“What If” Lockheed L-131 fighter
As the US entry into WWII neared, Lockheed was sketching out a heavy fighter design that would leverage the company’s experience with the P-38 Lighting, Model 522/YP-49 development, and the then-unbuilt XP-58 Chain Lightning. Indeed, the L-131 could be thought of as a single-engine Lightning, retaining the twin-boom layout, but with a Wright R-2160 Tornado engine fitted in the fuselage pod. The R-2160 was a 42 cylinder liquid-cooled radial that was projected to power other fighter programs such as Republic’s AP-12 Rocket and the later AP-18/XP-69, and the Vultee XP-68. Performance at high altitude was estimated at a little over 400 mph, and armament would have consisted of a pair of 20mm cannon and six .50-cal machine guns. Two of the weapons would be fitted in aft dorsal and ventral positions on the fuselage pod to provide protection from the rear, while four other guns would be in the wing, and the remaining two in the forward sections of the booms.
American Secret Projects: Fighters, Bombers, and Attack Aircraft 1937-1945 Chapter One has coverage of the L-131 and Republic XP-69, which would also have been powered by an R-2160.