Martin Kitten K-III
The Martin K-III Kitten was designed in 1917 by James V. Martin for the U.S. Army as a high-altitude fighter. Of wood and fabric construction, it was fitted with oxygen tanks behind the pilot's seat and had provisions for electrically heating the pilot's clothing. Unfinished at the war's end, Martin shifted his goals for the K-III toward the post-war civilian light airplane market. About sixty test flights were made in the summer of 1919, but with little success.
Despite its failure as a practical airplane, the K-III is generally recognised as the first airplane in the United States to be equipped with an in-flight-operated retracting landing gear. The "K-strut" wing truss was intended to equalize the moments and forces acting on the wing support, as well as to save weight and to reduce drag.
Engine: one two-cylinder 45-horsepower ABC Gnat
Wingspan: 6.3 m (20 ft 8 in)
Length: 4.1 m (13 ft 5 in)
Height: 2.3 m (7 ft 6 in)
Weight: Empty, 159 kg (350 lb)
Undercarriage: retract tail