Why so few Tri-s with 1 CCW prop?

[eoosting]

Most Tricopters I've seen have 3 CW rotating props. Why not balance some of the yaw effect of the props by using 1 CCW prop for one of the front motors? You would still have an imbalance, with 2 CW and 1 CCW, but that would seem better then 3 CW.

 

[Cyberdactyl]

Many do exactly that.

 

[Supergoldfish]

Price and availability.