RE: ESM Dornier DO 335
1. The accepted standard for a/c orientation is always Aft looking Forward (ALF).
2. What you describe is the normal setup for engines that rotate clockwise, ALF. (Thats looking from the back of the engine, prop driver pointing away from you). When you point the engine backwards, like the rear engine in the Dornier, it now rotates anti-clockwise, ALF, so you need a prop that is carved for opposite rotation in order for it to push the model forward. The curved side of the blades will face forward on both front and rear props. Oh, and the correct term for a 'regular' prop is 'tractor'.
Evan, WB #12.