Modeling AAF Equipment

by Brian Hedges

Scale models of new AAF equipment aid in planning design of aircraft and in developing new tools and hangar layouts.

Working from rough sketches, Army Air Forces technicians more than two years ago built a tiny model of a mobile repair shop. Scaled down to one-thirtieth of actual size, the model was used experimentally to see how it would work with various types of Army planes. On the basis of their experiments, equipment experts drew up blueprints and built a full-sized model. Again satisfied, they ordered manufacturing plants into production. Today, real life "big brothers" of that carefully constructed model are being flown into every war zone to aid in servicing and repairing Allied combat planes.

That is but one example of hundreds in which engineers at the Air Forces experiment center at Wright Field, Dayton, OH, have utilized models to help them develop new maintenance and repair devices and other equipment. It's their favorite, however, because they estimate their model shop saved the Government thousands of dollars and many man-hours necessary to have built several life-size units.

Following the automobile and ship-building industries as well as that of aerodynamic experts at wind tunnels, engineers of the Materiel Command's miscellaneous equipment branch have built models of almost every known piece of Air Forces equipment in use plus some still on the drafting boards.

The models are used in technical discussions and at conferences in Washington. One small precision-built model of a Lockheed Lightning has served as a means of developing more than 10 vitally needed pieces of maintenance equipment — including hangars, ladders, gasoline servicing units and even portable jacks.

The plant for construction of these models is a small workshop manned by a highly trained staff of enlisted men. Here the models are scaled down from sketches or full-sized blueprints and then fashioned, mostly by hand, out of light wood and metal. Models built by these soldier-technicians range in size from a tiny half-inch light jack to a three-foot scale model of a four-engined bomber complete with retractable landing gear.

Models became an integral part of the development of new devices when Col Rudolph Fink, chief of the miscellaneous equipment laboratory, discovered he needed some means of adding perspective to illustrate his verbal explanations. He found, too, that actual, small-scale tests with the models made possible many more experiments than did the drafting board and ruler.

Searching for a technician who would understand his ideas and his problems, Colonel Fink finally discovered a young soldier who once had fashioned scale models of Liberty ships for a southern ship builder. Thus, more than two years ago, the equipment model unit was set up and a few weeks later a replica of the mobile repair shop was placed on Colonel Fink's desk.

The colonel was delighted with results of the first use of the model. The tiny shop had a packing case which could be removed easily. The shop's plastic top could be opened to permit a small figure, one-thirtieth the size of the average Air Forces mechanic (who is 5' 10" tall), to be placed inside at miniature machine tools which had been carefully fashioned as tiny counterparts of the life-size tools.

During conferences held to decide the worth and practicability of such a mobile unit, Colonel Fink time and again placed the small, telescoped model in the replicas of transport and cargo planes which were coming from the new workshop. His ideas were portrayed vividly and the colonel and other engineers quickly realized the mobile shop was everything it was hoped to be. The rest is history. The full-sized models started off the production line and now are in use by the Air Service Command.

"Building the models first," Fink explained, "makes it possible to study desirable shapes and sizes for the large equipment without going into the tremendous cost involved in building full-sized products."

He cited a specific example. "We found that portable repair scaffolds were needed, We drew sketches and specifications and then built 12 models of different sizes and shapes before we finally found the one that was right. We fitted the model scaffolds on miniatures of almost every type of Army plane. The final model was interchangeable on many different types of planes as is the present full-scale scaffold now in use.

"Life-size scaffolds of each type would have cost us about $2,000 each and would have required much time on the part of workmen. By using the models we saved several thousand dollars and more than six months' time which would have been required for building and testing the full-size scaffolds."

Colonel Fink's offices and the equipment laboratory are well stocked with models of various pieces of Air Forces equipment. On Colonel Fink's desk is a miniature truck modeled after the two-ton version which is seeing service in Australia and North Africa. On a nearby desk is a sleek model of a Lightning. In other offices are scaled-down jeeps, mobile repair shops, portable houses and hangars, gasoline trucks, replicas of a Curtiss Caravan, a Douglas Skytrain and a Flying Fortress.

One of the most interesting is the replica of a six-wheeled truck-trailer combination, so complete in detail that it even has a tiny rear view mirror. It is painted the same Army drab which covers every large piece of Army equipment. Another intricate unit is a model of a 25-ton crane which lifts large bombers as though they were sacks of wheat. Hundreds of parts went into that model and the soldiers who built it declare it took their full time for three weeks.

Lift the cover of a miniature jeep's motor and you'll find a replica of a regular engine, complete with carburetor and spark plugs so small you have to look twice to make sure you see them.

