The Klemm Kl 31 was a German light touring and training aircraft developed by Klemm Flugzeugbau in the early 1930s. Designed by Robert Lusser, it represented a significant step towards more comfortable and enclosed cabin aircraft compared to Klemm's earlier open-cockpit designs, such as the widely successful Klemm Kl 25.
Development The Kl 31 was conceived as an evolution of Klemm's successful line of light aircraft, incorporating lessons learned from previous models. Hans Klemm, the founder of the company, advocated for simplicity, light construction, and efficiency, principles that were central to the Kl 31's design. The design work was led by Robert Lusser, who would later become a prominent aerospace engineer. The aircraft aimed to provide greater comfort and refinement for private pilots and touring, moving away from the purely utilitarian nature of earlier light aircraft. Its introduction occurred during a period of significant growth in private aviation in Germany, where there was an increasing demand for versatile and user-friendly aircraft.
Design The Klemm Kl 31 was a low-wing monoplane with fixed conventional landing gear. Its airframe typically consisted of a wooden structure, often covered with fabric, reflecting the common and efficient construction techniques of the era for light aircraft. A key distinguishing feature of the Kl 31 was its fully enclosed cabin, which offered improved protection from the elements for its two occupants (pilot and passenger), a substantial upgrade from the open cockpits prevalent at the time. The wings were designed for efficiency and ease of handling, characteristic of Klemm aircraft, ensuring stable flight characteristics. Various air-cooled inline piston engines were fitted, with common choices including the Argus As 8 or Hirth HM 60, providing sufficient power for touring and basic training operations.
Operational History The Kl 31 saw limited production and use. While it offered advanced features for its time, it did not achieve the widespread commercial success or production numbers of its more basic predecessor, the Kl 25. It primarily served as a private touring aircraft and was used by some flying clubs for advanced training purposes. Its influence, however, was in demonstrating the potential for more comfortable and refined light aircraft, paving the way for future designs that emphasized pilot and passenger comfort. A related and often conflated variant, the Kl 32, was a three-seater developed around the same time, sharing many fundamental design characteristics with the Kl 31.
Specifications (General Characteristics - typical for Kl 31)
- Crew: 1 (pilot)
- Capacity: 1 passenger
- Length: Approximately 7.2 meters (23 ft 7 in)
- Wingspan: Approximately 12.0 meters (39 ft 4 in)
- Height: Approximately 2.05 meters (6 ft 9 in)
- Wing Area: Approximately 19.3 square meters (208 sq ft)
- Empty Weight: Approximately 460 kg (1,014 lb)
- Max Takeoff Weight: Approximately 770 kg (1,698 lb)
- Powerplant: One Argus As 8 air-cooled inverted inline piston engine (or similar), delivering around 75 kW (100 hp)
- Maximum Speed: Approximately 180 km/h (112 mph, 97 kn)
- Cruise Speed: Approximately 155 km/h (96 mph, 84 kn)
- Range: Approximately 700 km (435 mi, 378 nmi)
- Service Ceiling: Approximately 4,500 meters (14,800 ft)