----- Original Message -----
Sent: Sunday, March 13, 2005 9:41
PM
Subject: [FlyRotary] Re: peripheral
ports
Years ago, I was buying something from some
feller and he was kind of high. When I asked for a little better deal
and said I was used to buying 'em from this other fellow for a lot less but
he was out; he told me real quick like that he could even sell 'em
cheaper than the other fellow when he didn't have 'em either. I
guess price is not something to even gripe about if you can't get 'em.
And, I will admit that the price might not seem too bad when/if you need
housings anyway. Oh well, I 'll just stay happy with my junker, as long as
it lasts; then I can worry about some of that kind of stuff. But, let's face
it, if the pp engines don't keep running at low rpms and/or idle well, even
though their high rpms can be right down our aircraft use alley with
proper psru gearing, they will not be much good to us; it seems aircraft
actually do have to have an engine that keeps running on/in slow
flight, too.
Group,
I really would like to know where the idea that the PP rotary won't
idle came from?
This is total baloney. Lynn Hanover has commented several times that
his PP 12A idles just fine. Some carburated engines with unusual
manifolds sometimes have problems. This is true for both PP and side port
engines. Many of the earlier rotary engines used P ports.
If and engine is radically ported in either port type, (just like a
radically cammed piston engine), it can be difficult to make idle. If you keep
the port timing reasonable the engine ?WILL IDLE FINE, especially a EFI
engine. The throttle plates being close to the housings makes things work
better. The MB C111 used various rotary configurations. Most of the
engines were peripheral ported. There was no problem with idle, but
the sealing problems of that era prevented a production version. If your
engine is set up carefully without radical timing idle won't be a
problem. The real problems encountered by many people are caused by large
ports and extended port timings.
Bill Jepson
Bill,
I have been asking that question myself, and the group at last years
rotary meeting in Lake City. Initially I believed it and started out with the
combination port on the one-rotor. Total disaster! Than I made a beautiful
close up butterfly only to find out that it had no impact on controlling the
engine. Now, with a carburetor that has not been tuned for the engine in any
way it idled at 1200 RPM rightaway. That will be a lower prop speed than
a LIC on a 3.3:1 gear box.Throttle response is also as good as good as
it could be.
As long as the mixture is rich enough, it will idle.
Richard Sohn
N-2071U