Completed in 1931, the USS Akron (ZRS-4) and her sister ship, the USS Macon (ZRS-5), are the largest helium airships ever built. (The Hindenburg was larger, but she was filled with hydrogen.) They were also the last airships built for the U.S. military, as both airships had short careers that ended in disasters.
The USS Akron's maiden flight was in November 1931, following the eastern seaboard to Washington. She made a series of other flights, logging 300 hours of flight time. In January 1932, the USS Akron participated in a search exercise over the Atlantic, successfully spotting a fleet of U.S. destroyers en route to Guantanamo Bay. In May 1932, the airship was fitted with four trapeze apparatuses for use by Curtiss F9C Sparrowhawk biplanes, allowing the Akron to catch and store these "parasite" fighters while in flight. Judicious deployment of these aircraft also allowed them to be used as ballast during operations of the airship. The USS Akron then departed for the west coast, again fairing well in another search exercise. She returned to the east coast, and sailed to Cuba in 1933. Then, on April 3, 1933, the USS Akron cast off to aid in calibrating radio direction finder stations. She met foul weather over the Atlantic, and crashed into the sea, killing 73 crewmembers. Among those dead was Rear Admiral William Moffett, one of the primary advocates for airships in the U.S. Navy. Although the USS Macon was finished (as she was already under construction), the U.S. military never built another airship.
The USS Akron had a crew of 89 officers and men. The airship carried 50 sailors, 10 officers, 15 mechanics, 4 engineering officers, and pilots for the Sparrowhawks. A control gondola was located below the ship near the nose, with a backup bridge located within the ventral fin to the rear. She had a range of 12,180 miles at a cruising speed of 58 mph. The USS Akron burns 168 gallons of gasoline per hour at routine usage. She uses 1,400 lbs. of ballast per day. A full load of helium, fuel, ammo, and provisions costs $1,834. Construction cost in 1931 was $4.5 million.
Subassemblies: Large Zeppelin chassis +12; Huge Naval control gondola [Body:U] +6.
Powertrain: Eight 420-kW HP gasoline engines with eight 420-kW old props [Body] and 20,000-gallon ultra light tanks [Body]; 1,200-gallon ultra light ballast tanks [Body]; 32,000-kW batteries.
Occ.: 60 CS Body
Cargo: 659 Gondola
Armor F RL B T U
Body: 2/2C 2/2C 2/2C 2/2C 2/2C
Sup.: 2/3 2/3 2/3 -- 2/3
7xAircraft LMG (1,000 rounds each).
Body: Backup driver option, hangar for four Sparrowhawk biplanes, ultralight fuel tank with 240 gallons of aviation gas, 1,200 gallon ultralight tank for ballast. Gondola: Medium radio transmitter and receiver, very large radio transmitter and receiver, navigation instruments, autopilot, 3 galleys, 440-man/days provisions, large radio direction finder, searchlight, 8 toilets, luxury cabin, 3 cabins, 22 bunks, 60 crew stations.
Size: 785'x133'x153' Payload: 91 tons Lwt.: 201.5 tons
Volume: -- Maint.: 18 man/hours Cost: $1,344,067
HT: 12. HPs: 39000 Body, 4200 Gondola.
aSpeed: 83 aAccel: 0.42 aDecel: 0.5 aMR: 0.125 aSR: 4
Lift: 147 tons. Stall Speed 0.
Design aSpeed was only 35; this was increased to the historical figure. Loaded weight was increased 8% to the historical; payload was also light by 9%. Most of the components and crew spaces are a guess, as there were few historical references to the internal construction of the craft. I also could not determine were the defensive MGs were located. The airship is equipped for a five-day cruise, but this is again a supposition on my part. As with the K-Class Blimp (p. W:MP106), the ballast is seawater, at 8.3 lbs. per gallon.
The USS Macon (1933-1935) had a dead weight of 108 tons and a 72-ton useful load. She carried 91 crew and five biplanes. She was lost as the result of a structural failure of her upper tailfin which ruptured her gas envelope.
From the Aerodrome for GURPS
© 2008 by Jim Antonicic