My first .60 sized pattern plane was a Super Kaos .60 back in 1975 (after having 2 Super Kaos .40s). I put a brand new OS .60FSR with Pery pump and carb in it. I still have a vivid memory of my first flight - wow, now I really have enough power (of course any pattern flier will tell you that you can never really have enough power VBG). I discovered that having an 'overpowered' Super Kaos revealed a minor design issue resulting from the excess power: fishtailing. Yep, at full throttle, in straight and level flight, the tail would oscillate from side to side. The fix was simple: just add more fin area. Unfortunately, I never got the chance to make the modification. The radio failed during 3 horizontal rolls and she went screaming through the woods at full bore in a shallow descent. The fuselage (and about 4" of wing on either side) came to rest about 60 feet off the ground in an oak tree. Took a while to retrieve it, but the engine and radio escaped completely unscathed - good news to a teen-ager. There was balsa and monokote strewn over a 100 yard crash pathway in the woods.
The early .60 FSRs had a habit of breaking the crankshaft at the the intake opening, but were great engines otherwise. The Perry pump had wayyyyy to much pressure and had to be closed down to the minimal pressure setting. Once OS got hold of the design they refined it to a very reliable system. I had a Hanno Special with 1700 flights (the bearings and piston/sleeve had been replaced) it was well worn when retired, but the pump/carb still workde great.
Favorite engine? Probably the OS .61VF, but the YS .60FR is a close second. The early YSs required a long break-in (like an hour) because of the ABC piston/ sleeve fit, but they were the most powerful pattern engine of their time (BY FAR). YS did have a slightly annoying habit of continually making minor changes to the carburetor.
Man, lots of great memories.
-Will