Lakehurst class Helicopter Carrier Airship
Length: 845 ft
Diameter: 148 ft
Height: 154 ft
Volume: 9,157,801 cu ft
Useful Lift: 168,440 lbs
Powerplant: 8x Napier Culverin 6-cylinder, 12 piston diesel engines, 890 HP each
Propellers: 13 ft, 4 blade Curtiss Electric C542S constant-speed propellers
Top Speed: 71 knots
Cruise Speed: 58 knots
Range: 6,531 nm
Service Ceiling: 10,000 ft at combat loading
Armament and Sensors
Guns: 16x M2 .50 cal Browning Machine Guns (4 twin turrets per side)
Aircraft: 6x Sikorsky R4 helicopters (dorsal hangar)
Radar: 1x SK-2 Air Search Radar (nose)
1x SG-1 Surface Search Radar (control car pod)
1x SC-1 Air Search Radar (tail)
Electronics: 1x YG Aircraft Homing Beacon
2x 66ACF IFF Antenna
2x 66015 Talk-Between-Ships Antenna
1x Radio Direction Finder
Designed as all-seeing eyes in the sky from which hunter killer groups could be commanded, the Lakehurst class
airships came from a culmination of two ideas. The first being the airship as a platform with which to move the bulky early radar sets to an airborne observation position. The second, a revival of the airship carrying parasite aircraft as a potential solution to the problem of providing air cover over Allied Convoys in the North Atlantic.
The former idea began to take hold in earnest when the old airship USS Los Angeles was reactivated in 1939 and overhauled at the Goodyear-Zeppelin airship works in Akron, Ohio. The work included repairs to the frame, all-new latex gas bags, and the addition of a nose cone structure housing the experimental CXAM-1 air search radar. The weight allowance for this device was taken out of the fuel capacity, which limited the airship's range, but this was considered acceptable. After her year long reconstruction, the Los Angeles
would spend 1940 and 1941 patrolling off the US East Coast, using her new sensors to monitor maritime traffic off American shores, including a few U-boats which ventured that far. Reports were generally positive, and despite several endemic issues to airborne operation, when the radar worked it enjoyed greater range and a clearer picture than ground mounts or shipboard sets.
During this period she made one transatlantic flight, operating off the tender USS Patoka
to make the journey with her now limited range. Operating from neutral Spain, she made flights into France to monitor the ongoing air battles on the Western Front, testing the capability of her radar in acquiring military airborne targets. These operations were highly top secret, and neither Spanish nor Allied officials were made aware of the nature of Los Angeles's
"electronic equipment" she was testing. All flights over France and into contested airspace were made at night under radio silence, and it was not until after the war that most Allied officials realized that there had been an American airship spying on the air war over Europe.
The second idea that would underpin the concept of the Lakehurst class
airships was that of the parasite aircraft carrying airship, an idea pioneered by the ill-fated USS Akron and USS Macon in the 1930s. With the much greater ranges of German U-boats compared to their WW1 counterparts, they could now sail well into the Atlantic Ocean and outside the reach of air over from English bases. A long range airship could both search for U-boats itself from it's perch high in the sky, and deploy smaller aircraft to cover a wider swath of sea, at any point along the journey. As the convoy war began to take shape in 1940, Goodyear was requested by the Navy to produce a series of design studies into the feasibility of a new type of aircraft carrying airship to escort convoys in the Battle of the Atlantic.
One point of particular interest in the development of these studies was a new type of aircraft that had emerged in the 1930s well after the final design work on the older Akron class had completed. The gyrocopter was viewed by many airship engineers as a promising solution to the issues faced in recovering craft launched from the airship. The trapeze system had never been wholly satisfactory, and it was undesirable to return to such a form after experiences aboard Los Angeles
had shown the difficulties in it's use. At the maximum speed of an airship, a gyrocopter could potentially have enough lift to rise vertically from its hangar, which could thus be mounted dorsally. This was highly attractive to designers, as the pilot would thus only have to land on a marked platform, instead of carefully and precisely latching the skyhook onto the crossbar in flight as had been done with previous parasite fighters.
