Muffler on AeroVee?

[mike.smith]

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.

I bought the same kit and it's really made a difference for me, too. My ears area completely comfortable flying for several hours.

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.

Wow, I've never had those kinds of problems with vibrations. But I will say that when I rebuilt my engine last year (due to a prop strike) and replaced the ground-adjustable prop with a fixed pitch prop, the amount of vibration went noticeably down. So I don't know how to tell someone to replicate that, but I'm assuming maybe I did a better job of assembly the second time, and perhaps the change in prop made a difference, too.

[sonex892.]

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.

Hey Phil.
Did you manage to squeeze a muffler in on your Sonex? I looked at your log but couldn't find a photo.
I had a muffler on my Jab 2200 Sonerai, whilst it was still noisy in flight it was nowhere as noisy as the Sonex. My Sonex is a 3300 with straight through exhaust. Other pilots love the sound it makes, but I would happily give that up for less cockpit noise.

The Jabiru silencers are simple but very effective. The one on my Sonerai had 2 exhaust pipes. The inlet pipes are cut off where they enter. The large cross tube is just a capped of hollow tube. The outlet pipes just pass all the way through the large tube from the back to the front with a lot of holes for the gases to pass. I think a jabiru one would fit in the Sonex. I would need to re locate the oil cooler. When I built, I just followed the flock and went 3 into 1 exhaust.

In my opinion in ear headsets are the best the way to isolate noise. For 10 years I used to use a DC headset with Headsets inc ANR conversion always with earplugs inserted. My hearing deteriorated to the point where I was struggling to understand any transmissions at all whilst in flight! Last year I bought some good quality noise isolating earbuds, some comply foam tips and made my own set of in ear headphones, I can now hear every readable transmission. They are a huge improvement for noise isolation over any other muff type headset I have tried, Lightspeed included.
Steve
Sonex 892

[Corby202]

Hi Steve. Yes I fitted a muffler.http://www.mykitlog.com/users/display_l ... 4458&row=2
I do get comments about how quiet the plane is flying overhead.
As funny as it sounds my Sennheiser headset works well, it works even better straight after I have had a haircut.

[peter anson]

Onex Paul wrote:

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.

My meter was just a general purpose noise meter - no details of the worst frequencies. You are all welcome to try taking similar readings.

kmacht wrote:

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.

If you follow the link in my earlier post you will see that I tried completely filling the baggage area with foam rubber and even made a blanking board of 5-ply covered both sides with a layer of sound deadening material to try to cut noise from the tail cone. The effect was negligible.

My ANR head set works fine, except when the battery goes flat. The main problem is when talking to a passenger. The microphones don't seem to be capable of cancelling the cabin noise.

When I built my Sonex I was pretty keen to fit the stock Jabiru muffler but it was a horrible fit and it took up the space that I wanted for the oil cooler. It really is crowded in there.

Peter
Sonex 894

[peter anson]

kmacht wrote:

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.

Can I suggest you look again at prop balance? Can't guarantee a dynamic balance will help but it might. The last time I did a static balance it was so good that a dynamic balance couldn't improve on it but a few years ago I had a problem with low speed vibration around 1500 rpm. A dynamic balance by Xenos builder, Brian Rebbechi, totally eliminated it. It is important for more than just comfort. Bad vibrations are high frequency loads that could reduce the fatigue life of parts of the airframe.

Peter

[sonex892.]

Hi Steve. Yes I fitted a muffler.http://www.mykitlog.com/users/display_l ... 4458&row=2
I do get comments about how quiet the plane is flying overhead.
As funny as it sounds my Sennheiser headset works well, it works even better straight after I have had a haircut.

I missed that photo Phil. My Sonerai was apparently very quiet in the air also.

[peter anson]

That's odd Phil. I've never noticed any difference with the headset after a haircut.


Peter

[kmacht]

kmacht wrote:

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.

Can I suggest you look again at prop balance? Can't guarantee a dynamic balance will help but it might. The last time I did a static balance it was so good that a dynamic balance couldn't improve on it but a few years ago I had a problem with low speed vibration around 1500 rpm. A dynamic balance by Xenos builder, Brian Rebbechi, totally eliminated it. It is important for more than just comfort. Bad vibrations are high frequency loads that could reduce the fatigue life of parts of the airframe.

Peter

I have thought about a prop balance but didn't want to shell out a few hundred dollars for it. The vibrations aren't any worse than the other sonex airplanes that I have flown in. It just wears on your feet after a very long cross country. 2 or 3 hours at a time and it isn't a problem at all.

Keith
#554

[unifex]

This looks promising. Its a stainless screen wrapped in to a tube the diameter of your exhaust wrapped in glass weave slid in to a very lightweight aluminum tube. Cosmetic maybe not but it won't increase heat under the cowl and it doesn't weigh much

http://www.piteraq.dk/flight/muffler.html