General Dynamics Aircraft and Their Predecessors since 1912

J.Wegg - General Dynamics Aircraft and Their Predecessors since 1912 /Putnam/

By far the most widely-produced design by Dayton Wright was the DH-4. This is the 1,000th example, suitably marked for publicity photographs. Completed on 31 July, 1918, it arrived in France on 7 September.
DH-4 Conversions

   During the war, Dayton Wright received contracts for 5,000 DH-4s following modification of a pattern aircraft sent from Britain to accept the Liberty 12 engine and American 0.30in Marlin machine-gun. The final total of DH-4s delivered was 3,098, the rest being cancelled. In addition, there were substantial numbers remodelled or converted to DH-4A or DH-4B standard and 155 were transferred to the Navy and Marine Corp with the designation O2B.
   Dayton Wright also built the DH-4R, an unarmed advanced trainer conversion with dual controls, modified rear decking, and the gunner's position modified to an instructor's position. At least one Nine Hour Cruiser was completed, a DH-4 (30130) with an enlarged fuel tank positioned directly over the undercarriage, aft of the Liberty engine and ahead of the two open cockpits. With double the normal endurance, nonstop flights were claimed possible between New York and Chicago. The D.W.H.4 Blue Bird was a dual-control trainer version, with the same modifications, produced in small numbers for the Army.
   Three USD-9As (equivalent to the D.H.9A) were also built (40044, 40118/40119) and the second was tested at McCook Field with the number P-80.
   The first postwar civil conversion offered was the DH-4K Honeymoon Express, a three-seat sport conversion of a DH-4B with a 1ft longer fuselage, displayed at the Aeronautical Exhibition, Madison Square Garden, New York City during 1-15 March, 1919. The two passengers were carried in an enclosed cabin behind the pilot's open cockpit and it was powered by a 400hp Liberty 12. One aircraft (race number 32) was entered in the Aviation Country Club Trophy Race at the Pulitzer Races, Detroit, in October 1922. Piloted by Lt H R Harris of the USAAC, it won against three other competitors.

   One 400hp Liberty 12 twelve-cylinder water-cooled engine.
   Span 42ft 5 1/2in; length 31ft 1 1/2in; height 11 ft 9in.
   Weight empty 2,400 lb; gross weight 3,410 lb.
   Maximum speed 115mph; climb 10,000ft/10min; endurance 2.25hr (88US gal fuel capacity).
Nine Hour Cruiser (30130) with enlarged tank between the Liberty engine and cockpits.
This Dayton Wright conversion of a DH-4 is believed to be the Honeymoon Express. In any event, it has an enclosed rear cockpit seating two in tandem.

   A few months after the United State entered the Great War, a scheme was devised to spring a surprise attack on German cities and industrial targets behind the front line using large numbers of unmanned flying bombs. By this action, it was hoped that morale would be broken and the conflict brought to a swift conclusion.
   The Aircraft Production Board issued specifications in great secrecy in early October 1917 to three manufacturers, Dayton Wright, Curtiss, and Lawrence Sperry. The requirements were simple, a small self-controlled aircraft capable of flying 200 miles, carrying 200 lb of explosives, with the cost not to exceed $200 each. The trajectory had to be predetermined on the ground and an electrically-driven gyro controlled the direction of flight, an altimeter the height, and a subtracting anemometer the distance. A speed of over 100mph was desired but not specified.
   Initial studies were undertaken by Fred Nash and Orville Wright designed a small biplane which came to be known as the Bug. Constructed of scrap aircraft spruce, plywood, and paper, the Bug could be assembled in five minutes by two men with a screwdriver and spanner. Initially, a two-cylinder engine was planned for the Bug, but this idea was abandoned in favour of a 37hp four-cylinder engine designed by Dayton Wright and built by the DePalma Manufacturing Co. This drove a 5ft diameter wooden propeller and the control surfaces through a system of valves and bellows.
   Early in 1918, Kettering decided to build a man-carrying biplane to test the new engine and a lightweight single-seater was designed by O W Thomas, formerly of Thomas Brothers, and now with Dayton Wright. The aircraft was built at South Field and flown by Howard Rinehart in early spring. However, the engine was unsuited for manually-controlled flight and the testbed was quickly abandoned.
   Test flights with Bugs started in late spring, launching Bugs from a car driven on a track, and in calm air the Bug flew well at 120-125mph. After inspection by the Army, at least twenty Bugs were sent to NAS Pensacola for trials and 'shot' at anchored targets 90 mil s away in the Gulf of Mexico. Evidently, these were successful and a contract for full-scale production awarded but the signing of the Armistice caused the Bug's cancellation.

