WW1 Rotary engines

[MMEMatty]

Hi

While browsing my dad's copy of "Practical Classics" (a classic car restoration mag, for those not familiar) i came across an article on the Wankel Rotary engine. One paragraph in particular caught my eye, it read:
"The only true rotary engines ever to be used were in World War 1 fighter aeroplanes....these aeroplanes were constricted by only being able to run at full power, and were controlled by having a Magneto "Blip" switch which was used to temporarily switch the engine off on final approach"
Now i always thought that the Sopwith camels, SPADs etc all had a throttle as well as this blip switch, and the blip switch was used for taxiing so as not to get away from ground handlers etc.

anyone care to shed some light on this please?

Many thanks,

Matty

[inbalance]

Most of the rotary engines I know, but I can´t talk about all, had of course a Carburator. The crankshaft was conected to the Firewall and it was not turning. The whole Rest of the engine was turning. With this design it wasn´t possible to connect the Carburator in the way we know it for more modern designs. The Carburator was connected at the end of the Crankshaft, near the Firewall and it wasn´t turnig as well. The fuel Air Mix flows thrue a drilled Hole in the Crankshaft into the Crankcase and from there to the Cylinders.
This gives you a very big Volume between the Carburator and the Cylinders, witch makes it difficult to controll the enginespeed without a big delay.

If you close the Throttle for example, afer a few sconds the whole Crankcase is empied from any Fuel-Air Mixture. If you advance the Throttle, you have to fill that big Crankcase with fuel/Air first. For the engine is running with low RPM now the Air Flow is low as well, and it takes a very Long Time to fill the Crankcase and for the Engine to respond.

The use of Blip switches gives you a better and faster Respond.

[sycamore]

Hi MATTY

Just a few points to add to" Inbalance"`s comments. The engin does not have a conventional throttle, rather you have two levers, one for air, one for fuel, but they must be used together.
The engine is started by pumping air pressure into the fuel tank,so it will flow to the engine when the fuel lever is opened, via a needle valve. Each cylinder is then primed individually( or "doped",as it was called),by hand-turning the prop.
there are two magnetos, one is the starting mag. which is hand-cranked by the pilot when the engineer(s) call" contact," and after they have released the blades.The other mag is switched on at the contact call.If you get the sequence wrong, there is a good chance the engine may fire and clobber the prop swinger---If so you may well be relieved of your command!
The air valve may have been opened slightly at the start; hopefully everything will burst into life,on the prime so to speak. It now requires the pilot to pick-up the engine on the fuel and air levers to get it to run smoothly,and stop winding the starter mag.,pump a little more air pressure into the fuel tank as it is normally supplied by a small wind -driven pump in flight!

The engine wil not normally idle well, so after the usual check on fuel pressure and oil, the run-up is done by opening the air lever,followed by the fuel valve until max rpm and smooth running are achieved-again by small variations in the air and fuel valves. It is handy at this point to mark the levers positions on the quadrant with a china graph, as you need this position for t/o. Now one can check low speed running by now closing the fuel valve first,followed by the air lever.
The reasons for operating the levers in this order is that it is better to have an engine which has more air in the system than excess fuel, as it will flood, and will not respond at all until all the fuel has been blown-thru`-- in flight the a/c leaves a black trail of smoke.
As the levers are closed towards shutoff a position is reached where the engine will idle ok .Mark this position as well. the magneto cut-out,a push-button on the control-column can now be pressed to allow the engine to run-down to lower revs, for taxiing,and released briefly to stop it from stopping.
Assuming all is well you now taxi out doing all the t/o checks as you go, line-up and open the levers to the previously noted settings, remembering that there is a lot of gyroscopic energy in front, requiring a lot of fancy footwork to keep it straight, balanced etc------- and so far we`ve only just got airborne!!

In flight the levers can be used together in the same manner as normal throttle control to set a cruise or low power for descent, as long as one remembers to always have more air than fuel when changing conditions-- A lot written- even longer than some of my flights! :) :)

[Lu Zuckerman]

I attended an airshow where a WW 1 aircraft with a rotary engine was on static display. Some jerk moved the prop and an exhaust valve opened and about a quart of fuel spilled on the ground.

:rolleyes:

[Intruder]

Also, don't forget that the Wankel rotary and the leRhone (and others) rotary of WWI fame are entirely different engine concepts!

[I know most people here realize that, but introducing the topic with the Wankel reference and digressing to the earlier rotary engines might confuse the newbie.]

[MMEMatty]

Intruder: I do realise the difference, i was just trying to set context, that is all,

Everyone else: thanks for the replys, thats got it all straight in my head. I knew there was some sort of lever(s) controlling engine speed! Thanks once again everyone!

Matty

[seacue]

Is it true that those white scarves were to wipe the unburnt castor oil off the pilot's goggles? I've heard rumours that the unburnt castor oil had other unwanted aircrew side effects.

[Frangible]

If you see Dawn Patrol, aerial combat war film made in the early 30s with genuine WW1 Sopwith Camels, in the scenes where they are on approach and landing you can clearly hear the endless "blipping" of the engines, sounding as if they are about to splutter out of fuel, like incontinent mosquitoes.

[saman]

I bow to your superior knowledge. I've never knowingly heard an incontinent Mosquito - natural or the true De Havilland.

[Skycop]

Saman,

It was the pilots who suffered from incontinence, as Seacue suggested.

Castor oil reaches the parts that other oils can't, blip, blip, thrarp, oops. :D

[Specnut727]

Thanks to inbalance and sycamore for their informative comments

I think there's another nasty aspect of the Rotary, which is the effect of the rotating mass of the crankcase, cylinders, and prop. As I understand it, this caused the engine speed to react very slowly to changes in position of the air and fuel levers. This is worst on accelleration, where the engine could be flooded if the levers were opened too quickly. The way around this was to make small adjustments to the levers, and allow the engine RPM to catch up.

On the point of Castor Oil, most aircraft had an engine cowl with only a small open section around 6 o'clock. This was an attempt to collect the exhaust gases and direct them out under the fuselage, so the pilot's didn't get the s***s. I think this was only partially successfull.

We're finding out some of the reasons why the Rotary engine soon gave way to the 'static' radial.