Stinson L-5 Sentinel
Light Reconnaissance / Observation / Liaison Military Aircraft
The Stinson L-5 Sentinel series was a purpose-built Army liaison light aircraft that appeared during the fighting of World War 2 and saw service into the Korean Conflict.
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Light aircraft were a common sight throughout the wars of the 20th Century where their loitering and short-field/rough-field capabilities allowed commanders to have active, in-the-sky liaison, observation, spotting and other over-battlefield roles handled by such types. The Stinson Aircraft Company, an aero-company established in 1920, made a name for itself producing these sorts of aircraft for both civilian and military service. Their business ran into the 1950s before going defunct but, before that time, the company was well-recognized for such high-winged designs as the L-5 "Sentinel".
The Sentinel became a major player for the Americans during World War 2 (1939-1945) and was produced to the tune of 3,896 aircraft from the period spanning 1942 until 1945. The series was developed directly from the existing, experimental Stinson "YO-54", another high-winged vehicle that appeared in 1939 and was eventually taken into service by the United States Army (the aircraft was based in the earlier Stinson HW-75). The Sentinel, however, found greater success for its time in the air and went on to be used by all the major services of the American military as well as the Royal Air Force (RAF) among others.
The L-5 became a purpose-built liaison military aircraft specifically for use in World War 2. Prior to this, the military had simply adopted, and modified, existing lightweight civilian aircraft for the role. The then-United States Army Air Corps (USAAC) evaluated the YO-54 during 1940 even before the United States committed to the fighting of the Second World War but the aircraft had a poor showing. This forced Stinson to modify the design from a side-by-side twin-seater to a slimmer, lighter tandem-seater with more power to boot. Reinforced for the rigors of military service, the aircraft re-emerged as the Model V-76. By this time, Stinson fell under the Vultee Aircraft brand label and its path was set.
With America now fully involved in World War 2, the V-76 was fast-tracked into service and adopted in 1942 as the "O-62". It was not until 1943 that the official designation of L-5 "Sentinel" was finally assigned - this coinciding with the official creation of the "liaison category" within the United States Army regarding its aircraft.
The series proved its value throughout the conflict, ferrying VIPs, evacuating wounded, spotting for artillery, photographing key areas, delivering vital communications, food, medicines and the like for its part in the war. Its high-winged design allowed for excellent short-field capabilities where lift was needed quickly to get the aircraft airborne in short order. Additionally, such aircraft had the capability to seemingly "hover" for short periods of time, extending loitering times, preserving fuel and providing stable reconnaissance platforms for the observer in the second seat. Its rugged nature soon earned the series an excellent reputation that lasted well beyond the end of the war in 1945.
The aircraft saw service in all major and minor theaters of conflict for the Allies during the period. This included operations in the Pacific as well as Europe and the Far East. Its availability in the post-war world also ensured it a place in the Korean War (1950-1953) to follow where its legacy continued to be written.
The United States Navy and Marine services both utilized the type under the designation of "OY-1". The later-production OY-2, missing out on service in World War 2, was a refinement of the line by way of a 24-volt-based electrical system over the original 12-volt installation. The British acquired about 100 L-5 Stinsons for their part in the Second World War and this stock encompassed both L-5 and L-5B models (variants detailed below). As always, the British redesignated these American aircraft by naming them rather simply as "Sentinel I" and "Sentinel II", respectively. Many L-5 aircraft were used in the post-war period across civilian industries and were widely exported to American allies.
The line began with the O-62 with its Lycoming O-435-1 piston engine to which 275 of these were built to the standard. Variants then included the first L-5 marking 1,538 total examples which were known to the USN and USMC services as the OY-1. The L-5A became a cancelled version intended to carry a Ranger engine of 200 horsepower output as well as the 24v electrical system. The L-5B made it to production and numbered 729 in all - these differentiated by having an easy-access rear fuselage door and could furthermore accept a float undercarriage for water landings. The L-5C was finished with the K-20 reconnaissance camera fit specifically for photographic work. The L-5D designated was skipped which led to the L-5E produced in 750 examples with improved short-field/rough-field performance. The P-5G was the L-5E with the 24v electrical system and was powered by a revised Lycoming O-435-11 engine. 115 of this mark were produced.
The newly-founded United States Air Force redesignated their aircraft in 1962 so L-5 Stinsons became the "U-19" (A- and B-models based in the L-5 and L-5G, respectively). The L-5/235 was a glider towing variant of the line and the XL-5F was a one-off prototype aircraft fitted with the Lycoming O-435-2 engine.
L-5 Stinson Walk-Around
As built, the L-5 had a crew of two seated in tandem. Overall length of the aircraft was 24 feet with a wingspan reaching 34 feet and a height of nearly 8 feet. Empty weight was just 1,550lb with a possible MTOW of 2,050lb. Power was from a single Lycoming O-435-1 engine of 185 horsepower driving a two-bladed propeller at the nose. The never-exceed speed of the design was 163mph and range was out to 375 miles. Its service ceiling reached 15,800 feet and rate-of-climb was 900 feet-per-minute.