i have a hobbistar 60 trainer with an os 61fx engine that is broke in already. what size prop should i use. i am a beginner..thanks for your time..jim

Looks like a 12x6-8 should work. A copy of the manual is below.

http://manuals.hobbico.com/osm/50sx-...1fx-manual.pdf

I am running a 12 X 7 on my OS .61fx.

Edit: You will need to pick up a prop reamer also as the hole on a standard prop is too small for the shaft of the .61. Do not try to make the hole bigger with a drill bit. The reamer has a slight taper on it, and will make the prop seat alot better on the shaft.

Hi!
If in a high winged trainer ...a 13x4, 13x5 or even a 13x6 APC or RAM if flying from sea level.
12x6 will work too but not as good as the above sizes

what would be the difference in a 12-6 prop verses 13-5?

12-6 is a little faster top speed, takes slightly longer to reach top speed. 13-5 has more pull; shorter take-offs, better vertical performance, a touch slower top speed but better acceleration.

Trainers tend to be 'dirty' designs, meaning they have lots of drag (largely due to the fat, flat bottomed airfoil). They also are not the most graceful aerobats, so I would go with the 12-6, but it's probably best to try them both and see what YOU personally like.

Jstiener, in your trainer arf kit you should have a os 61fx manual. Evolution and O.S. has a graph near the back of the booklet showing what prop size that is recommended. It's hard to find... but it's in there.

I used a 12-6 with mine. I thought it was perfect

i do see the list and it says you can use about five different props, i was just asking which one i should use and why...thanks for your input......

I like the Master Airscrew 12x6 K Series on a trainer with a .61 two stroke. These are the black props with white tips. They are more flexible than APC props which means they do not break if the prop touches the ground when landing.

I'm going to run a OS.61 on a TF Piper Arrow that I built. Some thoughts were that engine is underpowered for that plane. In your opinion can you use a different size prop to make up for an engine that may be underpowered for a plane? I oringinally had a 11x5 prop but after reading through this thread that may be way to small both in pitch and dia. Tell me what you think as well.
Thanks

chopper

The minimum prop for the OS 61 is a 11 X 7

The standard everyday prop for the OS 61 is a 12 X 6

save this as a jpeg for a reference[8D]