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Composite & parasite aircraft.

The US Navy's Sparrowhawks

par Philippe Ballarini
translation Mike Leveillard

In the thirties, competition still reigned between the airplane and the dirigible. The dirigible had the endurance advantage over the "heavier than air" machine, but it was handicapped by its limited maneuverability, and its vulnerability. None the less, following the Treaty of Versailles in 1918, the Allied recalling the air raids over Great Britain by the German dirigibles, they adapted the Zeppelin technology, and in the USA, the mark Goodyear-Zeppelin was created.

Facing financial difficulties during the thirties, the United States refused to embraced a full utilization of the expensive dirigibles, so it became the US Navy's mission to developed the technology and usage doctrine for the dirigibles. Aware of the vulnerability of these vessels, but taking into consideration its usefulness for observation, the US Navy rapidly abandoned the idea to use the dirigibles for offensive purposes, but to use them instead for aerial reconnaissance over the immense Pacific Ocean.

To transform a dirigible into a military craft useable in combat was not an easy task. The German Zeppelin crews had paid a heavy price in casualties during the big war, and although the American dirigibles unlike their German counterpart would not be inflated with highly combustible hydrogen, but with helium inert gas, they would still be very vulnerable.

A hangar was even provided inside the dirigibles. The protecting airplanes were loaded through an opening in the form of a T under the dirigible's envelope, and suspended by a "trapeze". This was the method by which the airplanes were released one by one, and recovered in the same fashion. After miscellaneous tests, the Curtiss F9C "Sparrowhawks" was retained as the "heavier than air" machine embarked aboard the dirigibles. The pilots had first been trained on the Consolidated N2Y two-seater for the delicate maneuvers of launching and hooking back up. At first, the "Sparrowhawks" were equipped with a classical landing gear which was soon removed and replaced with a supplementary fuel tank, which could likewise be used for additional floatation in case of ditching.

The first tests of launching-recovering were made under the Los Angeles on the 17th of October 1931. In 1932, six "Sparrowhawks" were assigned to the Akron. Its hangar permitted to transport four airplanes, plus one that could be suspended under the trapeze. In wartime, four trapezes would be installed under the dirigibles holding the suspended protecting airplanes. This configuration would provide rapid intervention.

The arrival of the first crews provoked heated discussions as to the best method of utilization. The pilots argued that the dirigibles would be vulnerable in case of attack by enemy aircraft catapulted by naval vessels, and therefore they should be the ones performing the reconnaissance missions with the dirigibles staying at a distance serving only as a "flying aircraft carrier".

Of course the officers and crew of the Akron did not subscribe to this theory; it was indeed the role of the dirigible to perform the reconnaissance missions, with the airplanes ensuring its aerial protection.

The only missions performed by the Akron took place without any embarked airplanes, and therefore the debate remained unsolved. The Akron met its tragic end as a result of a storm off the California coast in April 1933, and the Macon sustained fatal damages in February 1935.

Due to the fate of the Macon, it was the end of the great rigid American balloon era, and it was also the end of the dirigibles "aircraft carrier" experience. For some looking back at history, a question will remain unanswered: "what if" the Akron and the Macon had been in the Hawaii sector on December 7, 1941? 

Aérostories, 2001.

[ Short Mayo ]

Artist's vision. For the cover of "La Science et la Vie" magazine of January 1934, the artist had interpreted his own concept for the recovery mode by the ZR1 "Los Angeles" of a patrolling airplane. The takeoff concept from the ZR2 (the future "Akron") is closer to reality, but we see the airplane launched directly out of its hangar via a ramp, without any doubts more acrobatic than the spectacular reality.

Author's collection.                     Click

October 1931: A Vought UO-1 coming in for hook up to the trapeze of the Los Angeles.

DR  via "L'Illustration"                        Click

The Akron over Manhattan: in 1931, it was the world's largest dirigible. Length: 240 meters. Diameter: 48 meters. Volume: 208,000 cubic meters. Equipped with machineguns, it had a range of over 20,000 kilometers at 74 kilometers per hour cruising speed. On the enlarged document, two Sparrowhawks can be seen under the airship, including one approaching the trapeze located aft of the ventral opening.

US Navy Archives                Click

A Curtiss F9-C Sparrowhawk suspended to its trapeze under the Akron.

Archives US Navy                Click

Launching and hook up maneuvers were not easy to perform. The Sparrowhawks pilots were know as acrobats, as depicted by the marking on the fuselage side of their airplanes.