Stinson L - 5 Sentinel The Stinson L - 5 Sentinel was a World War II era liaison aircraft used by all branches of the U . S . military and by the British Royal Air Force . Along with the Stinson L - 1 Vigilant , the L - 5 was the only other American liaison aircraft of World War II that was purpose - built for military use and had no civilian counterpart . All other military liaison airplanes adopted during World War II were lightly modified " off - the - shelf " civilian models . Development . The origins of the L - 5 , affectionately known as the " Flying Jeep " , can be traced to the pre - war civilian Stinson HW - 75 . The 75 horsepower civilian high - wing design was built by the Stinson Aircraft Company at Wayne , Michigan and first flew in 1939 . The HW - 75 featured two seats up front side - by - side , and a third " jumpseat " in the rear in which a small passenger could sit sideways . The design was easy to fly , and it was difficult to stall or spin . Shortly after the introduction of the HW - 75 , Stinson became a subsidiary of the Vultee Aircraft corporation . Under Vultee management , the HW - 75 was equipped with an 80 - horsepower four - cylinder engine for the 1940 model year and the HW - 75 became known as the Model 105 " Voyager " , touting its 105 mph cruise speed . Fitted with a four - cylinder 90 hp Franklin engine for the 1941 model year , the type became known as the Model 10A . In the post - war era , the fuselage of the Model 10A was enlarged to accommodate four seats , and the four - cylinder powerplant was replaced with a Franklin 150 hp six - cylinder engine . This conversion became the Stinson Model 108 Voyager and the only civilian aircraft commercially produced by Stinson after WWII . Six examples of the Model 105 Voyager were equipped with 100 horsepower Franklin O - 200 engines and provided to the military for testing under the experimental designation YO - 54 . Evaluated by the U . S . Army and Air Forces in 1940 for potential use as a low - cost short range observation aircraft , it failed to meet performance requirements . The Voyager was then completely re - engineered by Stinson into a much stronger and more powerful tandem - seat airplane that met rigorous Army engineering handbook standards for the design of military aircraft . The prototype , designated as the Model V - 76 by Vultee / Stinson was accepted by the military after accelerated service trials and entered into service in December 1942 as the Army O - 62 ( ' O ' for observation ) . In March 1943 , with the creation of the liaison category of light observation aircraft , the designation was changed to L - 5 . The primary purpose as a liaison aircraft was courier and communication work , artillery spotting and casualty evacuation . The fuselage of later models was redesigned so the aircraft could also be used as an air ambulance , or for cargo work . With a wider and deeper rear fuselage section and a large rear door that folded downward , a litter patient or 250 pounds of cargo could be quickly loaded aboard . The L - 5 series was manufactured between December 1942 and September 1945 , during which time 3 , 590 of the unarmed two - seaters were built for the United States armed forces , making it the second most widely used light observation aircraft of the war behind the Piper L - 4 Cub . Construction . The fuselage was constructed using chrome - moly steel tubing covered with doped cotton fabric and the wings and empennage were constructed of spruce spars and plywood ribs and skins , also covered with fabric . The use of aluminum , which was in critically short supply and more urgently needed for other aircraft , was limited to the engine cowling , tail cone , framework for the ailerons , rudder and elevator and the landing gear fairings . The L - 5 was powered by a six - cylinder 190 horsepower Lycoming O - 435 engine . Operational history . Capable of operating from short unimproved airstrips , the L - 5 " Sentinel " delivered personnel , critical intelligence and needed supplies to the front line troops . On return flights , wounded soldiers were often evacuated to rear area field hospitals for medical treatment , providing a huge boost to the morale of combat troops fighting in remote areas . L - 5 ' s were used for many other important activities , such as aerial photography , controlling vehicle convoys , para - dropping food , medical supplies and ammunition , laying communication wire , distributing propaganda leaflets , spraying pesticide , transporting prisoners , and directing fighter - bombers to ground targets . The L - 5 was also popular with Generals and other high - ranking officers for fast , efficient short - range transportation . During the Battle of Okinawa , L - 5 operated from an LST using the Brodie landing system which allowed a light aircraft to take off and land without a flat surface by snagging a wire hung between two booms . One of the L - 5 that used the Brodie system off Okinawa is now on display at the Smithsonian Institution Aerospace Museum in Washington , DC . Variants . Five versions of the Sentinel were produced for the U . S . Army Air Force ( USAAF ) ; the L - 5 , L - 5B , L - 5C , L - 5E and L - 5G . There was no official L - 5A variant as is often reported because the designation was intended for a version of the aircraft that was never built . Nonetheless , many people in and out of the military still refer to the standard " observer " version of the L - 5 as an L - 5A . Like the L - 5A , the L - 5D was a planned version that was not adopted . A single L - 5F was an L - 5B equipped with an experimental low - noise " stealth " propeller and exhaust system for research purposes . An L - 5H version was on the drawing boards at Stinson when the war ended , and it never reached the prototype stage . The L - 5 carried a pilot and observer in a tandem seating configuration , which was preferred by the military for observation work . The L - 5B through L - 5G models were modified to carry a litter patient or light cargo , or a rear seat passenger sitting in the normal position . The Navy and Marine version of the L - 5 through L - 5E were designated 0Y - 1 , and all these aircraft has 12 - volt electrical systems . The 24 - volt L - 5G became the 0Y - 2 . Neither the L - 5G nor OY - 2 saw combat during World War II because production did not begin until July , 1945 , just weeks before the war ended , but they were used extensively during the Korean War . The British RAF procured 40 L - 5s and 60 L - 5Bs , and designated them Sentinel Is and Sentinel II ' s respectively . These aircraft were used exclusively in the India - Burma theater of operations . Aircraft markings . Standard camouflage as delivered from the factory was non - specular " Bulletin 41 " medium gray # 43 undersides with olive drab # 41 above , broken around the edges of the wing and tail surfaces with medium green # 41 . Stars , or " stars and bars " were applied to both sides of the fuselage and on the upper left and lower right wingtips . The USAAF number appeared on both sides of the vertical stabilizer in either yellow or black . The USMC number appeared in smaller size in black only . Most aircraft were repainted silver during the post - World War II period . Some Marine Corps and Navy aircraft painted overall non - specular Sea Blue . A variety of unit identification markings including nose art were applied in the field . Interior surfaces were generally finished in yellow - green chromate primer and slightly darker ANA 611 " interior green " . Instrument panels were " raw " phenolic sheet naturally matte black in color . Units using this aircraft . The USAAF , US Marines , and US Navy used this aircraft in the European , Pacific , and Far East theaters during World War II , and in Korea during the Korean War . The Royal Air Force operated 100 Sentinels in India and Burma . After World War II , the Philippine Army Air Corps used this aircraft from 1945 to 1947 . This aircraft remained in service after 1 July 1947 when the PAAC was renamed the Philippine Air Force . The Italian Air Force operated approximately 100 L - 5s from 1946 into the 1950s . Many other countries also received L - 5s after the war , particularly India which received 200 . A number of these went to Pakistan after the partition of India in 1948 . Postwar use and current status . After World War II , the L - 5 was widely used by the Civil Air Patrol for search and rescue work . Today there are about 300 known examples left world wide and less than half are in flying condition . A restored , flying example of the 0Y - 1 ( L - 5E ) variant ( VH - NOY ) is located in Coolangatta , Queensland , Australia . This example was built for the USAAF but was delivered directly to the US Navy instead , serving until 1949 . A group called the Sentinel Owners and Pilots Association is dedicated to the preservation and enjoyment of this aircraft type . Post 1950 , In India a lot of L - 5s were used by Flying Clubs for hobby flying and to teach Student Civilian pilots . These were used till about 1973 when due to lack of spare wings the DGCA withdrew their C of A all over India .