MANUFACTURER(S): Stinson - USA
OPERATORS: United Kingdom; United States
LENGTH: 34.25 feet (10.44 meters)
WIDTH: 50.85 feet (15.5 meters)
HEIGHT: 10.17 feet (3.1 meters)
WEIGHT (EMPTY): 2,668 pounds (1,210 kilograms)
WEIGHT (MTOW): 3,406 pounds (1,545 kilograms)
ENGINE: 1 x Lycoming R-680-9 radial piston engine developing 295 horsepower.
SPEED (MAX): 121 miles-per-hour (195 kilometers-per-hour; 105 knots)
RANGE: 280 miles (450 kilometers; 243 nautical miles)
CEILING: 12,795 feet (3,900 meters; 2.42 miles)
RATE-OF-CLIMB: 410 feet-per-minute (125 meters-per-minute)
Detailing the development and operational history of the Stinson L-1 Vigilant (Model 74) Liaison / Observation / Utility Aircraft.
Entry last updated on 6/12/2016.
Authored by Staff Writer. Content ©www.MilitaryFactory.com.
The massive American military of World War 2 (1939-1945) fielded various "Light Observation and Liaison" aircraft during the years-long conflict. One entry became the Stinson L-1 "Vigilant" of which 324 were completed. A first-flight was had on July 15th, 1940 and service introduction arrived in 1941. The system went on to be used by both the United States Army Air Corps (USAAC) and the British Royal Air Force (RAF). Design of the aircraft is attributed to A.P. Fontaine with all manufacture stemming from the Stinson Aircraft Corporation.
Observation and Liaison aircraft in military service provide improved communication for ground forces by giving a much-needed "eye in the sky". These aircraft are typically constructed as light as possible with few creature comforts for the crew and allow for basic performance while being very rarely armed. A high-wing monoplane fit is also typical as this generates inherent lift and allows the already light aircraft to loiter on station for longer periods of time when compared to traditional aircraft. It also allows these aircraft to operate from short, little-prepared airfields or rough terrain. A Short Take-Off and Landing (STOL) feature became common to such aircraft.
Prompted by the impressive showing of a German Fieseler "Storch" liaison aircraft at the Cleveland Air Races, the USAAC pushed forth a requirement in 1938 for a similar-minded aircraft. Nearly a dozen concerns threw their hats into the ring but Stinson was able to convince USAAC authorities of the merits of their proposed lightweight platform. The aircraft became known internally as the "Model 74" and carried the usual traits - a high-wing monoplane, fixed undercarriage, limited internal space, a nose-mounted engine, and traditionally-arranged tail unit. Internally, the aircraft's construction was largely of steel tubing while its skin consisted of fabric and some light metal.
Stinson L-1 Vigilant (Model 74) (Cont'd)
Liaison / Observation / Utility Aircraft
The prototype was taken on by the Army for evaluation as the "YO-49" and managed a first-flight on July 15th, 1940 (American had yet to officially enter the war). Power was from a Lycoming engine which drove a two-bladed constant speed propeller at the nose. Satisfied with their new little aeroplane, the YO-49 graduated into the O-49 "Vigilant" through a 142-strong initial production batch. Then followed 182 examples of the O-49A standard which brought along an increased (13 inches) fuselage. The O-49B was a modified air ambulance with fewer than five converted for the role.
In 1942, the line was redesignated under the more familiar "L-1". The L-1 was the original O-49 while the O-49A and O-49B became the L-1A and L-1B respectively. The L-1C were additional air ambulance types modified from the L-1A stock and 113 conversions to this standard followed. The L-1D became a training glider tug (mothership) aircraft and as many as twenty were converted for the role. The L-1E became another air ambulance (based on the L-1 form) but these were given special equipment to operate as amphibians for water rescues. Seven conversions followed. The L-1F was similar and built up from the L-1A production stock - five conversions were seen. CQ-2 marked L-1A conversions by the United States Navy (USN) for service as target control aircraft. Few were procured.
Under Lend-Lease, the Vigilant was adopted by the RAF and arrived in the Vigilant Mk I (L-1) and Vigilant Mk II (L-1A) offerings.
Beyond its typical over-battlefield roles, the L-1 was pressed into other non-direct-combat roles - artillery spotting, light transport, special forces/mission support. Many saw modification in-the-field to fulfill even more non-official roles as needed. The series saw wartime service until the end of the conflict in 1945 and soldiered on for a time longer. Before the cessation of hostilities, the L-1 was already being challenged by entries from Piper (L-4 "Grasshopper") and by Stinson's own L-5 "Sentinel".
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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.
Relative Maximum Speed Rating
This entry's maximum listed speed (121mph).
Graph average of 112.5 miles-per-hour.
Graph showcases the Stinson L-1A Vigilant's operational range (on internal fuel) when compared to distances between major cities.
Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units