Westland Whirlwind

The Westland Whirlwind was a British twin-engine heavy fighter of the Second World War, the first British fighter to be armed with four 20-millimetre Hispano cannon, and one of the fastest and most heavily armed fighters of its time. Only 114 were built between 1938 and 1941, and they served with two Royal Air Force squadrons, No. 137 and No. 263, flying low-level fighter-bomber missions over France, Belgium, and the Channel coast from 1940 to 1943. The Whirlwind was a fast, agile, and powerful aircraft, but it was let down by its unreliable Peregrine engines and by the decision to build it in small numbers. Its story is the story of a promising design that was overtaken by events, and that is remembered as one of the most elegant fighters of the war.

1. Key Facts

Field	Value
Type	Twin-engine heavy fighter / fighter-bomber
Country	United Kingdom
Manufacturer	Westland Aircraft, Yeovil
Designer	W. E. W. Petter
First flight	11 October 1938
Production	1938–1941
Number built	114 (plus 2 prototypes)
Crew	1
Length	9.83 metres (32 ft 3 in)
Wingspan	13.72 metres (45 ft 0 in)
Height	3.53 metres (11 ft 7 in)
Empty weight	3,900 kg (8,600 lb)
Loaded weight	4,650 kg (10,250 lb)
Engines	2 × Rolls-Royce Peregrine I, 885 hp each
Maximum speed	About 580 km/h (360 mph) at 4,600 m
Range	About 1,300 km (800 miles)
Service ceiling	About 9,100 metres (30,000 ft)
Main armament	4 × 20 mm Hispano Mk I cannon (240 rounds per gun)
Bomb load	2 × 250 lb or 2 × 500 lb bombs (fighter-bomber role)
Main theatres	Channel coast, France, Belgium 1940–1943
Main squadrons	No. 263 Squadron; No. 137 Squadron

2. Origins and Development

The Heavy Fighter Requirement

The Westland Whirlwind was developed to meet Air Ministry Specification F.37/35, issued in 1935, which called for a twin-engine, single-seat fighter, armed with four 20-millimetre cannon, that could intercept bombers and fight at high altitude. The specification was a response to the growing threat of German bombers, and it reflected the belief that a twin-engine fighter, with a heavy cannon armament, would be more effective than a single-engine fighter with machine guns. Westland Aircraft at Yeovil, under the designer W. E. W. Petter, won the competition with a sleek, low-wing monoplane, powered by two Rolls-Royce Peregrine engines, with a nose armament of four Hispano cannon, and the first prototype flew on 11 October 1938. The Whirlwind was one of the most advanced fighters in the world when it first flew, and it promised to be a formidable weapon.

W. E. W. Petter and the Design

W. E. W. Petter was one of the most talented British aircraft designers, and he later designed the Canberra jet bomber and the Lightning fighter, but the Whirlwind was his first fighter, and it showed his flair for clean, efficient design. The Whirlwind was a low-wing monoplane, with a slim fuselage, a single-seat cockpit, and two Peregrine engines mounted in nacelles on the wings, with radiators in the leading edge. The aircraft was built of metal, with a stressed-skin structure, and it was one of the first British fighters to be designed with a cannon armament from the start, rather than having cannon added to a machine-gun design. The Whirlwind was an elegant aircraft, fast and agile, and it was praised by the pilots who flew it, who liked its handling and its firepower.

Production Delays

Production of the Whirlwind was delayed by problems with the Peregrine engine, which was a development of the Rolls-Royce Kestrel and which was unreliable and difficult to manufacture, and by the decision to give priority to the Spitfire and the Hurricane, which were already in production and which were needed for the Battle of Britain. Only 114 Whirlwinds were built between 1938 and 1941, and they were issued to two squadrons, No. 263 and No. 137, which were the only squadrons to operate the type. The Whirlwind entered service in June 1940, just as the Battle of Britain was beginning, but it was not used in the battle, because it was still being tested and because its engines were unreliable. The Whirlwind was a fighter that arrived too late and in too small numbers to have a major effect on the war.

