Rotary engines in WW1

[Stuart Chapman]

The thread above reminded me of a question I have about rotary engines....

Just how was fuel & air admitted into the cylinders?????

The only way I can think of is some sort of central machined plate, that has
holes in the right positions so that when it turns (along with the cylinders
/ propellor) it meets up with inlets (non-rotating) for fuel & air, that
inject into the appropriate cylinder.....

thoughts everyone?

Stupot

[M. J. Powell]

In message >, DAN
> writes
>Stuart Chapman wrote:
>
>>The thread above reminded me of a question I have about rotary engines....
>>Just how was fuel & air admitted into the cylinders?????
>
>>The only way I can think of is some sort of central machined plate, that has
>>holes in the right positions so that when it turns (along with the cylinders
>>/ propellor) it meets up with inlets (non-rotating) for fuel & air, that
>>inject into the appropriate cylinder.....
>
>>thoughts everyone?
>
>Basically correct. The rotary engines had fixed inlets and outlets for
>indiction
>and exhaust, in front of which the cylinders would scroll.
>
>If you want more info you can look up the most famous of them, the "Gnome-Rhone
>Monosoupape".

I've always been fond of that name. Sometimes I chant it to myself.
"Gnome-Rhone Monosoupape', "Gnome-Rhone Monosoupape"

Lovely!

Mike
--
M.J.Powell

[Cub Driver]

On Mon, 10 Nov 2003 14:53:43 +0100, DAN > wrote:

>Basically correct. The rotary engines had fixed inlets and outlets for indiction
>and exhaust, in front of which the cylinders would scroll.

My understanding is that this didn't work very well for exhaust--that
the pilot basically lived and breathed in a foggle exhaust fumes and
castor oil droplets.

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

[Greg Hennessy]

On Mon, 10 Nov 2003 09:58:17 -0500, Cub Driver
> wrote:

>On Mon, 10 Nov 2003 14:53:43 +0100, DAN > wrote:
>
>
>My understanding is that this didn't work very well for exhaust--that
>the pilot basically lived and breathed in a foggle exhaust fumes and
>castor oil droplets.
>

On a plus note, it was a rather effective cure for constipation.


greg
--
$ReplyAddress =~ s#\@.*$##; # Delete everything after the '@'
The Following is a true story.....
Only the names have been changed to protect the guilty.

[QDurham]

Cub driver wrote in part:
>My understanding is that this didn't work very well for exhaust--that the
pilot basically lived and breathed in a foggle exhaust fumes and castor oil
droplets.>

Partially correct. The engines were lubricated with castor oil injected (or
mixed with fuel.) No crankcase to hold oil. I think fuel (+ oil) was admitted
to cylinders via a hollow, non-rotating crankshaft. I've been told the engines
ran flat out almost ll of the time. Don't think thjey had a throttle. Had a
"kill switch" on control stick. Incidentally, these engines had impressive
power-to-weight numbers. Furthermore, essentially nothing reciprocated. Each
piston, for example, traveled in its unique circle -- reciprocated compared to
cylinder, but circled in relation to the world. Very smooth engine.

I've read that at the end of WWI some rotary-powered planes reached 20,000 feet
regularly. At that altitude I bet the pilots were so hypoxic they shot down
their wingmen as often as the enemy.

Quent

[Stuart Chapman]

"QDurham" > wrote in message
...

> Furthermore, essentially nothing reciprocated. Each
> piston, for example, traveled in its unique circle -- reciprocated
compared to
> cylinder, but circled in relation to the world. Very smooth engine.
>


That's a bit confusing....

If the piston is reciprocating relative to the crankshaft then isn't also
reciprocating relative to the world??

Although I can imagine opposing cylinders being in phase to cancel out
reciprocating forces.

Stupot

[Stuart Chapman]

"DAN" > wrote in message
...
> Stuart Chapman wrote:
>
> >The thread above reminded me of a question I have about rotary
engines....
> >Just how was fuel & air admitted into the cylinders?????
>
> >The only way I can think of is some sort of central machined plate, that
has
> >holes in the right positions so that when it turns (along with the
cylinders
> >/ propellor) it meets up with inlets (non-rotating) for fuel & air, that
> >inject into the appropriate cylinder.....
>
> >thoughts everyone?
>
> The rotary engines had fixed ... outlets for ...exhaust, in front of which
the cylinders would scroll.
>

That's interesting.....I thought it would have been simpler for each
cylinder to have its own exhaust port, controlled by rods riding over cams
on the crankshaft. But maybe this is just introducing too much complexity.

