Probably not noticeably at high RPM because the rotary is reputed
to run at high RPM without apex seals.

Research at Curtiss Wright and Deere led to the hypothesis that engines running at VERY high speed
might work without apex seals, but this was never tested. I would guess that the equivalent speed
for a 13b where this might work would be above 20,000 RPM. I can tell you that a large (5.8liter
per rotor) engine operating at 3600 RPM (equivalent to a 13B speed of about 7200RPM) will make
zero power with malfunctioning apex seals.

Has anyone seen the Graupner RC engine? What does it have for apex seals?

I have no experience with the trailing hole modification.

Jon Lauter
Rotary Power Marine Corporation
www.rotarypowermarine.com

Dear Jon,
I have a book on model engine and the Graupner is also briefly mentioned. Apparently, this engine uses
apex seals only and no side seals due to its small dimension and  the difficulty of placing side seals.
The O.S. Graupner, build in Japan by O.S., depends on highly precise surface grinding of the rotor sides
and the housing, where axial differential cold clearances are held to a minimum. The clearances are
consistent with the relative thermal expansion of rotor and housing.
The apex seals were a special cast-iron, the aluminum housing was steel metal-sprayed. The side walls,
initially metal sprayed as well, were later on not coated and it was found that a plain aluminum alloy
was adequate as wear surface.

It uses a side inlet and a peripheral outlet port. Peak power of .67 hp at 16,000 rpm at .30 cu in
chamber displacement and fuel of 5% nitromethane.
Peripheral inlet ports were used on their earlier model 49-PI. A two rotor engine was also tested.

I am also experimenting with rotary engines. If you wish you may contact me directly.
Rolf Pfeiffer, "rpfeiffer@rogers.com"

 
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