Span 15ft; length 12ft.
A Bug on its launching framework.
A Bug about to be launched during trials as NAS Pensacola, Florida.
In 1919, Orville Wright designed the O.W.-1 Aerial Coupe, a three-passenger cabin design based on the DH-4 with a 180hp Wright-built Hispano-Suiza E or Packard 8. The advertising brochure described it as 'luxuriously furnished, combining comfort and beauty with safety.' The entrance for the pilot, who also sat in comfort, and the passengers was through a full-size door in the cabin side which bisected the upper longeron. Thus, usual longeron stress was carried up and over the door frame. A five-hour endurance was claimed at 87mph (350-400 miles). Shown at air exhibition in Chicago, New York, and San Francisco in 1920, the sole aircraft established a new American altitude record on 22 May when B L Whelan carried three passengers to 19,710ft over McCook Field. The three-passenger record was popular in 1920, the OW broke one set at 17,150ft five day earlier, but itself was beaten four days later by an Army aircraft topping 20,000ft. Another publicity gimmick was the delivery of ice-cream from Cleveland to Washington for the banquet of the Retail Ice Cream Dealers' Association on 30 May. The O.W.-1 was sold to J G Montijo, California.

   Span 46ft; length 2 ft 6in; height 9ft 9 1/2 in; wing area 534sq ft.
   Weight empty 1,450 lb; gross weight 2,492 lb.
   Maximum speed 95mph; range 500 miles (70US gal fuel capacity).
O.W.-1 Aerial Coupe used the wings and basic frame of the DH-4, but had a four-seat cabin.
T-4 Messenger

   Based upon experience with the man-controlled Bug testbed, the single-seat Messenger was similarly-powered by a 37hp DePalma four-cylinder air-cooled engine. The fuselage consisted of longerons with veneer sides and wooden strips instead of wires. The sole aircraft built was shown at the Aeronautical Exhibition, Madison Square Garden, New York City, during 1-15 March, 1919, but development was abandoned later in the year. Contemporary reports refer to it as an intended army liaison type adapted for civil use.

   Span 19ft 3in; length 17ft 6in; height 6ft 1 in; wing area 106 sq ft.
   Weight empty 385 lb; gross weight 636 lb.
   Maximum speed 85mph, climb 3,000ft/10min; endurance 2.5 hr (12US gal fuel capacity).
T-4 Messenger (37hp DePalma).

   The United States had received a sample Bristol F.2b Fighter in September 1917 and immediately started work to convert it with a Liberty 12 engine. This resulted in an aircraft weighing 3,600 lb and the programme had been abandoned after twenty seven were completed by Curtiss. Instead, lighter engines were adopted including the 300hp Wright-Hispano and the Liberty 8.
   At McCook Field, the Engineering Division designed a new plywood fuselage, lighter and stronger than the original, and with the 300hp Wright-Hispano H engine the conversion was known as the XB-1A. Armed with two Browning and two Lewis guns, three Engineering Division prototypes were built, the first flying on 3 July, 1919. Dayton Wright completed four more (64115/P-171, 64300/P-180, 94107/P-150, and 94108/P-151). These were followed by a contract for forty XB-1As (64156/64194, 64300) placed with Dayton Wright on 28 June, 1920. Four of these were tested at McCook (64158/P-179), 64160/P-181, 64161/ P-182, 64177/P-205) and two were transferred to the Navy (BuA 5974/5975). The others were assigned to the 12th Observation and 13th Attack Squadrons in Texas.

   Span 39ft 4in; length 25ft 6in; height 9ft 10in; wing area 406sq ft.
   Weight empty 2,155 lb; gross weight 3,791 lb.
   Maximum speed 130mph; cruising speed 101mph; climb 6,500ft/7.5 min; service ceiling 18,900ft; range 495 miles/4hr at 10,000ft (100US gal fuel capacity).
XB-1A 64158/P-179 at McCook Field.

   Thomas started work on his first aircraft at Hammondsport in November 1909 and the pusher biplane was first flown from Page Farm, Hornell, New York, the following spring by Bert Chambers. The machine seated pilot and passenger side-by-side on the leading edge of the lower wing. In its first form, large panels pivoting on fore and aft hinges at the centre of the outboard wing struts served for roll control. Later, these were replaced with ailerons. The four-wheel undercarriage was mounted on bamboo skids attached to the wing centre section that supported the 22hp Kirkham automobile engine with its chain-driven propeller. With two on board it could stay aloft for 20 minutes. Subsequently the elevator, supported by bamboo struts, was modified and twin rudders fitted and the chain-drive was abandoned in favow' of a direct-drive system.

