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There is a rumour circulating in the industry, that Rotax may in the near future stop
supplying engines to the ultralight industry. While this is just a rumour, it is good to
see that several other ultralight engine manufacturers are either entering the market or
improving their products.
Over 35 years ago, there was a four stroke engine used in snowmobiles called the Wankel.
While the engine had great potential, it also had numerous problems one of these being
heat. But technology has advanced a great deal in the past 35 years, and it appears with
this advance the problems associated with the Wankel engine had been eliminated.
This year at Sun N Fun, at Canadian company Rotor Power Corporation Inc, had at display
featuring the Wankel engine from Germany. According to George Payne the Canadian
distributor Wankel engines will soon be produced from a facility at the Oshawa airport.
According to George, Wankel originally licensed Mazda, to produce the Mazda rotary engine.
While the Mazda rotary engine, uses the same principles as the Wankel engine it is a
totally different design.
For those not familiar and with the rotary engine I will try to give you a very simple
explanation. The piston engine has a crankshaft connected to pistons that move up and down
in cylinders, at the top of each stroke the piston is forced by an explosion back down the
cylinder. Since the piston and crankshaft have to stop at the top and bottom of each
stroke at great deal of vibration is created.
A Wankel engine has a disk,shaped like a triangle, that rotates in a circle, thus there is
no top and bottom of the stroke, which practically eliminates vibration. In fact the
demonstration model run at the show had no rubber mounts to dampen the vibration at all.
Yet looking at the engine you could see no vibration, and when reached out and touch
the engine I could not feel any vibration.
The Wankel is a four stroke engine, and it is liquid cooled, the aircraft Wankel engines
are unique in that they use both a charged oil lubrication system and that charged water
cooled system. These two cooling systems, plus the use of nickosil coating have eliminated
the heating problem which plagued the early Wankel design.
During the interview with the factor representative from Germany for Wankel the theme,
reliability durability, and dependability were stressed. These have apparently been
reached by the use of modern materials, a purpose built aircraft engine, which has had its
rpm range limited to 6000 rpm. This vs. the 7500 to 12,000 rpm is the engine is capable of
producing in other applications.
The Wankel engine comes to the customer with dual ignition, fuel injection, exhaust
system, electric start, alternator with several cooling systems available depending on
aircraft make and model. The reduction drive system is a belt drive available in two
ratios a 2 to 1 reduction and a 3 to 1 ratio. Currently there are five distributors and
service centers available for the engine. The factory recommended TBO is 2000 hours or
three years. When asked how many of the current aircraft Wankel engines have reached 2000
hours the factor representative indicated that the factory aircraft has just over 1600
hours on it, with two other aircraft with over 1000 hours on them. He also reported that
these engines have had no problems to date. Another example the factory representative
gave was that there are several go cart racing teams in Europe using the Wankel engine who
have over 400 hours of racing time on them, with the engines having never been taken
apart. This compared to the piston engines that they formerly used where they had to be
disassembled every 5 to 10 hours.
Well now for the tough question. How much money? After all there are only seven moving
parts in Wankel engine! Well you had better sit down. The 35 hp single rotary engine which
weighs 79 pounds was quoted at $6300 American! The 75 hp twin rotor Wankel engine which
weighs in at 109 pounds was priced at $8850 U.S. dollars.
It was pointed out that while the single rotor
engine was quite a bit more expensive than say a 2 stroke 447, the investment was in a
four stroke engine, with a longer life cycle, better fuel economy and reliability.
It should also be noted that the 75 hp version
was comparable in price to a 912 Rotax with fewer moving parts, fuel injection, and a
lighter weight.
For more information contact
George Payne
Rotor Power Corporation
Oshawa Airport
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