Hello Bob Hunt

[Dwayne]

Hi
Thank you for being a part of this forum. I remember when you used to write for Flying Models, You used to write about and feture everything that was about Control Line Stunt, if there was something new you wrote about it and also a little about the old, but allways about the new, i remember the first time I read about the tuned pipe, I also remember when you said the .32 engines were the hot stuff, I bought a OS.32F becouse you said the .30 size engines were the bomb! What you didnt tell us was that these engines needed a thing called a "Blow Down" to get them to run right, or maybe you did but I wasnt paying atention!Anyway I now have a OS .32 on A Gotcha Streak , It's winter here now but I'm looking forward to spring and taking it out and trying it out. It's stock but I think  it should work real well.
Thanks Bob for everything you do
It's amazing a world team flyer, please forgive me but did you ever win the World Champs!! I know you've been there I know you and Bill won the overall but did you ever win the individual championship?
Thank You
Dwayne

[Phillip Bailey]

Dwayne;
  Yes he did, 1978 ,Flying the Genesis 46 powered by an O.S. 40 FSR with A three blade four pitch wooden  prop  custom made by his father Jim.
   Phillip

[L0U CRANE]

Dwayne,

I was fortunate to watch Bob Hunt win the WC in England in '78 - I was on leave from duty station in Germany. A real kick! Made a family vacation tour out of it, too.

Blowdown describes the difference in cylinder port open time between the exhaust port and the bypass(es). A certain range of delay in opening and closing those holes on the cylinder wall goes with the pressure waves echoing back and forth inside the tuned pipe.

When it is all working right, a returning "echo" (pressure wave, really) stuffs some of the fuel and air -that blew out the through the exhaust port- back into the cylinder to be burnt the next time the piston passes through top dead center.

This is also pretty self-limiting - if RPM goes too high, the pressure waves go "off tune"  and don't give all that boost. The engine doesn't run away, IOW. In effect, RPM settles to where the engine is just above max boost RPM, where the pipe is starting to fall off max boost tune. When loads drag RPM down, from cruise speed, the boost improves, and reduces RPM loss.

And it starts working within one or two revs... Remember, 9,000 RPM is 150 revs per second, so that is quick response.