Hi;

I have a World Models Extra 300S 80.5" wing span with a OS-MAX 1.60 Engine. What size Prop and Pitch I should use for torque rolls and prop hanging?.

Cheers
Vic

How much do you weigh? 13+ pounds?

The 1.60 on a heavy plane lot of people like the:

1) APC 18x6w--heavy prop though and spool up is a bit slower
2) 18 x6 pro zinger wood
3) 19 or 20x6 Mejzlik --$ but efficient

The OS recomends 16" prop diameter.

I have the Sig Extra 300XS with a OS 1.60 and an 18x6 Zinger... It weighs right around 13lbs and I can tell you that the pull out will probably not be that great. I personally think it's a little too much weight for that engine as far as 3D is concerned. That's just my humble opinion though.

16" diameter will work fine if your plane weighs 10 pounds or less. My guess is you will want more thrust though, as you are at what 13+ pounds?


From manual:
"Suggested Props: Aerobatic: 15x12-14, 16x10-14, 16.5x10-13 Sport: 17x10-13, 18x10-12"

This motor likes to be loaded. Some are running a 20 x6 prop for thrust. What are you running for a muffler & what prop & rpm's are you getting now?

What RPM are you getting with that zinger? Is it the zinger or the pro zinger. I have a 12.8 pound edge with 1.6 and although pull out is good, it is not brisk. My best pulling prop has been the apc 18 x6W--felt like a big improvement over the zinger and the pro zinger. If you did not mind investing the money there would be significant gains in going to the 19 x6 or 20 x6 Mejzlik.

It's a pro zinger and to be honest I haven't tached it.. If I had to guess I would say around 8500 - 9000, does that seem right?... I didn't really by it for 3D and it flies great the way it is.... I bought to get my feet wet in the larger stuff. I wonder how this motor would be in a 68" EF Yak?? Maybe after the Extra dies I'll have to get one

Motor would be great in the E.F. yak. Use throttle management though as you will be at 9.75 pounds or so--Under prop it with a 16 x8 or 17 x6 on a plane this light.

ZINGERS are good for test flights (Cheap) and Mixing Paint (Cheap)... not for making a lot of thrust (Cuz they are cheap!!)
I have 300 plus flights with the APC 18 x 6 IMAC Prop on this motor with a BISSON Pitts Muff and a Perry Pump... GREAT RUNNING MOTOR!!! ... if there is a good prop with a little more diameter and a little less pitch (And NOT a Zinger) that is prob'ly gonna be a little better. We basically want to tend towards a helicopter rotor... longer with less'ish pitch. This is how efficiency is achieved! Mejzliks are good, but the 18 x 6 Mejzlik will not be enuff.. the APC is better in this size. The 19 or 20 inch Mejzlik with less pitch would be where you want to be! I typically ran 15% nitro... but life gets better with more nitro...(Up to maybe 30% with little risk).... jus' don't over lean or she will be unhappy!!!

Now if a guy could get an EF Yak I would be in buisness

We run APC 18x8 on our 74" Imac models, seems to work well for sequence and 3D flying. Around 8000 rpm on 10% nitro. Thrust seems about the same with the std or wide blade. The std blade accelerates faster.