Hello Everyone.
I have been advised that something like a Rev Up 9x12 prop would be a god starting point for a McCoy 60 series 20. Can anyone tell me what sort of RPM will this make on the ground (and perhaps a guess as to in the air?).
I suppose what I am really asking is what RPM to set on the ground so that I get the maximum revs in the air? When I last flew speed near 50 years ago, I wasn't too good at setting the needle and I don't suppose I have got any better in the intervening years! So any info to get me near the right ground revs would be much appreciated. There are not many place that I can fly vintage speed and those few places will only give me a few flights per session, so the nearer I get first time , the better.

Thanks,

Andrew.

The flights we did last year were on a rev up wood speed prop 8x 9  using 10% nitro set a little rich on the ground. the great thing about using hard tanks is the repeatability. never did put a tac on it.

I ran a narrow Rev-Up 9 x 12 on my McCoy -60- with a pen bladder and 60% nitro. The drill was to get the engine started and bring the needle to peak, back off a bit, lean to peak again and then back off rich just a little. The engine would unload in the air. I don't recall any particular problems. The McCoy is a pretty tolerant engine. I never did put a tach on it. I always started it by hand using 10% as a prime fuel.

Hi Paul,
I still have one of the old mechanical tachs somewhere. You only had to put it on an engine and you could hear the revs drop way off! Not really much good, now why haven't I thrown the tach away, I suppose that it might come in useful someday! Probably go in the dumpster when I shake off the mortal coil. The kids will have a field day with most other flying bits and pieces going in the same place!

Regards,

Andrew.

I still have a OS multi-rod tach.  You held it against the mount and one rod vibrated, indicating the RPM.