nooobs
Key Veteran
Location: Toronto, Canada
| HeliCommand FAQ - #18FYI...
Digital servos: minor servo jitter, major servo jitter!
One effect of the auto-pilot is to cause the servos to be just perceptibly "nervous" (constant minor movements) even when the model is stationary. This applies in particular if you are using high-speed digital servos. The movement is uncritical. It may result from the signal output rate or from minor fluctuations in measured values, as frequently occur with conventional tail gyros and tail rotor servos. Since using a HeliCommand means that the constant movement affects four servos, this can certainly increase the current drain of the receiver battery. However, in practice this mainly occurs when the model is flying, when all the servos are operating as "control loop" servos; they certainly operate more often than they would if "manually controlled" by an average pilot. Incidentally, this "extra workload" is present whether you notice the fluctuations on the ground or not; it's just that you don't hear the servos working when the model is in the air. In fact the degree to which the servos have to "work hard" depends much more on the level at which the regulatory system is working in the air, and on the gain setting, i.e. whether the HeliCommand is set towards the "agile" or "smooth" end of the scale.
It is not really significant if the servos appear to be working slightly more than usual when the helicopter is on the ground.
None of this applies if you suffer severe servo jitter.
The cause for this may be that the internal fail-safe is over-responsive ("too sharp" - this was the case with the first few examples shipped. (With many RC systems, and with certain combinations of equipment, the fail-safe then thinks it has detected interference to the radio link, even though the RC system is working perfectly; it may then switch the servos to the set fail-safe positions for a brief period. If this happens with your HeliCommand, it is essential to have the unit updated (at no charge). A direct express service has been set up by the manufacturer to correct this specific fault. The only devices affected are those whose type placard does not bear a data code (two-characters or four-digits) to the left of the Order Number). |
