Finland decided to develop an indigenously built fighter that had better performance than the license-built D. XXI prior to the Winter War, but that conflict forced any such efforts to be postponed. Development began in earnest after the end of the Winter War and the first flight was on 23 December 1941. Not surprisingly for a first effort the Mysrsky (Tempest) suffered from many teething problems that included wing failure in a dive and compression problems that resulted in the port elevator being torn off in a dive. A number of structural modifications had to be made to aircraft on the production line that further delayed its introduction into service. The three pre-production aircraft were referred to as the I series and the remaining 47 aircraft on order comprised the II series. 14 of these were completed by the end of July 1944 and another 16 by the Armistice on 4 September with production being completed by 30 December. An additional batch of ten had been ordered as Myrsky IIIs in early 1944, but this was cancelled after the Armistice. Fifty were built in two production variants by Valtion Lentokonetehdas, the state aeronautical industry founded back in 1928.

A Myrsky II 26 HLeLv (Fighter Group) Finnish Air Force - Kemi Finland 1944

The project, entrusted to E. Wageluis, the technical director, was launched in 1941, and appeared in the form of a prototype the following year. It was a low wing monoplane with retractable rear tricycle landing gear, a wood and metal airframe and covering and a Swedish version of the Pratt & Whitney SCG-3 Twin Wasp built on license and capable of generating 1,650 hp (794 kW). The armament planned consisted of four machine guns installed in the fuselage, synchronized to fire through the propeller disc.

The first prototype was followed by three pre-series aircraft, designated Myrsky I, and together these were submitted to tests and initial evaluations which lasted for a lengthy period. In fact, there were many structural problems which the technicians had to solve before creating the definitive production version, the Myrsky II. The wings' composite covering tended to become detached under strong pressure. In addition the main landing gear proved to be dangerously weak and the joinings of the half wings showed signs of giving way, making it necessary to redesign them completely, as well as to reinforce the whole wing structure. In fact, due to these problems (to which was added a pronounced lateral instability during flight testing), all four initial aircraft were destroyed during flying accidents, and consequently, the timing of the entire production program was subject to serious delays.

All the modifications which originated from the test flights were incorporated into the production version, 46 of which were built during 1944. However, the Myrsky II went into service too late to contest the Soviet offensive against Finland. The rapid evolution of the conflict and the peace treaty stipulated in September 1944, led to a drastic change in the scenario and the Finnish fighters were employed against their ex-allies, the Germans, above all in the role of tactical support. In combat the Myrsky was not particularly successful, and moreover did not meet with the full approval of its pilots.

Prior to September 1944, a new version of the fighter had been prepared, with the aim of improving the aircraft's mediocre performance. It was designated Myrsky III and ten were put into production. However, they were never completed.

The Myrsky's performance didn't compare to the Bf 109G's and it wasn't wanted by the fighter units, especially considering all its structural problems during flight testing. Reconnaissance units were desperately short of aircraft and TLeLv 12 received some 20 aircraft before the Armistice. It flew 66 sorties before that date with no losses recorded and only a couple of Soviet fighters claimed damaged. TLeLv 16 also received 6 Myrskys before the Armistice, but wasn't yet operational when it took effect. TLeLv 12 flew reconnaissance missions against the Germans in Lapland, but no combat resulted, with only one Myrsky being lost in a landing accident. 

Specifications (Valtion Lentokonetehdas Myrsky)

Type: Single Seat Fighter

Design: E. Wageluis as Technical Director

Manufacturer: Valtion Lentokonetehdas (State Aeronautical Industry)

Powerplant: One 1,065 hp (794 kW) SFA-SCG-3 14-cylinder air-cooled radial engine which was a licensed version of the Pratt & Whitney R-1830 Twin Wasp.

Performance: Maximum speed 328 mph (529 km/h) at 10,690 ft (3250 m); maximum speed 292 mph (470 km/h) at sea level; initial climb to 19,685 ft (6000m) in 10 minutes.

Range: 579 miles (933 km) on internal fuel.

Weight: Empty equipped 5,479 lbs (2485 kg) with a maximum take-off weight of 7,085 lbs (3213 kg).

Dimensions: Span 36 ft 4 in (11.00 m); length 27 ft 5 in (8.35 m); height 9 ft 10 in (3.00 m); wing area 193.752 sq ft (18.00 sq m).

Armament: Four 12.7 mm (0.50 in) LKK/42 machine guns plus provisions for two 220 lbs (100 kg) bombs.

Variants: Myrsky (one prototype), Myrsky I (three pre-production), Myrsky II (47 production), Myrsky III (10 ordered but never completed).

Avionics: None.

History: First flight (prototype) 23 December 1941.