Author Topic: Rotary Engine Control and Other Questions  (Read 914 times)

Offline David 63

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Rotary Engine Control and Other Questions
« on: February 19, 2015, 08:47:46 PM »
I'm starting to build WnW's E III (late) and, simply because I like to have an understanding of what I'm putting together, I have to ask a couple of questions. First, I have read some articles and watched some videos of Oberursel engines and what I have read leads me to believe that the only engine control was accomplished through the use of a "blip switch" that cut power to the magneto completely or partially to control engine power, in other words, the engine ran at full throttle unless the "blip switch" was used to cut power. If that was the case, what is the throttle on the left hand cockpit frame for? Was it a "fuel on or off" lever or did it work as a modern throttle works? (I have also read that because of the manner of fuel intake to the cylinders it was impossible to effectively "throttle" the engine). Second, and not having anything to do with engines, where did the wire from the trigger switch on the control stick hook up to the machine gun? I am assuming also that this wire had some slack to it because of the photograph in the instruction booklet that shows one wrapped around an instrument panel switch. Hope some of you folks can help out.
Thanks, Dave
I apologize if this is not the proper section in which to ask these questions, but it sounds like the right section as it will help in my modeling.

Offline uncletony

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Re: Rotary Engine Control and Other Questions
« Reply #1 on: February 19, 2015, 10:21:41 PM »
You are correct, no throttle on these particular rotary engines (Gnome Lambda / 9C / Oberusal U series). Some later rotaries did have throttles but blipping was still employed. The lever on the left hand side of the cockpit is the mixture control -- adjusting it has some effect on RPMs and is used to correct the mixture at altitude. Also leaning out the mixture when blipping is advised as the fuel is still flowing while the engine is turning -- the cowling tended to fill up with raw fuel during extended blipping with sometimes fiery results when the spark was resumed!

Offline David 63

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Re: Rotary Engine Control and Other Questions
« Reply #2 on: February 19, 2015, 11:46:19 PM »
Thanks for the answer, Bo. I looked at Umlaufer's build log for his E I/II and noticed also that the "throttle" on the museum aircraft has two pipes running to it. I kept wondering if that might be the method used to switch between the fuel tank behind the seat and the fuel tank in front of the insrument panel. There must have been a different method of doing that.
Dave

Offline uncletony

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Re: Rotary Engine Control and Other Questions
« Reply #3 on: February 19, 2015, 11:46:42 PM »
Oh -- second question...

The trigger was connected to the synchronizer (technically not an interrupter!) gear via Bowden cable which engaged the drive, which essentially pulled the trigger on the MG, each revolution cycling the gun one time (later this was increased). Note that engine RPM directly affected rate of fire!

 

Offline David 63

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Re: Rotary Engine Control and Other Questions
« Reply #4 on: February 20, 2015, 07:06:07 AM »
Thanks again. Guess I'll have to figure a way to simulate your photo. Shouldn't be too bad since most of the bottom of the MG looks like it's hidden by the cowling.
Dave