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Thomas Morse Scout

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Documentation

Thomas Morse Scout 54-C
The production record achieved by U.S. airframe and engine manufacturers during World War II will probably rank as an all-time industrial miracle. By comparison, the 1917~1918 effort appears insignificant, yet upon closer inspection the record discloses that the then infant aviation industry, starting from scratch, did a pretty fair job.

Outstanding among the American training aircraft produced in quantity during the participation in World War I was the Thomas Morse Scout, of which more than 550 were delivered to the Signal Corps during 1917 and 1918.

This plane, dubbed the "Tommy" by the student Army pilots who flew it, had a long and varied career sold as surplus after World War I in much the same manner as AT-6's and BT-1 3's have been after World War II, Tommies by the score were bought up by ex-Army pilots, sportsman pilots, and flying schools throughout the country.

The birth of the Tommy dates back to 1916. With the entry into the war imminent, the Aviation Section of the Signal Corps had at that time already realized the vast training gap which existed between the Curtiss primary trainers then In use and the French scouts that American pilots were to fly in France. Early in 1917, B. D. Thomas, then chief de signer for the Thomas Company produced the answer with his model S-4 biplane. The power plant chosen for the S-4 was the 100 hp Gnome rotary.

Ensuing tests carried out with S-4 at the government experimental station at Hampton, Va., were highly successful. The airplane's small size and low wing loading, coupled with its large control surfaces, produced excellent handling qualities. Power-on and off stability was good and its maneuverability remark able. The S-4s top speed of a little over 90 mph was considered too slow for combat service, but its possibilities as a combat trainer for the expanding air force were soon utilized by the government. Shortly after the entrance into the war, a production order for the Model S-4 Scout was placed with the Thomas Morse concern at Ithaca N.Y.

The first hundred production models delivered to the War Department in the fall of 1917 with modified fuselage and wings, were designated as Model S-4B's. The structural changes and design improvements made in the S-4B over the S-4 showed an in crease in top speed and a better rate of climb with the same engine. Type B-9 100 hp Gnome rotary engines were used in the production version. At about the same time that the Army version was being developed, a similar model, the S-5, fitted with floats, was produced for the Navy. Due to the added weight and drag of the float installation, the S-5 was slower than the S-4B model, but its performance was good enough to warrant a small order from the Navy Department.

By the summer of 1917, with the need for training machines ever, increasing, a large additional order for Thomas scouts was placed by the War Department. This order resulted in the last and best known of the Thomas scout-trainers, the Model 5- 4C. The principal differences between the S-4B's and the S-4C's were changes in the aileron control sys tem and power plant, and the addition of armament provisions. The first Model S-4C's were equipped with Gnome engines, but the Gnome was later re placed by an 80 hp Le Rhone rotary, manufactured by the Union Switch and Signal Company of Swissvale, Pennsylvania. As delivery in quantity of the S-4C Scouts began, they became the standard fighter-trainer.

Just as World War II saw the ultimate reached in the development of the piston-engine, low-wing fighter, so World War I witnessed the evolvement of a configuration that produced the most highly maneuverable combat airplanes ever built, the rotary-powered fighting scout or chaser. This biplane scout formula influenced fighter design for more than a decade after World War I.

The highly strung sensitivity of these early fighters resulted from, many factors which, added together, gave them their excellent handling qualities. The speed and climbing ability essential in a fighting airplane were gained by reducing the wing loading. This was accomplished principally through the use of the lightweight rotary engine. The weight carried per horsepower was about eight pounds, as com pared with the 18-18-lb. loadings of the heavier re connaissance types. Weight was also reduced in the structure, with a result that the average scout had a safety factor of about 5.5, or approximately half of that of the larger machines. High speeds and maneuverability called for small wing areas and short spans. The large control surfaces made for the extreme sensitivity with which the scouts were endowed, but also made them exceedingly difficult for, the novice to fly.

The short turning radius, which was the biggest advantage of the rotary scout over the in-line engine types, was due to two factors, a short stubby nose, with resultant reduction In propeller side forces, and the terrific gyroscopic action of the rotary engine.

