by gossie » Thu Sep 21, 2006 12:51 am
I found the "road test" of the McCoy in Aeromodeller October 1953 magazine today, and it does make mention of the O ring showing early signs of wear.
It peaked at 12500rpm and turned wooden props as follows-------
9x4= 5700, 8x4= 6700, 7x4= 8000, 6x4= 11650, 6x3= 12250.
Modern APC props. being thinner than the old wooden ones would also raise the revs I should think.
Fuel mix was, Kerosene 40%, Castor oil 25%, Ether 32.5% and Amyl Nitrate 2.5%.
With it unloading in the air looks like 7x3, or 6x4 is the prop. to use for competition, larger for fun flying would do the job.
Amyl Nitrate is very hard to get these days, but it should run well just bringing the Ether up to 35%.
I know Ace Hardware in USA, as have bought plenty off them over the years, when over your way,and "Wally World", or an auto spare parts store will have them too. Good luck. :D