hi i was flying my trainer with an 11x6 graupner prop and after having crashed it and rebuilt it im nearly ready to maiden her again!!.ive read lots of things about prop sizes and now im wondering if this prop was the right size?,would i be better with an 11x5 or a 10x6 or something else?.anyone know which would give me the best prerformance?.im taking off a grass runway and sometimes she takes a long time to get airborn would a 10x5 give me more speed on take off?.

I have the 46 LA, and I've flown a 10x6, 10x7, 11x4, 11x5, and 11X6. By far the best performance is with the 11x5. It turns it at 11,000 rpm. The 10x5 will probably increase your take off roll, since you won't get as much thrust. For comparison, I ran the numbers in Thrust HP. You should be getting about 10400 rpm from the 11x6 prop, for a thrust of about 4.7 lbs. The 11x5, at the same horsepower rating and 11,000 rpm, gives 5.3 lbs. The 10x5 should come in around 12500 rpm and 4.7 lbs. I also like the larger props for landing, since the larger disc gives better braking. Try the 11x5 APC with the 46 LA. I think you'll like it.

Brad

I second that 11x5 apc i use them on my 46fx's and ive tryed them all! ultra stk 40,Aero works edge 540 fly just fine

thanks guys ill try the 11x5 thanks again!!

Since you don't need speed, an 11-4 is also an excellent choice for the .46 LA in a trainer -- it will give even more thrust than the 11-5 & let the engine wind up to ~13,000 -- close to its torque peak @ 12,700 & its power peak @ 13,400.

The 11-5, while much better than the 11-6, is still too much prop for that engine.

i use a 10x7 .... of corse i dont have the ground clearence to run the 11s

when getting into such large diameter props would it be a good idea to look at possibly getting a 3 blade prop? I to am getting a 46 la and mounting it to a lt-40. just asking is all.

I use APC 10.5x6, 11x5 and 11x6 on my .46 and .50 size 2-strokes. Right now they both have 10.5X6 on them.

Your preference will likely depend on your flying style. I started using the 10.5x6 in one plane because the 11" props "ticked" the ice when flying with skis. Liked it so much I stuck with it year-round.

May I point out that while the shallower pitch engines allow you to reduce the load on the engine and achieve higher RPM/torque, you also have reduced "bite" in the air. The 6" moves 17% farther through the air in 1 revolution than the 5". Variations in air temp, humidity, the plane-to-plane of total weight and "cleanness" of profile may give you more thrust with a higher pitch prop. And you, hopefully, ain't always flyin at full throttle. The braking effect of the larger props helps or hinders on slow downward maneuvers at low RPM.

Hook the plane up to a fish scale and see which prop pulls harder at full RPM.

I think you will be pleased. I run an APC 11X5 on a 40LA mounted on a trainer with very good results.