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Jerry, With regards to the VAM as was run at Tracy's, the design is ABSOLUTELY DEPENDENT on the tail pipe. The test at Tracy's ran the pipe with the tail pipe removed so the pipe would fit on Tracy's test stand. This was dumb as the cool tube was designed to form a venturi in the TAIL PIPE to draw in the cool air. Your test installation was better, but by that time Paul L was advising you, (incorrectly IMHO) that the idea was crappy. The VAM will work, but you should run a tail pipe and a thicker one right at the junction would be better. Your cool tube will help and isn't as finicky. Blending the cool air and exhaust streams should help quiet the muffler more but you have to do it carefully.
Bill Jepson In a message dated 3/8/2005 4:14:12 PM Eastern Standard Time, Jerry Hey <jerryhey@earthlink.net> writes:
Ed, you are referring to the VAM which did not have a cooling tube,
just an open end. It was very loud, I understand. It was in
looking at the VAM that Ed Klepeis and I finally asked each other, what
if we weld a tube in there? We still think it is a good idea. The
large diameter is also important. The idea is that the exhaust gases
will lose heat and energy (sound) as they expand within the can. Also,
note the exit pipe (rectangular, 1.75 x 4) is has a much larger area
then the two 2" o.d. pipes coming out of the engine. The idea is to
create a completely free flowing exhaust in which the exhaust gases
become very disorganize as they expand and cool. Jerry
On Tuesday, March 8, 2005, at 03:50 PM, Ed Anderson wrote:
Well, I hope it works out. A somewhat similar muffler (although not as
large in diameter) with a cooling tube has been tried. It was fired
up at
Tracy's, it is my opinion that the design failed to mute the exhaust
very
much. But, not certain how much the two designs have in common other
than
appearances. Seeing as the exhaust BTU is equivalent to approx twice
the
heat discharged through the radiators and mufflers together, it is my
opinion, that its going to take a LOT of cooling air to make any
difference
in temps of the oven. However, I would love to see it work, I've got
the
room - just can't take the heat. {:>)
Ed
----- Original Message -----
From: "Jerry Hey" <jerryhey@earthlink.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, March 08, 2005 3:33 PM
Subject: [FlyRotary] Re: Tangential muffler
Thanks for your comment Ed. The cool tube is intended to extract a
lot of that heat and pump it overboard. We shall soon see if it
works
as Bob White will be running his engine soon. I got my fingers
crossed.
On Tuesday, March 8, 2005, at 03:17 PM, Ed Anderson wrote:
Jerry, Tracy Crook flew with a similar Tangential muffler for a
number
of
hours. The neat thing is it does fit under the cowl and suppress
sound
nicely, the un-neat thing is it acts like a large oven under the cowl
and
keeps cowl temps highly elevated. I am fairly certain that is why
Tracy
removed it.
Ed A
----- Original Message -----
From: "Jerry Hey" <jerryhey@earthlink.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, March 08, 2005 3:01 PM
Subject: [FlyRotary] Tangential muffler
From the "other" list comes the report that someone has tested a
similar exhaust system to what I have been building on his
PowerSport
p
ported engine. . He reports the muffler worked well to quiet the
exhaust note and that the engine seemed to breath freely. The neat
thing about this exhaust system is that it fits inside the cowl.
Here are a couple of photos showing the muffler on a Mustang 2. The
muffler is 6" o.d. x 10 inches long. Construction is 321 16 gage.
The cool tube running through the center is intended to cool the
exhaust gas. Fresh air is plumbed through it. The engine mount is
the S-beam. Jerry
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