The Boeing PT-17 Stearman in Flight Over Massachusetts

Climbing over the narrow, wing-root walkway and stepping on to the cushioned seat of the tandem, two-place, blue and yellow fabric-covered open-cockpit Boeing PT-17 Stearman registered N55171 in Stow, Massachusetts, I lowered myself into Magnetic Spine Stretch Therapy position with the aid of the two upper wing trailing edge hand grips and fastened the olive-green waist and shoulder harnesses. Donning era-prerequisite goggles and helmet, I surveyed the fully duplicated instrumentation before me and prepared myself both for an aerial sightseeing fight of Massachusetts and a brief, although temporary, return to World War II primary flight training skies.

The Boeing PT-17 Stearman had its origins in a self-financed design project intended for military training purposes. Just beginning to see a flicker of light at the end of Great Depression’s tunnel and hitherto only surviving by manufacturing parts and components for other aircraft, primarily those for the Boeing B247 twin-engined airliner, the Stearman Aircraft Company believed that its future could only be secured with a military design.

Investing its own funds in 1933, it modified a Model 6 Cloudboy, an earlier Lloyd Stearman aircraft, by introducing a new, circular fuselage cross-section similar to that used by the Model 80, another Stearman design, providing only lower-wing ailerons, incorporating a cantilever undercarriage, and mounting a new tail with adjustable trims on the trailing edge of its elevators. Designated Model 70, it had first flown from Wichita, Kansas, on January 1, 1934 powered by a nine-cylinder, 210-hp, Lycoming R-680 radial engine, proving rugged, reliable, and well-suited to rigorous training regiments with the ability to tolerate the aerobatic maneuvers to which fledgling pilots often subjected it. Although it exhibited excellent handling characteristics during its demonstration flights to the Army Air Corps and the United States Navy in Dayton, Anacostia, and Pensacola, its almost docile response to stalls proved inadequate to fulfill its intended purpose; as a result, the installation of triangular stall strips, made of wood, on its lower wings severely interrupted the air flow during high attack angles and remedied the deficiency.

The Navy, the more interested of the two, ordered 41 aircraft, plus spares, in May of 1934 for a version with a 200-hp Wright J5 radial engine called the Model 73, but designated NS-1 for the Navy. The first production aircraft was rolled out in December of that year.

A modified version, incorporating a new main undercarriage and alternatively powered by a 225-hp Wright R-760 and an equally powered, nine-cylinder Lycoming R-680 radial engine, had been designed that summer and had been targeted toward the Army Air Corps. When funding had ultimately been allocated the following year, the Army Air Corps itself had issued specifications to the Stearman Aircraft Company, resulting in an order for 20, as well as spares, of the Lycoming version designated Model X75, but called the PT-13 for Army operation.

The two-seat primary training biplane design, identical to both operators with the exception of some minor features, incorporated a rectangular welded steel tube fuselage which had been covered with metal panels on its forward section and fabric on its aft end and rendered a 25-foot, ¼-inch overall length. Its single-bay, unequally spanned, staggered upper and lower wings, using an NACA 2213 wing section, were built up of spruce-laminated spars and ribs. The center section of its upper wing was carried by wire-braced steel tube struts, while “N”-type steel tube interplane struts carried it on either of its sides. Fabric-covered, they attained motion about its longitudinal axis by the duralumin ailerons installed on the trailing edge of its lower wings, and collectively featured a 32.2-foot span and a 297.4-square-foot area.

The fabric-covered, welded steel tube, wire-braced tailplane and vertical fin featured trim tabs on its elevators.

The divided, cantilever undercarriage, incorporating a metal fairing-enclosed, torque-resisting oleo spring shock absorber in each of its main legs, had been fitted with hydraulic wheel brakes and a steerable tail wheel.

The dual, tandem, open cockpits accommodated a flight instructor and a student pilot, and baggage could be stored in the enclosed compartment behind the rear of the two.

Powered by a twin-bladed, adjustable-pitch, metal propeller mounted on a steel tube whose radial engine was fed by a center-section, 43 US gallon fuel tank and a four US gallon oil tank installed in the engine compartment itself, the aircraft, with a 1,936-pound empty weight and 2,717-pound gross eight, could climb at 840 feet-per-minute, attaining a maximum 124-mph speed and an 11,200-foot service ceiling. Range was 505 miles. Cruise speed, at a 65-percent power setting, was 106 mph, while landing speed was a docile 52 mph.

