Guys hello!

On my TRex 500 DFC the pitch works slowly. In the range of about zero (hovering) the pitch is very unresponsive, inaccurate. The helicopter falls down. When the pitch becomes larger the response is absolutely normal. What parameter is responsible for this?

I tried to calibrate the ESC, different governor modes, but nothing changes. It is difficult to hover the helicopter at a small pitch.

Spirit GT
HW 80A V4
about 2500 rpm

Hello,

the problem could be:
a) Axial bearings are not working well in the rotor head. When rotor is rotating bearings could lock itself and servos might be unable to overcome this force. This is very common issue. You can't discover this easily without rotating head.
b) Rotor blades are not optimal (not likely)
c) Servo issue

I fear you can't fix this problem with any settings of the unit. You could possibly only improve the feeling little bit, but without resolving main issue it will get worse with increased flight time.

If you want more responsive collective pitch but the mechanics is good you can improve it with Pitch Pump booster parameter in the Expert settings.

_________________
Spirit System developer

For clarification, what ZeXx86 refers to "axial bearings" is what is more commonly known as "thrust bearings". I am finding that these thrust bearings need to be replaced fairly often. I would say I can start noticing signs of "worn" thrust bearings on 550-700 size helis after about 125 to 150 flights or so, and they get progressively worse from there. The faster the head speeds, the faster these thrust bearings tend to wear and need more frequent replacing.

Thanks for your advice, but the helicopter is mechanically in perfect condition. I recently updated the bearings (even trust bearings) and servos, everything works fine. The blades are stock 425 mm.

The problem appeared after changing the ESC to the HW80A. I calibrated the ESC many times and changed the governor modes, but the problem remains. The helicopter is difficult to control while hovering.

- i will try.