The Lockheed XP-58 Chain Lightning: Lightning never strikes twice

From the Planes You’ve (Probably) Never Heard Of Department of Wingspan, we bring you the Lockheed XP-58 Chain Lightning.

San Diego Air and Space Musem

With its remarkable service in both the European and Pacific Theaters of WWII, the Lockheed P-38 Lightning became one of the iconic fighters of the war. Designed by Hall Hibbard and Clarence “Kelly” Johnson, over 10,000 Lightnings were produced, and it was the only US fighter to be built continuously throughout the war. Orders for more than a thousand more were canceled when the war ended. Based on the brilliant success of the P-38, it only made sense to try to improve upon it. Though many great aircraft have been born out of the subsequent development process, the results can also be a resounding thud. Such was the case with the XP-58 Chain Lightning.

In 1940, the US Army gave Lockheed permission to sell the P-38 to Britain and France, and in return, Lockheed agreed to develop an improved variant of the Lightning at no cost to the US government. The Army drew up a requirement for a long-range, twin-engine escort fighter, and Lockheed got to work. But the program was constantly plagued by engine problems and changing design requirements.

US Air Force

At first, Lockheed planned to use two Continental IV-1430 12-cylinder engines, a so-called hyper engine currently under development that was supposed to produce 2,100 hp at full power. But when development of that engine was canceled, Lockheed switched to the Pratt & Whitney XH-2600, a 24-cylinder H-block engine that was also canceled after just one was built. Hoping that the third time was a charm, Lockheed opted for the massive Wright R-2160 Tornado, an inline radial engine with no less than 42 cylinders that promised to deliver 2,350 hp for takeoff.

Wright R-2160 Tornado 42-cylinder inline radial (photo by Bill Maloney via Wikimedia Commons)

Not only was the engine choice in flux, but design of the center crew compartment was a victim of continuously changing combat requirements. With the addition of a second crewman came a powered rear turret, and a second 20mm cannon was added in the nose. Then the decision was made to add a second powered turret and to pressurize the hull. With all the changes in design, the initial estimate of a gross weight of 20,000 pounds had ballooned to 34,000 pounds, and still more changes brought the weight to over 35,000 pounds. By this time, the hoped-for Tornado engine was also canceled, so it was decided to use the Allison V-3420, yet another experimental engine that promised as much as 2,600 hp at full power.


But the Army wasn’t done with making changes. By early 1942, it became clear that the Chain Lightning would not live up to its billing as a high-altitude fighter, so the decision was made to turn it into a low-altitude tank buster. The superchargers and pressurization would be removed and a single 75mm cannon was planned for the nose. But this put the Chain Lightning into direct competition with the Beechcraft XA-38 Grizzly, a plane that was designed from the wheels up as a purpose-built tank and bunker buster, though it too never entered production. So the Chain Lightning’s role was changed yet again to a ground attack bomber. By now, the XP-58 had bulged to 39,000 pounds, almost twice weight of the original requirement.

San Diego Air and Space Museum

The first of two proposed prototypes finally took its maiden flight on June 1, 1944, and the on-again off-again work on a second prototype was resurrected. But with so many high priority projects underway, flight testing of the XP-58 was limited. The engines proved to be a maintenance nightmare, and constant problems with the supercharger caused torching that often scorched the tail. The second prototype was then canceled yet again, and the sole prototype was flown to Wright Field in Ohio in October 1944, where it was used for ground instruction duties and was eventually lost to history.


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