We asked why this had two sets of props. Without remembering technical details the engine it has provides such great torque that without the sort of opposing prop angles the plane would spin from the torgue and power. Don't hold me to every word there, ha ha. It was one of my favorites. Evidently there aren't many in existence. They didn't perform up to promises and many were catapulted off a carrier into the sea. This one was at base for maintenance and survived.