P.Bowers Curtiss Aircraft 1907-1947 (Putnam)

Model S (Model 10)

   The first Model S of 1916 was a single-seater built to the concepts of what European builders had called a Scout in 1914. This was a single-seat tractor biplane originally used for the work its name implied - the scouting of enemy activity. Early scouts were unarmed but new designs were soon fitted with fixed forward-firing machine-guns; even though they then became fighters or pursuit planes, the term Scout stuck to the single-seaters almost to the end of the war.
   Curtiss developed several different Scout models in its S-series of 1916-17, but succeeded in selling only a few to the US Army and Navy. The inadequacy of these aeroplanes cannot be blamed on lack of skill among the Curtiss designers; rather, it showed how far the US aviation industry had fallen behind that of Europe, which was operating under the immediate requirements of the European war. American designers were almost completely cut off from the latest European advances and had to progress from the 1914 designs on their own without the stimulus and large-scale financing of a war economy.

S-1 Speed Scout - Also called Baby Scout, the original Model S-1 was the smallest aeroplane that Curtiss could build around the 90 hp OX engine. Construction was thoroughly conventional for the time, but the 20-ft (6,09 m) span of the single-bay wings was inadequate. The upper wing was lengthened and the strut arrangement was altered to two spanwise Vs. The S-1 did not sell, and Curtiss kept the modified prototype for its own use.

S-2 Wireless - The S-2 was essentially the Model S-1 fitted with new wings and a strut arrangement that eliminated the need for wing bracing wires, hence the name Wireless. The problem of fining shock absorbers in the undercarriage when the wing struts were anchored to the ends of the cross-axle was solved by using the new Ackermann Spring wheels, which featured curved spokes made of flat spring steel that served that purpose; these wheels did not have good resistance to side loads, unfortunately, and were not widely used.

   Powerplant: 100 hp Curtiss OXX-2. Span 21 ft 10 in (6,65 m) (upper), 11ft 3 in (3,42 m) (lower). Aerofoil Eiffel 32. Empty Weight 805 lb (365 kg). Maximum speed 119 mph (191,5 km/h).

S-3 (Model 10) - The only 'production' models of the S-series were four S-3 triplanes sold to the US Army early in 1917 (serial numbers 322/325). These used the basic fuselage, engine, and tail of the S and S-2 fitted with single-bay triplane wings using the RAF 6 aerofoil. These were the Army's first single-seat Scouts, but they were still more than two years behind equivalent European types.

S-3
   Speed Scout. Single-seat. 100 hp Curtiss OXX·3.
   Span 25 ft (7,62 m); length 19 ft 6 in (5,94 m); height 8 ft 7 in (2,61 m); wing area 142,6 sq ft (13,24 sq m).
   Empty weight 970 lb (440 kg); gross weight 1,320 lb (599 kg).
   Maximum speed 115 mph (185 km/h); climb - 9,000 ft (2,743 m) in 10 min.

S-4 (Model 10A) - This was a triplane similar to the S-3 intended as a seaplane Scout for the US Navy (serial A149). This was Curtiss's first experience with the twin-float configuration. As with other Curtiss seaplanes, it became necessary to increase the span of the S-4 to carry the extra weight. The front float struts collapsed during a heavy alighting in January 1918 and the aircraft was struck off charge.

S-5 (Model 10B) - This was similar to the S-4 except for being fined with a single main float and small wingtip floats. Navy serial number A150, struck off on 6 August, 1919.

S-6 (Model 10C) - The S-6 was an improved version of the S-3 and was the first American Scout fitted with twin forward-firing machine-guns. This may have been only an inoperative test installation intended to check weight, balance, and location, for the guns were gas-operated Lewis models which were not used for synchronized fire through the propeller. The Army ordered twelve early in 1917 but only one, serial number 492, was delivered.

