Heinonen HK-1

HK-1
Role	Sport aircraft
National origin	Finland
Designer	Juhani Heinonen
First flight	August 1954
Status	Sole example in the Finnish Aviation Museum
Number built	1

The Heinonen HK-1 Keltiäinen^[1] is a Finnish single-seat, single-engined sport aircraft of the 1950s. Only a single example was built, which was used by its designer to set a class distance record in 1957 that stood for 18 years before being beaten.

Design and development

Juhani Heinonen, an aeronautical engineer who had previously worked for the Valmet aircraft factory at Tampere, and then for Finnair, designed a single-seat, single engined aerobatic sport aircraft, the Heinonen HK-1. It was a low winged monoplane of all-wooden construction, powered by a Walter Mikron air-cooled inline engine rated at 48 kilowatts (65 hp) driving a two-bladed propeller. Split flaps were fitted to the wings, while the aircraft had a fixed tailwheel undercarriage, with a steerable tailwheel but no brakes. The pilot sat under a sliding perspex canopy.^[2][3] A prototype was built at the glider school at Jämi,^[4] first flying in August 1954.^[2]

Operational history

The HK-1 was displayed at the 1955^[5] and 1957 Ypenburg airshows.^[6] On 10 July 1957, Heinonen flew the HK-1, fitted with an additional ventral fuel tank,^[3] non-stop between Madrid, Spain and Turku in Finland, covering a distance of 2,844 kilometres (1,767 mi) in 17 hours 1 minute, setting a class world distance record for aircraft of less than 500 kilograms (1,100 lb) take-off weight.^[7][8] For this flight, Heinonen was awarded a Louis Blériot medal by the Fédération Aéronautique Internationale.^[9] This record was not broken until 2 July 1975.^[10]

The aircraft is now preserved at the Finnish Aviation Museum near Helsinki Airport.^[1]

Specifications

Data from Jane's All The World's Aircraft 1956–57^[2]

General characteristics

• Crew: 1
• Length: 5.35 m (17 ft 7 in)
• Wingspan: 6.86 m (22 ft 6 in)
• Height: 2.08 m (6 ft 10 in)
• Wing area: 7.0 m² (75 sq ft)
• Aspect ratio: 6.8:1
• Empty weight: 250 kg (551 lb)
• Gross weight: 400 kg (882 lb)
• Fuel capacity: 58 L (13 imp gal; 15 US gal)
• Powerplant: 1 × Walter Mikron III air-cooled inverted four-cylinder inline engine, 48 kW (65 hp)

Performance

• Maximum speed: 215 km/h (134 mph; 116 kn) at sea level
• Cruising speed: 185 km/h (115 mph; 100 kn)
• Range: 700 km (435 mi; 378 nmi)
• Rate of climb: 4.5 m/s (880 ft/min)
• Take-off distance to 15.25 m (50 ft): 240 m (790 ft)
• Landing distance from 15.25 m (50 ft): 350 metres (1,150 ft)

See also

Aircraft of comparable role, configuration and era

• PIK-11

Notes

1. "Heinonen HK-1 Keltiäinen" (in Finnish). Suomen Ilmailumuseo. Retrieved 12 July 2014.
2. Bridgman 1956, p. 124.
3. Best-Devereux Flight 17 January 1958, p. 85.
4. Flight 17 June 1955, p. 846.
5. Flight 10 June 1955, p. 783.
6. Flight 21 June 1957, p. 829.
7. "FAI Record ID #1894". Fédération Aéronautique Internationale. Retrieved 12 July 2014.
8. Taylor 1962, p. 30.
9. Flight 30 May 1958, p. 727.
10. "Powered Aeroplanes World Records: C1a - Landplanes:take off weight 300 to 500 kg: Distance". Fédération Aéronautique Internationale. Retrieved 12 July 2014.

References

• Best-Devereaux, H. (17 January 1958). "Ultra-Light Pot Pourri". Flight. Vol. 73 no. 2556. pp. 85–86.
• Bridgman, Leonard (1956). Jane's All The World's Aircraft 1956–57. New York: The McGraw-Hill Book Company, Inc.
• "Club and Gliding News". Flight. Vol. 67 no. 2421. 17 June 1955. p. 846.
• "From All Quarters: F.A.I. Awards". Flight. Vol. 73 no. 2575. 30 May 1958. p. 727.
• "Ilsy 6: Brute Force and Elegance at the Ypenburg Show". Flight. Vol. 71 no. 2526. 21 June 1957. pp. 827–830.
• Taylor, John W. R. (1962). Jane's All The World's Aircraft 1962–63. London: Sampson Low, Marston & Company, Ltd.
• "Ypenburg Impressions". Flight. Vol. 67 no. 2420. 10 June 1955. p. 783.