Span 27ft; weight empty 650 lb.
The first Thomas design in its original configuration with large panels mounted outboard of the wing struts.

   The second Thomas design was a refinement of the first and initially flew at Bath with a 50hp Kirkham six-cylinder aero-engine that permitted up to three persons, including the pilot, to be carried. During 1911, it was converted into a successful hydroplane by substituting pontoons for the wheels, and was still able to carry one passenger.
   In 1912, a further improved model TA was built with a 65hp Kirkham engine and on 31 October, was flown by Walter E Johnson at Bath with a passenger for 3hr 51min, an American endurance record. The improved TA also won a series of races including the 25-mile $1,000 prize event at the Syracuse State Fair in 1912

TA Tractor

   In 1912, an unsuccessful tractor version of the TA biplane was built (or converted from an existing TA) with a 50/65hp Kirkham engine, fitted with a single pontoon and outrigger floats for water-based operations. Performance was not as good as the original TA and further work was abandoned in favour of pusher designs.

Span 37ft; weight empty 900lb; maximum speed 58mph; endurance 2hr.

Model E

   Developed from the TA, twelve aircraft were reportedly built from 1913 with 65hp Kirkham engines. The specifications were similar to those of the TA but at least one, known as the Special Biplane, had 33ft span wings and a gross weight of 850 lb. Fitted with an 80hp Curtiss engine, one was flown by Frank H Burnside, an early graduate of the Thomas School of Flying and subsequently chief pilot of the company, to 13,000ft in 1913 to claim a new US altitude record. One aircraft survives with Cole Palen's collection at Old Rhinebeck, New York.
The Model TA in its original form with a 50hp Kirkham engine with single pilot controls.
A Model TA converted as a hydroplane. This may be the improved version with a 65hp Kirkham as it has dual controls
TA Tractor with 50hp Kirkham engine.
Model E single-seater.
Model B Flying-boats

   A side-by-side two-seat biplane flying-boat with a 60/65hp water-cooled engine was built and flown from Lake Salubria in 1912. A second, more refined 'boat, was built with a 90hp Austro-Daimler engine and was capable of 65mph.
Original Flying-Boat, on Lake Salubria in 1912.
Second Flying-Boat, with a steel-covered hull and a 90hp Austro-Daimler engine.

   A single-seat monoplane with a 50/60hp Maximotor four-cylinder engine was built in 1913 and was flown during the spring. The paired four-wheel undercarriage was supplemented by skids. The intention was to install a 70hp Kirkham engine but it is unlikely that this was done.

Span 32ft, length 30ft; weight empty 750 lb.
Thomas Monoplane (50hp Maximotor).
Nacelle Pusher

   Two similar 'nacelle pusher' biplane designs were built and flown during 1913. Both featured paired four-wheel/skid undercarriages and had the elevator and twin rudders supported by a bamboo frame extending from the wing centre section. The single-seater, also referred to as the Standard Biplane, had a 10ft longer-span upper wing, a 65hp Kirkham engine, and a nacelle mounted in between the wings. The three-seater, powered by a 90hp Austro-Daimler engine, had the longer nacelle attached directly to the lower wing.

(Single-seater): Span 37ft; weight empty 900 lb; maximum speed 58mph, endurance 2hr.
Single-seat Nacelle Pusher (1913).
Three-seat Nacelle Pusher (1913) with 90hp Austro-Daimler engine.
Model B Flying-boats

   A side-by-side two-seat biplane flying-boat with a 60/65hp water-cooled engine was built and flown from Lake Salubria in 1912. A second, more refined 'boat, was built with a 90hp Austro-Daimler engine and was capable of 65mph. As the Thomas brothers had trouble with the wooden hull absorbing water, thus adding weight to the aircraft, 30-gauge galvanised iron sheets were used to cover the wooden frame hull of the second aircraft, reinforced at the bow and underneath with wood planking. In 1914, a third design appeared with the same engine and this, together with a more streamlined model produced in 1915, also with a 90hp Austro-Daimler, has been referred to as the B-3. Possibly, one of the airframes was a conversion of an earlier aircraft. In any event, the final aircraft was built of mahogany and intended as a luxurious cruiser for two or three people.

1914 model
   Span 36ft 4in; length 25ft 6in
   Weight empty 1,275 lb.
   Maximum speed 65mph.