Head of the model workshop is Staff Sgt Joseph Fallo, 25, of New Orleans, LA. One of the first to help Colonel Fink in developing the model program, Fallo formerly built scale models of Liberty ships for Higgins Industries, Inc, the New Orleans shipbuilding firm. Assigned to the laboratory and told to produce models, the sergeant worked night and day on the first ones and soon had them rolling smoothly toward Colonel Fink's desk.

Sergeant Fallo is especially proud of an exact, model of a North American Mitchell. The full-sized version reached Japan in the Doolittle raid, while Fallo's Mitchell has traveled thousands of air miles to serve as an example for engineers all over the country.

Recently the sergeant finished another Mitchell bomber — a one-tenth scale flying model powered by two one-fifth hp gasoline motors. It has a wingspan of 6 ft 8 in and weighs only six pounds. Like the other models, covering for the wings and, fuselage is a heavy drafting detail paper found to be most satisfactory because of its light weight and sturdy qualities, Turrets and cockpit openings are of Plexiglas and the landing gear, also like other smaller models, is retractable.

"Models aren't hard to build if you know something about engineering and drafting," Fallo declared. "I usually fashion pieces of a model as I go, putting them in the framework as I complete them. Of course, you have to be sure when to put the right piece in at the right time so that you won't have to tear it down to add a forgotten strut or something."

Tools used by Fallo and. other model builders — among whom is another former Higgins worker — include wood-turning lathes, jig saws, planers and many hand tools. "Most of the work is done with small hand tools," Fallo explained.

Materials include balsa and light plywood, thin aluminum and tin, all of which goes into the wings, fuselages and tail surfaces. Plexiglas simulates cockpit shields, windows and turrets. Drafting paper, of course, is used for skin covering.

Parts of the planes and trucks are glued or tacked together. Thin wire forms control columns, seats and other equipment.

Builders of the models are quick to point out that problems of fashioning such miniatures are much different from those of the aerodynamic experts who use models in wind tunnels for air flow and stress tests. Wind tunnel models are usually built of solid pieces of mahogany or other hardwoods. Months are spent in developing a wing or tail surface. Whereas solid models are heavy and usually not made to be moved about, the scale models built in the equipment laboratory must be light, serviceable and constructed so that as many parts as possible are movable.

Recently, Wright Field designers were asked to develop a new hangar. Many hangars were needed to house planes and repair shops for units overseas and one of the biggest problems was the need to design one which could be used for all types of planes. Designers drew complete blueprints and sent them to the workshop. There the model builders made one-thirtieth scale units from the blueprints. In the conference rooms those hangar models were placed on the tables and engineers fitted miniature Lightnings, Fortresses, Skytrains and many other types of craft into various parts of the tiny structure.

Corrections in design were made to permit the huge (by comparison) Fortresses to be placed in the hangars — wider doors were needed and slightly more space above the ship seemed necessary. Corrections were made on the blueprints and contracts let to manufacturers. Weeks later the first hangars were shipped to Wright Field for exhaustive tests. Those hangars now are gracing the edges of flying lines at numerous Allied bases in England.

Not all models used at the field and in Washington are built in the experimental center's workshop. A number of models fashioned by soldiers in combat areas have been sent back to illustrate developments which have proved successful on the combat lines. One model was built from parts of .50-caliber shells. Colonel Fink and his staff won't talk about those models because many developments still are unknown to the enemy.

Engineers are finding more and more uses for the models. Some have been used on tiny sets for making training films. Still others have been used in the camouflage laboratories where "daubers" paint and repair them to discover the right color combinations to make them hard to see. Hundreds of thousands of civilians have gasped over the realistic qualities of the models which are being used in displays and expositions sponsored by the Army Air Forces. Museums all over the country are clamoring for the right to display the models "after the war."

Officers in the field laboratory say they are finding it increasingly difficult to keep the models on their desks — "they keep disappearing and then suddenly turn up in some other laboratory where a technician has found he needed a good model."

The following scene is duplicated at Wright Field day after day:

Army officers with a sprinkling of civilian experts are clustered interestedly about a table which holds several models — planes, small trucks, a jeep and even a tiny scaled figure of a man. The onlookers seem not unlike the familiar group of boys experimenting with a new kite in some neighborhood workshop. Unlike boys, however, the men are not playing. Their faces are tense as they push a tiny jeep into the nose of a glider. Then they push another piece of equipment into the glider and stand erect, smiling their satisfaction.

With the aid of the models, they have solved another difficult technical problem. Soon, jeeps and guns which the models have proved could be carried in planes and gliders will be unloaded from advanced landing strips ready to roll up roads leading to the enemy.

This article was originally published in the December, 1943, issue of Flying magazine, vol 33, no 6, pp 58-59, 104, 108.
The PDF of this article includes photos featuring B-17 and B-25, and a color photo of a table top of models.
Photos credited to Bervin A Johnson, US Army Air Forces.