This gyroscopic action meant that the revolving engine would resist a turning force when It was applied, and yet at the same time would exert a tendency to turn about its center on a line in the same plane but at right angles to its axis of rotation. This action produced a nose-down pitching moment during a left turn. This same action, however, when coupled with reduced propeller side forces and a short fuselage, made unbelievably fast right turns possible. It was this ability 'to turn on a dime and leave change' that as late as 1918 made even the best Fokker D VI pilots decline to fight the then obsolescent Sopwith Camels at lower altitudes. The Heinies weren't taking a chance.

The overall design of the Tommy was typical of fighting scouts produced during this period. The wing in plan form was a low aspect ratio biplane arrangement with positive-ranked wing tips. Both wings were of wooden two-spar construction with spruce and spars and box-type spruce compression members. The wings were arranged in a staggered decalage arrangement with the upper panels set at one degree positive incidence and the lower panels at onehalf degree. The upper wing was made up of two panels bolted together at the center without dihedral. The aileron control on the S-4C consisted of steel tubes connected to each aileron and running inboard along the rear spar. Oval bellcranks at the inboard ends of the tubes were connected by rod linkage to the aileron control torque tubes on the cockpit floor. The lower panels were bolted to steel crossover tubes mounted on the lower longerons.

The fuselage was conventional 'wire truss' construction with ash longerons and spruce vertical compression members. The upper longerons were swept down to provide a solid mounting for the stabilizer close to the thrust line. The fuselage upper deck was covered with aluminum from the cockpit forward. Aft of the cockpit, the upper and lower fuselage sections were faired with spruce caring strips. The cock pit area contained the pilot's metal seat, controls, and instrument panel.' The oil pulsation gauge, fuel gauge, tachometer, airspeed Indicator, altimeter, clock, and compass were standard equipment.

The landing gear was of the standard NV" type, made up of steel tubing faired with spruce and bolted to the lower longeron. The ash axle bearer was slotted to hoId the steel split-axle assembly. The axles Were bound at each outer extremity with shock cord. The tangential spoke wheels mounted 26 x 3 high- pressure tires and were faired with fabric covers that were laced to the rims.

The Le Rhone engine was installed In typical rotary fashion. The forward end of the fuselage was' fitted with an ~X type steel spider to which the nonrotating rear engine section was bolted. The oil and fuel tanks were mounted on the upper longerons, directly aft of the firewall. The circular firewall and engine cowlings were constructed of 20-gauge aluminum, and the engine cowlings were secured with six automotive-type trunk-lock fasteners. Tri angular-shaped engine accessory cowlings were located on either side of the fuselage. Flexible air-In- let tubes for the Le Rhone engine's block and tube carburetor, mounted on the end of the crankshaft, passed through the accessory cowlings.

When equipped as a gunnery trainer, the Tommy was fitted with a Mann .30-caliber aircraft machine gun mounted on the right side of the fuselage upper cowling. The gun was synchronized to fire through the propeller arc, and ammunition was carried in a compartment built integrally with the fuel tank.

Standard overall color scheme for the Tommy was olive-drab enamel. All exterior metal fittings were in dull black and the struts were treated with clear varnish. As was standard practice on all American training aircraft, serial numbers were painted in on the black fuselage sides. The serial numbers were also carried on the rudder, in addition to vertical red, white, and blue striping. The earlier versions of the S-4C's carried the concentric red, blue and white cocardes on the upper and lower wing surfaces. In late 1917, after adoption of the white star with a red center on a blue roundel, as the national insigne, all production Tommies reflected this change.

The photos in this documentation are from Scale Model Research, Bob Banka, 3114 Yukon Avenue, Costa Mesa, CA 92626. More extensive documentation is available from this source. Color prints with reference #142/19 for the civilian version at Antique Aero Ltd and 1989/22 for the A/C in Cradle of Aviation Museum at Mitchel Field, Long Island N.Y., presently crossed but reopening in 2000.


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