I've got a UCD 46 and i am using a os 55AX.
I'm currently using quite a large prop for the engine for running in, but now it has run in i just wanted to know what the best prop would be for good 3d performance?

Also, is anyone else running the same engine in the UCD 46 and what do you think of the performance?

I have a UCD 46 and have flown it with a YS 63 and a Saito 91. Mine weighs about 6 lbs . Your 55 will produce about 7 lbs of static thrust which will not do much 3d on a 6 lb plane. My Saito produces 10 lbs static thrust which is not bad for 1a 6 lb plane.

The UCD 46 weighs 6 lbs, has 1000 sq inches wing area. That is identical to the Mojo 60 which is a fine 3d plane when powered by a Saito 100. Yet the box says it is a 46 size plane. A 40 size 3d plane should weigh 4 lbs RTF, dry.

A 13x4 will be about the best for the 55.

My first 3D plane was a "40 sized" one as well. It was similar to the U can do. Not knowing any better I put a 46 in it. It weighed over 5lbs and flew well but nowhere near 3D power.

Later switched the 46 out for a 91 four stroke. Then it was a 3D monster.

The plane will fly well with that engine but no prop is going to give good 3D.

Thanks
It will hover but at almost full power and just wanted that little bit more and wondered if a different prop would do it
probably just stick to the same prop if thats the case then lol

Try a 12x3.75 or 11x4 That should get you plenty of "Hover Power" I've been flying my 60 sized Do on an O.S. 91 4 stroke with a 15x4, does everything I want it to.