The Navy Thought These 'Balloons' Could Become Flying Aircraft Carriers

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June 15, 2019 Topic: Security Region: Americas Blog Brand: The Buzz Tags: MilitaryTechnologyWeaponsWarAirship

The Navy Thought These 'Balloons' Could Become Flying Aircraft Carriers

That didn't work out.

It is sometimes difficult to understand just how immature aviation was in the 1920s and 1930s. Everything about flying was new. Planes sported two sets of canvas-covered wings, had limited navigational ability, and had significantly less ocean-going range than a traditional destroyer. After their debut in World War I, planes held promise as instruments of war, but air tactics were still being refined and the planes themselves were unreliable, evolving, and still unproven. They may have been safe enough to carry mail, but not paying passengers—to say nothing of soldiers. The Air Force did not even have its own branch of the service until 1947.

Nevertheless, after World War I there was a strong feeling among certain members of the United States military that rigid-framed airships, or dirigibles, had a great deal of potential as instruments of war. Anything seemed possible during the quickly changing period of aviation. Between 1923 and 1933, the U.S. Navy’s Lighter Than Air (LTA) program produced four such dirigibles. At the time, they were the largest, most expensive aircraft ever built and were spectacular to behold. And though the dirigible seems in retrospect like something of a white elephant, for its time the LTA program was daring, imaginative, and highly innovative.

The Dirigible Craze

Dirigibles seemed poised to surpass trains and ocean liners as a better, faster form of transportation, especially across the Atlantic Ocean. The American military had seen the tactical success the Germans achieved using blimps during the Great War, and it acquired what would become the Los Angeles (ZR-3) as war reparations from Germany for study and experimentation. The public was also intrigued by the behemoths. They were especially captivated by the German Graf Zeppelin, which carried passengers from Europe to the United States, Brazil, and Japan long before commercial aviation was a going enterprise. Indeed, the 1930s saw a craze in America for all things dirigible. Airship designs became an integral part of Art Deco style and could be found on plates, pins, postmarks, and neckties. Newspapers lavished detailed coverage on each transcontinental crossing as if it were an Apollo program moon shot, and miniature Graf Zeppelin children’s toys, fashioned out of tin, were wildly popular.

The Navy’s dirigible program produced the USS Shenandoah in 1923, the USS Los Angeles in 1924, the USS Akron in 1930, and the USS Macon in 1933. The Macon, at 785 feet long, was literally the queen of the skies. To put her size into perspective, the Macon was three times longer than a Boeing 747, 971/2 feet shorter than the Titanic, more than 15 stories tall, and four times the length of modern-day Goodyear blimps. She even edged out Germany’s Graf Zeppelin in terms of size. Like the Saturn V rocket, Navy dirigibles were the high-tech aircraft of their day. The Macon, the last of the Navy’s dirigibles, was built at a cost of $2.5 million by the Goodyear-Zeppelin Company of Akron, Ohio, a joint venture between the Goodyear Tire and Rubber Company and the Zeppelin Company of Germany.

The Macon: a New Class of Airship

The Macon pushed the envelope in every conceivable way. She weighed more than 200 tons, carried a complement of 83 officers and crew over a range of 7,000 miles, and could stay aloft for more than three days. Fully outfitted with a galley, three dining messes, sick bay, smoking room, and separate sleeping quarters for officers and enlisted men, the Macon was a self-contained world in the sky. She was kept aloft by nonflammable but very expensive helium gas. Her 12 helium cells were made from gelatin latex and were suspended from a complex internal skeletal structure made of a German-invented alloy called Duralumin 17-SRT. Composed of aluminum, copper, magnesium, and manganese, Duralumin was designed to be both durable and lightweight, the carbon fiber of its time.

Because of her clean lines and overpowering size, the Macon was one of the most beautiful airships ever designed. She was powered by eight German-made Maybach VL-II, 12 cylinder engines, each of which generated 560 horsepower at 1,600 rpm. The Maybachs drove an external, triple-bladed propeller that enabled the ship to reach speeds up to 75.6 knots (about 80 miles per hour), a bit faster than her sister ship, the USS Akron, which could only do 69 knots, and her props could swivel up and down as well as in reverse. At top speed, she could cross the entire United States in 37 hours.

