Stinson L-5 Sentinel

https://en.wikipedia.org/wiki/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. It was
produced by the Stinson Aircraft Company. 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.

The origins of the L-5, affectionately known as the "Flying Jeep", can be traced
to the prewar 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 on which a small passenger could sit sideways. The design
was easy to fly. 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 postwar 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 80 horsepower
Continental O-170 engines and provided to the military for testing under the
experimental designation YO-54. Evaluated by the Air Corps 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). The L-5 carried
a pilot and observer in a tandem-seating configuration, which was preferred by
the military for observation work.

In March 1943, with the creation of the liaison category of light observation
aircraft (previous examples came from Taylorcraft Aircraft as the L-2, and from
Aeronca as their L-3, along with the numerous Piper L-4) the designation for
Stinson's new purpose-built military design was changed to the 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 and
mahogany plywood box 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.


Role
Liaison / observation / light plane

Manufacturer
Stinson

Produced
1942–1945

Number built
Over 3,896

Developed from
Stinson YO-54

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, boosting the morale of combat troops
fighting in remote areas. L-5s were also used for 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-5s 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-5s that used the
Brodie system off Okinawa is now on display in the Boeing Aviation Hangar
facility of the Smithsonian's NASM's Udvar-Hazy Center annex at Dulles Airport
just west of Washington, DC.

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 Navy and Marine version of the L-5 through L-5E were designated OY-1, and
all these aircraft has 12-volt electrical systems. The 24-volt L-5G became the
OY-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 Royal Air Force
(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.

Specifications (L-5)

General characteristics
Crew: two (pilot and observer)
Length: 24 ft 1 in (7.34m)
Wingspan: 34ft 0 in (10.36m)
Height: 7 ft 11 in (2.41m)
Wing area: 155 ft² (14.40m²)
Empty weight: 1550 lb (702 kg)
Useful load: lb (kg)
Loaded weight: 2020 lb (916 kg)
Max. takeoff weight: 2050 lb (929 kg)
Powerplant: 1 × Lycoming O-435-1, 185hp (138kW)

Performance
Never exceed speed: 145 knots (163 mph (262 km/h)(200 mph (322 km/h military, in
dive))
Stall speed: 38 knots (42 mph, 70 km/h)
Range: 375 sm (603 km)
Service ceiling: 15,800 ft (4,815.6m)
Rate of climb: 900 ft/min@sea level (4.6 m/s)
Wing loading: lb/ft² (kg/m²)
Power/mass: hp/lb (W/kg)

Armament




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