The Valentin Kiwi is a specialized single-seat sailplane developed in Germany, derived from the Mistral-C design. It was engineered to meet the 1970s Club Class rules and was among the first glassfibre-reinforced plastic (GRP) designs created for this category. The aircraft's primary significance lies in its exceptionally low empty weight, which was approximately 205 kg in its unpowered configuration—significantly lighter than contemporaries such as the Astir, which weighed roughly 260 kg.
The aircraft's development is tied to several small German firms. The base airframe was designed by Manfred Strauber and Hartmut Frommhold, along with a team including Alois Fries and Horst, operating under entities such as Ingenieurbüro Strauber-Frommhold (ISF) and Mistral Flugzeugbau. The Kiwi first flew on October 21, 1976. Production began with ISF, which built at least 25 units by early 1980. Manufacturing continued through a period of re-firming to Mistral-Flugzeugbau until mid-1981, and further examples were produced by Valentin Flugzeugbau GmbH in Haßfurt. While the exact total production number is undocumented, it is characterized as a very small series consisting of dozens of aircraft at most.
Technical versatility was introduced via the "Kiwi-TOP" (or Kiwi S) variant. Developed by composite expert Thomas Fischer, this modification featured a semi-retractable, top-mounted self-launch engine unit. The power plant was a small 3-cylinder radial engine manufactured by König, producing 18 kW (approximately 24 hp). This system allowed the glider to operate independently of winches or aerotows while maintaining a high glide ratio; the base aircraft achieved a ratio of approximately 38:1, which decreased to roughly 35:1 when the TOP unit was installed.
In civil service, the Kiwi was operated primarily by private owners and gliding clubs in Germany and the Netherlands. It was praised for its forgiving and good-natured handling characteristics. Performance specifications include a wingspan of 15 meters, a length of approximately 6.73 to 6.8 meters, and a maximum speed reaching between 240 and 250 km/h. The maximum takeoff weight (MTOW) ranged from 350 to 400 kg depending on the configuration.
Valentin Flugzeugbau GmbH ceased operations by the late 1990s, and the company is now defunct. Despite the lack of institutional museum preservation, several airframes remain airworthy in private hands, including registered examples such as D-KBEI and D-4790. The aircraft remains a technical curiosity for its early adoption of composite materials and retrofittable self-launch systems.