The Thulin K was a Swedish naval fighter aircraft in the 1910s. It was operated by both the Swedish and Dutch armed forces.

Dr. Enoch Thulin, of AB Thulinverken, designed the Thulin K in December 1916. It was a shoulder-wing monoplane of wooden construction employing wing warping for lateral control. Powered by a 90 hp Thulin A Gnôme derived rotary engine, it could be configured as a single seat or tandem seat aircraft.^[1]

After initial flights in early 1917, the Swedish Army purchased two of the single seat K versions. However, it was more successful as an export plane; the Royal Netherlands Navy bought twelve Ks between 1917 and 1918 and three Thulin KAs. Both types were delivered without armament but the Dutch Navy fitted theirs with machine guns firing through the propeller arc and also experimented with 20 mm Madson cannons.^[1]

The aircraft's performance was good - Thulin himself broke the Swedish altitude record in it in 1919. However, on 14 May 1919^[2] Thulin's own Thulin K lost an aileron in a steep dive, crashing and killing him. The rest of the Thulin Ks were written off in 1920 and the Thulin KAs were withdrawn in 1922.^{[citation needed]}

Thulin K

Single-seat production variant, two built for Flygcompaniet and twelve for the Dutch Navy.^[1]

Thulin KA

Two-seat version for the Royal Netherlands Navy, three built.^[1]

 Sweden

• Swedish Air Force

 Netherlands

Data from Green 1994^[1]

General characteristics

• Crew: 1
• Length: 6.50 m (21 ft 4 in)
• Wingspan: 9.10 m (29 ft 10.25 in)
• Height: 2.55 m (8 ft 4 in)
• Wing area: 14.00 m² (150.7 sq ft)
• Gross weight: 520 kg (1,146 lb)
• Powerplant: 1 × Thulin A rotary engine (license-made Le Rhône 9C) , 67 kW (90 hp)

Performance

• Maximum speed: 150 km/h (93 mph, 81 kn) at sea level
• Service ceiling: 5,485 m (18,000 ft)

Armament

• 1 x synchronised machine gun
• 1 x 20 mm Madsen cannon