I have a U-Can-Do .46 running a Thunder Tiger .46 Pro two-stroke engine. I would like to hear from anyone running this combo. I need to know what prop you would recommend. Thanks for any help.

APC 12.25x3.75

I was running an APC 12 x 4 and recently switched to the APC 12.25 x 3.75. Hover is somewhat better with the new prop. The TT .46 Pro will hover the airplane but will not fly out vertical if the airplane gets way out of shape. Because the performance is so marginal, you can really tell the difference as the fuel load gets lighter! With a running start and quick application of power the airplane will pull vertical out of sight. Works fine for my use but I always stay a mistake high when hovering. For tail touching I use my Extra foamy with AXI 2212/34 - Yipeeee! I can not get the UCanDo to harrier like the other guys with the larger gas models. I don't know if the 2 stroke has something to do with it or if the airplane just does not do that beautiful of a harrier.

I don't have any problem with Harrier. It rocks the wings pretty much but not a big problem to get over it.
The problems are in Waterfall.
I'm using OS 46 FX with APC 12.25X3.75 Wide and it hovers at almost full throttle, but climbing out of the hover with full throttle is not a problem.

Etai, I am using an OS 46 FX with the same prop. I was working with gettting a hover down on this plane, but was way too nose heavy. I could go stationary at 3/4 throttle and back off for a bit and tail slide down for a few feet, but could go WOT and it would shoot out very easy. I just screwed up, doing a wall from two feet off of the ground and as soon as I snapped up and got about 6 feet up the engine just quit. Needless to say, I have been putting the landing gear block back in and fixing monokote from the gear punching through the wing. I eleminated about 8oz. out of the nose by getting rid of the sub c battery pack I was using for balance, and getting rid of the wheel pants. I can't wait to see how it performs with a little less nose weight and a healthy weight reduction overall.

OK, set up the CG and you'll see it's amazinglly easy to hover.

You guys should try an 11.5x4 Apc. This prop gets the TT and OS 46 top RPM up where they seem to make more power. I was running an OS 46 with a 11.5x4 APC Ucan do. It flew really well. Another consderation is a Tower Hobbies muffler. You will see a 1000 rpm gain on the OS 46. They are 14.99 from tower. Cheapest hop up ever. After trying every APC from 10 to 12 inches the 11.5x4 is what the .46 produced the most pull with. Now if your running a OS .50 SX use the 12x4 APC. The .50 will pull that prop. If you can't find the 11.5x4 at your hobby shop the 11x4 work almost as well. The .46s are making all there power in a higher rpm range so you have to prop so it can get up there.
Jason Danhakl

I'm trying not to get the engine to it's high RPM. With the 12.25X3.75 W it should be around 12500-13000 at full throttle but the thrust is higher. I can't say anything about your suggestion because I didn't try it yet, but I can tell you that only for the engine's first tanks I used 11X6, same reason.
Maybe I'll try your suggestion. Thanx.

I ran the thrust numbers also. The 11.5x4 ends up flying the plane better. The engine doesn't have to work as hard to pull the plane. Overheating is a major concern with the Ucan DO. You may like the 12 inch prop better. On a close to 6 pound airplane you will find it just loads the engine down to much. I have tryed all of the APC' and always end up back with the 11.5x4 on a .46. The 12.25x3.75 will work much better on a lighter airplane. Just my findings. Good luck. Jason