A could of been from the intra-war period. The Grumman XF5F. It was supposed to compete to fill requirement SD112-14. Which was supposed to be effectively point defense fighter that could climb and meet bombers at 20k ft in a quick climb. Interestingly SD112-13 leads to F4U & F4F

Due to questions and issues within BuAir about which engine to use a P&W or a Curtiss-Wright engine. Development was protracted for about a yr. Before C-W engine was selected. Contract was awarded in '37. Wind tunnel testing to help solve a buffet->stall condition thru '40

All this time the plane gained weight. From structure to support a planned 23mm Marsden Cannon. In addition to bomb bays for anti-bomber fragmentation bombs.
https://en.m.wikipedia.org/wiki/Madsen_20_mm_cannon?wprov=sfla1
Note both the F4F and F4U would be developed with these bomb bays.

During testing the XF5F and XF4U would be testing in rate of climb. The XF5F would out climb the XF4U. Eventually though the buffet stall and landing gear issues would prevent the XF5F to be selected.

The only people that would fly the plane is the DC hero Blackhawk in his war time comics.
They would also feature him and the plane on the 2000s cartoon "Justice League" episode "Savage Time"

Grumman would try to develop a version for the USAAF. Called the XP-50. This was supposed to replace the P-38 in service. However, even this airplane would fail to be picked up for production. The one prototype would be lost over Long Island sound when a turbocharger exploded.

All the experience in production and testing of both planes would lead Grumman to successfully develop the F7F.