In gliders there's also an aerodynamic issue. A centerwheel/tailwheel arrangement is conveniently located at the places where the airframe sits on the ground by itself: The airframe is thickest near the pilots bum, and that happens to be just ahead of the CofG. Compensate that with a (non-steerable) tailwheel at the back end and the wheels, even if not retractable, offer minimum drag since they're mostly contained within the fuselage. A nosewheel/centerwheel or tricycle arrangement would require the wheels to protrude from the fuselage quite a lot.
Of course gliders don't need to taxi on their own, so the tailwheel doesn't need to be steerable. Making things even simpler.
But that has a disadvantage too. Recently we were forced to land with a 2-3 knot tailwind. (Wind veered throughout the day and switching the whole field arrangement around, winch and everything, takes about an hour. As this was the end of the day anyway, we didn't bother.) That made things really interesting, and quite a few of us groundlooped a bit at the end of the landing run. With no directional control whatsoever (no steerable tailwheel and no airflow over the rudder due to the tailwind) this was inevitable. Fortunately the speeds at that stage were very low, none of the groundloops exceeded 90 degrees, and no damage was done. But it did give me an appreciation of the dangers of losing control in a tailwheel.
Last edited by BackPacker; 10th Jul 2012 at 09:50.