Even if you make your tailwheel steerable, leave some caster in. Do not make the tailwheel without caster. If you do, you may be in for a nasty surprise when you rip the gears out of the servo. Caster is what keeps the wheel following the spindle, instead of trying to turn at will. This may sound overly simple, but you would be surprised at the number of people who do not know this principle.

Bill, AMA 4720
WACO Brotherhood #1