The Plane with the Most Insane Cannons of WW2

YouTube / World War Made Simple

The Westland Whirlwind is the RAF’s twin-engine fighter that never reached its full potential. This video explores how Air Ministry specification F.37/35 led to a groundbreaking cannon-armed design, why Rolls-Royce chose to prioritize the Merlin over the Peregrine engine, and how the Whirlwind shifted roles to become a low-level “Whirly-bomber” before being retired in 1943.

The “Cannon Fighter”

The Westland Whirlwind emerged from an ambitious concept. In 1935, the Air Ministry issued Specification F.37/35, calling for a twin-engine fighter equipped with no fewer than four 20mm cannons. At a time when most aircraft still relied on rifle-caliber machine guns, this was a bold and forward-looking requirement. Westland Aircraft’s chief designer, W.E.W. “Teddy” Petter, answered with a sleek, compact design that was both modern and heavily armed.

The Whirlwind’s construction was ahead of its time. Its flush-riveted, all-metal airframe minimized drag, while its tricycle landing gear provided greater stability on the ground. The cockpit offered excellent visibility, and its twin-engine configuration provided an extra layer of safety in case one failed. These features set new benchmarks for aircraft design and showcased the innovative mindset of Westland’s engineers.

Powered by twin Rolls-Royce Peregrine engines, the Whirlwind could reach 360 mph, fly up to 30,000 feet, and cover 800 miles. Compact and aerodynamic, with a 45-foot wingspan and 32-foot length—it combined speed, agility, and low-altitude effectiveness, making it a capable escort and ground-attack fighter.
The first prototype took to the skies on October 11, 1938, quickly proving its remarkable speed and concentrated firepower. Impressed, the Air Ministry placed an order for 400 aircraft, confident that the Whirlwind would become a cornerstone of Britain’s aerial defense.

Firepower Unleashed

The Whirlwind was the RAF’s first fighter to carry four nose-mounted Hispano-Suiza HS.404 20mm cannons. Concentrated in the nose, this firepower made it highly effective against enemy aircraft, vehicles, and ships. With each cannon capable of firing 600 rounds per minute, the Whirlwind earned the nickname “Cannon Fighter,” as even a brief burst could bring down a bomber or devastate ground targets.

However, its firepower came with a limitation: only 60 rounds per gun. To enhance versatility, the aircraft could also be fitted with two 250-pound bombs or a single 500-pound bomb.

Drawbacks

The Whirlwind’s greatest weakness lay in its dependence on the Rolls-Royce Peregrine engines. Although advanced for their time, the Peregrines were unreliable, demanded heavy maintenance, and, crucially, were abandoned when Rolls-Royce chose to focus on the more successful Merlin that powered the Spitfire and Hurricane. When the Peregrine was discontinued in 1942, the Whirlwind was left without a future powerplant.

Operational limitations compounded the problem. It’s relatively short-range, restricted flexibility, while its compact design makes maintenance difficult. Although developed during the Battle of Britain, the Whirlwind never took part. Engine shortages and production delays meant it only reached operational units later in 1940, by which point the RAF had shifted from defensive fighting to offensive missions over Europe, leaving the Whirlwind somewhat out of step with strategic needs.

The Whirlwind’s service ended in 1943 after just 114 were built, hampered by the scarcity of its Peregrine engines. Replaced by more versatile aircraft like the Mosquito and P-38, it nonetheless left a legacy through its advanced design and heavy firepower, shaping future twin-engine fighters and ground-attack aircraft.