VL Sääski (Mosquito) is a Finnish two-seat primary training and general aviation biplane designed by Osakeyhtiö Sääski (Sääski Ltd.) and built by Valtion lentokonetehdas (VL, State Aircraft Factory). It saw extensive military and civilian use from late 1920s to 1940s. The Finnish Air Force used it as a trainer and a liaison aicraft from 1928 to 1942. The Sääski was the first truly Finnish aircraft to be produced in series, as the IVL A.22 Hansa was a licensed copy.
In fall 1927 high-ranking members of Ilmailuvoimien lentokonetehdas (IVL, Aircraft factory of the Air Force, later known as Valtion lentokonetehdas) founded a ten-person team to create an indigenous aircraft. The Sääski was seen as a better alternative to the de Havilland DH.60 Moth the Suomen Ilmapuolustusliitto (Finnish Air Defence Union) was interested in buying. The building of the Sääski prototype began at Kruunuhaka in late 1927 even before decent plans had been made. The prototype was known as Nyrkki-Sääski (Fist-Mosquito) and received the registration code K-SASA. It made its first flight on 27 February 1928. It was sold to the Finnish Air Force in summer 1928, becoming SÄ-95.
The Sääski team was converted into a limited company named Osakeyhtiö Sääski in October 1928. Gunnar Semenius redesigned the Nyrkki-Sääski, creating the Sääski II. Osakeyhtiö Sääski decided not to found its own aircraft factory, and instead ordered a Sääski II prototype (K-SASB, later OH-ASB) from Valtion lentokonetehdas (VL) in November 1928, and four more in May 1929. A more advanced Sääski variant with an enclosed cabin, Sääski III, was planned but never built.
The FAF ordered ten Sääski IIs in November 1929, although it had not been satisfied with the Nyrkki-Sääski. The first one, SÄ-117, was delivered on 8 March 1930 and the tenth (SÄ-126) on 17 June. Two more series were reluctantly ordered in October 1930 and April 1931, respectively. The orders were placed mainly due to the FAF's shortage of aircraft, and to give the factory something to do while it was struggling with the production of the Blackburn Ripon. The third series consisted of improved Sääski IIAs with larger wings.
The FAF modified one Sääski II (SÄ-120) into the Sääski IV with significant changes, such as new airfoil and ailerons in the upper wings in August 1935.
Osakeyhtiö Sääski's OH-ASB was destroyed in an accident in Sweden in September 1931. The company went bankrupt on 18 April 1935 due to its debts to VL for building OH-ASB.
The FAF criticized the Sääski for being slow and having poor glide ratio, climb and controls in slow speeds. Nevertheless it used its 33 Sääskis extensively, although partially due to the general shortage of aircraft. The attrition was heavy, and by 1938 only 19 were left. Some retired examples had been overhauled seven times. 17 were left when the Winter War began on 30 November 1939. A year later the FAF was down to 15 Sääskis, but only 13 engines, and three planes were retired. The final Sääskis were removed from the FAF inventory in January 1943, but their use had probably ended already in September 1942. The type flew for some 38,000 hours.
Norwegian female pilot Gidsken Jakobsen bought one Sääski II floatplane in 1929, naming it Måsen (Gull). It cost 19,000 Norwegian kroner, equal to her nine-year salary.
The last flying Sääski was OH-VIA (previously K-SILE and OH-ILF) that was retired in February 1954 and burned in a bonfire in the midsummer.
- K-SILE crashed during an air show at Perho on 22 June 1930, killing two spectators.
- The FAF's SÄ-119 struck trees at Kuolemajärvi on 3 July 1930, killing the pilot. The passenger survived.
- The FAF's SÄ-139 crashed at Sortavala on 11 October 1938, killing the two pilots.
- Sääski IIA SÄ-122 is at the Finnish Aviation Museum in Vantaa, Finland.
- Sääski II LK-1 of the Sea Guard is at the Maritime Centre Vellamo in Kotka, Finland.
- A replica of Gidsken Jakobsen's Sääski II is at the Norwegian Aviation Museum in Bodø, Norway.
The Sääski is mainly made out of pine wood, with fabric and plywood covering.
- Nyrkki-Sääski (K-SASA) – The hand-made prototype.
- Sääski II – Larger wings and longer fuselage.
- Sääski IIA – Larger wings.
- Sääski III – Enclosed cockpit. Not built.
- Sääski IV (SÄ-120) – New airfoil and ailerons in the upper wings.
- Crew: 2
- Length: 7,40 m (24 ft 3 in)
- Wingspan: 9,90 m (32 ft 6 in)
- Height: 2,40 m (7 ft 10 in)
- Wing area: 24 m² (258 ft²)
- Empty weight: 563 kg (1,241 lbs)
- Gross weight: 860 kg (1,896 lbs) on wheels, 964 kg (2,125 lbs) on floats
- Powerplant: 1 × Siemens-Halske Sh 12 9-cylinder radial; 120 hp (89 kW)
- Maximum speed: 150 km/h (93 mph) on wheels, 138 km/h (86 mph) on floats
- Cruising speed: 125 km/h (78 mph) on wheels, 100 km/h (62 mph) on floats
- Endurance: 3,5 h
- Service ceiling: 4,500 m (14,764 ft)
- Climb to 2,000 m: 20 min