We have covered checking the compression of a rotary. Is a rotary that has
had a seal failure a paperweight? Does a seal failure destroy enough of the
rotor housing to make it unusable? Other than compression, is there anything
else to be concerned with? To build a lightweight engine such as the 109 lb
13b on the AREN web-site, would one start with a used engine? As Paul has
designed both an intake, and finalizing ignition and fuel injection control,
the factory automotive intake, engine control, and exhaust manifolds are
essentially unnecessary? It is safe to say that intake, exhaust and cooling
all would be user designed and fabricated?
I know that probably all of these questions have been answered before, it is
difficult to sort them out from all of the individual news letters. With the
apparent demise of Rotamax, the 13b lightweight looks like the next best
option. I'm looking for no more than 240 hp for my aircraft, therefore would
not be pushing the engine to it's limits, as far as I can tell from reading
the information on the website.
Any other relevant advice is appreciated. Also, if the questions are
answered in articles published on AREN, the list of links is sufficient for
me to review.
C. Smith

"Is a rotary that has had a seal failure a paperweight?"

Not necessarily.  Only one rotor housing may need replacing.


"Does a seal failure destroy enough of the rotor housing to make it
unusable?"

Usually yes. Seal failures are rare on normally aspirated engines.

"Other than compression, is there anything else to be concerned with?
To build a lightweight engine such as the 109 lb
13b on the AREN web-site, would one start with a used engine?"

It is very rare to have any problems with any of the bearing.
They can usually be reused. Same goes for the e-shaft. It never
gets cracked. Some times a rotor is damaged when a apex seal fails
or is subject to FOD.

On a high mileage engine that has been taken care the side housings
may be worn to the point they need re-lapping. My guess is around 300,000
miles. If it is necessary to lap them more than .003 they may need to
be rehardened in the form of nitriding.

500 HP per rotor at 11,000 RPM is pushing the engine to its limits :)

Paul Lamar

Paul,
I am also interested in using a lightweight 13b engine.
My question is: Can the forward and rear counterweights be consolidated into
counterbalance weights located on an aluminum flywheel? I recognize that
there would be additional torsion on the e-shaft but the shaft is short and
strong and in an aircraft installation, there would be a minimum of quick
stops and starts. The increased length of the moment arm would serve to
reduce total weight of the counterweights. The system would have to be
balanced of course.
The distance from the counterweighted flywheel to the rear rotor would be
the same as the distance from the interior rotors to the counterweights in
the 1991 4 rotor engine.
Doug

It is tricky but it can and has been done. I have equations so remind
me later. Or download Kenichi Yamamotos book Rotary Engine.

http://www.wankel.net/~krwright/cars/rx7/manuals.html

Paul Lamar

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