August Haefeli (Häfeli) (29 January 1887 - 5 June 1960) was a Swiss aircraft designer. Under his direction, 185 aircraft were built, and some were flown by such notable airmen as Walter Mittelholzer, Oskar Bider, Robert Ackermann, and Max Cartier.[1] Haefeli was born in 1887, in Leuzigen, to Emil Haefeli and Marie Haefeli-Bärtschi. After moving to Mümliswil-Ramiswil, he attended school in Balsthal, where his father served as a clerk.[2] He then studied mechanical engineering at the Burgdorf technical center.[3]
From 1912 to 1914 he worked for Henri Farman in Paris, and then in 1914 he was hired on as an engineer at Aerowerke Gustav Otto (Otto Flugmaschinenfabrik in Berlin.[4] From 1915 to 1929 he was chief designer and head of the aircraft construction department at the Eidgenoessische Konstruktionswerkstaette in Thun.[5] Under his leadership, the Häfeli DH-1, Häfeli DH-2, Häfeli DH-3, Häfeli DH-4, Häfeli DH-5 and Militär-Apparat MA-7[6] were developed. From 1929 to 1947 he was an engineer in Oberdiessbach at Maschinenfabrik Adolf Vogt and in Villeneuve at Construction Mécanique. He then worked as a freelance engineer in Thun until his death in 1960.[7] A memorial stone for Haefeli was erected at the Balsthal baths in Switzerland on June 7, 2019.[8]