1915 model (B-3 or B-4)
   Span 38ft; length 28ft 6in; wing area 360sq ft.
   Weight empty 1,250 lb.
   Maximum speed 70mph; endurance 4hr.
The 1914 model Flying-Boat (B-3) on Lake Salubria.
1915-model Flying-Boat (B-4) with streamlined bow and extended fin.

   The first design by B Douglas Thomas for Thomas Brothers was based on the Model J he had designed for Curtiss. Work started at Bath then moved to Ithaca, New York, on 7 December, 1914, and the first flight was made soon after arrival there. Powered by a 90hp Austro-Daimler, the T-2 had two-bay wings and was rated as the best performing aircraft of its day achieving a maximum speed of 83mph and climbing with one passenger and a 1,000 lb payload to 3,800ft in ten minutes.
   A British purchasing commission tested it and placed orders for twenty four for the RNAS in 1915 in two batches of twelve (3809-3820, 8269-8280) powered by 90hp Curtiss OX-5 engines. Reportedly, there were no additional orders because of a growing shortage of the Curtiss OX.
   A single main float development with a three-bay wing and enlarged fin and rudder was the SH-4 of which fifteen were ordered by the Navy (A-134/136, 395/406) in 1916.

   Span 36ft; length 26ft; wing area 350sq ft.
   Weight empty 1,075 lb; gross weight 1,972 lb.
   Maximum speed 83mph; climb with full load 3,800ft/10 min.
Prototype T-2 at Ithaca (90hp Austro-Daimler).
D-2, HS, D-5

   A two-seat, two-bay equal-span biplane of fabric-covered wooden construction similar to the T -2 was first flown in spring 1915 by Frank Burnside. Powered by a 135hp Sturtivant engine, the D-2 achieved an unofficial world record of 97.4mph and a rate of climb of 4,500ft in ten minutes. Two D-2s with twin main floats and a pontoon skid fitted directly underneath the rear fuselage were ordered by the Navy in July 1915 with the designation HS (AH-20/21, later A-57/58). A prototype HS was first flown from Renwick Park, Cayuga Lake, in late summer 1915 but the extra drag of the floats demanded higher power settings for which the radiator was inadequate. A heavy alighting was suffered early in the flight-test programme, following radiator problems, which necessitated repairs and subsequently the aircraft was destroyed, without fatal injuries to the pilot, when it crashed into the lake in early winter.
   The two Navy aircraft were modified after the crash of the first HS to incorporate side mounted radiators for improved engine cooling, an upper wing with 11ft 6in increased span and larger ailerons, instead of upper and lower ets previously. The rear pontoon underneath the tail was lowered by mounting it on struts that lifted the rear fuselage out of the water. The first (AH-20) was shipped to Pensacola, Florida, with a 135hp Sturtevant engine in late February 1916, and accepted after flight tests on 30 March. The second, with a 135hp Thomas 8 engine, almost a duplicate of the Sturtivant, was handed over on 18 June. Both were used for training flights until November, when they were reassigned for experiments with 'wireless', and both were struck from Navy records the following June.
   The D-5 was similar to the D-2 but had unequal span wings, the upper wing with a considerable over-hang. Two D-5 observation models were built for the Army for evaluation in 1915 (114/115) with 135hp Thomas engines.

HS (revised version)
   Span 48ft 6in; length 29ft 9in; height 10ft 3in; wing area 441sq ft.
   Weight empty 2,600 lb.
   Maximum speed 82mph.
Prototype HS (135 hp Sturtivant) at Renwick Park (now Stewart Park), Ithaca, in summer 1915. The small window in the fuselage forward of and below the cockpit assisted judgement in landing.
One of two D-5s built for the US Army in 1915 (135hp Thomas 8).

   Twin 186hp tractor-type 'battleplane' with pilot and two gunners in central nacelle, twin booms and tail. Two seaplane designated Type S for Navy (BuA-140/141) were cancelled.

   Span 44ft; length 28ft 9in; wing area 440sq ft.
   Gross weight 2,860 lb.
   (Estimated) Maximum speed 81mph; climb 330ft/min; endurance 4.5hr.

