The Airplane - Jay Spenser [111]
Aviation was everywhere in the press that year thanks to Wilbur Wright’s performances in France. Completely seduced, J. V. Martin founded the Harvard Aeronautical Society and organized the Harvard-Boston Aviation Meet of 1910. Learning to fly in England soon thereafter, he returned to barnstorm in the United States and start a small aviation firm.
As America entered World War I, Martin talked his way into a government contract with the U.S. Army Engineering Division at McCook Field. A natural promoter, he pressed his idea for a miniature fighter plane capable of intercepting high-flying dirigibles. Although it was something America did not need, the Army provided experimental funding to see what he would come up with.
The result was the J. V. Martin K.III Kitten, a tiny single-seater weighing 350 pounds (160 kilograms) empty and powered by a 45-hp engine. Equipped with oxygen cylinders and provision for electrically heated flight clothing, it had several novel features that raised questions about Martin’s competence as a designer.
The first was a structurally questionable wing-strut configuration, and the second was pivoting wingtips instead of ailerons. But it was this little machine’s third distinction that would bring it into the record books, because the Kitten also featured retractable main wheels.
Mechanically actuated by a hand crank in the cockpit, this landing gear rotated up and aft to tuck the wheels into form-fitting covers along the fuselage sides. Even with the gear retracted, the bottom half of each wheel protruded into the slipstream. This arrangement allowed emergency wheels-up landings with little resultant damage.
The Douglas DC-3, Boeing B-17, Beech 18, and many other airplanes have since shared this arrangement, which reduces damage when bellying in. In some cases, it also afforded some measure of steering through individual use of the retracted wheels’ brakes.
Martin’s pride in his landing gear is evidenced by the form-fitting fairings he carefully affixed behind the wheels where they protruded into the slipstream while retracted. This aerodynamic refinement looks oddly out of place on the K.III’s otherwise crude airframe.
Completed too late for World War I, the Kitten was tested in the summer of 1919 and proved capable only of brief, ground-level hops of under 300 feet (90 meters). Even so, it remains the first U.S. land airplane to feature retractable wheels. Martin received a U.S. patent for his landing gear in 1916.2 Today the J. V. Martin K.III Kitten is preserved in the collection of the National Air and Space Museum, Smithsonian Institution.
In 1922, the Verville-Sperry R-3 and Dayton-Wright XPS-1 both flew with retractable wheels. Like the Kitten, they were experimental U.S. Army concepts. Despite this early interest, however, retractable wheels did not come into general use until the early 1930s because before then airplanes flew too slowly to justify their added weight, complexity, and maintenance requirements.
The world’s first all-metal, semi-monocoque production airplane was of course the Northrop Alpha of 1930. It seems odd that this bold airplane, which cruised at 145 mph (233 km/h), lacked retractable wheels, but Jack Northrop was reluctant to cut into his multicellular wing for fear of compromising its strength. To mitigate drag, most production Alphas at least had their fixed gear legs encased in aerodynamic fairings.
The Boeing 200 Monomail, which also flew in 1930, was similar overall but did have retractable wheels. Boeing also applied retractable gears to its Boeing 247 airline and YB-9 bomber immediately thereafter. Douglas, Martin, and other companies followed suit with their commercial and military offerings.
Almost from the outset, therefore, retractable wheels were part of the revolutionary formula that was semi-monocoque design. However, the value of this innovation was proportional