If the U.S. Navy and Goodyear gained icon status as operators of blimps in the United States, the U.S. Army was a big player in the interwar years.
U.S. Army lighter-than-air aircraft can be traced to reconnaissance balloons used during the Civil War by Thaddeus Lowe in support of the Union Army.
In 1921 the U.S. Army operated the semi-rigid Italian-built airship Roma, the largest semi-rigid design in the world at the time, with a length of 410′.
Buoyed by hydrogen, the Roma came to grief near its base at Langley Field, Virginia, in 1922 when the nose collapsed during high-speed flying, and the ensuing hydrogen fire gave the U.S. military the resolve to fill all of their future airships with nonflammable helium instead.
Ever protective of their own mission priorities, the U.S. Army and U.S. Navy agreed in that decade that the Army would pursue non-rigid or semi-rigid designs for coastal and inland patrol duties, while the U.S. Navy embarked upon its large rigid dirigible program for scouting at sea.
The Army airship program thereafter blossomed during the Roaring Twenties.
In the Depression of the 1930s, Army funding for airships declined until Army Air Corps Chief General Oscar Westover decided to end the Army’s airship program in 1936. Some of the last activity carried into 1939.
During the hey day of Army airship operations, sometimes several contractors would build designs created by the Air Service. At other times, the Army bought available existing machines.
The airships’ identities were linked to the car or gondola, which carried a serial number. The fabric balloon or envelope was not numbered, and was replaceable as needed. Produced in smaller numbers than production line aircraft, the Army’s lighter-than-air vehicles tended to be more individualized pieces of equipment.
Early captive spherical observation balloons became less stable in wind. In the late 19th Century, German designers tamed this problem with elongated gas envelopes and stabilizing fins.
Progress led to elongated powered free-flying lighter-than-air craft. The early use of hydrogen gas, with its potential for fire, is cited as a reason hydrogen-filled airships had their cars suspended away from the undersurface of the envelope for safety. When helium became the Army’s gas of choice, gondolas could be mounted close to the envelope.
The first free-flying powered airship for the U.S. Army was the so-called SC-1, for Signal Corps No. 1, built in 1908 by Thomas Baldwin. It featured a long open trusswork structure for the crew of two, a single 20-horsepower Curtiss engine, and guiding vanes.
Variations on the tethered observation balloon shapes of World War I led to the Army’s use of the United States Motorized Balloon, or USMB, by late 1922. This elongated balloon could either be used tethered or as a free-flying powered vehicle.
In 1923, the USMB (also sometimes called the MB-1 or OA-1) was loaned to the U.S. Department of Agriculture, which used the airship, fitted with an insecticide hopper, to combat a gipsy moth infestation in New Hampshire.
A French design, the ZDUS-1 (later RN-1), was received from a U.S. Navy order of 1918. It was unique for its day in having a cannon in the bow of the car and a defensive machine gun emplacement atop the envelope.
The Army’s brief foray into semi-rigid airships began with the ill-fated Roma. In 1923, another semi-rigid LTA, the RS-1, was ordered from Goodyear. Most Army machines were variations on non-rigid blimp designs.
The U.S. Army received the Goodyear TC-13 in 1933. At the time, it was the world’s largest non-rigid airship. The TC-13 and TC-14 used five-fin tail surfaces instead of the traditional four. By 1934, the modified Army TE-3 airship had an eight-fin tail array.
Not surprisingly, Army airships of the early 1920s used some of the most prevalent American aircraft powerplants of the era, the OX-5, Liberty, and Hall-Scott engines. Foreign-supplied designs sometimes used European powerplants, and later developments included radial engines.
Army blimps experimented with tasks as diverse as picking up mail from a moving train to serving as a carrier vehicle for aircraft — a concept later evolved by the Navy in its huge dirigibles.
While the Army’s observation needs were met by fixed-wing aircraft by the time of World War II, the U.S. Navy expanded its use of blimps during World War II for patrol missions.
The Army used an exhaustingly varied set of nomenclature schemes to designate its airships over the years. A detailed listing of designations and specifications can be found in “United States Military Aircraft Since 1908” by Peter M. Bowers and Gordon Swanborough.