Resonance noise....

[RV9798]

A high pitch metalic resonace noise developed at speeds above 130kts. I think it is the step on my RV9A. Does anybody encountered this? It is very annoying. When the plane was test flown for the first (I was on the ground), I heard this metalic ringing from the ground when the plane was high speed gliding (engine was idling). Any input how to eliminate the noise?


Pete

[cytoxin]

if it is actually the step, and it has a high freq its gonna cause stuff to crack. change its frequency.(like the rubberband on a brake rotor while machining) drill a hole in it and fill it with some type of weight..you copuld test this by taping some type of weight to it and test fly it. use alot of electrical tape. my .02
good luck

[DanH]

Cytoxin is correct with his suggestion to change the mass of whatever part you suspect. The natural frequency of an object is a function of it's mass, mass distribution, and stiffness. That can include the stiffness of it's mounting of course. A FIRMLY attached weight is a reasonable test method.

Dan Horton

[vlittle]

Pete, it could be your aft canopy skirt that's making the noise. I don't think it's the steps.

Vern