World War II’s momentum had both paralleled and dictated the aircraft’s production run. The war department’s increasing need for primary trainers resulted in the $243,578 order for 26 PT-13As for the Army Air Corps and the $150,373 order for 20 for the Navy, while a subsequent, $3 million order for PT-13Bs represented the highest in Stearman’s history and necessitated the expansion of its factory and the increase of its workforce to a hitherto record 1,000.

In addition to the United States, the design equally had foreign application. The Model 76D1, for instance, featured a nine-cylinder, 320-hp, twin-bladed, adjustable prop Pratt and Whitney R-985-T1B engine, three.30 caliber machine guns, a two-way radio, and floats, and ten were initially ordered by the Argentine Navy. The Model 73L3, featuring a 225-hp Lycoming R-680-4 engine, was flown in the Philippines, and the aircraft also saw service in Brazil.

Indeed, by 1940, Stearman produced one PT-13-type trainer every 90 minutes, and the momentum, once set in motion, had been unarrestable. On June 25 of that year, the Navy signed a $3.8 million contract for 215-hp Lycoming R-680-8-powered N2S-2s and -5s, sparking another 40,000-square-foot factory expansion. By August, 1,100 personnel worked two eight-hour shifts six days per week, while the following month 1,400 worked round the clock on three daily eight-hour shifts.

Completed aircraft were ferried either to the Army Air Corps’ base at Randolph Field in Texas or the Navy’s in Pensacola, Florida.

In order to avoid production delays because of engine unavailability, Stearman produced two sub-versions. The first of these, the PT-17, featured a stressed airframe with 300-hp engine capability, although it was standardly powered by the seven-cylinder, 220-hp Continental R-670-5 radial, while the second, the PT-18, was produced with a 225-hp Jacobs R-755. Only 150 of the latter, however, had been built. Both appeared in 1940.

The type reached a major milestone on March 15 of the following year when the Army Air Corps took delivery of the 1,000th primary flight trainer in Wichita, the only Stearman design ever to have achieved such a production run. But the milestones, fueled by the war, mounted in rapid succession: only five months later, on August 27, the 2,000th aircraft, a PT-17, had been delivered to the Army Air Corps. These production rates could only be supported by an equally increasing workforce, eclipsing 3,000 in April and 5,000 in June.

In September of 1941, the Stearman Aircraft Company, which had since become the “Stearman Division of Boeing,” for the first time altogether eliminated the Stearman name, redesignated, simply, the “Boeing Aircraft Company, Wichita Division.”

The basic design also had civil application under Approved Type Certificate No. 743, which had been granted on June 6, 1941 for the Model A75L3, a 225-hp Lycoming PT-13 equivalent, and the Model A75N1, a 220-hp Continental R-670 counterpart. The types, concurrently manufactured along existing military production lines, were sold to Parks Air College in Illinois, one of the Civilian Pilot Training Program operators, and to Peru as the A75N1.

By December of 1941, an airframe had been completed every 60 to 70 minutes.

Another specialized version, the PT-27, featured a modified Continental engine for arctic-temperature operations, a canopied cockpit, an instrument flight training hood, installation of an electrical system, and landing lights. Of the 300 ordered by the Royal Canadian Air Force, 287 had been returned between December of 1942 and June of 1943 because of failure to complete the necessary post-delivery modifications, rendering them unsuitable for sub-zero temperature operations.

When the war had ultimately ended in 1945, the Wichita Division of Boeing had produced 8,584 primary flight trainers, or 44 percent of all flight trainers for the war. Yet, more than a year after the production line had closed, it had received an order to 24 N2S-4s from the People’s Republic of China. Two such aircraft–one with serial number 37902, which had first been delivered on October 31, 1942 and had logged 1,564 hours, and one with serial number 55759, which had first been delivered on July 20, 1943 and had flown 1,116 hours-had been located in Clinton, Oklahoma, and, after overhaul and installation of six-cylinder Lycoming O-435-II opposed engines, had been shipped on May 23, 1947. They were later joined by 20 220-hp Continental R-670-4-powered N2S-3s.

In all, Stearman had produced 11 major primary trainer versions for the Army and the Navy.


