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Extraordinary Inventor
Circling the prairies near Bashaw, Alberta that day, young Harry wondered what would happen if the plane went down in a remote area. How would people know where to look? He mused that a bird sitting on the plane would fly away at the earliest indications of trouble, and would survive the crash. Years later, Stevinson put that flash of insight to work in a National Research Council (NRC) project spanning the 1950s and 1960s. The result, called the Crash Position Indicator (CPI), helped to save lives not just in remote parts of Canada but all over the world. Even the U.S.A.'s Air Force One came equipped with one during the 1960s.Stevinson, who has lived in Ottawa since 1953, is among the "who's who" of Canadian inventors. His brilliant inventions, many of them tested at the home laboratory in his basement, sometimes left his colleagues at the NRC scratching their heads.The CPI, however, made his name as an inventor. This specially shaped airfoil, containing a radio that generates a distress signal, automatically jettisons from a crashing plane and flutters gently to the ground.Because the CPI was developed in the days before transistors, its design had to protect the fragile vacuum tube circuitry from the shock and fire of a plane crash. It also had to be able to float on water, and to protect the radio from cold temperatures. When jettisoned, it had to miss the tail of the airplane and fly far enough to avoid being destroyed in the crash, yet it also had to land near the crash site in order to aid search and rescue crews. Each airfoil had to be specially shaped and balanced to match the speed and design of the aircraft.Stevinson was born 1915, in the now-abandoned town of Passberg, near the Frank Slide, on the British Columbia-Alberta border. His father was a church minister and his mother was a journalist. His father's postings took the family over vast parts of B.C. and the prairies. The family moved 17 times before Harry left home at the age of 19. His parents settled in Bashaw, Alberta for several years, and when they decided to move yet again the teenaged Harry decided to stay on his own. Stevinson's inventing career got off to an early start. Right after completing high school, he built a custom car out of pieces of old Model Ts that he found behind the barns and in the fields. By putting a Chevrolet transmission backwards, behind the original Model T transmission, he was able to get seven speeds forward and five reverse. Harry made an aerodynamic wooden frame over the old Model T's running gear and fitted a steel skin over that. The resulting overdrive gear ratio and aerodynamic shape resulted in a 23-horsepower car that could travel up to 70 miles per hour with the engine revving at not much more than idle speed. The whole car cost only $23 to build, and attracted swarms of curious onlookers whenever he parked it in a new town. With only 23 horsepower, the car took a while to get up to speed. At the time, there were only 10 miles of paved road in Alberta, and Stevinson got tired of losing speed every time he came up behind slower traffic. His solution was to install a large truck horn to clear the way. Because the rear seat faced backwards, Harry's passengers could easily enjoy the startled looks on the faces of the drivers as they were passed by this speedy, strange-looking contraption.After high school, Stevinson earned 15 cents an hour working as a mechanic at the local garage. Three years later he opened a general repair business with his friend, Al Hurt. During the depression, the business grew to include radio, lock, gun, and bicycle repair, and eventually took over the building next door to allow tractor sales and repair. Later in life, Harry would often laugh as he recalled taking a particular old horse as a trade-in for a tractor. Try as they might, Harry and Al never managed to unload the horse, since any farmer could tell at a glance that the poor creature had no work left in it. In 1939, Stevinson enrolled in Electrical Engineering at the U of A. Between classes, he taught basic electrical circuit theory to Navy cadets. He was drafted to fight in World War Two, but a professor wrote explaining that Stevinson would better serve the war effort by completing his schooling as an engineer. On campus, Stevinson was prone to episodes of exceptional tomfoolery. A 1940 yearbook picture shows him spewing gasoline from his mouth, over a lit match, producing a flame over five feet long. Other tales have him parading around the snow-free university campus on skis, and clacking down lecture theatre stairs during classes.He joined the navy upon graduation, in 1944, and was posted to National Headquarters in Ottawa. There, he helped solve electrical and mechanical problems with the Navy?s ship-borne radios and other equipment.In 1945 he joined the NRC in what later became the aeronautical division, and quickly put his remarkable imagination and problem-solving skills to good use. His colleague and friend Jack Templin says the NRC was perfect for someone like Stevinson. "The place was pretty free and easy, and Harry was just like a big kid." Finally, in the late 1950s and through the 1960s, Stevinson was able to put his teen flash of inspiration to the test. The NRC invited him to develop the CPI and pledged to support his work on every aspect of its development.Despite the considerable resources at Stevinson's disposal at the NRC, Templin says, he always tried to make his experiments "easy on the taxpayer." To test the parachute and airfoil dynamics, Stevinson dropped his prototypes from balconies, rooftops, out of airplanes, and even launched them from giant catapults. Templin also recalls one time when Stevinson fired a rocket from the cliff of an unused gravel pit, to test the CPI's design under more lifelike conditions.After many years of fine-tuning, the CPI was ready for use on subsonic aircraft. Early crashes of bush planes proved that the CPI could preserve the radio on land or water and transmit a strong distress signal for several days.The CPI was first commercially produced in Carleton Place (near Ottawa) by Leigh Instruments. At the NRC, Stevinson eventually designed successful supersonic CPIs that Leigh Instruments then produced. Over the years the CPI generated over $100 million in sales for the company. The U.S. Air Force credited the device for saving many lives in the Vietnam War and elsewhere. Stevinson was always humble about his achievements, and pleased to receive letters of thanks after a rescue. Templin marvels over Stevinson's ability to visualize creative solutions where others have given up. In one top-secret assignment, the NRC team was trying to come up with a way to drop an object from a low, fast-flying aircraft onto a small target zone. Stevinson stunned a boardroom full of colleagues saying he could design a parachute that could open, close, and reopen again. When some of them told him it was impossible, Harry made a small working model using a handkerchief, string, and staples.The result was the repeating parachute. As soon as the payload is released from the plane, the chute opens to stop the forward momentum. Stevinson designed the canopy to spin when open, thereby twisting the shroud lines and forcing the chute to collapse. This allowed the payload to freefall for a designed length of time, thereby keeping it from drifting with the wind. Meanwhile, the shroud lines transferred the twisting momentum to the payload. Once the chute had collapsed, the payload continued to spin, eventually untwisting the lines and allowing the canopy to open a second time "just soon enough to slow the payload's descent before landing." Templin accompanied Stevinson for the initial drop test, and everyone was amazed when the payload hit the target on the first attempt (it took a while to achieve consistent results). Templin believes the military eventually used the design, though the exact details of the project were classified. After leaving the NRC, in 1979, Stevinson spent a decade working as a consultant for Leigh Industries. The last five of those years were voluntary, because he could not be bothered to file timesheets. Sadly, Stevinson now suffers from Alzheimer's disease, a cruel blow for a sharp and active mind like his, and has recently been admitted into special care. The family takes comfort in the lasting and beneficial effect of his many achievements.
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Winter 2005
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