flyrotary@lancaironline.net Mailing List Archive

Subject: [FlyRotary] Re: 20B install issues overcome

My exhaust exits about 6-7 inches from prop and goes through near the root of the blades (pusher). It occurs to me that having my exhaust exit through the prop may help reduce or mask the exhaust noise. On a takeoff roll there is a prop blade breaking that exhaust stream about 130 times per second. Let’s see, that’s about 1 blade passing for every two exhaust pulses on the 20B – could make a difference.

The secondary muffler/resonator I have also helps. On the dyno we measured that resulted in about 6 db reduction.

Al G

Agree. Unfortunately, that's not a comment I hear. On the contrary, they usually tell me that they can hear me before they can see me. ;-(

Mark S.
ANR headsets mandatory

On Sun, Jan 4, 2009 at 12:22 AM, Al Gietzen <ALVentures@cox.net> wrote:

I'm presently gathering materials to fabricate a tangential muffler made from inconel, similar to your design. I take it from your report that your muffler is holding up well?

Mark S.

So far it is doing fine. And the inconel tangential and the 321SS secondary muffler (my own design) quiet it down nicely. A few days ago I picked up my brother to go for a ride, while my sister-in-law waited and watched other planes come and go. When we got back her remark was that my plane was quieter than all the rest. I consider that to be 'expert testimony'J.

Al G

On Sat, Jan 3, 2009 at 5:47 PM, Al Gietzen <ALVentures@cox.net> wrote:

Al,

That's a great shot. Have you had any "significant issues" with your install? If so, how did you overcome them?
Mark S.

I had 2 issues that required some time and determination. The first was the RWS EC2. I had an early version for the 3-rotor, and perhaps the first installed in a composite airplane. I had some kind of electrical noise related corruption of settings which persisted through a lot of effort for over a years time. It has been resolved, and the engine running fine. That has been discussed here more than once in the past.

The other was less-than-expected performance of an oil cooler built into the wing root, without much of a scoop for the inlet below the wing. The theory was that the differential pressure below/above the wing would help provide the necessary air flow. Not the case here as the location is too far back on the wing; and behind the strake (the inboard section on the canard airplane). The pressure differential turned out to be only about 1" H20 – very little help. I added a ram scoop, and installed a small oil/water heat exchanger in the cowl. Currently oil temps are fine, and the coolant temp is running a bit lower than I like at cruise. I may eventually install some sort of air flow adjustment, or even consider installing a thermostat in the engine. You may recall discussion of these changes here in the past as well.

I'm just past 140 hours flying time, and feel quite fortunate with how well things have worked out. Performance and economy are great.

Al G http://members.cox.net/alg3/airplane.htm