Anyone else have this high-pitch vibration noise?

[500helicrazy]

I am getting some type of high-pitch vibration sound around 80mph. It can be heard inside the cockpit when the power is pulled back. You can hear it in this video on the outside views, mainly around 1:13. I have heard it on another video, but have had no response from him yet. Any help in identifying where it might be coming from? Don't know if it might be coming from the springs on the cabane gear, maybe the gear leg fairings, or something else, but its definitely loud!

https://www.youtube.com/watch?v=KgptZw0cu-8

[Rodney]

Well that's an interesting problem. The sound from your recording is occurring at just less than 1K Hrz or 1000 cps or 60000 cpm. That probably takes it out of the mechanical realm.

Need to find out if the sound is related to airspeed or engine rpm. Can you test for that with your camera recording the sound?

If airspeed, can you find upper and lower limits. Same for engine rpm.

Rodney

[efwd]

you specifically state an airspeed of 80mph. If I were to guess, I would say it my be a harmonic due to wind. Possibly air moving over the camera. Is it present without the camera mounted?
Eddie

[Esser]

Could even be the holes in the strut fairings being like a bottle with the top being blown across. Sound like air resonating more than anything.

[500helicrazy]

Rodney
I flew it today and tried to play with the power and airspeed a bit, seems to make the sound a little at climb-out (high power setting, and only heard on an external camera, not in the cockpit) as well as being the loudest around 80 when I pull the power back. I kept it around 80 and modulated the throttle a bit and the sound seemed to go in and out a bit.

I did notice the other day when cleaning the underside and gear of the plane, that when I was wiping off the gear springs, they had a slight hum to them. From that sound, it seems to be the closest thing to what I'm hearing in flight. And it would make sense, as air going over them, as well as engine/prop vibration, could cause a harmonic vibration to resonate throughout the aircraft... I do not feel this vibration, and I still can't pinpoint what area it is coming from, but it's definitely noticeable!

Eddie
I have not tried removing the camera yet, but that was an initial thought.

Esser
I will have to look at the struts and see if there are any holes I can close up, as the struts were another area of thought.

Thank you all for the help so far!

I am having a blast with it regardless, most fun plane I have ever flown!

[efwd]

The spring thing could be something you might want to investigate. Those are right below you though and I don't think the camera mic would pick it up and your ears wouldn't. I just installed my 912is exhaust and the manual advises using a heat resistant silicone on the exhaust retention springs to dampen vibration so.. seems that springs can do strange things.
Eddie

[David47]

Jared, is you external camera close by the wing strut to wing interface ?.

[Rodney]

Suggest you eliminate the springs by putting a 3/8 thick maybe 1/2 inch strip of silicon seal on them like efwd talked about. This will dampen the springs and change their resonate freqeuncy. Fly and retest

Rodney