The Peregrine Engine

The Rolls-Royce Peregrine was the Achilles’ heel of the Whirlwind, because it was a new engine, developed from the Kestrel, that was unreliable, difficult to maintain, and no longer in production by 1941, when Rolls-Royce concentrated on the Merlin. The Peregrine produced 885 horsepower, which gave the Whirlwind a top speed of 580 kilometres per hour, but it was prone to overheating, to oil leaks, and to failure, and it was difficult to repair in the field. The Whirlwind’s pilots liked the aircraft, but they did not trust its engines, and the type was grounded several times for engine problems. The Peregrine was the reason why the Whirlwind was built in small numbers and why it was retired early, and it is a lesson in the importance of a reliable engine for a fighter aircraft.

3. Technical Design

Airframe and Handling

The Whirlwind was a low-wing monoplane, 9.83 metres long, with a wingspan of 13.72 metres, and a loaded weight of 4,650 kilograms. Its airframe was built of metal, with a stressed-skin structure, and it was one of the cleanest and most aerodynamic fighters of its time, with a slim fuselage and a low drag. Its handling was excellent, with light controls, a good rate of roll, and a tight turning circle, and it was praised by its pilots as one of the best-handling fighters they had flown. The Whirlwind was a delight to fly, and its pilots, who included some of the most experienced in the Royal Air Force, rated it highly. Its handling was its greatest strength, and it made up for its unreliable engines.

Engines and Performance

The Whirlwind was powered by two Rolls-Royce Peregrine I engines, each producing 885 horsepower, which gave it a top speed of about 580 kilometres per hour at 4,600 metres, a range of about 1,300 kilometres, and a service ceiling of about 9,100 metres. Its performance was good for a twin-engine fighter, and it was faster than the Hurricane and almost as fast as the Spitfire, though it was less manoeuvrable at high altitude. Its twin engines gave it a good rate of climb and a good performance at low altitude, where it was used as a fighter-bomber, and they gave it a measure of safety, because it could fly on one engine if the other failed. The Whirlwind’s performance was a strength, but it was limited by the unreliability of its engines.

The Four Cannon

The main armament of the Whirlwind was four 20-millimetre Hispano Mk I cannon, mounted in the nose, with 240 rounds per gun, which gave it a firepower that was unmatched by any other British fighter in 1940. The Hispano cannon fired a 130-gram shell at a muzzle velocity of about 850 metres per second, and it could destroy a bomber with a short burst, and it could penetrate the armour of a tank or a ship. The Whirlwind was the first British fighter to be armed with four cannon, and its firepower was a revelation, because it could destroy a target that a machine-gun fighter could only damage. The Whirlwind’s cannon were its greatest weapon, and they were the reason why it was used as a fighter-bomber, attacking trains, ships, and airfields.

4. Combat Service with No. 263 Squadron

The First Operations

No. 263 Squadron was the first to operate the Whirlwind, receiving its first aircraft in June 1940, and it flew its first operations in December 1940, patrolling the Channel coast and escorting convoys. The squadron was based at Exeter and later at Warmwell, and it flew defensive patrols, protecting the south-west of England against German bombers and fighters, and it shot down several German aircraft, including a Ju 88 and a He 111. The Whirlwind was used as a day fighter in 1940–1941, but it was not as effective as the Spitfire and the Hurricane in that role, because its engines were unreliable and because it was less manoeuvrable at high altitude. The squadron’s early operations were a learning experience, and they showed that the Whirlwind was better suited to low-level operations than to high-altitude interception.

Fighter-Bomber Missions

From 1941 onwards, No. 263 Squadron used the Whirlwind as a fighter-bomber, flying low-level missions over France and Belgium, attacking trains, airfields, ships, and gun positions. The Whirlwind was well suited to this role, because its four cannon could destroy a locomotive or a ship with a short burst, and because its speed and its low-level performance made it hard to intercept. The squadron flew “Rhubarb” missions, low-level attacks on targets of opportunity, and “Circus” missions, escorting bombers to France, and it achieved useful results, destroying trains, damaging airfields, and shooting down German fighters. The Whirlwind’s service as a fighter-bomber was its most important role, and it showed that a twin-engine fighter could be an effective ground-attack aircraft.

The Channel Dash

In February 1942, No. 263 Squadron took part in the attempt to intercept the German battleships Scharnhorst and Gneisenau and the cruiser Prinz Eugen as they sailed through the English Channel, the Channel Dash, and its Whirlwinds attacked the German ships with cannon fire, though they could not sink them. The Channel Dash was a failure for the Royal Air Force and the Royal Navy, because the German ships escaped, but it showed that the Whirlwind could attack a heavily defended target and survive. The squadron’s Whirlwinds were among the few aircraft that attacked the German ships, and they earned a reputation for courage and for determination.

