I’m still struggling with tuning my rotary/microtech. I spent an hour or so running it yesterday and ended up a little closer on the tuning front but also ended up with a blown out exhaust/muffler. It’s come apart at a bunch of places – not the welds but the Inconel itself next to the welds.

 

The exhaust pipe coming out of the “tangential tube” is/was in the profile of an “8” without the connection in the center. An engineer friend of mine who looked it over said it makes sense - after the fact - that the exhaust pulses were causing the tube to flex at the center joint.  It appears to have started at the outboard end and went all the way to the center tube and then, perhaps from vibration, cracked out the pipes except for about ½” from the center connection.

 

The main manifold – runners and the tangential tube – are all sound with no signs of stress.

So, be careful out there!

 

Pics attached.

 

Thanx,

Joe Hull

Cozy Mk-IV #991 (Done Building! In Phase1 Flight Test - 0 hrs flown)

Redmond (Seattle), Washington