einarak

I have 91fx with macs hedder and tunedpipe, in an f3a airplane.
I want to try out few prop sizes, I had a rather heavy 15x7 and it only turned 9500 rpm, I tried 14x6 it turns 12500 on the ground. I liked that much better. Is it safe for me to try 14x4w on it or will I over rev it? if it shows 12500rpm on the ground what can we expect when its in the air? and how much rpm can the 91fx handle?

Bax

My Feedback: (11)

We''d use 12,000 RPM as an upper limit for most practical uses. If you get 12,500 RPM on the ground with a pipe, then expect close to 13,000 RPM in the air. That RPM level is getting to be near the limit of the engine, and you should not expect a long life out of it.

balsaeater

If you fit a prop cut down 12*8 or 12*10 down to 10*8 or 10*10 to the OS 90 VR which is used for the DF rametec or similar than 20K rpm should be possible and make a F£A plane really shift

I will probably do similar to that in a few months with a fast plane before making a DF project

Have you guys in Iceland got a good LHS or is it all mail order as I might visit you next year with my work