With the Battle of the Atlantic rapidly escalating throughout 1941, design work on the new airship was proceeding in earnest now. On September 30, 1941, the Navy awarded Goodyear-Zeppelin the contract to build four new airships, and authorized major expansions to the existing airship bases to build hangars large enough to accommodate the new giants. The final specifications called for an airship of 9 million cubic foot volume, to carry six autogyros. Though no modern types were in production, it was expected that by the time of the airships completion a suitable model could be procured. Sikorsky's experiments in rotorcraft were known to the designers at the time of the contract being awarded, and remained of considerable interested throughout the design and construction work. The requirements also called for a large radar to be nose-mounted as had been done experimentally in Los Angeles. The radar would be the in-development replacement for the CXAM, what would eventually become the famous SK radar.
As the airships began construction, the doctrine for their use developed from experience in the battles against the U-boats in the Atlantic. The emphasis gradually moved away from the airship as a spotting platform. As radar proved it's value and effectiveness in combat, the plan became one of the airship using its radars to see contacts far beyond the range of ship mounted sets. Once the contact was being tracked, the airship would dispatch its aircraft to investigate. From there, if a submarine was found, the gyrocopter could loiter on site and report it's position and speed back to surface ships by radio. If the submarine dove, the gyrocopter could hover overhead, looking down vertically to see the U-boat. In this way, the airships could lead hunter killer groups against the German submarine threat, finding and marking the enemy for death with a huge radius of sight.
Laid down in late 1941 and early 1942, the four ships of the Lakehurst class were all assigned names in the same convention as the previous airships- cities and towns, just like cruisers in the surface fleet. USS Lakehurst ZR-6
, USS Kittyhawk ZR-7
, USS Arlen ZR-8
and USS Lawndale ZR-9
, would be the largest flying objects ever constructed, nearly as long as the Iowa class battleships, and over 50 feet longer than the previous Akron class. Their design incorporated a unique, four-keel arrangement, a development of the three-keeled structure pioneered by the preceding ships. Arranged in an X formation, this design supported the dorsal hangar bay between the two uppermost keels. The landing platform for the rotorcraft was also the hangar door. When an aircraft was securely aboard, the door would swing downwards and function as a ramp to roll an aircraft back into the hangar, or up to the flight deck for launch.
The Lakehurst class
also incorporated other innovations into their design as well. Their engines were of a unique type, the Napier Culverin 6-cylinder aviation diesel. This was a license copy of the Jumo 205 engine, used by the Axis in the BV 138 triple-engine floatplane. It had excellent fuel efficiency and endurance, ideal for long range airship cruises. It employed a very odd, opposed-piston design not seen in any other type of engine. Due to British manufacturing tolerances not meeting American standards for interchangeability of parts, after the first 32 engines were delivered by Napier for use in Lakehurst
, the Packard company was tasked with creating a copy satisfactory for American needs. These engines would power the Arlen
, and would be refitted to the two older sisters following the war.
By the time USS Lakehurst
commissioned into the Navy on July 18, 1944, Germany had already surrendered, and the U-boat threat had long been extinct in the Atlantic. With the war in Europe shifting towards a focus on the conflict against the Soviets, largely a ground war with no major naval component, a new mission was envisioned for the giant rigids. They would be dispatched to the Pacific, to serve in the ongoing war against Japan, serving as early warning stations for the fleet against incoming air attacks. Ultimately, their most intensive deployment would come in the Spring of 1945, as they were all assigned radar picket duty against the kamikazes during the Okinawa campaign. In this capacity they provided an invaluable early warning network ahead of the picket destroyers, allowing USMC and Navy patrol aircraft to blunt dozens of strikes. Through careful positioning and situational awareness the airships remained undetected in their work, using their own radars to track potential Japanese scouts and carefully dance around them to avoid being spotted.
After the war they remained in service, and served in some capacity closer to their original envisioned role tracking British and French submarines, as tensions rose throughout the 1950s over colonial crises. Though it never escalated to open shooting, the airship crews performed stellar work in tracking and monitoring the deployment of increasingly advanced post-war submarines. The crews would state after the fact they were confident in their ability to find and kill such threats, should the tensions ever escalate to a hot war.