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Thomas-Morse S-4

Advanced Flight Trainer Biplane Aircraft

United States | 1917

"The Thomas-Morse S-4 series of advanced flight training biplanes emerged during the World War 1 period from American aero-industry."

Authored By: Staff Writer | Last Edited: 11/09/2018 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site; No A.I. was used in the generation of this content.
What became the Thomas-Morse Aircraft concern of the United States was started in 1910 by brothers William Thomas and Oliver Thomas as the "Thomas Brothers Company". It remained in operation until 1929 when it was taken over by the Consolidated Aircraft Corporation - makers of the famous World War 2-era B-24 "Liberator" heavy bomber. From 1910 until that time, the brothers managed a healthy collection of products related to the world of aviation including the D-2, T-2, and S-4 offerings. The S-4 was of particular note, developed as an advanced flight trainer of biplane form and extensively utilized by the United States military during the World War 1 (1914-1918) period.

Over 500 of its type were produced and many ended up in private circulation after their military days had ended.

The United States entered World War 1 in April of 1917 following the sinking of the passenger ship Lusitania by German U-boat. This spurred American industry into action in support of the war effort in Europe. The S-4 owed its design roots to one Benjamin Thomas (unrelated to the brothers), and English engineer who had previously plied his trade with the famous Sopwith Aviation Company (makers of the classic Sopwith "Camel" biplane fighter of the First World War). The Thomas-Morse S-4 aircraft was constructed as soon as June 1917 and recorded its first-flight over Ithaca, New York, that same month. In this form, it carried a Gnome rotary engine of 100 horsepower output with two-bladed propeller unit.

The end-product was of traditional biplane wing arrangement with an upper and lower wing member in play supported by angled, parallel struts and cabling. The wings were of equal span and single-bay arrangement. A fixed, two-wheeled undercarriage with tailskid unit allowed for ground-running. The pilot sat in an open-air cockpit aft of the engine in the nose and under/aft the upper wing member. The tail unit was of conventional, single-rudder design. The engine fit drove a two-bladed wooden propeller in "puller"/"tractor" fashion consistent with the times.

Dimensions included a length of 19.9 feet, a wingspan of 26.5 feet, and a height of 8 feet. Gross weight became 1,330lb.

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Three prototypes proved the S-4B model and this carried the Gnome rotary engine of 110 horsepower. Some 100 of this mark were ordered during the summer of 1917 with the U.S. Army taking a stock of 97 of the aircraft while the U.S. Navy added another six in floatplane configuration as the "S-5". The S-4B became the definitive advanced flight trainer for the U.S. air service for a good part of the war until succeeded by the S-4C mark. These were given Gnome B-9 series engines of 80 horsepower and were represented through six prototypes followed by some 461 serial aircraft, four also added (again, in floatplane arrangement) to the USN stable. After the 52nd example came off the line, the C-mark was updated with the Le Rhone 9C engine of 80 horsepower.

With the 9C engine unit, the aircraft could make top speeds nearing 100 miles per hour and fly up to a ceiling of 15,000 feet. Endurance was a 2.5 hour window giving good range for a trainer type. A single air-cooled 0.30 caliber Marlin machine gun could be installed for gunnery training.

In service, the aircraft became known as "Tommy".

A post-war attempt to sell the military on a new model, the S-4E, with revised tail unit and Le Rhone 9J 110 horsepower powerplant failed, leading to this aircraft being re-engined with an Aeromarine unit of 135 horsepower and flown by air racer Basil Rowe as the "Space-Eater"

The S-4 proved a quite the success for both the American Army and Navy during the wartime period as its numbers and popularity would eventually show. Their availability in number naturally led to many being acquired by way of surplus at the civilian market level in the post-war years where they continued on as trainers, racers, aerobatic performers, and flyable Hollywood props - such was their versatility. Many of these post-war models adopted the Curtiss OX-5 engine for drive power instead of the original military fits.

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Power & Performance
Those special qualities that separate one aircraft design from another. Performance specifications presented assume optimal operating conditions for the Thomas-Morse S-4C Advanced Flight Trainer Biplane Aircraft.
1 x Le Rhone 9C air-cooled rotary piston engine developing 80 horsepower while driving a two-bladed wooden propeller unit at the nose.
96 mph
155 kph | 84 kts
Max Speed
14,764 ft
4,500 m | 3 miles
Service Ceiling
233 miles
375 km | 202 nm
Operational Range
City-to-City Ranges
Operational range when compared to distances between major cities (in KM).
The nose-to-tail, wingtip-to-wingtip physical qualities of the Thomas-Morse S-4C Advanced Flight Trainer Biplane Aircraft.
19.8 ft
6.05 m
O/A Length
26.5 ft
(8.08 m)
O/A Width
8.0 ft
(2.45 m)
O/A Height
882 lb
(400 kg)
Empty Weight
1,334 lb
(605 kg)
Design Balance
The three qualities reflected below are altitude, speed, and range. The more full the box, the more balanced the design.
Available supported armament and special-mission equipment featured in the design of the Thomas-Morse S-4 Advanced Flight Trainer Biplane Aircraft .
1 x 0.30 caliber Marlin machine gun.
Notable series variants as part of the Thomas-Morse S-4 family line.
S-4 - Base Series Designation
S-4B - Fitted with Gnome 110hp engine; three prototypes completed; 97 ordered by U.S. Army aviation and a further 10 examples for the USN.
S-5 - USN examples numbering six with floats for waterborne landings and take-offs.
S-4C - Succeeding B-model aircraft; six prototypes; completed with Gnome B-9 80hp (early) or Le Rhone C-9 80hp (52 aircraft onwards) engines; 461 examples to U.S. Army with four floatplane derivatives delivered to USN.
S-4E - One-off model with revised tail section and Le Rhone 9J rotary of 110hp for aerobatic service; later fitted with Aeromarine engine of 135hp for racing pilot Basil Rowe.
Global customers who have evaluated and/or operated the Thomas-Morse S-4. Nations are displayed by flag, each linked to their respective national aircraft listing.

Total Production: 583 Units

Contractor(s): Thomas-Morse Aircraft - USA
National flag of the United States

[ United States ]
Relative Max Speed
Hi: 100mph
Lo: 50mph
Aircraft Max Listed Speed (96mph).

Graph Average of 75 MPH.
Era Crossover
Pie graph section
Pie graph section
Showcasing Aircraft Era Crossover (if any)
Max Alt Visualization
Small airplane graphic
Production Comparison
Entry compared against Ilyushin IL-2 (military) and Cessna 172 (civilian) total production.
MACH Regime (Sonic)
RANGES (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hi-Hypersonic: 7673-19180 | Reentry: >19030
Aviation Timeline
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Image of the Thomas-Morse S-4
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Mission Roles
Some designs are single-minded in their approach while others offer a more versatile solution to airborne requirements.
Some designs stand the test of time while others are doomed to never advance beyond the drawing board; let history be their judge.
Going Further...
The Thomas-Morse S-4 Advanced Flight Trainer Biplane Aircraft appears in the following collections:
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