   A single main float development with a three-bay wing and enlarged fin and rudder was the SH-4 of which fifteen were ordered by the Navy (A-134/136, 395/406) in 1916.
SH-4 A-402 photographed on 18 June, 1918.
S-4 Series

   In late 1916, B Douglas Thomas designed a conventional biplane scout trainer around the 100hp General Vehicle Company-built nine-cylinder Gnome rotary engine. The prototype was tested in spring 1917 at Ithaca by Frank Burnside. In June 1917, it was evaluated by the Army at Hampton, Virginia, as an advanced trainer. The prototype's Gnome engine was unsuitable for cruising and it suffered from a 5 lb or 6 lb tail-heavy condition, therefore it was only used for short exhibition and training flights, accumulating a total of 250 hours by the time it was scrapped.
   At the request of the Engineering Division, a number of changes were made to the design including shortening of the fuselage by 2ft 9in, replacement of the Deperdussin-type control wheel with a stick, reduction in area of the ailerons, elevators and rudder, and trailing edges changed from wood to steel. In this form, one hundred S-4Bs (4276/4375) were ordered on 3 October and a second prototype incorporating all the specified revisions was flown in November. This, however, crashed on landing at Cornell University on 21 December, 1917, when being flown by Tex Marshall, and was destroyed.
   The wings of the S-4B were said to have the largest stagger of any aircraft built up until then, but structural tests with sandbags weighing over seven times the aircraft weight proved that there was no weakness. The fuselage was built of spruce and ash member with fabric covering except for an aluminium firewall and cowling. One S-4B (4355) was tested at McCook Field as P-26.
   These were followed by fifty S-4Cs (41359/41408) with push rods and torque tubes for aileron control, similar to the Nieuport, an example of which had been sent to Ithaca, and provision for one Marlin 0.30in gun.
   The Gnome had proved troublesome, using 3 gallon of castor oil an hour and depositing a fine spray of it over the starboard wing and cockpit. The high-pressure fuel system when fractured in an accident would also spray fuel over the hot engine. Therefore, a further 447 S-4Cs (36509, 38633/38982, 44578/44674) were delivered with a 90hp Le Rhone C-9, which only consumed one gallon of oil an hour, built by the Union Switch and Signal Co, Swissvale, Pennsylvania. Another 500 were cancelled, after over half the parts had been already made, and one more S-4C was completed by the company as a demonstrator, making a total of 601 S-4/B/Cs built. Large quantities were used at Carlstrom Field, Arcadia, Florida; Gerstner Field, Lake Charles, Louisiana; and Rockwell Field, San Diego, California. The Navy also used ten S-4Bs (BuA 3235/3244) and four S-4Cs (BuA 5855/5858) diverted from Army stocks. Noted for its relatively high speed, climbing ability and reasonably fine handling in the air, the 'Tommy Scout' retained the tail-heavy condition of the prototype and was prone to ground looping.
   Following tests at Cayuga Lake with the prototype S-4 fitted with twin floats, six S-5s (BuA-757/762) were built in 1918 for the Navy. These were basically S-4Bs with triple floats copied from the Sopwith Baby and were used at NAS Dinner Key, Miarni. At least one (A-758) flew with a revised rudder which was taller, but of reduced span.
   During summer 1918 and the immediate postwar period, several designs based on the S-4 basic concept were completed. The S-4E was an aerobatic trainer with a 110hp Le Rhone, tapered wings and redesigned tail surfaces similar to the SPAD, and a new undercarriage. The top wing had a span of 22ft and the lower 14ft. Possessing a marked tail-heaviness and inadequate propeller ground clearance, it was sold engineless to Basil Rowe.
   The S-6, with two single-seat cockpits and dual controls, fuselage lengthened by 10in and a wing span of 29ft, was intended as a civil sport/training type and was powered by an 80hp Le Rhone. Entered in the 1919 National Air Races at Kansas City, it came second and it was flown by Paul D Wilson from Ithaca to Washington on 30 April, 1920, and on to McCook Field on 10 May to demonstrate its cross country ability. Top speed was 105mph and its ceiling was almost 20,000ft. Later registered C98, the S-6 was used by the Ithaca Flying Service, then sold to Fred Krehnlein of Rochester, New York, in 1931, and crashed after a low-altitude spin.
   The similarly-powered, 32ft-span S-7 accommodated the pilot and passenger in a single wide cockpit and was advertised as the Sociable Seater. The S-7 was designed by W T Thomas, Agnew Larsen, and Raymond Dowd, and completed in 29 days after work started. First flown by Tex Marshall, it was eventually sold to Basil Rowe and Clarence Chamberlain and used for aerial mapping.
   Using the wings from the S-6 and standard S-4C tail surface, but with a side-by-side two-seat cockpit and powered by a 200hp Lawrance J-1, the S-9 trainer of 1923 featured a wraparound corrugated sheet metal fuselage in a conventional configuration to respond to current Army interests. The company-owned prototype was tested at McCook Field as P-313 and later at Kelly Field, Texas, and finally written off in a crash following failure of a wing strut attachment fitting.
   The S-4 series was popular on the secondhand market and over sixty were registered to private owners until grounded by the increased stringency of regulations in the late 1920s. Some were re-engined with the SuperRhone ZR-l and ZR-2, radials converted from rotaries by Tips and Smith Inc, Houston, Texas. Many S-4s were converted with 90hp Curtiss OX-5 water-cooled engines, some with a second seat behind the pilot. Another side-by-side two-seat version using the OX-5 was manufactured by the Yackey Aircraft Company, Maywood Field, Illinois, as the Yackey Sport. Several were produced as Dycer Sports by Charles Dycer at Dycer Field, Los Angeles, in 1926-27. Private owners made innumerable modifications and some S-4s were converted into parasol monoplane configuration. One such conversion was fitted with an arcurate control system, designed by R C Stroop, in Alabama in 1932. The upper wing panels of S-4Cs were used on the initial examples of the popular Heath Parasol built in 1927 and several S-4Cs were used by Hollywood for film making. One was leased to Northwest Airways for one month in October 1926 to start mail services.
   Also favoured for air racing, one S-4C flown by H F Cole came second in the On to St Louis race at the 1923 National Air Races. Another, registered G-CAEH, was entered at Dayton in 1924 and an S-4C modified with a Curtiss OX-5 came second in the On to Dayton race, flown by Charles Holman. For the following year's races, Basil L Rowe modified the S-4E with a 135hp Aeromarine 737 liquid-cooled V-8 engine. Named Space-Eater, it won first place in the Free-for-All race at Mitchel Field, New York, averaging 102.9mph. Second in the event was a S-4B (Curtiss OX-5) flown by E P 'Bert' Lott. Rowe won the B B T Trophy race at Philadelphia with Space-Eater in 1927.
   A number of S-4s are extant in museums in the United States and two are still regularly flying in the Spokane, Washington, area, and at Old Rhinebeck, New York.

