The Martin-Baker MB 5: Britain’s Finest Fighter That Never Was

The Second World War was an era of rapid innovation in aviation, as nations raced to produce faster, more powerful, and more capable fighter aircraft. Britain, whose survival in 1940 depended on the valiant efforts of the Spitfire and Hurricane, continued to experiment with new designs throughout the conflict. Among the most remarkable prototypes to emerge from this period was the Martin-Baker MB 5, often described by test pilots as one of the finest piston-engine fighters ever built.

Yet, despite its stellar performance and glowing evaluations, the MB 5 never progressed beyond the prototype stage. Overshadowed by the shift toward jet propulsion, it remained a brilliant “what if” of aviation history—a plane that could have been among the best piston-powered fighters of the war, had timing and circumstance not sealed its fate.

The Martin-Baker Story

The MB 5 was the product of Martin-Baker Aircraft Company, a small British firm founded in 1934 by James Martin, an innovative designer, and Captain Valentine Baker, a skilled test pilot. Unlike giants such as Supermarine or Hawker, Martin-Baker was a modest enterprise. But its engineers were ambitious, pursuing advanced designs intended to outperform contemporary fighters.

The company’s first prototypes, the MB 1 (1935) and MB 2 (1938), introduced unconventional features. The MB 2, for example, emphasized ease of production, with a straightforward structure and reliable performance. It compared favorably with the Hawker Hurricane in some respects but failed to secure official backing.

Undeterred, Martin-Baker pressed on with new concepts. The MB 3, designed around a powerful Napier Sabre engine, promised impressive speed and firepower. Tragically, during flight testing in September 1942, Captain Baker was killed when the MB 3 suffered an engine failure and crash-landed. His death devastated the company but also inspired Martin to continue in his friend’s memory.

The MB 3’s successor, the MB 4, was never completed, but the lessons learned set the stage for the company’s masterpiece: the MB 5.

The MB 5 Takes Shape

Work on the MB 5 began in 1941, but the prototype was not completed until 1944 due to delays, engine availability issues, and the company’s limited resources. The aircraft was powered by the formidable Rolls-Royce Griffon 83 engine, delivering over 2,300 horsepower and driving contrarotating propellers—a feature that eliminated the torque problems typical of powerful single-engine fighters.

The MB 5’s design emphasized both performance and practicality. Unlike many wartime fighters that sacrificed ease of maintenance for sleek lines, the MB 5 incorporated features that would have delighted ground crews:

Spacious, well-laid-out engine bay with easy access panels.

Durable construction, reducing the time needed for repairs.

Modern cockpit layout, with controls logically arranged for pilot convenience.

Visually, the MB 5 had a purposeful, muscular look. Its long fuselage and broad wings gave it a resemblance to later American fighters like the P-51 Mustang, but it was larger and more powerful.

Performance and Test Pilot Praise

When the MB 5 finally took to the air in 1944, it quickly earned a reputation as one of the best-handling piston-engine fighters ever built. Official trials revealed outstanding characteristics:

Top speed exceeding 460 mph, comparable to the fastest piston fighters of the time.

Excellent climb rate and acceleration.

Superb maneuverability, combining agility with stability.

Outstanding cockpit visibility, thanks to a bubble canopy.

Test pilots were effusive in their praise. Captain Eric “Winkle” Brown, one of the most experienced test pilots in history, later called the MB 5 “the best piston-engined fighter never to go into production.” He admired its handling, cockpit ergonomics, and reliability, noting that it felt as refined as a production aircraft rather than a prototype.

Why It Never Entered Production

Given its glowing reviews, why did the MB 5 never see combat or mass production? Several factors converged to seal its fate:

Timing – By 1944–45, Britain’s war industry was already focused on proven designs like the Spitfire, Tempest, and Mustang, which were available in large numbers. There was little appetite for diverting resources to a new type so late in the war.

The Jet Age – The advent of jet fighters like the Gloster Meteor and de Havilland Vampire made it clear that piston-engine fighters were nearing obsolescence. Military planners were reluctant to invest in a new propeller-driven aircraft, however capable, when jets represented the future.

Limited Industrial Backing – Martin-Baker, as a small company, lacked the production capacity of larger firms. Even if the MB 5 had been ordered, scaling up would have required major government investment.

In the end, the MB 5 remained a single prototype, admired but unused.

Legacy Beyond the MB 5

Although the MB 5 never entered production, it left an enduring legacy. For James Martin, the loss of his co-founder Valentine Baker remained deeply personal. Determined to improve pilot safety, Martin shifted the company’s focus after the war to developing ejection seats.

This decision proved transformative. Martin-Baker became the world leader in ejection seat technology, saving the lives of over 7,600 aircrew to date. Ironically, while the MB 5 never had the chance to save Britain in combat, its company went on to save countless aviators worldwide.

A “What If” Fighter

The MB 5 occupies a special place in aviation history as one of the greatest piston-engine fighters never to see combat. Had it entered service in 1943, it might have rivaled or surpassed contemporaries like the P-51 Mustang, Spitfire Mk XIV, or Fw 190D-9. Its combination of speed, power, handling, and maintainability was unmatched.

Yet history is rarely kind to latecomers. The MB 5 arrived at a time when technology was moving on, leaving it stranded as a fascinating but obsolete prototype.

Surviving Example

Only one MB 5 prototype was ever built. It made appearances at air shows and demonstrations into the late 1940s but was eventually scrapped. Today, only photographs, pilot reports, and scale models preserve its memory.

For aviation enthusiasts, it remains a symbol of unfulfilled potential—the fighter that could have been the best of its kind, had history unfolded differently.

Conclusion

The Martin-Baker MB 5 was the ultimate expression of piston-engine fighter design: powerful, reliable, and beloved by test pilots. Sadly, it arrived too late to influence the war and too early to escape the jet revolution.

Though it never fired a shot in anger, the MB 5’s legacy endures, both as a remarkable piece of engineering and as a stepping stone to Martin-Baker’s lifesaving work in ejection seats. For many, it remains the ultimate “what if” aircraft—a tantalizing glimpse of the best piston fighter that never was.