Stinson L-5 History

This page was last updated on December 7, 2004

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Welcome to the Stinson L-5 Sentinel Data Pages

Brief History of the L-5 Design

Sentinel Owners and Pilots Association

I...Introduction

.....The Stinson L-5 is one of the most important but overlooked American airplanes of World War Two. Overshadowed by the more glamorous fighters and bombers, and outnumbered by the popular Piper L-4 Cub, the Sentinel has been relegated to relative obscurity. Nearly 4,000 were built in Wayne, Michigan, by the Stinson Division of the Consolidated-Vultee Corporation between 1942 and 1945 but only a few hundred have survived.

.Stinson L-5B owned by Brad Hurley

.....The most versatile and robust of the Army's "grasshopper" fleet of liaison aircraft, the L-5 was a true workhorse and flew a wider variety of missions than any other type. Designed especially with combat support in mind the L-5 didn't require an airfield to operate and could be maintained under the most primitive of conditions. Routinely called on for artillery spotting, photo reconnaissance, re-supply, search and rescue, evacuating the sick or wounded, dispatching couriers, and transporting personnel, the Sentinel performed missions that are now mostly accomplished by helicopters.

.....Never far from the action, the sturdy Stinsons participated in most theaters of the war and became a familiar sight to friendly and enemy troops alike. American soldiers commonly used the nickname "Flying Jeep" when referring to the L-5 because it was rugged, versatile, and could be relied upon to accomplish nearly anything asked of it. British troops fighting in Burma also greatly admired the Sentinel and christened it the "Jungle Angel" for bringing life-saving ammunition, food, medecine, replacements and mail to areas not accessible to other aircraft. Thousands of people in all theaters owed their lives and welfare to the courageous men who flew these unarmed and unarmored machines.

A Civilian Origin

The L-5 Sentinel had a civilian origin and was roughly based on the Stinson Model 105 Voyager. Unlike other pre-war civilian aircraft that were adopted pretty much off-the-shelf by the military, the Voyager underwent a substantial redesign and emerged as a new type specifically tailored for the liaison role.

..1939 Model 105 Voyager.

(Photo obtained from Aerofiles)

.. The Model 105 Voyager was first introduced in 1939 as the HW-75. This was an engineering designation that indicated it had a high wing and a 75hp engine. The entire airframe was fabric covered and featured a welded steel-tube fuselage, predominantly wooden wings and tail, and a steerable tailwheel. Surprisingly, the wings incorporated the advanced concepts of slotted flaps and leading edge slots to enhance lowspeed flight and handling characteristics. An 80 horsepower version, called the HW-80, was also offered.

.....The 105 Voyager name came about as a marketing scheme in order to boost orders. Sales literature emphasized the comfort, styling, and 105 mph cruise speed while hinting at unlimited freedom and adventure. Specifically aimed at the growing personal use market, the Voyager proved quite successful and over 500 were sold. It had side-by-side seating and a third "jumpseat" in back where a passenger could ride sitting crosswise. In reality three occupants was not very practical unless the rear passenger was a child, but the extra space easily accomodated more baggage than competing 2-place designs.

.....Further refined in 1940, the Voyager was marketed in two versions: the spartan 75hp Model 10A (HW-75) and the luxuriously appointed 90hp Model 10B (HW-90). The fuselage was widened somewhat on both models and many other small improvements were made. These versions were even more popular than the original Model 105 and over 750 were produced. Voyagers were owned by notables such as Howard Hughs, Roscoe Turner, Jimmy Stewart, Wilbur Shaw, and Edgar Bergen and these celebrities undoubtedly helped improved sales . Eventually, the design also caught the eye of the U.S. Army.

