VL Pyorremyrsky (Whirlwind)

The history of VL Pyorremyrsky (cyclone)

Finland fought the Soviet Union twice during World War II (1939-1945). The first war, known as the "Winter War", lasted from November 1939 to March 1940 and ended with the pro-Soviet Treaty of Moscow.

From June 1941 to September 1944, the two went to war again, this time during the "continuation of the war", with the Finns now supported by the Germans. During this period, the Finnish authorities invested in a locally designed, developed and produced fighter jet, later known as the VL Pyorremyrsky (or "Cyclone"/"Hurricane").

The original plan was to develop a fighter type that would make heavy use of locally available materials, especially wood. Therefore, precious metals are only used when absolutely necessary.

At this time the Finns also flew German Messerschmitt Bf 109 fighters and gained extensive combat experience with powerful and modern monoplanes.

Finnish engineers developed a wooden monospar wing unit that runs through the fuselage. A tubular steel frame provides the critical underbody of the aircraft, while on the outside, plywood skin technology is used for a smooth contoured finish. The resulting design was as elegant as any modern fighter jet of the time. A framed canopy marks the position of the cockpit amidships, and a raised dorsal swivel extends from the pilot's tail to the base of the tail fin. The rear wing is conventional, with only one vertical element, and the horizontal plane is set low.

Plywood was also used to cover the rear using the monocoque frame. The main wing aircraft are straight appendages and mounted in the forward midship. A conventional "trailing" undercarriage was used - although consideration was given to widening the rails of the main legs to address the deficiencies of the original German Bf 109 design. As a result, ground operations have been improved, as have take-off and landing maneuvers.

An available German Daimler-Benz DB 605AC 12-cylinder, liquid-cooled, inverted-V in-line piston engine producing 1,475 hp was chosen to power the airframe.

The proposed weapons mimic some of those already seen in the German Bf 109 - a hub-mounted 20mm MG 151 series automatic cannon and a pair of wing-mounted 12.7mm LKK/42 series machine guns . In addition, plans were made for a pair of underwing hardpoints to carry conventional 440-pound bombs.

On 26 November 1942, the Finnish Air Force ordered the construction of two prototypes, but commitments elsewhere in the war meant that the Tornado was forced to go through a long gestation period. Construction was very slow by wartime standards, especially compared to the pace of development in Britain, Germany and the United States. Authorities set May 1944 as the initial availability of the prototype, but that wasn't the case. After the armistice with the Soviet Union was signed on September 4, 1944, everything changed, one of the prototypes ordered was canceled and the construction of the other almost came to a standstill.

In January 1945, the aircraft was returned to work, eventually installing the DB 605 engine. The war in Europe ended in May 1945.

The Cyclone made her maiden flight on November 21, 1945, shortly after the war. The plane proved stable in controls, very agile and a good climber, but on its maiden flight it was damaged by a board that came off the nose, forcing the test pilot to land the plane he was smoking now . Thirty-four test flights followed, with a flight time of approximately 30 hours. However, demand for indigenous fighters proved to be small, funding was limited, and a postwar oversupply of Bf 109s would only completely derail the program. The Tornado was still somewhat of a Finnish design triumph, but the planes arrived too slowly and too late to be of much use in the war.

Had the Tornado been given more time and attention to eventually grow up, it would have rivaled the Soviet fighter quite well.

The prototype completed its final flight on July 22, 1947, and was terminated. The only prototype is kept in the Central Finland Aviation Museum (Tikkakoski). Performance specs include a top speed of 385 mph, a service ceiling of 37,000 feet and a rate of climb of 3,640 feet per minute.

The prototype was never equipped with the proposed weapon.

Specification

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