What was the most powerful single-engine fighter of the war?

Short answer

The Boeing XF8B was the largest and heaviest single-seat, single-engine fighter developed in the United States up to that point. Its single Pratt & Whitney XR-4360-10, a 28-cylinder radial in four rows, delivered 3,000 hp (2,200 kW) and 3,600 hp in War Emergency Power. It flew in November 1944.

Published: November 5, 2026 · Updated: November 5, 2026 · Edited by Above Ten Thousand · Editorial policy

What was the most powerful single-engine fighter of the war?

Boeing XF8B

A 28-cylinder radial

The XF8B carried a single Pratt & Whitney XR-4360-10, a 28-cylinder radial arranged in four rows, delivering 3,000 hp (2,200 kW) and driving two contra-rotating three-blade propellers. In War Emergency Power mode, the engine reached 3,600 hp.

The "five-in-one fighter"

Boeing optimistically dubbed the XF8B-1 the "five-in-one fighter": fighter, interceptor, dive bomber, torpedo bomber, and horizontal bomber. It could perform several combat roles.

First flight in November 1944

The XF8B flew for the first time in November 1944. It was the largest and heaviest single-seat, single-engine fighter developed in the United States up to that point.