The inventor of the Christen Eagle aerobatic airplane.7
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Frank Christensen and the Kit Plane Revolution
How one man landed on the homebuilt scene with a kit that changed everything.

By David Gustafson and Frank Christensen Posted April 26, 2012


Frank Christensen

Thirty-five years ago, Frank Christensen started a revolution. He introduced his kit for the Eagle aerobatic biplane at the EAA Fly-In, and with that, he changed the image of homebuilding. Prior to that historic annual Fly-In Convention, no one had ever seen or even envisioned anything like the Eagle kit. On opening day it became the buzz of the convention, the thing to see, the new reason for building an airplane. Frank introduced his kit with such professionalism, so much class and theatricalism that suddenly all kinds of people realized that they, too, could build an airplane. And indeed they did.

The quality and thoroughness of the kits, the step-by-step “fail-safe” process detailed and richly illustrated in the construction manuals, and the option to order kits as needed, convinced people that there would be plenty of fun, education, adventure and excitement in working with one of Frank’s kits. He easily sold a hundred kits during the week at Oshkosh 1977.
Frank learned to fly at 16. He went off to Stanford to study industrial engineering and economics. He happened to be near a new movement in technology while it was still in its infancy: Silicon Valley. During his senior year at Stanford, he formed Tempress Industries, Inc. in Los Gatos, California. In 1972, his company had grown to over 400 employees and was the sole source of critical products used in microchip production. He sold the company and went off to the World Aerobatic Championships as the team manager. According to Tom Poberezny, “Frank never missed a deadline, never overlooked a detail and made it all look seamless and easy.” A couple years later, Frank formed Christen Industries, Inc., in Hollister, California.
Here, in Frank’s own words, is a description of how the Eagle kit came into being:

"We set out to produce a two-place aerobatic aircraft that could compete effectively with the Pitts S-2A as a result of better aerobatic performance, handling, appearance, comfort and convenience. The second objective was to develop a kit system by which the aircraft could be built in limited time by anyone with reasonable mechanical aptitude using only hardware store tools. There would be a series of kits, 26 in all, to be purchased and built one-at-a-time in a specific order until the complete aircraft resulted. Absolutely everything would be supplied in the kits including parts, materials, tools and highly detailed and illustrated step-by-step instruction manuals. The system would range from the ailerons kit all the way to a tie down kit, flight test kit, and aerobatic training kit.

"Many describe the Eagle inaccurately as a copy of the Pitts; however, there are no identical parts other than procured items like the engine, propeller, wheels, brakes, instruments, and so on. The wing size and airfoils are the same for both, but the Eagle has different ailerons and no dihedral in the lower wing, and the wood and metal structures are different. The Eagle has larger cockpit spaces with no aft instrument panel and a further aft CG to allow tighter aerobatic turning. The Eagle tail surfaces are a different shape and size with a different hinge design. The Eagle has a clean aluminum landing gear strut, whereas the Pitts has high-drag panel struts with bungee suspension. There are many other significant physical differences too numerous to mention. Pilots generally agree that the Eagle is faster with less drag and is lighter on the controls. It has a higher roll and pitch rate in aerobatics, and visibility and ground handling is significantly better. Equally important, the Eagle is better looking with its dramatic paint design, integrated canopy, clean landing gear and more streamlined shape.
“Eagles were built by people from all walks of life; doctors, lawyers, airline pilots, military pilots, women, trade schools—and people who were not pilots, but who just liked to build things. The latter group surprised us somewhat. Some pilots bought the kits and had friends or employees do the building for them, most notably, Thomas J. Watson, the retired Chairman of IBM and John Denver of country music fame.”

People who have been around the homebuilt movement for some time are aware that Frank created three hybrid copies of the Eagle, turned them over to Gene Soucy, Charlie Hillard and Tom Poberezny. They made airshow history as the Eagles Aerobatic Team. As expected, the Eagles drew attention to the kit and Frank enjoyed tremendous success.
He went on to purchase the Pitts factory in Afton, Wyoming, designed and certified the Husky and eventually sold the company to Malcolm White of Aviat Aircraft. Stu Horn bought the company next and still sells complete Eagle kits.4512
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Frank Christensen

Frank Christensen lives in Jackson, Wyoming. (307) 733-1789 (summer) (435) 275-2417 (winter) fchristen@earthlink.net

For many years my drafting work was focused on precision electromechanical machine tools and aircraft parts, but in recent years it’s much simpler — mostly depictions of architectural elements in which I’ve always been interested. I use PowerCADD with WildTools because it’s the most powerful and intuitive drafting software system I’ve ever encountered. Drawing is genuinely fun, and I never encounter a depiction I can’t produce quickly and easily.

Frank Christensen founded Tempress Industries in Northern California in 1960 while finishing his last year at Stanford University. He learned of the needs of the then infant semiconductor industry and set up shop with some special-purpose machine tools. Among the first people he called on were Robert Noyce and Andy Grove, then obscure engineers at Fairchild Semiconductor. (Noyce and Grove were later the founders of Intel). Fairchild was the first company to find a way to produce semiconductor devices in volume, and they needed specialized production tools and machinery to produce the ultraminiature microelectronic devices. They gave Frank an opportunity, and over the next dozen years his company grew at a phenomenal pace to hundreds of employees.

At age 34, Frank sold his company to an electronics conglomerate, purchased a ranch in Hollister, California, built a private airport, and “retired”; but he soon got the itch to design and build again, and he started Christen Industries to manufacture aerobatic aircraft accessory products (his inverted oil system for Lycoming aircraft engines has been the industry standard for decades). Frank is best known in the aviation community for the creation of the Christen Eagle II aerobatic kitplane, the first totally complete high quality aircraft kit to be marketed. The kit construction manuals are legendary — in all there are over 30 profusely illustrated 300-page instruction books that take you step-by-step through the construction of the aircraft. Christen Industries later acquired and operated the Pitts Special factory in Afton, Wyoming. Under Frank’s ownership, the company developed the FAA certificated Christen Husky aircraft.
Frank subsequently sold his aircraft manufacturing company, but he doesn’t consider himself retired. Rather, he describes himself as “between troubles.” Because of his experience with drafting and producing the Christen Eagle II manuals, he has long been interested in computer-aided-drafting. He purchased an IBM Fast-Draft system for his aircraft design work in the ’70s, but he eventually settled on the Macintosh and PowerDraw which he introduced to his crazy friend Alfred Scott. Since then, he and Alfred have been the principal unindicted co-conspirators in the creation of WildTools, often conferring by telephone on Sunday mornings on some new feature for WildTools. (Frank and Alfred both categorically deny being obsessive-compulsives.)4513