September 25, 2023

New engine for Sun Fli

I wasn’t really happy with the performance of the O.S .65 AX engine with 11 inch propellers so I’ve fitted a brand new O.S .61 FSR ABC engine that will use a Tore Paulsen style pipe and Hatori aluminum header.

This engine has been in its box since the 1980s and will finally see service.
I tried a Hatori 90NA muffler on the O.S .65 AX which gave lots of power but it was quite loud.
Tore Paulsen silent pipe custom made by √ėyvind Andreassen here in Moss
Hatori header. The pipe is fitted at the recommended (by Tore Paulsen) length from the exhaust port, which is 22 cm.
Break-in, it ran through 5 full tanks of 10 % nitro fuel and reached 10500 RPM on an APC 11×11. I backed off just a little and it now turns at 10200 RPM and is very stable. I think the pipe needs to be longer, it should be able to reach 12000 RPM on this setup.