What are thingsthat make a plane handle and fly well for 3D flying...I have a Seagull Yak-54 .90 with the O.S. 120AX.
What kind of weight bias?, prop to use?

Any suggestions would be appreciated...

Thanks!

The motor is a good choice, this Yak may not be ideal for best performance. not sure on prop ( 16x4W??) on this motor,but many had real good sucess with the funtana X100 and perhaps the new 125 for full on 3D for the OS 120 AX.

Work on the CG, max out the throws, bevel to bevel with at Least 60 % expo,once you have that, you can add differential mixing to clean up tracking. It takes some time,but will make big differences.

17x6 apc turning atleast 9000 will do the trick I have had 2 120ax's they are great running motors... I like them best with 4 stroke plugs OS F

Where do i want my CG?  Do I want it right at where the mfg. says to have it? or do i try and move it towards the rear?

When you talk about servo mixing...which channels would i want to eventually mix?

Would a lighter landing gear setup be somthing worth having....like maybe carbon fiber vs. the aluminum? 

Thanks again...

Trent 

It's all test and tune. Fly the plane, throw it into a hover. Do you have to fight the plane? If so, start moving the CG back to where it becomes easier. Make sure you have all you can get on the throws like was stated before. Mixing is generaly done for knife edge. Don't bother with that until you have the CG set as it will effect the knife edge coupling. Don't worry about lighter gear for now.

Keep in mind - should you decide to move cg back - do so in very small increments. A tail heavy plane is harder to control, especially if you are not used to it.

Do not spend $ @ this point. You are going to hit the earth a "few" times.
Things for 3D
Low wing loading (light plane/engine combo)
Big Dia low pitch prop
Ultra reliable engine with a perfect mid range (no hesitation)
Fast precise servo's (run 6V and digital)
Radio with mix
Huge throws and run expo 60% to start, adjust from there
Properly trimmed plane (find a pattern flyer to help you with this)
Rear CG (see above)
Big clackers and be willing to go low (eye level or better) see first line
Flight sim to learn new moves (will help keep the earth from testing your plane as often) see line one
Once the Seagull is done get a better plane.
My 3D fleet
Omp Edge 40 size ARF
Swany MoJo 60 Primo 40
Kalteisen Skeeter 30, Skeeter 36, KX2
Value Hobby Sabre
3DH Sukhoi
Maxair Velox
plus a couple of indoor depron foamys for winter gym flying

Haha...

Yeah...i'm sure the Seagull wont last too long...I think the next plane for this engine will be the the Funtana 125...getting excited for that...
.
But all these things have helped out alot with giving me a better understanding of what i need to do with the plane....I appreciate all the suggestions...
I was just at the field today during lunch...It seemed to hover OK, but i still had the 15/8 prop on it...so i think im going to get a 16/5, and even like 17/4 if i can...and try both of those...It seemed like i'll need to move some weight towards the rear...

Also...I noticed once my fuel gets near about 1/4 tank,  the engine seems to miss a bit while inverted or in a climb....Is this normal?  I didn't build this plane so i dont really know anything about how the fuel pick-up works in a plane?  Again all my experience up to this point has been with electric park flyers.

Thanks again!
Trent
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Hi Trent,
1THEPALMER gave some excellent suggestion hera and it would be hard add to it but here goes.

The aileron throws need to be 35 degs or greater to counter torque roll.
The elevator throw needs to be 45 degs min.
The rudder throw needs to be 45 to 55 degs.

Oh yeh, and I second the big nads and willing to go low. The closer it is to you (and the ground by proxy) the easier it is to see every little twitch and adjust accordingly. Good luck and have fun!!!!!

I wouldn't get it low until I practiced up high.

Terry in LP