Modification Center

UAL's Cheyenne base was asked to modify two Forts. Soon it was in business, and has since modified several thousand.

Forty years ago, Cheyenne, WY, was a typical western cow town with a population of 14,000. In later years it was headquarters for United Air Lines' major maintenance base.

Today, in place of the whoops and hollers of Indians and rootin', tootin' cowboys, the air around the town is filled with the roar of four-engined bombers, noise of riveting guns, clanking of sheet-metal work, and all the other sounds which go with a modern war plant. Now the town's population is more than 44,000.

Largely responsible for the transformation has been United Air Lines' modification center, devoted solely to modifying and building parts for AAF Flying Fortresses. United has modified several thousand Forts and has manufactured more than 4,000,000 parts used in them.

It all started in January, 1942. One wintry day, when the mercury was 30° "down under," WP Hoare, superintendent of United's Cheyenne base, received a telegram from the Army Air Forces Materiel Command stating that two Fortresses were about to be sent to Cheyenne for modification. Could United handle the work?

The Air Forces explained that these planes were to be used on a photographic mission and needed camera installations plus additional fuel tanks for long range flying. War plants still were flooded with the terrific blast of work set off by Pearl Harbor and couldn't do the job quickly enough. The Materiel Command turned to the well-equipped airline.

United complied by telephone and the planes soon arrived. Almost simultaneously came two civilian representatives from the Army and an engineer from the Boeing Aircraft Company at Seattle. The Air Force brought huge aerial cameras; the Boeing engineer data on how much additional load the Fortresses could stand.

No blueprints were forwarded for this first job. Three holes, each approximately 14 inches in diameter, had to be cut in the bottom of each plane's nose; three weighty cameras mounted so that the lenses would fit perfectly into the holes; additional fuel tanks installed on built-in cradles within the fuselages — all without designs or specifications.

Noses of the planes were held by manpower while mechanics cut the necessary holes. Makeshift mounts and supports were built in to hold the cameras firmly in position. With the installation of modified Douglas DC-3 wing tanks, the fuel loads and cruising range of the bombers were increased substantially.

Work on these two planes was accomplished in 30 days by 30 men, directed by Don Stombaugh, then United's foreman in charge of the sheet-metal shop, now assistant superintendent of the modification center. The company had to move its own planes out of the main hangar.

It apparently was worth all the effort because it later was learned that one of the planes was used to take the first aerial photographs of wartime Japan.

That was the first job and, at the time, United's personnel believed it would be the one and only. But in March, after two additional "projects" had been completed, the company began to realize it really had entered the modification business on a big scale.

Just as work on the first two planes was in the final stage, word came that seven more planes were on the way — this time for the British.

Lou Long, who has been with United's engineering department since 1937, had been on loan to the Materiel Command as a coordinator in the Government Furnished Equipment Branch of Production Engineering Division at Wright Field. He was instructed to report to Cheyenne to supervise future modification work.

In mid-February the Forts arrived. Again it was a case of no blueprints, no designs and no specifications — this time not even a Boeing engineer or Air Forces representative. Orders read to convert the planes to accommodate the British bombsight (which is shaped different from ours), to change the instruments and other measuring devices so they could be read in British units as well as American, to revamp the electrical system and wiring to suit British radio installations, to install racks and chutes to fit British flares, and to install special bomb racks and electrical solenoids for fusing British bombs.

February in Cheyenne is cold and working on planes out-of-doors isn't fun. United had no hangar space for the new arrivals and, although crews occasionally did work on one plane at a time indoors, the arrangement was much too slow. The engineers still thought plane modification at Cheyenne was somewhat of a wartime freak and they made no immediate plans for future permanent hangars. Instead, they constructed a temporary lean-to against the leeward side of the main hangar. This was built at right angles to the wall and was large enough to house the noses of two planes from the wings forward.

The planes were run in facing each other, separated by a wooden partition and covered with a wooden, sloping roof. A wall of canvas, which laced around the plane fuselages, extended from the roof's edge to the ground.

Gas furnaces identical with those used in homes were installed on the ground near the tail of each plane. Heat from these was piped through a window in the fuselage. This heat would drift through the whole plane and eventually into the lean-to, creating a fairly comfortable working condition.

Modifications to make possible a later installation of the British bombsight was a bit tougher than revamping a ship's nose to accommodate cameras. It necessitated changing the plane's wiring system and completely remodeling the original supports which had been built in to house the American bombsight. In the absence of blueprints, the men clamped a British bombsight in place and built, piece by piece, the necessary supports to hold it firmly.

The job of modifying measuring instruments to read in British units as well as American was comparatively simple. Small placards were printed with the British equivalents of American units and glued to the instrument panel alongside each instrument involved. On a fuel gauge reading in American units of measure the placard would read "100 gallons Am = 83.27 Imperial gals."

Changing the radio installations to suit British equipment necessitated removing most of the radio wiring plugs and supplanting them with plugs of a different size to fit British jacks.

The installation of racks to hold flares and drift recorders was easy. Loops of strip steel were mounted on the sides of the fuselage. Below these, the men installed cups to house the nose of each flare. Chutes, resembling rectangular boxes with a reel of string at the top and a release catch for opening a small trapdoor in the bottom of the plane, were installed below the racks.

Work on six of the planes was finished in less than 30 days. Army pilots arrived and flew them to unknown destinations. March blew in like a lion that year. With it came 17 more Flying Fortresses. This lot needed the same changes as the first batch of planes destined for Britain, plus such additional changes as the installation of more radio equipment, Aero-torque windshield wipers, application of British camouflage (for coastal patrol work), special antennae, installation of blackout curtains, British recognition lights and Very pistols.

