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Thomas-Morse S-4

Advanced Flight Trainer Biplane Aircraft

Thomas-Morse S-4

Advanced Flight Trainer Biplane Aircraft


The Thomas-Morse S-4 series of advanced flight training biplanes emerged during the World War 1 period from American aero-industry.
National Flag Graphic
ORIGIN: United States
YEAR: 1917
STATUS: Retired, Out-of-Service
MANUFACTURER(S): Thomas-Morse Aircraft - USA
OPERATORS: United States

Unless otherwise noted the presented statistics below pertain to the Thomas-Morse S-4C model. Common measurements, and their respective conversions, are shown when possible.
LENGTH: 19.85 feet (6.05 meters)
WIDTH: 26.51 feet (8.08 meters)
HEIGHT: 8.04 feet (2.45 meters)
WEIGHT (EMPTY): 882 pounds (400 kilograms)
WEIGHT (MTOW): 1,334 pounds (605 kilograms)
ENGINE: 1 x Le Rhone 9C air-cooled rotary piston engine developing 80 horsepower while driving a two-bladed wooden propeller unit at the nose.
SPEED (MAX): 96 miles-per-hour (155 kilometers-per-hour; 84 knots)
RANGE: 233 miles (375 kilometers; 202 nautical miles)
CEILING: 14,764 feet (4,500 meters; 2.80 miles)

1 x 0.30 caliber Marlin machine gun.
Graphical image of an aircraft medium machine gun

Series Model Variants
• 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.


Detailing the development and operational history of the Thomas-Morse S-4 Advanced Flight Trainer Biplane Aircraft.  Entry last updated on 11/9/2018. Authored by Staff Writer. 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.

Thomas-Morse S-4 (Cont'd)

Advanced Flight Trainer Biplane Aircraft

Thomas-Morse S-4 (Cont'd)

Advanced Flight Trainer Biplane Aircraft

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.


Our Data Modules allow for quick visual reference when comparing a single entry against contemporary designs. Areas covered include general ratings, speed assessments, and relative ranges based on distances between major cities.

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Relative Maximum Speed
Hi: 100mph
Lo: 50mph
This entry's maximum listed speed (96mph).

Graph average of 75 miles-per-hour.
City-to-City Ranges
Graph showcases the Thomas-Morse S-4C's operational range (on internal fuel) when compared to distances between major cities.
Aviation Era
Pie graph section
Pie graph section
Pie graph section
Pie graph section
Pie graph section
Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production (583)
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units

  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.

Altitude Visualization
Small airplane graphic
Supported Roles
Ground Attack
Aerial Tanker
A2A=Air-to-Air; UAV=Unmanned; CAS=Close Support; ASW=Anti-Submarine; AEW=Airborne Early Warning; MEDEVAC=Medical Evac; EW=Electronic Warfare; SAR=Search-Rescue
Commitments / Honors
Military lapel ribbon for Operation Allied Force
Military lapel ribbon for the Arab-Israeli War
Military lapel ribbon for the Battle of Britain
Military lapel ribbon for the Battle of Midway
Military lapel ribbon for the Berlin Airlift
Military lapel ribbon for the Chaco War
Military lapel ribbon for the Cold War
Military lapel ribbon for the Cuban Missile Crisis
Military lapel ribbon for pioneering aircraft
Military lapel ribbon for the Falklands War
Military lapel ribbon for the French-Indochina War
Military lapel ribbon for the Golden Age of Flight
Military lapel ribbon for the 1991 Gulf War
Military lapel ribbon for the Indo-Pak Wars
Military lapel ribbon for the Iran-Iraq War
Military lapel ribbon for the Korean War
Military lapel ribbon for the 1982 Lebanon War
Military lapel ribbon for the Malayan Emergency
Military lapel ribbon representing modern aircraft
Military lapel ribbon for the attack on Pearl Harbor
Military lapel ribbon for the Six Day War
Military lapel ribbon for the Soviet-Afghan War
Military lapel ribbon for the Spanish Civil War
Military lapel ribbon for the Suez Crisis
Military lapel ribbon for the Vietnam War
Military lapel ribbon for Warsaw Pact of the Cold War-era
Military lapel ribbon for the WASP (WW2)
Military lapel ribbon for the World War 1
Military lapel ribbon for the World War 2
Military lapel ribbon for the Yom Kippur War
Military lapel ribbon for experimental x-plane aircraft
* Ribbons not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns/operations.

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