The design although not quite set in stone is at least set in foam.
 I've already started building the fuselage and wing spars. I have a
 build thread on homebuiltairplanes.com here:
 http://www.homebuiltairplanes.com/forums/member-project-logs/16831-wa-1-2-spitsairwulfstang.html

 So although it hasn't been glassed yet it's still pretty much in
 final form.

 I had an idea that you will probably shoot down but it involves a
 ovoid ejector of smaller diameter than your design and much shorter.
 The screen caps will show better than words.



 Above you see the ejector (made from 4" tube split in half with flat
 sides) and the intake duct.



 Above shows the ejector removed so you can see the headers which
 would have the swiss cheese holes in them.




 And the last shows what it would look like with the cowl on. Not
 shown in the pic is the cutout in the side of the fuselage.

 This was very quickly roughed in just to give the general idea. Is
 this in any way feasible?

 You mentioned that most people have trouble with their mufflers and
 I'm wondering what they are?

 Thanks,

 Will Aldridge


 Very ingenious ejector. Solves the motor mount problem too.

 That will work of course but I doubt it will be quite enough.

 The six foot coax ejector is not exactly quite. It just has a more
 pleasant sound. This too may have a more pleasant sound but I doubt
 it will be quiet enough.

 We get lots of complaints about the noise. The six foot coax muffler
 is barely acceptably quite.

 Basically they melt from the 1400 t0 1700 F heat.

 Paul Lamar


 One additional idea I hade was to crimp the ends of the headers to make
 them fish tail shaped. That might conceivably cut down the noise a
 little more and it is almost over the wing so it might make It quieter
 under the plane. I know that parts melting is a problem but I was also
 wondering about a constricter plate at the end of the ejector?

 Will Aldridge

 You can do that but make the area constant and beef up the thickness of
 the metal
 as just flattening it causes it to vibrate and fatigue.

 Also extend the outer part back behind the cockpit. Beef up any long and
 large flat areas
 with thin SS hat sections on the inside.

 As you can tell we have been around and around on mufflers for the past
 16 years :)

 The coax muffler has been the best thing since sliced bread :)
 It is the culmination of 16 years of aircraft rotary muffler experience.

 Paul Lamar

Had an interesting though probably bad idea.  What if I pointed the headers the other direction?  That way you'd about double the distance the exhaust traveled in the augmenter since it would have to turn around and go back out.  The downside I can see is that I intend to use a wood/composite prop and if the propwash at idle isn't enough to turn the exhaust back the other way it could damage the prop.

Is there improvement using the tangential muffler with the fishtail exhaust over a simple round pipe?

Will Aldridge

You would build back pressure in the engine. Not good :)

Do it the way you are going... just make the outer part longer out of
thin hat section reinforced SS. You will get a bit of thrust that
should  cut some drag.

Do you have my book? Here is some stuff from it  about ejectors AKA thrust
augmenters.

BTW My book is being sold on the east coast and one can pay by PayPal so
I will upload that web site address  shortly.

Paul Lamar



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