A Stinson Model 10A in standard two-tone finish

(photo obtained from L. Westin)

The Army Takes an Interest

..... In 1938, the Germans brought their Fiesler FI-156 'Storch' to the U.S. for a public demonstration. The very-impressed onlookers included U.S. Army personnel and representatives from several aircraft manufacturers. Major General 'Hap' Arnold, by then appointed Chief of the Army Air Corps, recognized the possibilities of such an aircraft, so in 1940 the Army invited various manufacturers, including Stinson, to submit existing designs for field trials in order to assess the military potential of civilian aircraft. Among the planes tested were six Voyagers specially fitted with 100hp Franklin O-200-1 engines. These peppy little airplanes were designated YO-54's , the 'Y' meaning "evaluation status" and the 'O' meaning "observation" category. They performed and handled well enough that the Army ordered ten additional ones. They initially labelled the type AT-19A but the designation was ultimately changed to L-9A in 1942. Primarily used for training and coastal patrol work by the Civil Air Patrol and Civilian Pilot Training Program, this tiny fleet was eventually augmented by sixteen 90hp civilian models that were designated L-9B's.

.1941 YO-54

(photo obtained from AeroFiles)

A Winning Design

.....The YO-54, with its fixed leading-edge slats, had great handling qualities but lacked the power and many other features that the Army most desired. They really wanted an aircraft comparable to the impressive Fieseler Storch didn't didn't want to spend a lot of money or wait years for development of a new type. Many good designs were already around that could match the Fiesler, including the Vultee (Stinson) L-1 / O-49, but all were found wanting because they either required too many strategic materials in their construction, had high maintainance requirements, were too complicated for rapid production, or simply cost too much money.

..Fiesler Fi-156 "Storch"

(photo obtained from Gallery of Flight)....

...... In the end, the excellent aerodynamic qualities and relatively simple maintainance and construction of the Voyager won out, but not before it underwent a major redesign. Although a large number of components were retained , the upgraded version was substantially different from its parent in both appearance and structure. The slotted wing was substantially stiffened to endure greater aerodynamic stress, a new lengthened fuselage featuring tandem seating and 'greenhouse' windows increased visibility all around. Long-stroke main gear oleos and a telescoping oleo-damped tailwheel strut greatly improved its rough-field capability. The fin and rudder were also enlarged and the number of aluminum components throughout the airframe were substantially reduced. Many other changes (too numerous to mention here) were also incorporated. Most importantly, all these alterations required only a small change in factory tooling and assembly procedures so that production could commence almost immediately.

...L-5B owned by John Markham

(photo courtesy of John Markham).....

.....Known conceptually as the Model 75, the ptototype was tested with various engine configurations before the 185 horsepower six-cylinder Lycoming O-435-1 was finally selected. The features and performance of the final version, known as the Model 76, so completely impressed the Army that a contract for 275 airplanes was immediately awarded and the normally required evaluation period was waived. The Stinson Model 76 was originally given the designation O-62 but this was changed to L-5 by the time the first airplanes were delivered.

.....Congress ultimately allocated money for several additional batches of Sentinels.Seventeen hundred were requisitioned in 1942, and twenty-four hundred were ordered in 1944. By 1945, improvements to the design resulted in four other production designations: the L-5B, L-5C, L-5E, and L-5G . Navy and Marine versions were identical to the Army models but were known as the OY-1 and OY-2, while British Lend-Lease airplanes were known as the Sentinel I and Sentinel II

(photo by K.O. Eckland)

Post War Use

......After WWII many L-5's went to Korea and remained operational until replaced by the all-metal Cessna L-19 "Bird Dog". Other's served training and utility functions in Japan, Europe or the U.S. until the mid-1950's, and some even went to foreign Air Forces. A few survived in the U.S. armed services into the 1960's, but most Sentinels were removed from active duty by 1957. Large numbers were distributed to Civil Air Patrol squadrons where they continued to be useful for training or search-and-rescue missions up to about 1970. One notable Sentinel remained in the Air Force inventory for many years (re-designated U-19B) and was used at the Air Force Academy as a glider tug.

.Cessna L-19 Bird Dog

(photo obtained from IBDA)

.....Hundreds of surplus L-5's found their way into civilian hands and served many tasks including training, crop spraying, banner towing, aerial photography, patrolling, and surveying. Popular among warbird enthusiasts, quite a few Sentinels have been restored to military configuration and can be seen at fly-ins and airshows. About two dozen examples have been preserved in aviation museums around the United States, and several others can be seen abroad. (See the "Preserved Aircraft" page for details)

L-5 Observer owned by Dick Blosser

(photo courtesy D. Blosser)

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