Here is my 2c on the subject.
I nave a tangential muffler on my SOOB. It is a 4"
SS pipe with the two entrances at either end and the exit in the middle. The
muffler pipe is totally empty. The exit pipe is slightly smaller than
either one of the entrance pipes. The rational for this is that the inflow is
alternating from cylinder to cylinder, and the cooling down of the exhaust gas
is reducing the volume. This is not based on analysis, just on the thermo
dynamic principles.
Subsequently, I applied the same thinking to the
one rotor on the test stand. Running that engine with no muffler, you would not
want to be within 100ft of the test stand. With the muffler, I can stand right
at the running engine for an unlimited time. How much does that mean for the
installation in the airplane? I don't know until I install and fly
it.
Richard Sohn
N-2071U