5. Combat Service with No. 137 Squadron

Formation and Operations

No. 137 Squadron was formed in September 1941 as the second Whirlwind squadron, and it operated alongside No. 263 Squadron, flying fighter-bomber missions over France and Belgium. The squadron was based at Charmy Down and later at Manston, and it flew “Rhubarb” and “Circus” missions, attacking trains, airfields, and shipping, and it also flew night intruder missions, attacking German airfields at night. No. 137 Squadron was a successful squadron, and it destroyed many trains and ships, and it shot down several German aircraft, including a Fw 190. The squadron’s Whirlwinds were well maintained and well flown, and they earned a reputation for effectiveness.

The End of the Whirlwind

By 1943, the Whirlwind was showing its age, and its Peregrine engines were becoming difficult to maintain, because Rolls-Royce had stopped making them and spare parts were scarce. No. 263 Squadron converted to the Typhoon in December 1943, and No. 137 Squadron converted to the Hurricane in June 1943, and the Whirlwind was retired from service. The last Whirlwinds were scrapped in 1944, and no complete example survives today, though a project is under way to build a replica. The Whirlwind’s service ended after only three years, but it had flown more than 3,000 sorties and had destroyed many trains, ships, and aircraft, and it had earned the respect of its pilots and of the enemy.

The Whirlwind in Numbers

The Whirlwind flew more than 3,000 operational sorties, and its squadrons claimed the destruction of dozens of trains, ships, and aircraft, though the exact figures are uncertain. The type suffered losses, with about 20 aircraft lost in combat and more lost in accidents, but it was not an easy aircraft to shoot down, because it was fast and low, and because its pilots were experienced. The Whirlwind’s record was modest, but it was a record of a small force that punched above its weight, and that showed what a twin-engine fighter-bomber could do.

6. Strengths

Firepower and Handling

The greatest strengths of the Whirlwind were its firepower and its handling, because its four 20-millimetre cannon gave it a firepower that was unmatched by any other British fighter in 1940, and its light controls and its tight turning circle made it a delight to fly. The Whirlwind could destroy a bomber, a train, or a ship with a short burst, and it could outmanoeuvre a German fighter at low altitude, where it was at its best. Its pilots rated it highly, and they said that it was the best fighter they had flown, in terms of handling and firepower. The Whirlwind was a fighter that was ahead of its time, and its cannon armament became the standard for British fighters, from the Typhoon to the Tempest.

Low-Level Performance

The Whirlwind was at its best at low altitude, where its twin engines gave it a good rate of climb and a good speed, and where its cannon could be used against ground targets. It was a superb low-level fighter-bomber, and it was used for that role with great success, attacking trains, ships, and airfields in France and Belgium. Its low-level performance was a strength that made it useful even after it had become obsolete as a day fighter, and it showed that a twin-engine fighter could be an effective ground-attack aircraft. The Whirlwind’s low-level performance was the reason why it was kept in service until 1943, long after it had been superseded as a fighter.

7. Weaknesses

The Peregrine Engine and Small Numbers

The main weaknesses of the Whirlwind were its Peregrine engine and its small numbers, because the Peregrine was unreliable, difficult to maintain, and no longer in production by 1941, and only 114 Whirlwinds were built, which meant that it could never have a major effect on the war. The Whirlwind was a good aircraft with a bad engine, and its engine was the reason why it was built in small numbers and why it was retired early. The Whirlwind was also vulnerable at high altitude, where its performance fell off, and where it was less manoeuvrable than the Spitfire and the Bf 109. These were weaknesses that could not be overcome, and they were the reasons why the Whirlwind was replaced by the Typhoon and the Mosquito, which were better aircraft with better engines.

A Design Overtaken by Events

The Whirlwind was a design that was overtaken by events, because by the time it entered service in 1940, the Spitfire and the Hurricane were already in mass production, and the Mosquito, a twin-engine fighter-bomber with Merlin engines, was already being designed. The Whirlwind was a good aircraft, but it was not as good as the Mosquito, which was faster, more versatile, and built in larger numbers, and it was not needed as a day fighter, because the Spitfire was better. The Whirlwind was a fighter that arrived too late and in too small numbers, and that was superseded by better aircraft before it could prove itself. Its story is a reminder that a good design is not enough, and that timing and production are as important as performance.

