Vibrational Noise between 100 - 130 knots

[Hal]

I flew the first flight on my new RV7 yesterday. 8.1 hours on the Hobbs this evening (why not?!)! Everything is perfect except I am getting a high frequency vibrational noise that occurs between 100 and 130 knots IAS. I have not been able to track the source down. It is not related to engine RPM, airspeed only. Today I flew without the wheel pants and associated fairings to see if they were the source. No joy, just slower. After 8 hours today I looked for evidence of smoke. The only thing I noticed was some aluminum black smoke at the rear canopy skirt (slider). This is my fifth RV (and third slider) and I never have had this kind of a problem. Anyone in the RV world seen this before?

Thanks,
Hal Smith

 

[Norman CYYJ]

Check the holes in the elevator where the hinge bearings are. Sometimes they can develop a whistle. Put some tape over them and then try flying. If it goes away you will know where the problem is. Good luck and have fun.

 

[Hal]

Good suggestion Norm. I will give it a try. The smoke on the canopy skirt is a new one for me.

Hal

 

[N941WR]

Hal,

Any chance the exhaust is vibrating and contacting the firewall at those speeds?

 

[aerhed]

I built an 8 that had a sorta shrieky vibe at the back of the skirt (tight fit). A little strip of adhesive backed window felt on the underside of the skirt made it go away forever, so far. You can't see the felt at all.

 

[LifeofReiley]

The diameter of exhaust pipe outlets is larger now than on older systems... check floor board / exh clearance.

 

[pierre smith]

Yep....the rear skirt.......

.....also made a very high buzzing at around the same airspeed. My buddy reached back there and shoved upwards and the sound changed. At cruise speed it tended to go away and I could vary the power/speed and stop it. A strip of thin felt solved the problem and also the "smoking" aluminum.

The flap tape that Avery sells will also work.

Regards,