Pilot Manual for a 1940's U.S. Navy Blimp

This 122 page manual contains all of the operating instructions and technical details to pilot this sleek, silver 250 foot long weaponized anti-submarine dirigible.

The national discussion surrounding surveillance balloons offers up the perfect opportunity to share one of the more unusual public records I found while poking around deep in the Federal Aviation Administration’s website a while back (yes, this is a thing I do).

Listed on an FAA page titled “Aviation Handbooks & Manuals”, which includes links to a wide variety of recent pilot handbooks for weather, instrumentation, safety as well as guides for operating helicopters, gliders, hot air balloons and gyroplanes, there is one document that is significantly older than the others, and it kind of jumped out at me. The title is listed as “Airship Pilot Manual” with a publication date of 1942.

The actual title of the document is “UNITED STATES NAVY K-TYPE AIRSHIPS: PILOT MANUAL”. This 122 page manual contains all of the operating instructions and technical details one would need to pilot this 250 foot long, 79 foot high, silver, weaponized anti-submarine dirigible. This manual is incredibly detailed and surprisingly readable.  

This blimp (they seem to prefer “airship”) had the ability to lift just over 26,000 pounds and was powered by two 425 horsepower Pratt & Whitney Wasp engines, which could spin the three bladed, 12 foot long propellers at 1,775 rpm^[1]. Depending on the model of this K class airship, the vehicle could cruise along at an average of between 40-67.5 knots (40-77 mph). One of the things that made these blimps essential for anti-submarine warfare, is that at normal cruising speed they could go on 26 hour long missions. 134 of this class of airship were built for the Navy by the Goodyear Aircraft Corporation.

The volume of the blimp envelope was 425,000 cubic feet^[1], and was filled with helium.

This was no leisure craft. It carried a turret-mounted 50 caliber Browning machine gun and had racks that could carry up four torpex-filled MK-47 depth bombs (350 lbs. each). These airships were deployed by the Navy to help search for and destroy enemy submarines. The airship included a ASG-type radar system capable of detecting objects at 90 miles and sonobuoys used to probe for submerged submarines.

On July 31, 1943, The New York Times reported that airship K-74 was shot down over the Atlantic, after a U-boat it had been hunting with depth charges surfaced, and shot it down. All but one member of the crew survived the splashdown in the ocean.

The 40-foot long cabin, which sat nestled below the envelope could carry a crew of ten, and as weight was a key constraint, the manual listed the exact weight of each piece of equipment aboard, including the 85 lbs of canned and fresh food, 35 lbs of water and 16 lbs of rescue rations. A table of the electrical load analysis lists a “GE Grill - Stove - Oven” and a Manning Bowman #494 coffee percolator and an Everhot “roasterette”. Reading such hilariously specific data like this, I reassure myself that were I to ever acquire a time machine, and find myself piloting this blimp while hunting U-boats over the Atlantic in World War II, I’d know the exact amperage being drawn from the coffee maker (3 amps) if I needed to reduce power consumption in a pinch.  

The manual contains some beautifully executed cutaway diagrams with every single feature carefully annotated. When looking through this manual with its exquisitely drafted schematics, I thought about a used book I found a few years ago, “Illustrator Draftsman 3 & 2” published by the U.S. Navy Training Command in 1972, which was an instruction manual for the kinds of artists and draftsmen in the Navy who probably worked on this blimp manual. This draftsman manual deserves a post of its own in the future.

The National Archives has some incredible footage of these K-Class airships in action. One clip is from December 14, 1943 and shows a crew aboard one of these blimps actually dropping depth charges on suspected submarines. There is also some incredible color footage from 1944 showing one of these silver beasts taking off and landing on an aircraft carrier.

Seeing the crew members flying this behemoth really helped make these blimps come to life for me in a way I had not expected.