Stupot

[Alan Minyard]

On Mon, 10 Nov 2003 08:01:33 GMT, "Stuart Chapman" > wrote:

>The thread above reminded me of a question I have about rotary engines....
>
>Just how was fuel & air admitted into the cylinders?????
>
>The only way I can think of is some sort of central machined plate, that has
>holes in the right positions so that when it turns (along with the cylinders
>/ propellor) it meets up with inlets (non-rotating) for fuel & air, that
>inject into the appropriate cylinder.....
>
>thoughts everyone?
>
>Stupot
>
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

[JohnF73157]

>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?

[Orval Fairbairn]

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.

[David Windhorst]

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.

[Mike Marron]

>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.

[B2431]

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

Dan, U. S. Air Force, retired

[QDurham]

>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

[Keith Willshaw]

"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/engines/rotary-theory.htm

Keith

[Cub Driver]

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

[Robert Inkol]

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

[David Windhorst]

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/mcmuseum/mcphotos/millet.jpg

and the front http://www.magpie.com/nycmoto/guggenheim/megola_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.

[David Windhorst]

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.

>
>

[QDurham]

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

[Paul Hirose]

Le Rhone, Clerget, and Oberursel rotary engines used conventional
poppet valves in the heads for intake and exhaust.

Gnome rotaries were a little different: intake was through a poppet
valve in the piston crown! There was no actuating mechanism. The
suction of the intake stroke pulled the valve open.

Later Gnomes had no intake valves. In the "Monosoupape" design, the
exhaust valve remained open so long past dead center, it became an
intake valve. The cylinder drew some air in through the exhaust port.
(The port went directly to the air, so it didn't inhale too much of
its own exhaust gas.) After the valve closed, the descending piston
created a suction in the cylinder. Near bottom dead center, the piston
uncovered intake ports in the cylinder wall. A rich mixture rushed in
from the crankcase. Diluted with the air already present, it made a
correct mixture.

Compression and power strokes occurred in the normal fashion.

To prevent blowback into the crankcase at the end of the power stroke,
the exhaust valve opened early and released combustion pressure before
the cylinder ports uncovered.


As far as I know, the crankcase was the "intake manifold" in all
rotary engines. Mixture entered the crankcase via the crankshaft. The
portion that passed through the rear main bearing was hollow, like a
pipe. That passage connected the stationary carburetor to the spinning
crankcase.

Although rotary engines drew air and fuel through the crankcase, they
were not 2-strokes. Crankcase volume remained constant as the engine
revolved, so it couldn't pressurize the mixture like the crankcase of
a chain saw or motorcycle engine. There was no blower either, so
rotaries had to be 4-strokes.

--

Paul Hirose >
To reply by email delete INVALID from address.

[Mike Marron]

>QDurham wrote:
>>David Windhorst wrote:
>>>Mike Marron wrote:

>>>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.

Good question. As opposed to the orbital design (fuel injection) the
vast majority of aviation 2-strokes are still using carburetors
(usually two carbs with dual ignition and two plugs per cylinder for
redundancy). The 2-strokes rely heavily on fuel for cooling and at
wide open throttle it seems like 99-percent of your precious fuel
supply is going straight out the exhaust -- unburned! For the most
part, the industry is gradually moving away from 2-strokes altogether
in favor of 4-strokes. But the venerable ringy dingy 2-strokes are
still the most common engines by far due to the much greater expense
and complexity of 4-strokes. I've seen old Champs, Cubs, T-Crafts,
Cessna 120's, etc. in Trade-A-Plane listed for thousands less than my
4-stroke engine alone costs.

>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.

While we aren't required to adhere to the anti-smog stuff on our A/C,
you're absolutely correct about how vitally important a properly tuned
exhaust system is on 2-stroke engines and the requirement for a
reduction gearbox so as to slow down the prop. Instead of anti-smog
stuff, most 2-stroke aviation engines are equipped with intake and
exhaust silencers due to stringent noise-abatment laws in Europe.
Here in the good ol' U.S.A. however, you can run straight pipes if
you wish and if you're not worried about going deaf!

