Clivemc,

From post 222:

**I finally got a few numbers using my brand new TNC tach. I checked the engine's low end, mid throttle where I fly normally, and top end. I got the following:

Low end was reliable (19x11 apc 2 blade) down to 1750; engine only has 1 gallon through it so far so this may get a little lower, but it is low enough. Sounded like a YS 170 on low throttle...very neat sound

Half throttle stick, same prop, gave me approximately 6575-6780. Temptress will do everything in Masters pattern at half throttle

Full 7450-7600 average; The tach also records the hi or peak values and at full throttle the engine would occasionally hit 7800. So full throttle gives me an average of around 800 rpm more; that's what I have in reserve. Now I know why the engine drives Temptress to ballistic speeds.

Acceleration is instant even with this large load up front but it was 41 degrees today so cooling was not a factor. I leaned the low end needle a hair and it helped a little bit. How it does in warmer weather waits to be experienced **


I wrote that piece when the engine was still breaking in. Engine now has over 3 gallons through (about 40 flights) it and is considered fully broken in.

The 3 blade 18x10 Mezj spools to 7550-7650. The engine is happy turning this prop or the 19x11 apc. Terrific power in the air and quiet with either prop. The 3 blade prop produces a sound similar to what the apc 15.75x11 3 blader produced a few years ago

My MDK 20x10 hybrid also is very quiet and it turns at 7350. It has a wider blade area than the 19x11 hence just a bit more load. But the OS just runs the load and doesn't seems to get lugged down. It is quite impressive in its ability to turn such a load for only a marginal increase in displacement (and weight) over the 30cc engines available today