SonexBuilders.net

I've read some posts, mainly about headsets, mentioning the high noise level in the cockpit. Is anyone using mufflers on the AeroVee? I've seen some motorcycle mufflers that would be small enough to fit under the cowl, which would replace the last section on the exhaust that is held on by springs.

You're adding weight and complexity by adding a muffler; plus you're increasing the radiant heat under the cowling, making it harder to cool the engine.

It would be far easier just to buy a slightly better headset and call it good. Nothing you do will make a small light airplane quiet enough to fly without a headset, so why not just stick with that one piece of equipment and be good-to-go? :)

--Noel
Sonex #1339

P.S. Nothing about the AeroVee is any louder than a Jabiru or other small aircraft engine.

I'll put an opposing view Noel. The Aerovee might be quiet but my Jab 3300 is BLOODY LOUD. I know it doesn't sound too bad from outside and have even been told that it sounds good, sounds like it's on steroids, sounds like a dose of testosterone and sounds like a bigger aircraft, but inside it's just LOUD. I'm on my fourth head set, a Bose A20 at around $1200 in Australia, and that is just barely good enough. I have spent a fair bit of time plastering the inside of the cabin with sound deadening material for very little benefit, see http://sonexaus.wikispaces.com/Cockpit+Noise. I've come to the conclusion that the only way to improve my Sonex is to muffle the engine a bit. I'm intending to try some lightweight absorption, or "hot dog" mufflers to replace the last bit of tailpipe. Many years ago I raced motorcycles which at that time were predominately 2 strokes. At the end of a race day I always had a headache. In about 1974 a new law came out limiting the noise output on the bikes. The usual solution was to simply drill a lot of holes in the tailpipe and fit a little cannister around it that was packed with glass cloth (in my case I used steel wool). It just took the sharp edge off the noise and my headaches disappeared. I should try the mufflers some time this year give a report of my progress.
Peter
Sonex 894

I plan to modify my headsets with CEP earplugs. Some of the Sikorsky pilots I used to fly with used them. I doubt the mighty Aerovee cannot compete with the inside of a UH60.

https://www.cep-usa.com

Peter, thank you. I appreciate you sharing your hard data on noise. Something you said made me wonder what frequency is it that is most annoying / painful? And it would be cool if we could run the study again to see if any of the different mitigation arrangements affected the target frequency range. Of course I used the "royal we". Sorry. ;)

Paul
Onex 113 builder
Georgia, USA

I highly recommend the headsets inc ANR conversion kit if you have a set of non ANR headsets you want to use in a Sonex. I bought the kit out at airventure two years ago and did the conversion right at my campsite in Scholler. The ANR makes a world of difference in the Sonex. They probably can't compete with a Bose but they aren't $1000+ either. With them on I don't find the noise in a sonex that bad at all.

My biggest complaint is the vibration. On the flight out and back to Oshkosh I actually got some blisters on my heels from the balls of my feet sitting on the floor with my toes on the rudder pedals for 10 hours. I recommend putting a thin pad of memory foam under a piece of carpet there if you haven't yet installed your interior.

I haven't done it yet but putting something in the opening between the cockpit and the tail cone between the #1 turtledeck formers will help cut down on the noise as well. The open tailcone section acts like a giant megaphone aimed straight at your head. I think Sonex used to sell a fabric cover that went over this area. Not sure if they still do or not.

Keith
#554

peter anson wrote:The usual solution was to simply drill a lot of holes in the tailpipe and fit a little cannister around it that was packed with glass cloth (in my case I used steel wool).

See also http://www.piteraq.dk/flight/muffler.html :)

Ihab

quote]--Noel
Sonex #1339

P.S. Nothing about the AeroVee is any louder than a Jabiru or other small aircraft engine.
NWade
 
Posts: 166
Joined: Mon Aug 08, 2011 12:58 pm

[/quote]

Not sure what your comment is based on but from my experience my CAMit is much quieter than the AeroVee. I had the AeroVee on my Onex for about 30 hours and then removed it. The exact same cockpit is noticeably quieter now flying with the CAMit. Exhaust system pictured and no problems dissipating heat.

How about just running the exhaust pipes the full length of the fuselage and out the back like they did on the "African Queen"?

The 2200 Jab in my Sonex is way quieter than an unmuffled VW. In my Corby Starlet I had to use earplugs as well as my ANR headset on long flights. I also think using a noise deadener/ heat shield on the inside of the firewall helps a lot.
http://www.mykitlog.com/users/display_l ... 5935&row=6