Tail belts tend to be slightly less efficient than a torque tube driven tail, due to the energy needed to straighten and bend the belt as it runs around the pulleys. Tail belts have to be set to the correct tension to run properly: too loose and they will slip under load; too tight and drag will increase rapidly. Tail belt tension is usually adjusted by loosening the boom retaining bolts in the frame and moving the tail boom backwards and forwards slightly until the correct tension is achieved. As a guide to the correct tension, you should be able to push one side of the tail belt halfway to the other side using light pressure. Another way is to hold the tail belt drive gear, and try to rotate the tail rotor in the opposite direction to normal: it should take moderate pressure to get the belt to skip.
Tail belts are specified by three items: the width, the length and the pitch. Typical tail belt dimensions are:
- 450 sized helicopters: pitch: .080" or 'MXL' ; width 3mm.
Share your opinion