Rotary engines in WW1

Orval Fairbairn wrote:

In article ,
(JohnF73157) wrote:



The intake valve was actually located in the top of the piston, this allowed
the fuel/air mixture in the crankcase to enter the cylinder on the "down"
stroke.

Al Minyard



Were rotary engines 2 cycle or 4 cycle?



2-cycle -- hence all the castor oil, which was about the only suitable
oil at the time for that use. Incidentally, a lot of racing cars used
castor oil up into the 1960s.


Not to mention 2-cycle racing motorcycles. I have great smell-memories
of attending bike races in my early teens, when the sport was less
stratified, and more grass-roots, run-what-ya-brung. Sitting around an
abandoned quarry turned into a scrambles track, bikes (many converted
from street use) from five or six different displacement classes
screaming around in circles under a cloud of sweet-fragrance blue
smoke...not very environmentally friendly, but a spectacle I'm glad to
have witnessed.

David Windhorst wrote:

Not to mention 2-cycle racing motorcycles. I have great smell-memories
of attending bike races in my early teens, when the sport was less
stratified, and more grass-roots, run-what-ya-brung. Sitting around an
abandoned quarry turned into a scrambles track, bikes (many converted
from street use) from five or six different displacement classes
screaming around in circles under a cloud of sweet-fragrance blue
smoke...not very environmentally friendly, but a spectacle I'm glad to
have witnessed.

Although I have a 4-stroke behind me when I fly nowadays,
2-strokes have evolved into extraordinarily reliable engines
and I've accumulated more than 1,500 hrs. flying aircraft
equipped with "grassroot" 2-stroke engines. We normally
premix the oil 50:1 (not Castor oil) but except when starting
after a prolonged period of inactivity, they rarely emit the
characteristic blue 2-cycle smoke anymore. Given their
impressive power-to-rate ratio, 2-cycles are ideal for light sport
A/C. For example, in 1993 an intrepid Alaskan pilot flew a 2-stroke
over Mt. McKinley's 20,320 ft. summit, and on Sept. 29, 2000, Czech
pilot Jan Bem set a world altitude record of 26,546 ft. overflying
the peak of Annapurna, Nepal, in the Himalaya Mountains while
flying a 2-stroke powered trike. The U.S. military still uses 2-cycle
engines on numerous different remotely-controlled surveillance
drones.

Just as a matter of curiosity why were rotary engines used?

Dan, U. S. Air Force, retired

Just as a matter of curiosity why were rotary engines used?

Delicious weight/horsepower ratio. Simple, reliable. Being aircooled, perhaps
less liable to gunfire damage. Smooth operating. Available.

There is possibility that there still is a modern engine hidden in the concept.

Quent

"B2431" wrote in message
...
Just as a matter of curiosity why were rotary engines used?

Dan, U. S. Air Force, retired

see
http://www.aviation-history.com/engi...ary-theory.htm

Keith

On 13 Nov 2003 04:47:58 GMT, (B2431) wrote:

Just as a matter of curiosity why were rotary engines used?

Cooling. It was evidently the only way other than liquid cooling to
dissipate heat in 1914-era aircraft engines. Probably a matter of
technology in building "heat sink" fins. Horsepower advancing more
rapidly than knowledge? The first generation of WWI fighters would
have been designed less than 10 years after the Wrights' first flight.

all the best -- Dan Ford
email: (put CUB in subject line)

see the Warbird's Forum at www.warbirdforum.com
and the Piper Cub Forum at www.pipercubforum.com

One of the big advantages was that the rotary motion assured a
substantial flow of cooling air across the cylinders and cylinder
heads, even when the aircraft was flying slowly, or the engine was
instlled in a pusher configuration. This was very important since the
engineering knowledge and manufacturing technology available at the
time was not really sufficient to achieve satisfactory air cooling
with static cylinders. Most early attempts at air cooled aircraft
engines with static cylinders had limited success. At best, very rich
fuel-air mixtures had to be used to help with the cooling. In other
cases, such as the disasterous ABC Dragonfly (of which over 10,000
were ordered off the drawing board), the result was an engine that was
completely useless.

Robert

QDurham wrote:

Just as a matter of curiosity why were rotary engines used?



Delicious weight/horsepower ratio. Simple, reliable. Being aircooled, perhaps
less liable to gunfire damage. Smooth operating. Available.

There is possibility that there still is a modern engine hidden in the concept.

Quent


Rotaries got applied to motorcycles a few times, too, both to the rear wheel
http://www.motorcycle.com/mo/mcmuseu...tos/millet.jpg

and the front http://www.magpie.com/nycmoto/guggen...ola_engine.jpg

Gyroscopic effect and all that rotating mass reportedly made turning the
latter about like trying to roll an a/c into the rotational direction of
a big cubic-inch aviation powerplant.

Mike Marron wrote:

snip




Although I have a 4-stroke behind me when I fly nowadays,
2-strokes have evolved into extraordinarily reliable engines
and I've accumulated more than 1,500 hrs. flying aircraft
equipped with "grassroot" 2-stroke engines. We normally
premix the oil 50:1 (not Castor oil) but except when starting
after a prolonged period of inactivity, they rarely emit the
characteristic blue 2-cycle smoke anymore. Given their
impressive power-to-rate ratio, 2-cycles are ideal for light sport
A/C. For example, in 1993 an intrepid Alaskan pilot flew a 2-stroke
over Mt. McKinley's 20,320 ft. summit, and on Sept. 29, 2000, Czech
pilot Jan Bem set a world altitude record of 26,546 ft. overflying
the peak of Annapurna, Nepal, in the Himalaya Mountains while
flying a 2-stroke powered trike. The U.S. military still uses 2-cycle
engines on numerous different remotely-controlled surveillance
drones.

Has the Orbital design been applied to any aviation 2-strokes? After
Honda licensed it in the 90s there was much anticipation of a new,
cleaner generation of high-output, lightweight 2-stroke bikes, but it
hasn't happened yet.

Mike wrote in part:Has the Orbital design been applied to any aviation
2-strokes? After
Honda licensed it in the 90s there was much anticipation of a new,
cleaner generation of high-output, lightweight 2-stroke bikes, but it
hasn't happened ye

My understanding is that by the time the *much* needed mufflers are added, and
the anti-smog stuff and the cooling stuff, the weight/power/space advantages
aren't all that wonderful.
And of course, in planes there has to be some sort of gearing (not lightweight)
so that the prop turns much slower than the engine.

Quent