AOPA Pilot Magazine - July 2012 - 85

“Wait,” my instructor said. “That’s not what it should be.” A mechanic was called. Someone had run the end of the propeller into something. It would have to be removed and fixed. “That propeller,” he said, “would shake the engine right out of the airplane.”
“PROPELLERS HAVE their own story,” says

Jeremy Kinney, a curator at the Smithsonian National Air and Space Museum in Washington, D.C., “and it’s just as dynamic as you can imagine.” Kinney oversees aircraft propulsion and aerial propeller development. There are 527 propellers in the museum, many of them representing new ideas in design or materials. Walk in the main entrance on Independence Avenue and one of the first things you see is the Rutan Voyager, the first airplane to circumnavigate the globe without stopping or refueling, and the Hartzell constant-speed props crucial to its long-distance performance. A prop from the Enola Gay is there. While the prop from the original Wright Flyer is in a case near the Flyer (the airplane was overturned on the ground in a gust of wind and the prop was damaged), the Spirit of St. Louis boasts its original propeller. “Lindbergh insisted on a metal propeller,” says Kinney. “His was the first well-known use of the ground-adjustable pitch idea. “Our newest prop—the Dowty R391— is from a C–130 transport,” he says. “Six blades. Composite. Hydraulically actuated. It really is the latest, most up-to-date prop there is. But to me, the most important propellers are the Hamilton Standard props

HAMILTON STANDARD propeller on the

venerable Douglas DC–3.

pitch and angle of attack are the problems that keep engineers awake at night. The Wright brothers introduced the twist in the blade, but every inch of a blade should be maximally efficient. Remember calculus class? Change one variable, such as the engine or airframe behind the prop, and you have a whole new set of efficiency goals. Sensenich makes up to 100 fixed-pitch propeller models for more than 100 different aircraft. Now in its eightieth year of business, Sensenich divides its products roughly into 50 percent aircraft, 35 percent airboat, and 15 percent UAV for the military. “We also service the antique market,” where wooden props are made to order, says Steve Boser, a Sensenich vice president. “J–3 props are popular, as are Stearman, Fairchild, Stinson props,” he says. “There are some really obscure ones, too, like the

“Lindbergh insisted on a metal propeller,” said Jeremy Kinney, a curator at the Smithsonian National Air and Space Museum. “His was the first well-known use of the ground-adjustable pitch idea.”
of the 1920s, ’30s, and ’40s. These became the standard, especially the Hydromatic constant-speed propeller. Every DC–3 had these Hydromatic props. Every B–17. Just about every Allied airplane had Hydromatic props. They are the basic core of what all modern propellers are.” To be accurate, a propeller is a rotating wing in helical path. Because it’s a wing, Funk B or Bird BK. We even make the test clubs for overhaul shops, something to put a load on an engine that’s being overhauled.”
THE FIRST TIME enemy troops surrendered to a UAV, during the first Gulf War, the UAV was an RQ–2A Pioneer operated by the U.S. Navy. It had a 25-horsepower engine and a two-blade wooden Sensenich propeller.

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AOPA Pilot Magazine - July 2012

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