   Span 26ft 8in; length 19ft 10in; height 8ft 1in; wing area 234sq ft .
   Weight empty 963 lb; gross weight 1,373 lb.
   Maximum speed 95mph; climb 7,500ft/10min; service ceiling 15,000ft.
The prototype S-4 with 100hp Gnome had a 29ft 5in long fuselage.
More 'Tommy Scouts' were built than any other Thomas-Morse type and it was the most famous American aircraft of the First World War, even though it took no part in the conflict. This is an S-4B in 1918-style US Army Air Service markings.
S-4C 38635 (Le Rhone C-9) at Rockwell Field, San Diego, in late 1918.
The Thomas-Morse S-4C was the nearest thing to a single seat fighter that America was to produce during World War I. The design of the S-4 was started in the autumn of 1916, ahead of the January 1917 founding of the Thomas-Morse Company that was to produce it. Initially powered by the troublesome 100hp US licence-built Gnome Monosoupape, later replaced by a 100hp Le Rhone C9, the first S-4 made its initial flight in the spring of 1917, leading to its evaluation by the US Army's McCook Field in June 1917. Satisfied by these trials, the Army ordered 100 modified machines with a shorter fuselage and smaller control surfaces, known as S-4Bs, for use as unarmed fighter trainers. Ordered in October 1917, the first of the S-4Bs were delivered the following month. In January 1918, the Army placed an initial order for 50 of the single .300-inch Marlin armed S-4Cs. In all, the Ithaca, New York-based company went on to build a known 609 S-4s, of which the S-4C was the dominant version. Even US Navy bought a known twelve. Although clearly obsolescent by 1918 standards, the underpowered and underarmed S-4C, with its 95mph top level speed was reported to have been quite agile, if a little tail-heavy. The US Army S-4C seen here, serial no 38635, was photographed at San Diego's Rockwell Field in late 1918.
The S-4E was designed for aerobatic training, with a 110hp Le Rhone and tapered wings.
The S-4E was later raced by Basil Rowe with a 135hp Aerornarine 737 engine with the name Space-Eater.
The S-4E Space Eater, fitted with an Aeromarine B engine and cylindrical Lamblin radiator between the undercarriage struts.
With two seats and dual controls, the S-6 was intended for the civil market but only one was built.
Also a two-seater, the S-7 had a single cockpit and side-by-side seating and was advertised as the Sociable Seater.
This OX-5 conversion of an S-4 has the second seat behind the pilot.
The Yackey Sport, a two-seat conversion of the S-4, had an OX-5 watercooled engine.
Popular on the civil market after the First World War, there were a number of conversions made to the S-4. One of the more radical was made by Lawrence W Brown at Clover Field, Santa Monica, California, who turned an S-4 into a two-seat monoplane with a Curtiss OX-5 engine and a radiator from a Curtiss JN-4.
Thomas-Morse S-4C
S-4 Series

   Following tests at Cayuga Lake with the prototype S-4 fitted with twin floats, six S-5s (BuA-757/762) were built in 1918 for the Navy. These were basically S-4Bs with triple floats copied from the Sopwith Baby and were used at NAS Dinner Key, Miarni. At least one (A-758) flew with a revised rudder which was taller, but of reduced span.

