As part of the testing programme for the Airmaster we did a complete set of in
flight vibration tests of the hub/prop combination. We covered all flight modes
and, at the PFA's insistance, included rapid throttle backoff tests at VNE
where another brand of CS prop had shown bad vibrations.
The Airmaster hub/warp drive blade combination after static testing showed very
little vibration but still showed improvement after dynamic balancing - to the
extent that after the first flight following balancing we thought that the test
head had failed as there was almost no vibration indicated. We did note that
replacing the plastic spinner with a metal one had a marked improvement on the
ability to easily balance the prop which is why a decision was made to make
available metal spinners for use with the Airmaster hubs.
Also built into the controller is a function to lock out areas where a
particular speed range can cause vibration. On the controllers supplied for
Jabiru engines, for example, there are several bands which are locked out and
the controller will not permit constant speed operation at those engine rpm
settings. For the Rotax series no lockouts were necessary and the prop can be
set to operate at constant speed right across the range.
Regards
Tony
... in the middle of spraying control surfaces.
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