The OS 55AX is being advertised as a 3-D type engine capable of good torque at lower RPMs. I am planning on powering a Groovy 50 3D with this engine. I plan on using a MA 12x6 K-series prop. Fuel used is 5% nitro.

Any idea if this is the right sized prop for this engine and plane? The plane obviously won't 3-D like a profile would but the idea is to get the plane to do decent hovering along with general sport flying. My concern with a 13x4 is that top speed will really suffer. Since the MA K-series are wide blade props, the pulling power should be pretty good as well (I hope).

Thank you for your help.

I already put a 12x6 on my OS MAX 46AX, I don't see why this new 55 won't take it...
But actually, I switched back to 12x4 for 3D and acrobatics, I found it better.

I have been flying this engine for a couple of months. I kept putting bigger props on it and I'm now up to an APC 13X4W. That APC is a lot of prop but the engine is doing it well. I also have a 13x6 wood prop that works well. A 14x6 wood prop might still work but I'm sure that would be the biggest you could get away with and still have it spin up fast.

This engine is going to be a favorate for 40 size 3D planes.

[b]

I am going to try a Zingger 13x4 on my new Kangel CAP 232 profile..
I really have very little interest in flying FAST...

That is just me... to each its own...

[b][8D]

13x4W APC for 3D. Purrrrrrrrfect


Larry

Hmm.. based on these answers, if seems that I am underestimating the capabilities of the 55AX. A 12x6 seems too small for this engine. I think I'll do for the 13x6 as I would like to fly at a reasonable speed.

What rpm are you guys getting with the 13x4?

Thanks again.

falcon...

If you are going to be using 5% nitro, you're better off with a 13x4 sports or 12x6.

I currently have a 13x4w running on 15%. Spool up is good, but not as great as a ys63. Its close though, would try a 13x6 to improve spool up.

I assumed the plane would be slow but the plane I have it in flys pretty fast. It previously had a ST51 w Jett muffler on 12.25x3.75. All props used are APC.

Thanks ir, I'll try the 12x6W and see how it goes. Should give good verticals and fast speeds for the Groovy.

I have a 55AX in my WM CAP232. Tried the 12.25x3.75 and a 13x4W and now a 12x7, seems happiest on the latter prop, but may try a 13x4 normal. On the flat pitched props seems to hang a bit when going down to idle and runs a little rough in the mid range, again not as sweet as my YS63 on a 13x4W but still pretty pleased with it so far.

Falcon...

No problemo. Just wanna pass on some info.... A buddy and myself benchran a Ys110 with a MA 15x8 and APC 16x7. The APC was clearly too big a prop on 15% and the MA prop was faster by abt 300 rpm. However the MA prop was just beating air, and the APC was blasting everything away from its wash... scary...

Back to subject... if the MA 12x6 isnt lifting any skirts, maybe you may wanna try the scimitar series. Otherwise go for a APC.

The fuselage profile of your groovy is similar to my veko, IMO speed aint a issue. If you wanna go fast, this is not the plane...