VL Kotka (Eagle) is a Finnish two-seat maritime patrol biplane and light bomber. Six Kotkas were built in two series and used by the Finnish Air Force from 1930 to 1945. They were originally equipped with floats, but were given wheels in 1938.
Development[]
The Kotka was designed as a lighter, cheaper alternative to the Blackburn Ripon. The design was based on the British Westland Wapiti and the VL Sääski, and mainly wooden. The fuselage was rather wide to allow the pilot and the observer to move in the cockpit, but this limited the view from the cockpit. The 420 hp Bristol Jupiter 9Ab engine was chosen for the prototype. The building of the prototype was rushed, so it would be ready before winter. Many parts were made even before the aircraft was entirely designed, which resulted in problems during the assembly and delayed the first flight, which was completed on 1 October 1930. The prototype, KA-144, suffered an engine failure and had to land prematurely.
The FAF ordered five Kotkas in late December 1930. Different engines and airfoils were tested on them, and the fuselage was lengthened by half a metre. The deliveries of the engines were delayed, and the aircraft weren't completed before October 1931. KA-145, like KA-144, was also given an underpowered Bristol Jupiter engine, KA-146 and KA-147 a 575 hp Pratt & Whitney R-1690-B Hornet, and KA-147 and KA-149 a 575 hp Wright R-1820-E Cyclone engine.
The final Kotka, KA-149, was fitted with a new RAF 28 airfoil from the Ripon, a Townend ring and covered wheels. However, the Townend ring and the wheel covers were later removed.
KA-149 on skis at Tikkakoski in March 1940.
A third Kotka series with major modifications, most importantly a steel tube fuselage, was planned in 1932 but never built.
Service[]
The prototype KA-144 was handed over to the FAF in November 1930. Its handling and glide ratio were considered to be poor, the flight instruments were placed inpractically, and its performance was modest. Nevertheless, the Kotka was regarded as satisfactory.
Of the three different engines, the Wright Cyclone proved to be the best, and it was also installed in KA-146 and KA-147 from March 1934. KA-149, with its RAF 28 airfoil, clearly had the best flying characteristics of the Kotkas. The FAF considered buying a few more Kotkas in November 1931, but never did so.
From 1930 to 1938 Kotkas served as coastal reconnaissance floatplanes. From January 1938 onwards they were relegated to liaison duties, and in December 1938 they were permanently fitted with wheels. During World War II Kotkas were used as trainers, target tugs and "station hacks". Three of the six aircraft (KA-144, KA-145 and KA-147) were lost in accidents with one fatality, the passenger of KA-145. KA-146 was intentionally burned in March 1940 in Värtsilä, when it could not be flown away from the area to be handed over to the Soviet Union. KA-148 and KA-149 were retired in 1945, with KA-148 making the type's last flight on 26 February 1945. The type flew for a total of 7,106 hours in FAF service.
Surviving example[]
- The wreck of KA-147 is at the Päijänne Tavastia Aviation Museum in Asikkala. It crashed in Vesivehmaa in July 1943 when its target-towing cable hooked a tree.
Variants[]
- VL E.30 Kotka (KA-144 to KA-148) - The original version.
- VL E.31 Kotka (KA-149) - Significant modifications, such as a new airfoil.
Specifications (KA-147, land aircraft)[]
- Crew: 2
- Length: 10,25 m
- Wingspan: 12,70 m
- Height: 3,80 m
- Wing area: 50,0 m²
- Empty weight: 1,380 kg
- Take-off weight: 2,380 kg
- Powerplant: 1 × Wright R-1820-E Cyclone nine-cylinder radial; 429 kW (575 hv)
- Propeller: Two-bladed Hamilton Standard DWG No 35 B2-2
- Maximum speed: 225 km/h (at 3,000 m)
- Range: 650 km
- Service ceiling: 5,600 m
- Climb to 2,000 m: ca. 11 min
- Armament:
- 7,7 mm Vickers machine gun on left side of the fuselage, 500 rounds
- 2 × 7,7 mm Lewis guns in the rear cockpit, 8 × 97 rounds
- 3 × 100 kg or 6 × 50 kg bombs