That frame looks exactly like one I recently bought off ebay. I was told it was a Roadmaster. (It has no head badge.) I just looked up pics of Fleetwings and found variations in the down tube, some with a deep curve like yours, and some with a shallower curve. I am in the throws of installing a Whizzer engine in mine. Do you have any tips to pass along? It looks like you mounted the engine far to the rear of the triangle, did you have to modify the engine mounts much?