Did Anyone Ever Put Two Rolls-Royce Merlins on a P-38? What Would Be Its Performance Improvement?

No, But Kelly Johnson Threatened to Do It for Performance Enhancements

A famous aircraft designer, Kelly Johnson, once suggested adding two Rolls-Royce Merlin engines to the P-38 Lightning. While this may seem like a radical idea, the design and development of the P-38 involved numerous iterations to achieve its desired performance. By the time the P-38L model was developed, it was relatively well-balanced and efficient.

Conspiracy Theories and Political Decisions

There are conspiracy theories suggesting that political pressures and industrial interests played a significant role in stopping the project. The U.S. War Production Board, which had a majority of former General Motors (GM) executives with significant GM shares, allegedly imposed this decision to protect GM's interests. These executives may have been concerned about the potential loss of P-38 business if Rolls-Royce engines were installed, especially after the P-51 Mustang transitioned to the Merlin engine.

Experimental P-38 Night Lightnings and P-38L-LO

Despite the political obstacles, some experimental versions of the P-38 Lightning were indeed fitted with two Rolls-Royce Merlin engines. These variants were known as the P-38M Night Lightning and the P-38L-LO. The P-38M Night Lightning featured two Merlin engines with a total output of 3000 horsepower, while the P-38L-LO had two Merlin engines with a total output of 2800 horsepower. These engines were quite powerful compared to the standard P-38, which utilized two Allison V-1710 engines producing 2000 horsepower.

Significant Performance Improvements

The installation of two Merlin engines on the P-38 indeed resulted in notable performance improvements. The top speed of the P-38M Night Lightning increased to 440 mph (710 km/h), up from the standard P-38's 395 mph (636 km/h). The climb rate and ceiling were also enhanced. However, the added weight of the two Merlin engines reduced the range of the P-38M, compared to the standard P-38.

The P-38M Night Lightning: A Futuristic Interceptor

The P-38M Night Lightning was designed to counter the German Luftwaffe's V-1 flying bombs. Its high-speed and long-range capabilities made it an ideal candidate for this mission. Unfortunately, the war ended before the P-38M could see operational service, and only a few prototypes were ever produced.

Conclusion

The potential of the P-38 Lightning with Rolls-Royce Merlin engines was a fascinating concept, but political and industrial reasons prevented it from becoming reality during World War II. While the P-38 became a legendary aircraft in its own right, the idea of the P-38M Night Lightning remains an interesting footnote in aviation history.