Rotary vs. Piston
Rotary boy
did a good job defending my rotary but now I am just curious exactly why a
rotary is so much better and more efficient than a piston engine. She said
that her instructor told her rotary engines were not rebuildable which is
complete bull. Also, how are rotaries used besides in cars? Cheers!
Animalector
one reason why rotaries are better is because of the linear to rotary motion
conversion required in a piston engine. as the piston is moving downwards
the con rod has to move sideways as well as down. (circular path of crank
shaft) This means that a certain percentage of the power produced which
pushes the piston down is actually used up in sidewards movement. Rotars
don't have this problem since all the movement is rotational.
There's more of course but it's been covered hundreds of time.. find
yourself a good rotary forum and do a search through the tech topics..
you'll get lots of really good info explained better than I could ever
explain.
Good luck
Andy
The Raven
news:a446f81fa2dce77f...@news.sonicnews.com...
> Tonight I got in a debate with a friend about rotary vs. piston engines.
I
> did a good job defending my rotary but now I am just curious exactly why a
> rotary is so much better and more efficient than a piston engine.
Power for displacement is good.
More compact (but not necessarily light)
Less parts (but not necessarily easier to make)
Easy to get more power out of.
> She said
> that her instructor told her rotary engines were not rebuildable which is
> complete bull.
Agreed. By the same token if you read a Mercedes truck engine manual it
would have you believe they are near unrebuildable without all new parts.
Crank has 2+ thou wear? Throw it out and buy a new one according to
Mercedes.
A rotary is technically rebuildable forever as there is no one main "core"
part that cannot be rebuilt or replaced.
> Also, how are rotaries used besides in cars? Cheers!
The US military was hot for them in the early days. Brilliantly small and
quiet gensets by comparison to deisels.
Curtiss Wright ("Wright" as in "Wright Brothers" fame) have been building
rotaries for various applications for years. One of the other major
industrial engine companies got into them some years back but I never heard
much of it.
Moeller is building them for the infamous Sky Car.
OS build them for Remote Controlled aircraft.
They were used in snowmobiles and lawnmowers (Sachs engines IIRC).
Several motorcycle manufactures made or used them (Suzuki RE5, Van Veen,
Hercules, Norton etc )
--
The Raven
** Undisputed President of the ozemail.* NG's
** since August 15th 2000.
** Conqueror of the uunet.* NG's
Amur_
This site has a tonne of rotary articles, as applied to aviation:
http://home.earthlink.net/~rotaryeng/ACRE.html
Paul Lamar's excellent article comparing rotary and piston motors:
http://home.earthlink.net/~rotaryeng/rotor-verses-the-piston.txt
ttyl,
Amur_
Dave
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MK70
industrial engine companies got into them some years back but I never heard
much of it.
John Deere is the name of that industrial engine company.
They now drop the rotary project and a new company -
Rotary Power International is formed and carry on John Deere's rotary engine
development.
RPI offers high output multi-fuel ( Diesel, gas, kerosene, etc) rotary
engine up to 3000hp.
It is also converting Mazda 13B engine into multi-fuel engine for industrial
application.
http://www.rotarypowerinternational.com
I think the RPI engine still has potential in military as well as industrial
application,
especially the converted Mazda engine which is a very good small gas
turbines subsitute.
Gas turbine has terrible fuel efficiency and the price is very expensive.
Although Gas tubine weight substantially less than a rotary,
the additional fuel weight will probably offset this advantage.
Renesis is almost as fuel efficiency as 4 stroke piston engine now.
The gas mileage for RX8 is 20 mpg city 30 mpg highway according to the
specification in Mazda webpage.
The initial success of RX8 should generate a lot of interests for the RPI
engine.
> Moeller is building them for the infamous Sky Car.
SkyCar is a personal vertical takeoff and landing (VTOL) vehicle.
It is still under initial testing at low attitude ( less than 50 feet off
the ground ).
Paul Moller also developed a rotary engine for the Sky Car,
but sold the design to Freedom Motors, Inc. later on.
http://www.moller.com
At 3 April 2003, Freedom Motor announces two new motors,
650cc single rotor and 1300cc twin rotors respectively.
Pre-production engine will be available for Beta tester this summer.
http://www.freedom-motors.com/
> OS build them for Remote Controlled aircraft.
OS is still making the little 5 c.c. engine.
http://www.osengines.com/engines/osmg1400.html
> Several motorcycle manufactures made or used them (Suzuki RE5, Van Veen,
Hercules, Norton etc )
All of them have either stopped rotary engine development or bankrupted.
Bear Trucker Lvr
To be honest, just as a short answer (don't have the Massive Books of
Fact and Knowlege {TM} in front of me0 i honestly think itis 6 of one,
half a dozen of another. It is a personal preference. the piston
freaks will say thier engine is better than a Roto all day, same for
the Rotary camp.