2 - 3 mph with the installation of a new muffler (custom

Spintech,

see

http://www.spintechmufflers.com ).  Speed loss was due to dirty

aerodynamics of

exposed muffler, not HP loss.  I actually gained HP with the

spintech

(and

lost some noise).   Engine rpm at 215 mph is 6450 rpm.

Tracy Crook
tcrook@rotaryaviation.com
http://www.rotaryaviation.com

Can you get them in thick wall stainless steel Tracy? What material

is

yours

made from now?

Paul Lamar

Standard is 304 SS but they will make them from any alloy or gauge you

want

(for a price).  I specified 321 stainless, .062" wall.  They will also
configure the inlet & outlet size & location to your spec.

Tracy Crook
tcrook@rotaryaviation.com
http://www.rotaryaviation.com

What did that jewel cost you Tracy?

This is very interesting.

Here is an excerpt from their web site.

"Spin Tech's patented design provides maximum performance for today's
modern engines. Its all done by means of a Spin sound trap, which
captures sound vibration (noise) and turns it into heat within the
muffler case. As exhaust gases enter they are routed to the spin traps
which create a high velocity vortex trapping the sound waves. The
extremely high flow rates are achieved by a unique internal scavenging
system that creates a venturi effect."

What strikes me about this is the similarities with the tangential
muffler and the
long muffler you made with the turning vanes. All three spin the gases
around in a hollow
chamber thereby rubbing on the walls of the chamber and losing noise by
friction
and heat to the chamber walls.  I think there is a lot more potential in
your original
design. If you forget the holes and add more turning vanes first one way
and then the
other you might come up with a cheap streamlined muffler that would live
with a
rotary. We have length on our side while length is a drawback under a
car.
Muffler frontal area is of no consequence under a car while in an
aircraft it creates
a lot of aero drag of course.

Paul Lamar

Perhaps we could somehow apply jet engine noise suppression techniques.
Much of the noise produced by a turbine engine results when hot, high
velocity gases mix with cold, low velocity air surrounding the engine.
This high intensity noise includes both low and high frequency
vibrations, with low frequencies being predominant.
Turbofans seldom require noise suppression because their exhaust
sections are designed to mix hot and cold gas streams prior to their
release into the atmosphere which greatly reduces exhaust noise!

Noise frequency is also often accomplished by increasing the frequency
of the sound, by increasing the perimeter of the exhaust stream,
providing more cold and hot air mixing space. This reduces the tendency
of hot and cold air molecules to shear against each other and also break
up the large turbulence of the exhaust.

Perhaps we could duct high velocity cold air in an annual chamber around
the exhaust and discharge it simultaneously?
This doesn't address the pulsing discharge waves of the rotary, but what
the hey.
Shoot this full of holes anybody?
Marc Wiese

 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org