Errrr.... And exactley which aircraft has flown equipped with Wankel engines???
As to the pistons you've quoted, none of them had more than four engines because of redundency. They had that many because they needed that much power from the best avaialble engines at the time.
A three-engined pison would no have any distance restrictions on it, provided it could maintain height on any one, but the engineering difficulties of odd numbers of engines has meant that these have been a rarity (Tri-lader and Drover- both modifications of existing twins,and the 1930's Fokker and Ford tris are the only ones that spring to mind).
Last edited by Wizofoz; 6th November 2006 at 09:28.