Prop YS 120 propeller?

[mudbogger]

I’m starting a build for a Yak-54 20cc profile plane and I’m considering using a YS 120 nitro engine on it. The engine should fit, it’ll just burn through nitro rather fast. However, it is still a 20cc gas equivalent. One issue I’ve run into is trying to find a propeller for it. From the little research I’ve done it looks like the engine was built for a 15 x 7 prop. But finding a good one designed for gas engines has been kinda tough. I could go up to a 17 x 6 or 17 x 7, just not sure if it would work for it? The airplane is balsa / ply construction with carbon fiber reinforcement; and the wingspan is about 65” (maybe 65.5” with the side force generators on). I’m guessing it’ll run with somewhere between 2-3 horsepower. Just curious on everyone’s thoughts for a 3D setup? I’d also prefer to stay away from 3 bladed props as the traditional 2 bladed props seem to run better (at least in my experience). I already have the servos for it, just need a receiver and propeller - then it should be time to start assembly. Thanks for your help! Happy Flying!

 

[Tony]

Seems a 16x8 is what is suggested. It should still spin a 17, just have a little more load on the engine, lower RPM. This is where a tach will come in handy.

Question, why not save up for a 20cc gas engine? Insane flight times and I absolutely love the sound of them.

 

[mudbogger]

Tony, thanks for the info. I’ve been saving awhile for parts, overall just trying to weigh my options before committing to gas.

RCGF has a 20cc stinger engine that would work fantastic for the airplane as well, I simply haven’t ordered it yet. DLE would also be a option, but I believe you get more for your money with RCGF. They have a little more power, and come with more parts from the factory. While still burning a 30:1 mix for fuel. Just out of curiosity, for a 20cc gas airplane - what kinda flight times are you getting? Maybe 15 minutes with conservative throttle use? I honestly don’t know, I haven’t flown a gas / nitro airplane in awhile.

 

[Tony]

I don't own a gas model, this is just from what I have seen over the years at local flying fields and on the net. Gas gets quite a bit more flight time, and far less oil on the outside of the plane which to me is worth the extra cost. Nitro is just so nasty lol.