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It is interesting that when you go back into the early days of
ultralight aviation you will find that we were using an engine on our
Lazair ultralights called a Pioneer. It was manufactured by OMC in
Peterborough Ontario. While not designed to be used in aircraft, it was
actually a chain saw engine, we none the less adapted it to work on our
craft.
A number of years later OMC entered the snowmobile industry and spent
a small fortune developing a rotary engine. At one point they had a team
of over 40 engineers working to develop the engine.
Unfortunately just about the time they were about to start production
on the engine the snowmobile industry fell on hard times and the project
was put on the back burners. Recently a U.S. company RotaMax, purchased
the design rights to the engine and using today's technology has started
producing and offering the engine for ultralight and light sport
aircraft application.
Eric Barger President of RotaMax was at Sun N Fun showing a number of
aircraft installations that are currently using the RotaMax rotary
engine. These included Higher Class Aviation and it's Hornet, Sadler
Aircraft and the Sadler Vampire.
One of the reasons these manufacturers have installed the RotaMax
engine on their craft is the simplicity of the design. A single rotor
engine has two moving parts, while the twin rotor has only three moving
parts!
The engine is still a 4 cycle engine, with intake, compression, power
and exhaust cycles. It does not use the conventional valves, push rods,
camshafts etc. which makes for a very heavy installation.
Instead the " Wankel Style" rotary engine uses a triangle shaped
piston which rotates around in a circle, with ports in the case routing
the individual cycles. This gives the RotaMax engine a very high power
to weight ratio.
Another advantage is the low cost of maintenance and rebuild on the
engine because of the lack of wearable parts, no gaskets, and the
simplicity of design.
Engine vibration is nearly nonexistent because "it is a rotating mass
engine it is perfectly balanced." The engine is liquid cooled using a
water pump and radiator, with the type of cooling system used being
specific to each application."
This means that they system used on a slow moving gyrocopter would be
different that that used on a sleek 140 mph light sport aircraft.
The RotaMax single rotor 650 cc, 65 HP engine will use between 3 and
4 gallons of fuel an hour, while the twin cylinder 1300 cc engine uses 4
to 6 gallons per hour, again this will vary with the type of application
the engine is being used in.
All of the RotaMax aircraft engines are equipped with dual ignition
systems. Currently the single cylinder engine is only available in a
carbureted version, with the twin cylinder 1300 cc engine being fuel
injected.
The RotaMax engines have a very flat torque curve which means you can
bring the horsepower use back on the engine and still do the same work.
Less horsepower means less fuel burned.
The RotaMax 1300 cc twin rotor engine has a top RPM of 4750, with
cruise RPM being 4250. However RotaMax is working closely with Rotary
Aircraft Engines of Utah to develop horsepower/torque engine
application for specific aircraft.
Another unique feature of the RotaMax engine is that it uses a "lost
oil system." Regular 30 weight oil is injected into the engine, and is
burned off in the combustion cycle. This means you do not have an oil
pan, you do not require any oil changes, no oil filter, and no waste oil
to dispose of.
The RotaMax engines come with a standard charging system of 32 amps
but an optional unit of 45 amps is available. The engine uses an oil
bath spur gear reduction drive, with ratios from 1.9 to 2.7 available.
RotaMax is also developing belt drive systems to fit various
applications. A number of exhaust systems are being developed, all of
the systems are made from stainless steel due to the higher exhaust heat
that the engine produces.
Eric reports that the factory which has been producing engines for
over 3 years now for other applications such as hovercraft, dirt bikes,
motorcycles, and ATV's has the capability of producing 150 engines per
month, with the ability double this if necessary.
Nathan Oldham of Rotary Aircraft Engines is the master distributor
for the RotaMax aircraft engine. His company is the one that involves
itself with the aircraft manufacturer to develop the complete
installation requirements for each application.
His company is also responsible to training the aircraft manufacturer
on the differences between what they have been doing in the past and
what is different or what needs to be changed to ensure continued safety
and reliability of a RotaMax engine installation.
As more and more customers become more familiar with the RotaMax
series of aircraft engines Nathan will work with the aircraft
manufacturer to provide a complete installation package for specific
aircraft. One RotaMax conversion on display at the show on a gyrocopter
actually dropped the engine installation weight from what was being used
by 100 lbs., in addition to supplying more horsepower.
Nathan indicates that one of the goals of Rotary Aircraft Engines is
provide "a lower cost aircraft engine alternative, with a significant
power to weight ratio increase, with lower maintenance and operating
costs."
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