Quote:
Originally Posted by D.A.
I do have a question though: Watching them run the Oberusel, it would appear that they have incorporated a workable throttle into their program. It's my understanding that the Rotaries did have a throttle of sorts, but you basically didn't use it. You got the engine set to run at full RPM and blipped it from there so you didn't fowl up your power settings and adjustments. However, in the video, they seem pretty proud of the function of their throttle. The camera focuses on their throttle lever and the engine responds great to different advancements. Are they running a useable throttle?
Again, WOW!
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Throttles and rotaries are a very interesting and somewhat complex topic. The short answer is that it depends on the type of engine. What you stated above is essentially correct for the Gnome 160 HP engines. They did not have a fuel metering valve to change fuel flow, but did have a fine adjustment to regulate air flow.
The LeRone and Clerget engines, on the other hand, did have carbs and fuel metering (along with a fine adjustment lever, which is why there are two sticks on the throttles for those engines). Those engines could be throttled from approximately 700 to 1,300 RPM.
My research shows that the Oberursel rotaries were initially license-built Gnome engines (before the war), but they started manufacturing copies of LeRhone engines during the war. So, wartime Oberursel engines would have had throttles and an RPM adjustment range just like the LeRhone engines.
A ton of great information is available in the book,
The Rotary Aero Engine by Andrew Nahum (1987). A good part of it is available from Google Books
here.
There are also a ton of good threads on this board on rotary engines, like this one:
Oberursel rotaries
Finally, sometime next year, an article of mine on rotary engines is slated to be published in a major aviation magazine. It deals with the myths and misconceptions surrounding rotary engines. I'll let everyone know when it is published.
Regards,