A coupleof sharp motor tuners and a day or so on a good
repeatable dyno can zero in on acceptable intake design that should set a
good baseline for what really works. You can sliderule / use fancy computer
programs and other methods of determining optimum designs but nothing trumps
real time data in a running engine. Just my .02 cents
worth.
Ben Haas
Oh, to have my own dyno again.
The point was that there are many rotary engines to think about. Now
days you probably have a 13B side intake port, periphery exhaust, or the now
common Renesis with side intake and exhaust. And now converting both styles
to a home made periphery intake. Neither exsists in nature, so you may well
be on your own tuning wise.
Stick to the basics. Velocities reversions, harmonics DIE, radius, Mach
numbers. As in radio wave reception, you are probably operating in the
1/4 wave regeion. Remember the thing you built in the attic to get killer
reception on the black and white TV? The lower channel numbers had such a
long wave length that it took a big attic to hang just a 1/4 wave length
antenna. And the UHF antenna was just a loop with barely 12" of wire
involved.
Remember the Cross Ram Dodges, with 4 barrel carbs hanging outboard of
the rocker covers. 460 foot pounds of torque. The runners were at least 4
times the length of the dual plane regular manifold.
So was the cross ram the full tuned length and the regular street
manifold runners were the 1/4 wave length? Or was the cross ram the half
wave length? Usually the best harmonic peaks will be divisable by 4.
So all of this harmonic, standing wave, pulse tuning stuff applies to
one dynamic situation based on that engine RPM. Change the RPM and
everything else changes too. There is nothing static about airplane engines.
So the best guess is to get it close to cruise RPM and then tune the
daylights out of it. The airplane is a kind of dyno. It provides a variable
load. The engine controller provides the tuning capability. Every flight can
be used to recover usefull data.
Use the SAE tables to return all data to the SAE standard day at sea
level. Make only one change per test. Record everything. Keep the records.
Or, just copy the Mistral intake.
Lynn E.
Hanover