W.Green, G.Swanborough The Complete Book of Fighters

CURTISS S-3 USA

   Essentially a triplane derivative of the S-2 "Wireless" (signifying lack of wing bracing wires) unarmed biplane "scout”, the S-3, or "Triplane Speed Scout", possessed a similar fuselage and 100 hp Curtiss OXX-3 engine, and initially retained the ducted propeller spinner featured by the biplane. Interplane bracing employed ‘‘K”-type struts and, on its second flight during the summer of 1917, the S-3 attained an altitude of 16,500 ft (5 030 m), which was a record at the time. For initial trials, the centre wing was attached to the fuselage at low shoulder position, but the gap between all three wings was subsequently increased and the centre wing was raised above the fuselage. After redesign of the rudder and the discarding of the ducted spinner, the S-3 successfully completed evaluation trials and four were ordered during the course of 1917 for the US Army Signal Corps. It was proposed to arm the S-3 with two unsynchronised Lewis guns which were to fire over the propeller arc, but the S-3s were, in the event, delivered to the Signal Corps without armament.

Max speed, 115 mph (185 km/h).
Time to 9,000 ft (2 745 m), 10 min.
Empty weight, 970 lb (440 kg).
Loaded weight, 1,320 lb (599 kg).
Span, 25 ft 0 in (7,62 m).
Length, 19 ft 6 in (5,94 m).
Height, 8 ft 7 in (2,62 m).
Wing area, 142.6 sq ft (13,25 m2).


CURTISS S-6 USA

   A refined version of the S-3 with revised strutting carrying the centre section of the upper wing and the root attachments of the centre wing, a modified undercarriage and other changes, the S-6 triplane of 1917 was the first US "scout" to be fitted with twin forward-firing machine guns, these being gas-operated Lewis guns which were mounted side-by-side on inverted and inclined "V" struts immediately beneath the centre section of the upper wing and firing outside the propeller disc. Only a single example of the S-6 was built and tested.

Max speed, 110 mph (177 km/h).
Loaded weight, 1,377 lb (625 kg).
Span, 25 ft 0 in (7,62 m).
Length, 19 ft 6 in (5,94 m).
Height, 8 ft 7 in (2,62 m).
Wing area, 142.6 sq ft (13,25 m2).

G.Swanborough, P.Bowers United States Military Aircraft Since 1909 (Putnam)

CURTISS S-3

   The four Curtiss S-3s (serials 322/325) of 1916/17 were developed from two earlier Curtiss single-seaters that were not bought by the Army. The S-1, known as the Baby Scout, was the smallest aeroplane that could be built around the 90-100 h.p. Curtiss OX-series engine, with a 20-ft. span. The S-2 had a larger upper wing and a unique “wireless” system of wing bracing. The S-3 substituted wire-braced triplane wings but was otherwise identical to the S-2. Although tested with an armament of two forward-firing Lewis guns, the S-3s were unarmed in service and were used only as trainers.

Журнал Flight

Flight, September 7, 1916.

A NEW CURTISS "WIRELESS" SCOUT.

   ON August 9th some very interesting trials were carried out at the Curtiss Aerodrome, Buffalo, N.Y., when Victor Carlstrom, the well-known Curtiss pilot, put the new Curtiss model S-2 "wireless" scout through her paces. Equipped with a 100 h.p. Curtiss engine, the machine made a speed of 119 m.p.h. over a measured course. This is claimed to be a world's record for speed with an engine of this power.
   As regards the body, the new scout, it will be seen, is very similar to the previous type Curtiss scout, but several alterations are noticeable in the arrangement of the main planes. In the first place, the lower wing is of quite short span, and a single strut on each side connects it to the upper wing. This strut is spread out at its upper and lower ends so as to take care of the travel of the centre of pressure for various attitudes of the wing. No external wire bracing of any kind is employed in the wing structure, the single strut effecting all the trussing. The undercarriage is also of an unusual type. In addition to the usual "V" chassis, there are struts sloping backwards and outwards from the axle to the lower wing spars at the point where is attached the inter-plane struts. When the machine is in the air, these struts, it will be seen, are working in tension, thus partly taking the place of the usual lift wires. Some slight "cleaning up" changes in the design including an annular conical stream-lined casing over the boss of the tractor screw, are being made which will, it is anticipated, increase the speed of the machine to about 125 m.p.h. The span of top plane is 21 ft. 10 ins., and bottom plane 11 ft. 3 ins.