Niilo and Valto Karhumäki, also known as the Karhumäki brothers (Finnish: Veljekset Karhumäki), were Finnish aviation pioneers, aircraft manufacturers and airline founders.
Born in Multia, Niilo and Valto Karhumäki moved to Jyväskylä, where they founded a company called Veljekset Karhumäki in late 1924, which dealt with pilot training, public displays, aircraft maintenance and aerial photography during the 1930s. Niilo Karhumäki had completed in early Air Force reserve pilot course in Vyborg and received a pilot's license.
Niilo and Valto Karhumäki started in autumn 1924 the construction of an airplane at their home. The work also involved Emil Kankaanpää and Hope Hovinen. The machine was given the name Bear 1. The brothers built in the 1920s of four aircraft: Bear 1 Bear 2 Bear 3 and Tern. Construction was initially something of a hobby, but soon expanded into a versatile aviation business. The activity then changed and became more businesslike, and the brothers built a small aircraft factory at Keljo.
They formed a company called Veljekset Karhumäki Oy (Karhumäki Brothers Ltd.) and their operations comprised aircraft construction, repairs and maintenance, pilot training, taxi flying, public displays, and aerial photography and air photography. In addition to its own aircraft, the company used de Havilland Moths, which it built under license, and Cessna monoplanes during the 1930s.
The Finnish Air Force soon required their assistance, and as there was no airfield at Keljo, which made it necessary for their aircraft to take-off from either water or ice, the factory was moved in 1939 to Kuorevesi, where an airfield was available (presently known as Halli Airport), as well as a lake for seaplane or skiplane operations. This factory was further expanded during World War II, when the Valtion Lentokonetehdas (State Aircraft Factory) set up their dispersed location 2VL factory there (in 1951 Valtion became Valmet, into which the Karhumäki factory merged in 1963).
In the 1930s the Viri single-seat light monoplane was built, design by Finnish Club of Aeronautical Engineers. In 1939-1941 a new factory was built, near Halli airfield, where trainers for Finnish Air Force were built. The Karhumäki brothers designed the Karhumäki Karhu 48B light airplane, of which a small number was produced during the 1950s.
The number of workmen employed has varied between 120 and 250, and the factory was able to build all aircraft parts except for engines and instruments. After WW II an aircraft-radio service department was added to the plant. During its lifetime the company operated at least 16 aircraft, and by 1950 about 400 aircraft had either been built, repaired or overhauled, the majority belonging to the Finnish AF. About 60,000 passengers have been carried and over 100 students had received pilot training.
In 1950, Karhumäki Airways was founded by Veljekset Karhumäki, an airline initially offering scheduled passenger flights on mostly domestic routes. In 1963, Aero O/Y (today's Finnair) acquired the majority of its stake, and in 1996 Karair (as it was known by then) was fully absorbed into Finnair.
Successful air transport and repair activities were discontinued due to tougher competition in 1963. Aerial Photography and the Ministry of Agriculture and Forestry flights continued. Karhumäki developed the four-seat cabin monoplane Karhu 48 in collaboration with Valtion. The development team included Uuno Karhumäki, Matti Hahka and August Puukko from Karhumäki and Torolf Eklund, Johannes Joensuu, Oiva Lounivuo, Toivo Mäntysalo, Karl Konrad Wessman, Paavo Paitula, Olavi Raitio and Aaretti Nieminen from Valtion, Nieminen being appointed team leader.
Two prototypes were completed, the first, registered OH-VKK and named Nalle, was flown for the first time by Uuno Karhumäki (the youngest of the Karhumäki brothers) on July 20, 1948. The second, which flew later that year, was registered OH-VKL and named Tavi. Planned production did not materialize by the import of cheap military surplus aircraft, and subsequently both aircraft were used by Karhumäki.
The brothers have been honoured with a monument called Lentäjäveljestenaukio (which translates as "Pilot Brothers Square") in Halli.