows: a conventional gyro continuously accumulates the control signals and its measured rotational values, with the result that it stays motionless at every deliberate commanded position. If the commanded position is inclined, the gyro does not correct that tilt. When the HeliCommand is set to horizontal mode, two different fu