8. Comparison with Rivals

Against the Mosquito

The Whirlwind is often compared with the de Havilland Mosquito, the twin-engine fighter-bomber that followed it, and the Mosquito was a better aircraft, because it was faster, with a top speed of more than 600 kilometres per hour, it had a longer range, and it was built in larger numbers, more than 7,000. The Mosquito used Merlin engines, which were reliable and in mass production, while the Whirlwind used Peregrine engines, which were unreliable and out of production. The Mosquito was a versatile aircraft, used as a fighter, a bomber, and a reconnaissance aircraft, while the Whirlwind was used mainly as a fighter-bomber. The Mosquito was the aircraft that the Whirlwind should have been, and it showed how a twin-engine fighter-bomber could be a success if it had the right engines and was built in large numbers.

Against the Bf 110

The Whirlwind is also compared with the German Messerschmitt Bf 110, a twin-engine heavy fighter that served in the Battle of Britain and in the Mediterranean, and the Whirlwind was a better fighter, because it was faster, more manoeuvrable, and better armed, with four cannon against the Bf 110’s two cannon and four machine guns. The Bf 110 was a larger, heavier aircraft, with a crew of two or three, and it was vulnerable to single-engine fighters, while the Whirlwind was a single-seat fighter that could hold its own against the Bf 109 at low altitude. The Whirlwind was a better heavy fighter than the Bf 110, but it was built in much smaller numbers, and it did not have the same effect on the war. The comparison shows that the Whirlwind was a good design, but that it was not built in sufficient numbers to matter.

9. Legacy

The First Cannon Fighter

The legacy of the Whirlwind is that it was the first British fighter to be armed with four 20-millimetre cannon, and that its cannon armament became the standard for British fighters, from the Typhoon and the Tempest to the modern jet fighters. The Whirlwind showed that a cannon-armed fighter could destroy a bomber with a short burst, and that it was more effective than a machine-gun fighter, and it influenced the design of every British fighter that followed. The Whirlwind is also remembered as one of the most elegant fighters of the war, a sleek, fast aircraft that was loved by its pilots, and that is still admired by aviation enthusiasts. Its legacy is the cannon fighter itself, a type that dominated the skies for the next forty years.

No Survivors and the Replica Project

No complete Whirlwind survives today, because the last aircraft were scrapped in 1944, and only parts remain, in museums and in private collections. A project is under way in Britain to build a flying replica of the Whirlwind, using original parts and new construction, and it is hoped that the replica will fly in the 2020s. The Whirlwind is remembered by its pilots and by aviation historians as a promising design that was let down by its engines and by the decision to build it in small numbers, and as a fighter that deserved better. Its story is a reminder that the history of aviation is not only about the aircraft that were built in large numbers, but about the ones that were ahead of their time.

Frequently Asked Questions

What is the Westland Whirlwind?
The Westland Whirlwind is a British twin-engine heavy fighter of the Second World War, armed with four 20-millimetre Hispano cannon, built by Westland Aircraft at Yeovil. Only 114 were built.

When did the Whirlwind first fly?
The first prototype flew on 11 October 1938, and the type entered service with No. 263 Squadron in June 1940.

What was its main armament?
Four 20-millimetre Hispano Mk I cannon in the nose, with 240 rounds per gun, plus two 250-pound or 500-pound bombs in the fighter-bomber role.

Why were so few built?
Its Rolls-Royce Peregrine engines were unreliable and went out of production, and priority was given to the Spitfire, the Hurricane, and later the Mosquito.

Which squadrons flew the Whirlwind?
No. 263 Squadron and No. 137 Squadron were the only two squadrons to operate the type, flying fighter-bomber missions over France and Belgium from 1940 to 1943.

Does any Whirlwind survive today?
No complete Whirlwind survives. The last aircraft were scrapped in 1944, though a project is under way in Britain to build a flying replica.

Sources

• The Imperial War Museum, Westland Whirlwind collection
• The Royal Air Force Museum, Hendon, Whirlwind exhibits
• Victor Bingham, Whirlwind: The Westland Whirlwind Fighter
• William Green, Warplanes of the Second World War: Fighters, Volume 2
• The National Archives, Kew, Air Ministry records on the Whirlwind
• The Westland Aircraft Archive, Yeovil, design records