The new planes also needed fuel tank "sloshing." When aromatic fuel comes in contact with rubber bullet-proofing, the inner lining of the tanks swells up. United was instructed to slosh the inside of the tanks with a substance which would have no ill effects on either the fuel or the rubber. An agitating jig was constructed of welded metal strips and a heating device was set up to "bake" the liquid.

While the 17 Fortresses were still in the works, 16 more arrived from the factory. By this time, United had seen the handwriting on the wall and already made plans for increasing personnel and augmenting its Cheyenne hangar space. In March the Materiel Command authorized construction of additional hangar space and requested that United submit designs for the job, estimated to cost $800,000. Subsequently, plans were submitted for more hangars which raised the estimate to nearly $2,000,000.

United was instructed to submit a complete list of all machinery, parts and other appliances needed to Wright Field within 48 hours. According to Long, catalogues, descriptive literature and other data on machinery were spread on the floors of United's Cheyenne engineering offices and the men worked from mid-morning until dawn the following day compiling a list of equipment. It was delivered to Wright Field before the deadline.

Army engineers broke ground for two new hangars in May, 1942. Each hangar was to be 400 feet long, 160 feet wide, 55 feet in overall height and each equipped with a two-story lean-to, 40 feet deep and 400 feet long. Included in the building project was an L-shaped employee cafeteria occupying 3,750 square feet and capable of seating 180 employees at a time, and an airplane parking area of 1,000,000 square feet. While waiting for construction to be completed, two outdoor production lines, illuminated at night with large flood lights, were set up. The first plane moved into the new hangars early in September. In August, 1943, ground was broken for another building to include a hangar, warehouse and garage, all under one roof. The new structure was to be 160 feet deep, 400 feet long, 55 feet high and equipped with a two-story lean-to 400 feet long and 80 feet deep.

While these improvements were being made, B-17Es and Fs flowed through United's "temporary" setup in a steady stream. From April, 1942, to September of the same year, the output of modified planes averaged 30 per month.

October began to show benefits of the new hangar space, with production that month having stepped up to a monthly average of 60, which was continued until January, 1943.

During the first month of 1943, 111 planes rolled down the runways. Production was so increased that, for the first six months of that year, an average of six planes daily left Cheyenne on their way to combat areas. This average was increased for the last six months of 1943.

The reason for modifying so many planes should be explained. Airplane production today is on an assembly-line basis. Reports for desired changes frequently are received from combat zones and plane manufacturers can't revamp assembly lines and still keep up with production schedules. Furthermore, planes being built today are destined to go to all parts of the globe. Some need winterizing, some equatorial equipment. Mass production is a highly standardized procedure. Consequently, it saves time to have modification centers make last-minute changes according to special combat or geographical needs.

Many of the earlier modifications made at Cheyenne have long since been adopted and are being installed at the airplane factories. Parts and blueprints made by United have been sent to all companies manufacturing the Forts.

Planes sent to Cheyenne after June, 1942 needed different and frequently more complicated changes than did previous arrivals. Some of the major modifications included cheek-gun installations on either side of the plane's nose, construction of a monocoque gun mount for .50-caliber machine guns, installation of "chin" gun turrets, and revamping of entire tail turret assemblies.

Not all the orders for modification came from the AAF. Occasionally, employees make valuable suggestions. The monocoque gun mount was the result of engineering ingenuity of WW Erickson, a member of United's supervisory staff at Cheyenne.

Another suggestion, which since has proved a boon to aerial gunners, was made by members of the "Jack the Ripper" bomber crew returned from combat. They complained that use of their inter-communicating microphones had necessitated the removal of one hand from the gun controls in order to push the switch button on the mike. Sometimes this happened during critical moments of an air battle.

United engineers rebuilt the mike control switch, placing in on the machine-gun grip. This device now is used on most airplane machine guns. All the gunner has to do to switch on his mike is to slip his thumb to the side of the gun grip.

Production at Cheyenne steadily increased; the personnel roster grew longer.

In March, 1942, United had 625 employees at work in its maintenance base. These employees were, at that time, devoting 25 percent of their time to modification.

By the middle of April, 1942, the company started hiring additional personnel. Some of United's crack traffic salesmen were transferred from key cities to Cheyenne to help put over the job. They "beat the bushes," recruiting cowpunchers, tractor operators, farmers, high school and college graduates, garage mechanics, stenographers, beauticians, teachers and clerks from nearby towns and cities. By July, between 400 and 500 skilled and semi-skilled people were doing nothing but modification work. By the time a norm was attained in the spring of 1943, the company had over 1,600 modification workers.

Of these new employees, more than 50 percent were women. They were put to work as sheet-metal fabricators, drill and punch press operators, riveters, and at other mechanical operations. Their average age is about 26 years while the average age of men at the center is considerably higher, and a goodly proportion of the workers have have husbands, sons or daughters in the armed services, some of them flying the Fortresses modified at Cheyenne.

This article was originally published in the July, 1944, issue of Flying magazine, vol 35, no 1, pp 52-54, 114, 118.
The PDF of this article [ PDF, 11 MiB ] includes 3 photos of rework going on on B-17s, one photo of the "Cheyenne turret" tail gun station on a B-17, and two B-17 pilots conferring with UAL engineers.
Photos credited to United Air Lines.