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The Hoerner Wing Tip Design Story

The Hoerner Wing Tip Design Story

 

 

 by David Sakrison

 ****The story behind the Hoener design wing tip…

This is the story of an accomplished wartime aerodynamicist from Germany, a former Douglas Aircraft aeronautical engineer and self-professed "character" from California, an invisible corkscrew, and a revolutionary wing tip.

As an aerodynamicist for Germany's Fiesler Corporation, Dr. Sighard Hoerner, Ph.D., worked on the Fiesler Storch (Stork), a short takeoff and landing (STOL) reconnaissance and liaison aircraft.

During the Second World War, Hoerner worked as head of design aerodynamics for Junkers and later for Messerschmitt. After the war, he was invited to come to the United States to work on aerodynamic research at Wright Field, in Dayton, Ohio.

There, while working on new concepts for high performance for Navy fighters, Hoerner designed the wing tip that bears his name. He was one of the first aerodynamicists to acknowledge the existence of the wingtip vortex, the corkscrew-shaped wake that forms on a wing's outboard edge, and the Hoerner wing tip was specifically designed to minimize the effects of wingtip vortices on lift, drag, stability, and control.

In 1953, Tom Hebert quit work as an aeronautical engineer for Douglas and started his own company at Fullerton Municipal Airport, in California. Friends described Hebert as "a genius." He described himself as "a character." His new company, Met-Co-Aire, seems to have reflected both portrayals. His company was the first to offer "metalizing" of Stinson and Cessna wings, stripping off the fabric covering and replacing it with aluminum. Hebert's tricycle gear conversion for the Cessna 170 was copied by Cessna and gave birth to the Cessna 172. And Hebert was the first to hang 180-hp Lycomings on the popular but underpowered Piper Apache.

Hebert decided that Hoerner's efficient, high-performance wing tip design ought to work on civilian light planes, too. His only major change to the Hoerner wing tip was in materials. At Wright Field, Hoerner's design was rendered in metal; Hebert chose high-quality resin-based fiberglass.

GAINING MOMENTUM

Met-Co-Aire's Hoerner wing tip did not catch on right away. The Hoerner design first appeared on Piper factory-built aircraft in 1974, but av-gas was cheap and customers seeking better performance could ignore fuel efficiency. Still, word got around. Hebert and Met-Co-Aire were building a solid reputation for producing high-quality, high-performance fiberglass wing tips and replacement parts at affordable prices. Hebert passed away in 1976, and Ron Van Vliet took over at Met-Co-Aire, assuming leadership of a "small but very dedicated" group of craftsmen.

Then fuel prices went ballistic. Suddenly, fuel consumption was an important factor in aircraft performance. About the same time, the growing popularity of homebuilts and Experimentals began raising the flying public's interest in modifying factory-built airframes. Met-Co-Aire re-emerged as a leader in the design and production of high-performance wing tips, tip tanks, and fiberglass replacement parts.

DO THEY PERFORM?

Met-Co-Aire says that its Hoerner wing tips "will definitely add to the performance of your aircraft." They say the Hoerner tips will increase aircraft range by 1 to 2 percent, increase rate of climb by 60 fpm, boost cruising speed by 3 to 5 mph, cut takeoff distance by 15 to 20 percent, reduce stall speed by 4 to 5 mph, and improve overall aircraft stability.

Van Vliet says the company's performance claims are actually a bit conservative. "We didn't hire a hotshot test pilot to stand an airplane on its tail and produce inflated performance claims for us," he said. "We believe in the empirical evidence [from customers].

Still, customers can be subjective. When Al Hayes came to Met-Co-Aire for a set of wing tips, back in 1985, Van Vliet saw an opportunity. Hayes is an engineer with a Ph.D. from MIT, and his Cherokee 180 had just been nearly outrun by a PA-28-160 equipped with Hoerner wing tips. Hayes agreed to run a systematic before-and-after evaluation, with his buddy's -160 as a control. After installing the Met-Co-Aire wing tips, Hayes reported a shorter takeoff roll, a lower stall speed (by about 5 mph IAS), and more stability in moderate turbulence and in rolls during level flight. He admitted, however, that these findings were subjective.

The real test came in a side-by-side comparison of cruise speeds between Hayes' aircraft and the -160. Across a wide range of power settings, Hayes found an increase of about 4 percent in cruising speed, after the Met-Co-Aire wing tips were installed. In the 120-130 mph IAS range, he reported an increase of 4 to 5 knots.

Comanche owners also report dramatic reductions in landing speed and stall speed. One owner reported that he had spun Comanches with conventional wing tips but trying to spin his Comanche equipped with Met-Co-Aire's tips produced only a solid stall. The owner added: "Jumping on the rudder only produced a slow roll and a nose drop." Van Vliet says about 70 percent of the Piper Comanches currently flying carry Met-Co-Aire's Hoerner wing tips.

PIPERS, CESSNAS, AND BONANZAS

Met-Co-Aire offers Hoerner-design wing tips to replace the original tips on Beech Bonanzas (35 through P) and on a wide range of Piper and Cessna aircraft. They supply wing tips for pre-1974 Cessnas, including the 140A, 150, 170B, 172, 175, 180, 182, 185, and 210.

Hoerner-design high-performance wingtips are available from Met-Co-Aire for Piper Cherokees (140 through 200), Comanche (singles and twins), Apache, and Aztec. Also for Cherokees, Met-Co-Aire has fiberglass stabilator tips, dorsal fins, tail cones, and fixed-gear fairings to replace the original plastic parts.

Piper Aircraft used the Hoerner-design wing tip as standard equipment on its taper-wing Cherokees (151 through 236).

BIG BANG FOR THE BUCK

Someone once said that you can't use the words, "Cherokee" and "fast" in the same sentence without sounding sarcastic. A lot of folks have been proving that wrong, and creating some pretty hot Cherokees in the process. According to their customers, Met-Co-Aire's Hoerner wing tips offer a lot of "bang for the buck" in boosting the performance of Cherokees, as well as Comanches, Apaches, and Aztecs, along with Beech Bonanzas, and a whole bunch of Cessnas.

Note: Met-Co Aire is now owned by Texas Aeroplastics and Knots2u.

David Sakrison, Ripon, WI, is a former Editor of Cessna Owner Magazine and Pipers Magazine. He is a private pilot and a regular contributor to aviation magazines in the Untied States and Great Britain.

 

 

 

 

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