   After concentrating on trainers, attention was turned to an experimental two-seat, high-wing parasol monoplane (Mono-Biplane) fighter, powered by a 400hp Liberty 12. Faired struts offered additional lifting area and in an effort to make the airframe as light as possible, all metal parts were given holes and the plywood bulkheads had cut-out sections. Even the control column was perforated.
   Two aircraft were ordered (including one for static tests only) in 1918 and built at the Center Street building. But by the time the prototype had reached the flying field, towed behind a truck, the undercarriage had already been weakened and repairs had to be made. When the aircraft sat in the hangar, the tailskid fittings failed and the skid was pushed through the tail. Taxi-ing and flight tests were begun on the ice of Cayuga Lake but the undercarriage failed on take-off on its first flight. The MB-1 was repaired and flown only once more, then abandoned.

Span 37ft; length 22ft.

   The second attempt at a pursuit fighter, the MB-2 was a two-seat, two-bay equal-span biplane with a 400hp Liberty 12-C with spur-gear reduction mechanism and a two-bladed propeller. The top wing had conventional front and rear spars but the lower wing had an additional centre spar and radiators each side of the fuselage. The single prototype (25806) was later fitted with a 450hp Liberty, a four-bladed airscrew, and a new radiator system, but performance was still poor and it was scrapped in 1918 along with the half-completed fuselage of a second aircraft.

