Does anyone know what the advantage/disadvantage of the ring-type (spade grip) control stick used on British WWII fighters might be (Hurricane left, Spitfire right in pics below)? Maybe the point was to allow you to pull with both hands?
And not just on fighters, here's one from a Percival Prentice trainer.
It does seem to me that it would offer more alternate hand positions and easier changing hands than a conventional stick. Anyone every see one on a homebuilt plane and/or have dimensions/drawings for making one?