George,
That might have been a problem with the old carburettor fed rotarys, and in fact they ran a thermal reactor on the early ones. With modern EFI and even lean of peak operation and closed loop O2 sensor operation that shouldn't be a problem. When the O2 sensor is used the idea is to be SURE there isn't any O2 left, but more important that there isn't any FUEL left. The O2 sensor is really an unburned fuel sensor that just works backwards since it is easier to sense oxygen than any of the other exhaust gasses. Without fuel to ignite what is going to burn?
Bill Jepson
-----Original Message-----
From: George Lendich <
lendich@optusnet.com.au>
To: Rotary motors in aircraft <
flyrotary@lancaironline.net>
Sent: Mon, 5 Jan 2009 1:09 pm
Subject: [FlyRotary] Re: 20B install issues overcome
Bill,
I had a talk with Mistral a while back and the chief engineer had some concerns with introducing fresh air into the exhaust ( for cooling) as it might initiate burning of residual fuel - hence more heat rather than less heat.
That's why their cool tube (over the exhaust tube) is discharged separate to the exhaust.
Although I intend to proceed with out original design just to see the results.
Do you have any comments on this ?
George (down under)
Earnest,
I believe that the SuperTrapp muffler is an example of a band gap device and it worked well, if properly tuned.
I think the large block idea has merit too, but you will have to allow enough thickness to prevent the tubes that see the exhaust first to fight the harmonic vibration and heat. Different size diamonds in the exhaust stream might also help fight harmonics.
Bill Jepson