Being a lighter-than air-ship, weight was everything for the Macon. She was actually 8,000 pounds lighter than Akron, but keeping her trim while airborne involved a complicated ballet involving fuel, water ballast, helium gas, outside temperature, and altitude, not to mention barometric and wind conditions. To compensate for the decrease in weight that naturally came from fuel consumption, the Macon recycled her engine exhaust through condenser units designed to capture water vapor necessary to maintain the ship’s trim.

The Macon had two control cars, one near the bow where the officers managed the rudder and elevator controls; monitored the altimeter, air speed, and rise-and-fall indicator; and issued commands to the eight engine rooms. A second control car located in the lower stabilizing fin at the ship’s tail was a backup in case anything happened to the primary command car. The Macon also sported a spy car or “angel basket,” which was lowered from the ship’s bottom on 3,000 feet of cable to spy on the enemy below while the dirigible stayed hidden in the clouds. The spy car sported a tail fin and rudder pedals to provide a margin of control, and could be used as a raft to retrieve downed pilots. The spy car was the bane of whoever rode in it. It was difficult to control, open to the elements, and virtually guaranteed even its most hardened occupant a severe case of airsickness. The Macon carried her own defensive armament in the form of machine-gun installations in the airship’s bow, aft, and topside that could be used to defend the airship from attacking aircraft in any direction.

“Parasite Fighters”

One of the Macon’s most appealing features was her ability to launch and retrieve airplanes in mid-flight. She carried five Curtiss F9C-2 Sparrowhawk fighter planes in a hangar inside her belly. The Sparrowhawks, which were known as “parasitic fighters,” hung from a rail system inside the airship and were guided from their hangar’s four respective corners to a T-shaped opening in the Macon’s belly located slightly aft of the control car. A fifth Sparrowhawk could be accommodated in the center of the hangar, but was rarely carried. When ready to be deployed, the Sparrowhawks were transferred to a crane with a harness-like trapeze attachment that lowered the aircraft through the opening without their wheels ever touching the ship. With the aircraft hanging outside but still attached to the airship via a trapeze, an electric-ignition line would be lowered to the pilot, who would connect it to his aircraft and start the engine.

Sparrowhawk pilots turned over their engines outside the airship as a safety precaution to avoid a catastrophic explosion from occurring inside the dirigible. Once the engine was running, the pilot pulled a lever outside the cockpit near the top left wing and released the plane from the trapeze to fly off under its own power.

The Macon was not just a catch-and release-program, however; she also retrieved her aircraft in mid-flight. The Macon’s Sparrowhawk pilots would fly behind and underneath the airship, guided by two signal men visible from the T-shaped opening who helped them close the gap in the sometimes turbulent slipstream. Carefully maneuvering his throttle at near stall speed, a Sparrowhawk pilot inched his way upward beneath the giant dirigible until the skyhook latched into place on the trapeze catch mechanism. Then the pilot would cut the engine and the plane would be winched back on board. Another trapeze was located near the tail of the Macon, where a Sparrowhawk could “perch” while waiting its turn to come aboard. No wonder the pilots of this elite group were called “the men on the flying trapeze.” They even adopted a special insignia that depicted two trapeze artists poised to catch one another in mid-air (a fat one signifying the dirigible and a skinny one signifying a Sparrowhawk).

Because every pound on a dirigible counted, the protocol was to wait until the mother ship was airborne and then fly the aircraft on board. Neither the Akron nor the Macon took off with her full complement of fighters on board. In this way, the ship was spared lifting an additional 14,000 pounds that could make a real difference if there was no wind.

Questionable Utility in Modern War

Rear Admiral William A. Moffett, chief of the Bureau of Aeronautics, and Captain Garland Fulton were the Navy’s two most influential LTA evangelists. Both believed passionately in the strategic value of the rigid-frame airship and its ability to serve as the eyes of the fleet. The Macon and the other dirigibles were used as scouting ships to reconnoiter a larger area of ocean in search of the enemy and provide useful intelligence. They could do this faster and more cheaply than a typical destroyer, and great promise was seen in the Macon’s ability to warn the Navy of an approaching enemy in the days before radar existed. Meanwhile, the Macon’s complement of Sparrowhawks provided protection for the dirigible against enemy ships and aircraft. Although they provided some supplemental scouting, the Sparrowhawks were not the primary scouting vehicles—that was the dirigibles’ role.