hi guys i have a twist 40 v2 with a 46 ax engine runnig a 12x 6 apc prop anyone have better suggestion on prop size for hovering it will hover but can barly pull out also anyone have good recomendations for cg got the cg at 5 in back and it wont flatten out in a flat spin any help is much appreciated

For a flat spin, the farther back the flatter... the 12 inch prop is a good start, see what you can find with a flatter pitch, i.e. 3.5 or 4.
dan

okwill have to try it so bigger props less pitch is better for hovering and 3d

12x4 would be a much better choice. The 12.25x3.75 works OK too.

Thats what I use is a 12.25x 3.75

I also have tried a 13x4

Honestly you are not going to get a fantastic vertical performance out of a hover on a 40 size plane with a 46 in it... The twist 40 v2 has a weight (obtained from horizonhobby.com) of 5-6 lbs... if you want to get into 3d with it i would suggest getting a slightly bigger motor such as an os 55ax... it has the same mounting dimensions as the 46 and its inexpensive but it will allow you to spin a larger prop increasing airflow over your control surfaces... It will also make hovering easier. When you are hovering you are in a stalled position and are controlling the plane from the movement of air being pushed by the propeller over your control surfaces... a larger motor swinging a larger prop increases prop wash therefore giving you more control in a hover.


Regarding cg...I always spend some time messing with it until the plane flies upright and inverted without any elevator input (or very little). That seems to be a pretty good starting point I think. another point is that you should also laterally balance the plane...

I'm running a Saito 82 with a 14X4. It hovers and powers out with power to spare. It's a bit nose heavy for flat spins, but I haven't done anything to move the CG back.

[youtube]http://www.youtube.com/watch?v=IQJSwf_Lgxo[/youtube]

Agree, I run both of these and they are perfect for any 45-47 size 2 stroke. The 13x4 should be the newer "thin" style, not the other "fatty", it's way too much weight and drag. I run a 61 ST on mine and it really pulls great

I have a twist 40 with a eflite 60 with a 15x10 prop, It has lots of power, but to get this thing to hover, I had moved my CG back 5.5" and change prop size to 16x8. Very fun plane for 3D