Span 32ft; length 24ft.
MB-3 Series

   In 1918, Thomas-Morse was invited to design a new single-seat fighter, superior to the latest SPAD models, around the 300hp Wright H licence-built Hispano-Suiza water-cooled V-8 engine. The all-wooden design was entirely conventional with a one-piece upper wing and two separate lower sections of RAF 15 aerofoil with solid spruce spars and three degrees of dihedral. Ailerons were fitted to the upper wing only which accommodated a radiator and a 3-gallon gravity fuel tank and featured a large cut-away section to enable the pilot access to a very cramped cockpit. Space was so limited that there was no room for a panel for instruments and these were scattered around wherever space could be found. Two other fuel tanks were placed in the fuselage, one of 18US gal capacity forward of the pilot and one 20US gal under the rudder bar. Two 0.30in Marlin machine-guns were mounted beneath a turtle-deck cowling.
   Four prototypes (40092/40095) were ordered in September 1918 and the first of these flew at Ithaca on 21 February, 1919, achieving a speed of 168mph and climbing to 10,000ft in 4min 52sec - claimed as an unofficial world record for Service-type aircraft. Shipped to the Air Service's Engineering Division at McCook Field, Dayton, Ohio, for static testing, 40092 did not fly again. The other three prototypes were assigned 'P-numbers' by the Flight Test Section, P-66 (40093, cannibalised for parts after 1921), P-124 (40094, damaged in transit and returned to factory for repairs, crashed 30 March, 1921), and P-121 (40095, survived until October 1926).
   Although the McCook pilots found the MB-3 easy to taxi and the flight characteristics generally favourable, they reported that the pilot's view in the air was poor and the cockpit was far too small. Maintenance was a severe problem, especially concerning fuel leaks from the complicated shape of the main tank and oil would become trapped in the bottom of the fuselage causing the supports to rot and allow the tank to break through after only ten hours of flight. The radiator gave trouble, as did the untried and complicated fuel system which necessitated the cutting of holes into the fuselage structure to gain access to the magnetos. Also, the airframe suffered badly from engine vibration. In response to these criticisms, several modifications were made to 40095. The cockpit was lengthened (but not widened), the radiator was moved slightly to the right of the centreline to allow for a larger 12US gal gravity fuel tank, and structural strengthening increased the empty weight by 130 lb.
   In this revised form, together with a cut-down vertical fin, the Army ordered 50 production MB-3s (63331/63380) from Thomas Morse on 19 June, 1920, which were delivered from November. Four production aircraft were tested at McCook (P-164/63332, P-197/63336, P-201/63338, and P-208/63337) to develop further improvements including more structural reinforcement and a revised cooling system with radiators each side of the cockpit instead of one on the upper wing.
   A contract for two hundred MB-3As (68237/68436) with the above revisions plus an armament of one 0.30in and one 0.50in Browning machine-gun was given to Boeing in April 1921 which had underbid Thomas-Morse (and four other manufacturers) under the competitive bidding system then prevailing. Worth nearly one and a half million dollars, it was the largest contract for pursuit fighters awarded until 1937. One pattern aircraft (63332) was sent to Boeing but crashed on landing at Seattle. The first Boeing-built MB-3A was flown at Camp Lewis on 7 June, 1922, and on landing, ran through a small ditch and overturned. All aircraft were delivered between 29 July and 27 December, 1922. Two and four-bladed propellers, the latter an attempt to reduce vibration, were used interchangeably on the MB-3A and the final fifty aircraft had redesigned tail surfaces with the fin area more than doubled (a feature tested on 68237/P-259 at McCook).
   After replacement in front-line service by Boeing MB-3As, some MB-3s became MB-3M advanced trainers at Kelly Field, Texas, with the 43rd School Squadron and were finally withdrawn from use in 1929. The MB-3B was a Boeing-proposed model with a 2ft stretched fuselage and four ailerons but was not accepted.
   The MB-3 and MB-3A were both used for air racing, starting in 1920 when Capt Harold E Hartney was placed second in the Pulitzer Trophy Race in a prototype MB-3 (number 41). Another prototype MB-3 (number 43) was entered by Lt Leigh Wade but had to retire after the first lap. Army use of the MB-3 in the races continued until 1923.
   For the following year's races, Thomas-Morse received a contract for three MB-6s on 24 May, 1921 (68537/68539). These were clipped wing (19ft span) versions of the MB-3 with a 6in shorter fuselage, gross weight reduced to 2,023 lb, and a 400hp Wright H-2. The three were shipped unflown from Ithaca to McCook Field and after one was used for static testing (68539/P-370), another (68537) was first flown on 21 October by Lt John A Macready. However, this was destroyed in a landing accident four days later when flown by Capt C C Moseley (winner of the 1920 race). Therefore, the surviving MB-6 (redesignated R-2 in the Army Racer series) was shipped directly to Omaha, and with Macready came second with a speed of 160.7mph.
   A second Army contract had been placed on 16 May, 1921, for twelve MB-3s for delivery to the Marines. This was later changed at the Navy's request to ten MB-3s (BuA-6060/6069) and two MB-7 monoplane racers (BuA-6070/6071 ex-64373/64374). The MB-7 featured a modified 24ft span strut-braced parasol 'Alula' wing and a 400hp Wright H-2. First flown on 24 October at Ithaca by Hartney, the first MB-7 (64373) crashed after fuel pump failure during the races. Completed in February 1922, the second MB-7 had a Wright H-3 engine and was first flown on 14 April by Marine Lt Francis P Mulcahy. However, it failed to finish in the 1922 Detroit event because of an overheated engine. After the race, the MB-7 was stored at the Naval Aircraft Factory, Philadelphia, until scrapped in May 1925.
   An eleventh MB-3 was built to replace the crashed MB-7 and assigned the unused serial A-6070. All the MB-3s were delivered to MCAS Quantico during February 1922 for use by the Third Marine Air Squadron. After limited use they were stored, then delivered to the Army at Langley Field in 1923.
   In 1927, several MB-3Ms and MB-3As were used in the filming of Wings to portray SPADs and German aircraft. Filming was mostly done at McCook and several were destroyed in crash scenes.

   One 300hp Wright H (Hispano-Suiza) eight-cylinder water-cooled engine.
   Armarnent: Two 0.30in Marlin machine-guns.
   Span 26ft 0in (upper), 24ft 6in (lower); length 19ft 11 in; height 8ft 6in; wing area 250.5sq ft.
   Weight empty 1,506 lb; gross weight 2,094 lb.
   Maximum speed 152mph at sea level; cruising speed 144mph; climb 1,930ft/min; 6,500ft/3.9min; service ceiling 23,700ft; range 288 miles (41 US gal fuel capacity).
With the MB-3, Thomas-Morse had the chance to obtain a major US Army contact which would have guaranteed it a postwar role as a major manufacturer. However, through competitive bidding, Boeing obtained the order for the improved MB-3A and Thomas-Morse turned its attention to the less lucrative task of developing all-metal designs.
The second production MB-3 at McCook Field, marked P-164.
Thomas-Morse MB-3
Three clipped-wing MB-6s (400hp Wright H-2) were produced for the US Army for the 1921 National Air Races.
The first Navy MB-7 racer, with an Alula wing, crashed during the 1921 races at Detroit.