U.S. Naval Aviators: Daring Young Men on the Flying Trapeze; Under the Big Top - Circa 1934-1935

As recently as an article entitled “Blimps: New Life For An Old Idea”, appearing in the October 2017 of the journal Aerospace America (journal of the American Institute of Aeronautics and Astronautics), was the potential rebirth of the Dirigible. The article cited that TP Aerospace of Massachusetts was currently under contract to design a blimp called Skybase for an unnamed client. The airship could launch, recover and refuel five 90-kilogram drones equipped with cameras. The article cites that their client is not alone, as Walmart has applied for a U.S. patent in August 2017 for “gas-filled carrier aircrafts” from which unmanned aircraft would deliver products to customers. Last year, Amazon patented a similar idea.

To briefly quote the Aerospace America article;

“Amazon and Walmart are purposefully vague about their concepts, but airship industry observers believe their proposed floating warehouses would need to be massive to make sense economically and to accommodate the features described in their patent documents. Walmart’s patent application describes an airship with a kitchen, bunks and bathrooms for workers who sleep and work in shifts. Amazon’s patent calls for the airship to carry equipment like forklifts and trolleys. The Amazon patent does not say how big this floating warehouse would have to be, but says a “shuttle” airship measuring 30 meters long would loft workers to the warehouse and bring fresh inventory and new delivery drones.

Amazon’s main airship would float above commercial airspace at 45,000 feet and on occasion descend to 2,000 feet to make advertising visible to people on the ground, according to the patent. Two airship experts questioned the viability of the concept, saying that to fly at 45,000 feet, an airship would need about six times more lifting gas than would be required to carry the same weight at 2,000 feet. Spokesmen for Amazon and Walmart declined to comment on the retailers’ proposed airships. Amazon’s Prime Air division has been flying drones for private delivery tests in the U.K.”

This reminded the author of another dirigible program conducted in the early 1930’s by the U.S. Navy, which culminated in the design, construction, and albeit brief operation of two massive dirigibles, the USS Akron (ZPS-4) and USS Macon (ZPS-5). Even with the use of helium instead of the earlier use of highly combustible hydrogen, the inherent limitations imposed by nominally benign weather conditions, proved deadly in storm conditions. This factor ultimately causing the destruction of both gigantic airships. Even prior to their respective crashes this resulted in severe constraints in the area of operation of the airships, and the execution of their intended primary mission of extended long range oceanic reconnaissance patrols. There had to have been a continuous radio watch for weather reports, as well as a barometric pressure gauge watch, analogous to the sight-glass on a boiler. Wonder how the crew handled clear air turbulence, apparently not too well. The cause of the crash of USS Macon off Big Sur, California in 1935 was wind shear, resulting in structural fracture of the un-strengthened ring supporting the upper tailfin.

Naval historians have hypothesized whether the Japanese carrier fleet which attacked Pearl Harbor might have been detected as it approached the Hawaiian Islands if the Macon had been on station in the Pacific at the time. The reader may or may not recall that Japanese Vice Admiral Chuichi Nagumo’s carrier task force (six aircraft carriers plus escorting ships) that attacked Pearl Harbor, launched aircraft from a stormy quadrant of the Pacific Ocean north-east of the island of Oahu in the early morning hours of 7 December 1941. They had followed a previous example (which had been intentionally buried and forgotten by the "battleship admirals") set by U.S. Admiral Harry E. Yarnell, during annual naval maneuvers in February 1932. For those who might be interested in details, please see; http://arnhemjim.blogspot.com/p/military-strategy.html . With ADM. Yarnell's strong advocacy of naval airpower, combined with the near coincidence of the period of the Macon's operational deployment, it's interesting to conjecture how the admiral would have viewed and used it capabilities. Given the above discussed limitations imposed by weather conditions on all of Macon’s flight operations, this author personally feels that it would have been highly improbable that the dirigible, or its embarked aircraft detachment, would have been operating in range of the Japanese carrier fleet.

