oldironside,
The Airacuda illustrates perfectly what I was looking for - ridiculous ideas that somehow made it into the air.
Actually, it was a whole lot more than that.
In the 1930s the Air Corps was starved for funds. What little money it did get it had to stretch out as far as it could. So, when it did get some money to do some research and development it tended to pile as many development efforts into it as it could. Hence the Airacuda was more of what we'd call a "technology demonstrator" today than anything else. It incorporated electrical motors for what was usually hydraulically activated. The Air Corps hoped the weight savings, lack of flammable fluids, and lower maintenance on the electrical system would be worth its development cost. The type was also altered into a tricycle landing gear configuration and that was something new for the Air Corps as well. Those pusher engines gave an unobstructed forward field of fire. The entire mission of the aircraft was a proof of concept in that the Air Corps wanted to see if the idea of a "bomber destroyer" was a practical thing. When the Airacuda first took flight most air forces in the world considered rifle caliber machine guns to be of sufficient firepower to meet their needs. Some advanced aircraft of the day might sport a single .50 cal machine gun as a "heavy" armament. So for the Airacuda to have 37mm canon as its main armament was a huge leap ahead in capability. Then the Air Corps insisted Bell develop a long range sighting system for plane that was more akin to that of naval gun directors than aerial gunsight and you've got a really cutting edge machine.
No surprise then that so much it didn't work out well enough. The pusher prop layout meant the engines didn't get enough airflow over their radiators to keep them cool enough while the plane was on the ground. That electrical motor set up had tremendous problems and simply wasn't up to the loads demanded of it. The thing would short out and that'd leave the plane in dire straits at exactly the wrong times - like landing when you needed the flaps and the gear down. Those big heavy General Motors 37mm canon were awesome guns - when they worked. The things would frequently jam due to the movement of the aircraft imparting sufficient g-loading on their components that caused them to hang up.
And worst of all, it quickly became apparent that there'd be no streams of bombers coming across the Atlantic for the Airacuda to sink its fangs into. Thus all those operational problems were deemed too expensive for the Bell Company to resolve as the Air Corps suddenly had other needs.
As a technology demonstrator, the Airacuda accomplished its intended purpose - it demonstrated that many of the technologies it had stuffed into its airframe simply were not ready for operational use. If anything, that meant the type was actually more of a success than anything else.