RE: topflite spitfire retracts
here's the problem as I see it there is alot of stuff crammed in the wing near the landing gear, and center section, the flap bell cranks, and the flap servo is also in the center section, a rertact servo would fit in the forward area but it would be tight. the center section is strait and the wings angle off of it as well so its a bit tricky.
the gear have a slightly off center angle to them and rearward angle as well so working out the geometry for smooth action might be a bit of a challenge, it could be done of course but your not really saving that much money for the extra work and hassle since the wing is designed for air gear to be used.
the retracts from robart can be had for about 120$ U.S. for the TF spit, my wing at the retracts and my flight mech.