An unplayed substitute

When France fell in May 1940 and the Battle of Britain was imminent, there was a certain amount of panic in the British Ministry of Defense about the number of Hurricane and Spitfire fighters available and the consequences of the Germans bombing the factories that produced them.

As insurance against attacks, the British minister of air production, Lord Beaverbrook, issued Specification F.19/40 for a Royal Air Force fighter that could be produced quickly and cheaply and with roughly the same performance as the Hurricane and Spitfire.

The Miles Aircraft company, producer of the standard RAF trainer, the Miles Master Mk. I, had already converted 25 Masters into true emergency fighters by adding four .303 machine guns and fairing over the rear instructor’s cockpit. They then went one step further.

In a remarkably short time – 65 days – the Miles team designed, built and flew a prototype fighter, the Miles M.20, to meet the emergency fighter specification. With the exception of performance, all aspects of the fighter’s design had been subordinated to its ease of construction and rapidity of manufacture.
For a 1940 fighter, the two most striking aspects of the pugnacious-looking M.20 were a full bubble canopy (one of the first of its kind) and its seemingly anachronistic fixed, spatted landing gear.

However, there was method to the seeming madness of the fixed gear. It allowed the M.20 to dispense with the vulnerable, complicated hydraulic systems and at the same time freed up the entirety of the easy-to-build, two spar, single piece wing for fuel and armament.

The fuselage was a smooth, wood semi-monocoque structure (the load was mainly borne by the external skin instead of an internal frame) while the conventional tail was fabric and plywood covered. The powerplant of the M.20, the 1,460 horsepower Rolls Royce Merlin XX, was another concession to ease of production, since it was already in full scale production for the RAF’s Bristol Beaufighter and the Avro Lancaster bomber.

The M.20 first flew on Sept. 15, 1940, at the end of the Battle of Britain. Though its fixed landing gear led the test pilots to expect it to be sluggish, the test program showed its performance was surprisingly good and close to that of the RAF fighter the Hawker Hurricane, though the Hurricane was slightly faster and more maneuverable.

On the plus side, the M.20 accelerated “remarkably rapidly” in a dive and production versions were to carry 12 .303 caliber machine guns to the Hurricane’s (and Spitfire’s) eight, and the M.20 had 5,000 rounds of ammunition, giving it about twice the firepower. The M.20 also had double the range of these standard RAF fighters. However, the RAF’s need for the M.20 ended after the cessation of the Battle of Britain. Nevertheless, it’s performance interested the Royal Navy, which was desperate for a first rate fighter.

The M.20 landing gear spats were modified and made jettisonable for ditching, catapult launching points and an arresting gear hook were fitted, and then it was submitted to fill Royal Navy Specification N.1/41 for a single-seat shipboard fighter. Test flights of the navalised version of the M.20 confirmed its good performance – superior to any Royal Navy fighter of the time – and especially its excellent visibility from the cockpit. However, its carrier landing characteristics left something to be desired, showing a tendency to bounce and sluggish ailerons at low speed.

But its main drawback was determined to be its wooden construction, which would have suffered from salt corrosion and would have been easily damaged in the inevitable hard carrier landings.

There was some consideration of using it on the Catapult Aircraft Merchantman ships, where the M.20 would have been catapulted off to intercept German reconnaissance aircraft reporting on a convoy’s location. After its interception, the M.20 would have jettisoned the fixed landing gear and been ditched next to the convoy. But by that time, there were plenty of Hurricanes available for this dangerous mission, and the M.20 proposal was dropped.

The M.20 could have been a useful RAF second line fighter in 1942 – certainly in the Western desert or against the Japanese invasion of the British Empire in Asia in the beginning of that year – and even though it was never put into production it was certainly a brilliantly executed concept.

The fact this almost excellent fighter was designed, built and flown in 65 days is a tribute to the genius of the Miles designers and engineers, and the M.20 joins a number of other excellent World War II aircraft that were developed quickly – one is tempted to say thrown together – and turned out to be excellent aircraft from the start, notably the Mustang but also the Heinkel He 162.

(For questions or comments, contact Dr. Michel at marshall.michel@ramstein.af.mil.)