Stinson HW-75

1940 HW-75 / Model 10, NC26256

In mid-1938 the Stinson Aircraft Company decided to enter the 2-3 seat cabin monoplane market which had been the fastest-growing segment of the aircraft manufacturing industry since 1935. Designated HW-75, indicating a 75 horsepower high-wing design, the diminutive new plane was oriented toward personal flying, representing a radical departure from Stinson's renowned 4-5 seat Reliant series of expensive, radial-engined airplanes that were popular with businesses and small airlines. Test flown in February 1939 and awarded Type Certificate #709 in May, the new plane was marketed as the "105", hinting at its modest but respectable 105 mph cruising speed.

Powered by a 75-hp (63.4-Kw) Continental A-75-8 piston engine, the Model 105 retained many attributes of its larger brethren, such as oleo-damped main landing gear, hydraulic brakes, an electrical system, cabin heat, and a plush interior. The generous cargo space behind the front seats could accommodate a small passenger sitting sideways or up to 194 pounds of baggage, giving the 105 greater utility than aircraft of comparable size and power. It also had slotted wing flaps and Handley-Page leading-edge slots which had not been seen on such a small, commercially produced airplane before. The wing slots helped make the new plane stall-resistant and safer to fly, while the flaps improved its short-field performance.

The design was re-badged as the Model 10 in 1940 and an 80-hp (67.7-Kw) Continental A-80-8 engine became standard with the A-75-8 and A-80-6 or -9 engines being options. Advertised as the "new 105 for 1940", other revisions included wider seats, changes to the cowling and exhaust, and cosmetic alterations that made the plane subtly distinguishable from the 1939 model. Six Model 10s were delivered to the U.S. Army Air Corps In August 1940. Designated YO-54 for evaluation in the liaison and artillery-spotting roles, after several months of rigorous field testing they were rejected as unsatisfactory for military use and no further examples were procured.

In 1941 the Stinson Model 10A was released under CAA type certificate A-738. It featured a 90-hp (67.1-Kw) Franklin 4AC-199 engine, shortened cowling, and structural changes to the forward fuselage. Christened as the "Voyager", the gross weight was increased to 1,680 pounds (762 Kg.) and a two-tone paint scheme made the new offering instantly recognizable. An electric starter and a second 20-gallon fuel tank were now installed as standard equipment instead of options. During 1942 and 1943, Stinson purchased a dozen low-time Model 10As from their owners and re-sold them to the USAAF under the designation L-9B. These aircraft remained in the United States and were used for courier purposes.

Alternatively, an economy version of the 1941 Model 10A could be ordered with fewer standard features and a geared Lycoming GO-145 engine installed, but it was not commercially successful. This was designated as the Model 10B and ten of them (all but the prototype) were exported to Bolivia as new production under the military designation L-9A.

All of the 3-seat Stinsons operated by the RCAF during WWII were of the 1939 and 1940 HW-75 (Model 105 and Model 10) series. CF-BSK, which is owned by the Canadian Warplane Heritage Museum, is a 1939 Model 105, serial number 7041. Jim Gray Sentinel Owners & Pilots Association

Maj Bill March - Royal Canadian Air Force news article May 25 2016