During the 1920s and 1930s, the U.S. Navy began experimenting with rigid airships as military assets. Following the end of World War I, the Navy envisioned the rigid airship as an effective and efficient means of patrolling and monitoring the large amounts of ocean that border the United States to the East and the West. They were seen as a cost-effective alternative to traditional Navy ships capable of patrolling a greater amount of distance. Additionally, if these airships could carry fighters, then their ability to scout the coasts of the United States would increase significantly. This resulted in the late 1920s to the designing and building of two massive rigid airships, the USS Akron, and the USS Macon. Both were designed with internal hangars that could carry small scout fighter aircraft, marking the first time that a rigid airship had been designed from the outset to carry aircraft. The Akron would fly for the first time in late 1931, followed by the Macon in April 1933. The fighter aircraft that these aircraft would carry was to be the F9C-2 Sparrowhawk.
The Development of the F9C-2 Sparrowhawk:
The F9C-2 Sparrowhawk was designed originally to meet a May 1930 specification for a small carrier-borne fighter aircraft. It would be rejected as a carrier-borne aircraft, but a prototype was ordered, this receiving the designation XF9C-1. The prototype was delivered to the U.S Navy test centre at Anacostia in March of 1931. A small biplane measuring only approximately 20feet in length, the XF9C-1 had a crew of one, was armed with two Browning .30-inch machine guns and power came from a 421hp Wright R-975-C engine. During testing it was found to be a reasonably good aircraft to fly, although visibility over the top wing was poor. Furthermore, it was found to have a high wing and power loadings.
The XF9C-1 found its niche as a “hook-on” aircraft for use on the airships being operated by the U.S. Navy. Fitted with a skyhook, it underwent trials at Lakehurst, New Jersey, in the fall of 1931. On October 27, the XF9C-1 made its first successful hook on, attaching itself to the trapeze of the USS Los Angeles airship.
Curtiss continued developing the XF9C-1 on a private venture and this was helped when in July 1931 the Navy issued a specification to Curtis calling for an improved version of the XF9C-1. Within 90 days Curtiss had the XF9C-2 ready to go. The XF9C-2 differed from the XF9C-1 in a few keyways:
The XF9C-2 was powered by a Wright 438hp R-975-E3 engine.
The upper wing was raised 4 inches to improve forward visibility,
The propellor diameter was increased.
A steerable tail wheel added.
The landing gear was changed to a tripod type.
The balanced rudder was deleted while the vertical stabilizer was lengthened by 8 inches.
Overall, the XF9C-2 was 250lbs heavier than its predecessor. Provisions were also made to delete the landing gear and replace it with a 30-gallon auxiliary fuel tank that would further increase the range of the aircraft. In October 1931, the Navy placed an order for six production units, while in November they also bought the prototype XF9C-2 from Curtiss.
Operational Use and Challenges:
The F9C-2 was not the most ideal aircraft for the job of a skyhook plane, lacking in key areas such as speed and range, but it was small and the best of the few options the Navy had. The first production version of the F9C-2 undertook its maiden flight on 14 April 1932 and after a period of trials by the Navy made its first landing on the USS Akron’s trapeze on June 29, 1932. During hook on tests the skyhook attached to the F9C-2 caused directional instability and as such three inches were added to the rudder.
Production of the Sparrowhawks was undertaken at the Buffalo factory of the Curtiss Aeroplane Company and by September 1932 the Navy had taken delivery to all six F9C-2 and the XF9C-2 prototype which had been modified to production standards. The seven aircraft were designated to serve onboard the USS Akron, each featuring a unique and colourful paint job and the unit’s special “Men on the Flying Trapeze” insignia. The Akron’s internal hangar bay could hold up to five aircraft onboard, with a trapeze system that could be lowered through a t-shape opening in the floor of the airship to launch and retrieve the Sparrowhawks mid-flight. To land the aircraft on the trapeze, pilots would guide the sky hook to the horizontal bar of the trapeze. Once they had hooked onto the bar, they would cut the engine, and the trapeze would raise up into the belly where the aircraft could be stored in the internal hangar. This was all done while the airship was at full speed as this was just above the stalling speed of the FC9-2. It sounds complicated but as Richard k. Smith describes in his dissertation focused on the Akron and Macon, “There was a consensus among the hook-on pilots that landing on the trapeze was unusually simple.”
It was anticipated that the FC9-2s could be employed in both defensive and offensive roles. They could be used to defend the airship in the scenario of encountering an enemy force, or they could be sent out to attack an enemy position, or they could be utilized as scout aircraft to extend the search range of the airships. One tactic that was developed was to have two F9C-2s fly abreast of the airship using radios to report back and forth with the airship. They were also utilized to help train air gunners onboard the Akron, undertaking mock attacks against the airship.
Tragic Ends and Legacy:
The FC9-2s service onboard the Akron was rather brief as on April 4, 1933, the Akron crashed into the sea off the coast of New Jersey killing all but three of the seventy-six men onboard. No FC9s were onboard at the time of the crash and as such they continued operations being transferred to the USS Macon. This would be until February 12, 1935, when the Macon crashed off the coast of California killing two of the crew members. Four FC9-2s were onboard the Macon when it went down and were subsequently lost.
The Macon’s demise marked the end of the U. S Navy experimentation with rigid airships and the end of the FC9-2s career as a parasite fighter. Although the U.S would experiment once again with parasite fighters in the 1940s and1950s, results remained mixed. Of the remaining three FC9-2s, they would have their skyhooks removed and stay in service as general utility aircraft for a few years. Eventually, two of them were scrapped, while the final one was donated to the Smithsonian in 1939. Upon restoration of the aircraft in the early 1970s the donated plane was discovered to be the XF9C-2 prototype airframe and is the sole surviving Sparrowhawk.
Reference list:
Books:
The Airships Akron and Macon: Flying Aircraft Carriers of the United States Navy - Richard K. Smith.
Websites:
https://airandspace.si.edu/air-and-space-quarterly/issue-13/curtiss-sparrowhawk-restoration
https://airandspace.si.edu/collection-objects/curtiss-f9c-2-sparrowhawk/nasm_A19410007000
https://airandspace.si.edu/stories/editorial/how-airship-became-flying-aircraft-carrier
http://www.historyofwar.org/articles/weapons_curtiss_F9C_sparrowhawk.html
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