The instrument panel of the PT-17 in Massachusetts, located below the slender, Plexiglas windshield, featured a directional compass, a vertical speed indicator, an airspeed indicator (in miles per hour), a turn-and-bank indicator, an altimeter, a clock, an outside air temperature and oil and fuel pressure gauge (in pounds-per-square-inch), a propeller gauge (in revolutions-per-minute), and a fuel tank feed switch, the latter for “left,” “right,” or “off.” The engine power and mixture throttles were located on the left side wall, while the rudder and brake pedals were on the floor, just beyond my feet.

The uncowled, 220-hp Continental radial engine, feeding off of the 46-gallon fuel tank, and initiated with the properly advanced throttle and mixture controls, infused the airframe with lift-promising power, as its sputtering, smoking, avgas-reeking propeller rotated into horizontal stabilizer-bathed slipstream, instantaneously causing the stick between my legs to bolt toward its rearward-most position.

Responding to its advanced throttle, the Stearman moved beneath the gleaming, high-noon sun parallel to the Assabel River, turning to the right and executing its full engine run-up, angled toward the manicured, sloping, 2,300-foot grass field which would imminently serve as its runway. This had, after all, been World War II.

Inching forward under its own power and aligning with the grass field, the PT-17 bit into the wind with fully advanced throttles, raising its lift-generated tail before disengaging its two spinning main wheels at 60 mph and surmounting the field-perimeter trees in a climbing, left turn at 550 feet.

The green-carpeted, blue lake-dotted topography of Massachusetts, unobstructed in the crystal-blue, 80-degree June skies, retreated below me.

Angling through 1,200 feet at a 600 foot-per-minute climb rate and 72-mph indicated air speed, the biplane, registering a 1,800-rpm reading on its single-bladed propeller, moved over the myriad of mirror-reflective lakes, the grass field of Stow now reduced to indistinguishable green carpeting.

A predetermined, vigorous stick-shaking signal by the equally helmeted and goggled pilot behind me, whose presence could be visually verified by the tiny mirror installed in the upper wing’s underside, indicated a flying hand-off, and a touch of my helmet affirmed its acceptance.

The stick between my legs, the sole means of controlling the aircraft’s lateral (pitch) and longitudinal (roll) axes, had reduced my fate and direction to a single channel and, bombarded from all angles by the unobstructed wind, I had attained a new-found freedom which had eclipsed both earth-bound restrictions and adjective descriptions.

Maintaining a 240-degree, southwesterly heading over Hudson at an 80-mph air speed, I pointed the nose toward the still-nebulous outline of Wachusett Mountain, whose silhouette rose above the horizon line, now isolated unto my own world, disconnected from civilization, the ground, and even the pilot behind me, in a harmonious, soul-fusion with the universe. Isolated, with nothing to cling to, whether it be physical location or negative emotion, the soul always ultimately re-emerges to its autonomous state. If that state could have only been a permanent one…

Banking left to a southerly, 180-degree heading over Marlborough, I skirted the Sudbury Reservoir, the upper and lower wing-generated lift carrying me to 1,800 feet at a 90-mph speed, while the engine drank fuel with an 11 gallon-per-hour thirst.

A left pressure on the stick arced the PT-17 on to an easterly course over Southborough and Framingham toward Boston, its engine oil pressure registering 75 pounds-per-square inch.

Most of World War II’s civil and military pilot training occurred in the very aircraft type I currently flew.

Seeking to fill a massive need and tap into the university student population with up to 20,000 pilot trainees per year, President Roosevelt had signed a bill creating the Civilian Pilot Training Program in December of 1938, in which pilots, already armed with sufficient hours from civilian schools, would be qualified to complete their training at Army and Navy air bases in PT-13, PT-17, and N2S Stearman aircraft. In order to remedy the program’s two major flaws of insufficient military flying technique curriculum inclusion and initial obligation to serve in the armed forces immediately after graduation, the Primary Training School Program, in which the Civil Aeronautics Authority first inspected and approved civilian flight schools, had been created. The specially-contracted facilities, staffed by civilian flight instructors who themselves were required to attend pilot training courses at Randolph Field in order to “ensure uniformity of training in conformity with established Air Corps methods and standards,” were supplied with curricula, textbooks, and Stearman primary trainers directly from the Army. The first such pilots entered the program on June 1, 1939 and ultimately numbered 125 dispersed throughout 41 schools by December of 1941.

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