An integral element in the total system design of these dirigibles was their use as airborne aircraft carriers in a program that briefly paralleled the much more successful development of purpose built ships as aircraft carriers, and the birth of modern United States Naval Aviation. The following drawing depicts the hangar bay arrangement in the USS Macon (ZPS-5). It was virtually identical in USS Akron (ZPS-4).

After a brief competitive selection period the design of a parasite “fighter” aircraft (limited to two .50 cal. machine guns) evolved in what was ultimately designated the Curtis F9C-2 Sparrowhawk. The unique element of the design being a trapeze-like assembly above the cockpit and top wing of the biplane, which when mated to a suspension lift array within the dirigible, was used to both launch and recover the aircraft from a hangar bay in the dirigible. There were 9 aircraft built. One plane (9056) survives restored as an exhibit at the Smithsonian National Air and Space Museum.

Built by the Goodyear Zeppelin Company, a subsidiary of the Goodyear Tire and Rubber Company, under Navy contract, both the Akron and the Macon were magnificent engineering marvels of their day. Both were built in the same time frame as the Empire State Building (1931). Each had an overall length of 785 feet, a gas capacity of 6,850,000 cubic feet, a lift capacity 152,644 lbs., and a maximum speed of 75.6 knots. The hangar bay had the capability of housing and operating 4 Sparrowhawk aircraft internally and a fifth aircraft suspended on the dirigible’s portion of the “trapeze” launch and recovery apparatus, but within the hangar.

 The official insignia of the Sparrowhawk detachments in both Akron and Macon was apronriately, “The Magnificent Men on the Flying Trapeze”, appropriately one being fat and bulbous, the other a thin man. The Akron and Macon operated for just two years, 1934 -1935.

 The real Magnificent Men on the Flying Trapeze, two photographs, the first being Naval Aviators of the Air Group in the USS Akron (ZPS-4) circa 1933, and the second being the officers (including Sparrowhawk pilots) of the USS Macon (ZPS-5) posing below her control car, in the Naval Air Station Moffett Field, California, airship hangar, circa 1933–1934. Those present are:

Seated in front, left to right: Lieutenant Anthony L. Danis; Lieutenant Howard N. Coulter; Lieutenant Calvin M. Bolster, Construction Corps; Lieutenant Scott E. Peck; Lieutenant Commander Bertram J. Rodgers or Lieutenant Commander Joseph C. Arnold; Commander Alger H. Dresel, Commanding Officer; Lieutenant Commander Edwin F. Cochrane; Lieutenant Donald McA. MacKey; Lieutenant Charles W. Roland; Lieutenant Walter E. Zimmerman; and Lieutenant Frederick M. Trapnell.
Standing in back, left to right: Chief Boatswain William A. Buckley; Lieutenant (Junior Grade) George W. Campbell; Lieutenant (Junior Grade) John D. Reppy; Lieutenant (Junior Grade) Robert W. Larson; Lieutenant Howard L. Young; Lieutenant Harold B. Miller; Lieutenant (Junior Grade) Frederick N. Kivette; and Chief Machinist Emmet C. Thurman. Lt Trapnell went on to become a renowned test pilot.

A critical element in the execution of the extended long range ocean reconnaissance mission of the USS Akron and Macon (including the F9C-2 aircraft) would be reliable and effective communications. Not frequently discussed it suffices that historical documentation on the subject is scarce.

Historians are greatly indebted to the eminent Dr. Louis A. Gebhard for his research published in Evolution of Naval Radio-Electronics and Contributions of the Naval Research Laboratory, NRL Report 8300, dated 1979. Dr. Gebhard, as a young engineer, had jointed NRL in 1923 when it was formed. He rose to become Deputy Superintendent and head of the Radio Division. He held over 90 patents.

High Frequency (HF) radio communications were not widely introduced into the U.S. Navy until the 1920’s, and early equipment relying on vacuum tubes, was simultaneously both fragile and relatively heavy, compared to today.

