USS Macon (ZRS-5) - Specifications:
USS Macon - Development:
In 1926, the US Congress approved a plan put forward by the US Navy's Bureau of Aeronautics (BuAer) which called for the construction of two large rigid airships. Intended to serve as scouts for the fleet, they were to augment the US Navy's early aircraft carriers, USS Langley, USS Lexington, and USS Saratoga. At this time, the US Navy had experience with two earlier rigid airships, USS Shenandoah and USS Los Angeles. While the former was lost in a storm over Ohio in 1925, the latter remained operational until 1933. Unlike these earlier airships, BuAer envisioned the new class to serve as flying aircraft carriers capable of launching and recovering small fighters which would increase the vessel's scouting radius and provide a defensive force. As design of the new airships moved forward, the Curtiss F9C Sparrowhawk biplane was developed to serve as the parasite fighter.
USS Macon - Construction:
The construction contract for the two airships, dubbed USS Akron and USS Macon, was awarded to the Goodyear-Zeppelin Corporation, a partnership between Luftschiffbau Zeppelin and the Goodyear Tire and Rubber Corporation, and signed on October 16, 1928. As part of the partnership, Goodyear required that Zeppelin send their chief stress engineer, Karl Arnstein, and a team of experts to Akron to aid in designing and building the two vessels. Work commenced on Akron in October 1929 and the airship was completed in September 1931. As construction of Akron wound down, work on Macon pushed forward. Macon was launched on April 21, 1933, seventeen days after Akron crashed in a storm off the coast of New Jersey.
USS Macon - Design:
In designing Akron and Macon, Arnstein employed several new approaches and techniques. Unlike previous airships built by Zeppelin, the two new vessels would possess three keels. One ran along the top of the airship, while the other two were on either side at a 45-degree angle from the bottom of the duraluminum hull. These connected a series of "deep rings" which were placed approximately 74 feet apart. Whereas earlier Zeppelins had employed rings supported by a single braced girder, Arnstein's "deep rings" used large triangular structures to provide strength. Though these two new approaches substantially increased the airship's weight, it was believed the structure would greatly enhance the strength of the frame. Having recently lost Shenandoah to a structural failure, the US Navy was willing to exchange weight for a stronger airframe.
As the new airships were to be filled with non-flammable helium, their eight Maybach VL-2 engines were mounted inboard along the lower keels. These powered outrigger propellers which were mounted on bevel gears allowing them to provide thrust in forward, reverse, and downward positions. In designing the tail structure, Arnstein abandoned the strong cruciform framing structure that had been used previously. Instead, he elected to mount the stabilizing fins directly to three of the rings within the airship's frame. This was altered to only two when the US Navy specified that it want to be able to see the lower fin from the control car.
USS Macon - Aircraft Operations:
Upon completion, both Akron and Macon were capable of carrying five F9C Sparrowhawks. These were launched and recovered through a t-shaped hole in the bottom of the airship. For launch, a large hook atop the F9C's upper wing would be attached to a bar and the aircraft lowered. Entering the airship's slipstream, the F9C's engine would be engaged and the fighter would drop free. When the aircraft's mission was complete, it would approach the airship from below and hook onto the bar, known to crewmen as the "flying trapeze." Once the connection was made, the F9C would be lifted back into the airship. This recovery maneuver often proved difficult in windy conditions.
USS Macon - Operational History:
Commissioned on June 23, 1933 with Commander Alger H. Dresel in command, Macon flew to Lakehurst Naval Air Station for trials. While there, it received its first F9Cs on July 6. Completing testing, Macon was ordered to its new base at Naval Air Station Sunnyvale (later Moffett Field) in California. Arriving, it was housed in the base's mammoth Hangar 1. Operating from Sunnyvale, Macon began developing scouting techniques using its F9Cs. In April 1934, Macon endured an arduous trip across the United States en route to exercises off Florida. After being forced to exceed its maximum pressure height (the altitude at which an airship's gas bags begin to leak) to clear mountains in Arizona, it took damage during severe weather over Texas. This was repaired though additional strengthening to Macon's stabilizing fins was put off until the airship's next overhaul. Sufficiently repaired, it took part in Fleet Problem XV in the Caribbean that May before returning to Sunnyvale.
Taking part in various fleet exercises, leaders soon began to realize that though the airship itself had been developed as a scouting vessel, its slow speed and vulnerability made it an easy target. As a result, Macon adjusted tactics and remained towards the rear while allowing its F9Cs to conduct the actual reconnaissance aspects of missions. In an effort to increase the range of the little fighters, their landing gear was removed aboard Macon and the weight replaced with extra fuel. At the end of missions, the landing gear would be reattached allowing the F9Cs to land independently of the airship.
In July, Macon, with Lieutenant Commander Herbert Wiley in command, conducted a long flight over the Pacific and intercepted the heavy cruiser USS Houston which was carrying President Franklin Roosevelt back from Hawaii. Through the fall, Macon continued to operate over the Pacific and proved effective at conducting strategic searches across vast distances of ocean. On February 12, 1935, while returning to Sunnyvale, Macon encountered severe weather off Point Sur, CA. In the storm, violent winds tore off the airship's upper stabilizing fin which caused the structural failure of one of the rings to which it was attached.
As control was lost, the airship rose above its pressure height requiring Wiley to vent a large amount of helium to prevent Macon from gaining more altitude. Slowly descending, Macon landed in the water off Monterey Bay. Moving quickly, all but two of the crew of 76 were able to escape and be rescued. Had the crew been able to prevent the airship from exceeding its pressure height, it is likely that Macon could have limped back to Sunnyvale. In the wake of Macon's loss, there was some controversy over the design of the tail section and the fact that the German cruciform structure was not used as well as the fact that the fins were only attached to two rings.
Macon was the last rigid airship build for the US Navy. Though the service continued to operate lighter-than-air aircraft, these were limited to a variety of blimps which were operated through World War II. In addition, the 1930s saw the US Navy increasingly focus its aviation efforts on the construction of new aircraft carriers such as USS Yorktown, USS Wasp, and USS Hornet.