USN LTA: Rigid Airship Era

Wonder weapon of the Great War, secrets recovered from downed German Zeppelins allowed Britain to construct near-duplicates as America poured over secret plans the French reverse-engineered from downed Naval Zeppelin L-49. In 1919 victorious Allies dissected German facilities and divided surviving Zeppelins, while the US refused to sign the Treaty of Versailles and got nothing. Envious of the long-range scouting credited with saving the High Seas Fleet at Jutland, and impressed with the RAF’s R.34’s criss-crossing the Atlantic in 1919, the US Navy was funded to purchase a British rigid and renew the first floundered effort to build a rigid at home.

Navy airmen experienced in blimp ASW trained in the British R.80 as the larger R.32 was completed. Girder failures in test flights hinted the lightweight structure, extrapolated from high-climber Zeps, was not adequate. Newly decorated with American roundels and designated ZR-2, a two-day test flight in August 1921 included high-speed maneuvers in which structure failed, breaking the airship in two. The hydrogen-buoyed aft section grounded harmlessly with four unhurt survivors, but forty-four of the most experienced British and American airshipmen died as the forward section caught fire and fell.

Sailor airmen sail for England to crew the ZR-2 (top).

The devastating accident pushed the Allies into allowing America to order a German rigid, thereby saving the main Zeppelin factory from disassembly.

Back in Pennsylvania, ALCOA was tasked to duplicate the German “duraluminum” as a giant hangar rose at Lakehurst, New Jersey. A new industry was created to manufacture the high-tech materials needed (with one of the first “spin-offs” being the use of “airship metal” on wooden seaplanes) as Congress budgeted that flying must be under Bureau of Mines helium. The Naval Aircraft Factory, working from re-engineered Zep L49 plans (adding cells and strengthening strucures), created segments to be trucked to Lakehurst for assembly.

Christened USS Shenandoah, America’s first rigid used 20 helium cells inside a fabric-covered frame.

Following her launch on the 4th of September, 1923, flights were dominated by public appearances, but ZR-1 managed to loft developmental equipment as Americans learned the new art of rigid airship flying. Moored to the Lakehurst high mast during a January 1924 gale, ZR-1 broke away, but was brought under control by the small crew aboard and returned safely for repairs to her bow and  upper fin. Exhaust-gas water recovery condensers added to engine cars
decreased performance, but with her forward engine replaced with a radio, exercises finally proved her value as scout for the Fleet. In October 1924 Shenandoah embarked on an ambitious circle-America flight from which she was serviced from expeditionary high masts at Forth Worth, San Diego (right) and Seattle.

ZR-1 was then hung and propped up for six months as the Navy’s helium supply was pumped over to the newly arrived ZR-3, Zeppelin LZ-126, which was then christened USS Los Angeles. Again taking her turn with the helium the summer of 1925 following the removal of some overpressure safety valves and capping other leakers, Shenandoah practiced scouting with the Fleet and operated from the mast-equipped tender USS Patoka. Embarking on an ambitious schedule of Midwest country fair appearances in September, she broke in two as 14 crewmen fell to their deaths near Ava, Ohio. Survivors rode other still-buoyant sections to ground; the bow came to rest two miles from the stern.

Los Angeles moored to Patoka for extended deployments; she launched a piloted glider on two occasions; she practiced replenishment from a flattop.

Rebuilding helium supplies allowed Los Angeles to fly again in April 1926 as she continued the longest and most successful career of the Navy rigids. Using both the Lakehurst high mast and the Henry Ford tower mast at Dearborn, Michigan, she was used in the development of the fixed stub and the first mobile mooring masts. On 27 January 1928, ZR-3 “landed” aboard the aircraft carrier USS Saratoga and in 1929 she began experimenting with launching and retrieving airplanes while in flight. In February, 1931, during maneuvers in the Caribbean and Panama, she was away from Lakehurst for 27 days and traveled a total of 14,500 miles during 272 flying hours.

All known motion pictures of ZR-1, ZR-2, and the best movies of ZR-3 are included in the DVD American Zeppelins. Specifications and individual histories of all five US Navy rigid airships are included in James Shock’s US Navy Airships.

Congress had funded two airships to replace ZR-1 in 1926, with Goodyear-Zeppelin’s design winning in 1929. The company constructed the world’s largest hangar and built the ZRS-4, a new tri-keel design featuring 12 cells totaling 6.5 million ft3. Christened USS Akron at Lakehurst in October 1931, she flew with Los Angeles one day before ZR-3 was mothballed. Troubles in early Akron operations received undue press scrutiny during the crew’s learning curve. Overcoming limitations of the skyhook-equipped N2Y-1 basic trainers (below left), the small carrier-based F9C-2 Sparrowhawk (below right) happened to fit through the airship’s door; six were ordered as the Akron’s airplane handling trapeze was perfected. ZRS-4 criss-crossed the country in the spring of 1932.

Akron’s water recovery condensers had been improved when seen recovering an N2Y-1 over Panama in the spring of 1933.

By 1933 the evolving ZRS-4 was becoming a more capable flying carrier when a routine land radio calibration mission caught her unaware of a massive April storm that slammed her into the water, drowning all but three aboard. The unprecedented disaster overshadowed the following weeks’ commissioning of Sunnyvale NAS and ZRS-5, christened USS Macon. Nearly identical in appearance, ZRS-5 benefited from Akron’s experience and never had a ground handling incident.

Production F9C-2s (left) drilled on Macon’s trapeze scouted for the fleet. N2Y-1s (right) and later Wacos ran personnel and small cargo to and from the airship while underway.

Deployed to California late in 1933, two condensers were removed and an outside airplane perch was added allowing up to six airplanes to be carried. Maneuvers in 1934 enhanced airplane-scout techniques while the two-seat planes could be used for personnel and small cargo. A flight to Florida demanded attention for suspected tail weakness, and a fix began. Fuel tanks substituted for wheels and added homing gear allowed the Sparrowhawks to later range 200 miles from the mothership. A daring demonstration to find vacationing Roosevelt’s cruiser proved the open-Pacific search to reluctant leadership, and Macon was scheduled to operate from Hawaii in 1935. Before tail reinforcements were complete the upper fin suffered metal fatigue, leading to errors that lost the ship and two crewmen off Point Sur.

The best motion pictures of the ZRS program construction and operation, including virtually all known film of launches and recoveries of hook-on airplanes, is included in the DVD The Flying Carriers.

Navy officers worked with passenger Zeppelins, making most of the flights of the Hindenburg in 1936.  The last Navy rigid, USS Los Angeles, was dismantled by 1940. BuAer’s 9-bomber ZRCV was destined never to be built, even at the height of WWII.

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