Dr. Gebhard cites one of the early and successful uses of HF radio was in the dirigible USS Shenandoah (ZR-1) in its epic flight from Lakehurst, New Jersey to the west coast and return in October 1924. The dirigible maintained continuous communications with the Naval Research Laboratory and many radio stations, during its entire voyage. Both transmitter and receiver were developed by the Naval Research Laboratory, but no specific nomenclature is cited. The transmitter was capable of both voice and keyed operation on 3332 kHz with a power output of 50 watts. The receiver used three “N” (first successfully “miniaturized”) tubes and covered a frequency range of 2000 to 6000 kHz. Portending the fate of both the Akron and Macon, the USS Shenandoah crashed during a severe storm over Ohio in 1928. It’s radio receiver was salvaged in good condition.

The first specific aircraft radio-communications equipments giving effective and extended service were developed 1922. Both fighter aircraft (SE1375, 500 watts, 570 to 750 kHz and patrol plane (SE1385, 500 watts, 300 to 570 kHz) were provided.

Given no further significant technological advancements occurring in the intervening 10 year period, both Akron and Macon would have used equipment evolved from the USS Shenandoah installation or possibly Patrol Plane Communications Equipment, Type SE 1385.

The radio equipment in the F9C-2 aircraft was designated type XF and XH installation (“X” - crystal controlled) Deemed satisfactory by the Navy, but not further identified or described.

When Master Chief William C. Riley retired from our Naval Reserve Intelligence Unit in Long Beach, California, we had presented him with a 1:20 scale model of the Sparrowhawk. In addition to being a fountainhead of knowledge of all things administrative dealing with the Naval Reserve Intelligence Program, Bill was an expert and author in the field of historical markings of United States Naval aircraft, and a lifetime member of the American Aviation Historical Society. He also was fascinated by both the dirigibles and the parasitic aircraft that operated from them. From their initial introduction in 1931, the Sparrowhawks have always been an extremely popular subject for scale modelers. Personally, as an engineer and military historian I’ve always been fascinated by the entire concept, even given the inherent fundamental weaknesses.

For decades, the same solid mahogany scale desk-top model has been built  by various manufacturers in the Philippines. Unlike most modern diecasts or plastic scale models, quality control and accurate details have greatly varied on these aircraft. Recently a small inventory of these Sparrowhawks were made available on, of all things, Amazon. With prices widely ranging for essentially the identical model, planes from this group seemed like a real bargain. Both Bill Riley and myself, as well as any seasoned aviation historian, would be able to point out a series of inaccuracies, but overall it is a very nice 1:20 scale model, capturing a bygone colorful era of U.S. Naval Aviation.

A fascinating adjunct to this page is the long term project of a retired computer engineer, Jack Clemens, who lives near Moffett Field (formerly NAS Moffett) in Sunnyvale, California, has built a fully operational radio controlled flying model of the USS Macon (ZPS-5). Two years in construction it is 1:40 scale (1 inch to 1 meter, 20 feet in length, and barely able to fit diagonally into his two car garage). Suffices to say Jack Clemens is a very serious and accomplished model builder. His first two attempts ran into disasters paralleling the real dirigibles (including the family cat and a wind storm), but the third time was a charm being completed in 2011. Note the similarity of the model's construction to that of the actual airship. With both sincere gratitude and full acknowledgment to Mr. Clemens, here are some photographs from his project and a full video, for those who may be interested.

A video of the 1:40 scale model USS Macon (ZPS-5) flying inside the real Macon's hangar at Moffett Field, California.

    

Some videos from vintage films of the USS Akron and USS Macon during construction and flight operations.

 

Part 3 can be seen at the following site; https://www.youtube.com/watch?v=phYl4LCjsXo&t=35s+. (Author's note:As an observation regarding this final part, who ever the technical advisor was on the US Navy uniforms severely errored (specifically LCDR Wiley's cap device), and unfortunately it tends to cast some doubt on the overall credibility/accuracy of the rest of the segment.)