[Mike Marron]

> Paul Hirose > wrote:

>Le Rhone, Clerget, and Oberursel rotary engines used conventional
>poppet valves in the heads for intake and exhaust.

>Gnome rotaries were a little different: intake was through a poppet
>valve in the piston crown! There was no actuating mechanism. The
>suction of the intake stroke pulled the valve open.

>Later Gnomes had no intake valves. In the "Monosoupape" design, the
>exhaust valve remained open so long past dead center, it became an
>intake valve. The cylinder drew some air in through the exhaust port.
>(The port went directly to the air, so it didn't inhale too much of
>its own exhaust gas.) After the valve closed, the descending piston
>created a suction in the cylinder. Near bottom dead center, the piston
>uncovered intake ports in the cylinder wall. A rich mixture rushed in
>from the crankcase. Diluted with the air already present, it made a
>correct mixture.

>Compression and power strokes occurred in the normal fashion.

>To prevent blowback into the crankcase at the end of the power stroke,
>the exhaust valve opened early and released combustion pressure before
>the cylinder ports uncovered.

>As far as I know, the crankcase was the "intake manifold" in all
>rotary engines. Mixture entered the crankcase via the crankshaft. The
>portion that passed through the rear main bearing was hollow, like a
>pipe. That passage connected the stationary carburetor to the spinning
>crankcase.

>Although rotary engines drew air and fuel through the crankcase, they
>were not 2-strokes. Crankcase volume remained constant as the engine
>revolved, so it couldn't pressurize the mixture like the crankcase of
>a chain saw or motorcycle engine. There was no blower either, so
>rotaries had to be 4-strokes.

Correct me if I'm wrong, but based on your description above the main
reason that WW1 rotaries don't meet the criteria of a "two-stroke" is
because they required 720-deg's of crankshaft rotation to complete one
power cycle as opposed to one power cycle in only 360 degrees of
crankshaft rotation.

Another critical difference is how the crankcase volume remained the
same in WW1 engines. As you said, the pressure varies in the crankcase
of a 2-stroke. When the crankshaft has rotated past bottom dead center
the crankcase pressure is below atmospheric. This is necessary
so as to produce a vacuum and allow a fresh charge of unburned mixture
gasses to flow through the reed valve into the crankcase at the start
of the next compression cycle.

[[email protected]]

(B2431) wrote:

>Just as a matter of curiosity why were rotary engines used?
>
>Dan, U. S. Air Force, retired

Dan, did you mean 'rotary' or perhaps 'radial'?. Also the thought
occurs that you might have meant 'rotary' as in a Wankel?
--

-Gord.

[B2431]

>From: "Gord Beaman" )
>Date: 11/13/2003 9:49 PM Central Standard Time
>Message-id: >
>
(B2431) wrote:
>
>>Just as a matter of curiosity why were rotary engines used?
>>
>>Dan, U. S. Air Force, retired
>
>Dan, did you mean 'rotary' or perhaps 'radial'?. Also the thought
>occurs that you might have meant 'rotary' as in a Wankel?
>--
>
>-Gord.

This thread is about rotary engines as in "bolt the prop to the engine case and
hold the crankshaft."

I would have thought it would act like a huge gyroscope with the ensuing
handling problebs..

Dan, U. S. Air Force, retired

[Keith Willshaw]

"B2431" > wrote in message
...
> >From: "Gord Beaman" )
> >Date: 11/13/2003 9:49 PM Central Standard Time

> >-Gord.
>
> This thread is about rotary engines as in "bolt the prop to the engine
case and
> hold the crankshaft."
>
> I would have thought it would act like a huge gyroscope with the ensuing
> handling problebs..
>

It did, thats one of the reasons why the Sopwith Camel was such
a dangerous aircraft to fly. An expert pilot could use the effect
to advantage but it killed a lot of novices.

Keith

[Cub Driver]

>I would have thought it would act like a huge gyroscope with the ensuing
>handling problebs..

The rotary did just that.

Of course, the horsepower was comparatively low. The Nieuport 28 was a
late-model fighter with 160 hp.

Even at that, I recall that pilots preferred to turn in the direction
favored by the torque.

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

[Alan Minyard]

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

>Just as a matter of curiosity why were rotary engines used?
>
>Dan, U. S. Air Force, retired

They were a lot easier to manufacture than radials,
fewer moving part (by number, not by mass :-) ).

Al Minyard