I tried the Picolo tubes on my RV-4. It cut the noise done by only 1-2 decibels in the cruise rpms and seemed to slow the rv down a couple of mph.lucky said:Larry,
From which perspectives are the comments about "quiter" aimed? From passengers inside your plane comparing it to other RV8s or from people on the ground comparing your planes sound as compared to another RV8's flying by or both?
Lucky
lucky said:Larry,
From which perspectives are the comments about "quiter" aimed? From passengers inside your plane comparing it to other RV8s or from people on the ground comparing your planes sound as compared to another RV8's flying by or both?
Lucky
Low Pass said:IMO, it's 100% due to the pulsations from the exhaust gases.
Good point. I hadn't considered prop wash. But it seems that stiffening the skin and damping the resonance with some filler would solve the prob in either case. Extending the pipes is not a very serious option for me.AlexPeterson said:You may be correct, but what do you base it on? The prop pulses are proportional to the exhaust pulses, so the only way to separate them is to extend the pipes way back and see what happens.
The pulses from the prop are impressive, just stand up with the canopy open at idle power! (Not recommended for tip-ups )
I'd stiffen the cowling outlet air ramp and the outer skin immediately aft (the one between the gear penetrations, I believe). As for how to do it, there are many possibilities. Everything from refab'ing out of thicker sheet to adding angle stiffeners to laminating the sheets from the inside with some FRP material. Just have to look at the possible internal interferences and how you want to alter the sheet.mlwynn said:Hi folks,
I am at the beginning of building the fuselage. Which skin are you suggesting stiffening and how would you go about doing so? If this is the forward section of floor, i.e. right under your feet and just aft of the pedals, then stuffing it with fiberglass wouldn't be difficult--but I am thinking that the time to do so is early in the construction process.
At any rate, if I should make this mod, I would really appreciate some advice on where exactly to beef things up.
Tom Schad said:Rick Freeman had what sounds like the same problem with his RV-8. In addition, he was getting some small cracks in the fuselage sheet metal behind the exhaust. We solved the problem by installing some turned down exhause extensions that came with the exhaust system I had purchased from John Forsling for my RV-8 project. His system is almost identical to the Veterman system with the exception of the extensions which seem to get the vibrations away from the fuselage. Anyway, you might try an extension and see what happens on your airplane. My RV-8 has been flying for over a year, and it has very little if any vibration in the feet area.
Tom Schad said:We solved the problem by putting some turned down exhaust extensions on his pipes.