Originally published January 1997
Cessna: Wings For The World by William D. Thompson. Available from Aviation Book Company, 800-423-2708, $20.
This is an outstanding book about the history of Cessna and the development of the single-engine aircraft. Unlike many such books, this one is written by a man very well qualified to do so. Bill Thompson spent 28 years at Cessna as an engineering test pilot and Manager of Flight Test & Aerodynamics.
Unlike programs we're probably more familiar with, like the B-2 or the F-22, Cessna found that it was generally cheaper to develop light aircraft by flight test (fly-fix-fly) than to do extensive wind tunnel or analytical study. As such, the history of Cessna flight test is essentially the history of the aircraft development. Not only does the book chronicle the developments, but it also details the reasons behind them. Also apparent is the ongoing strain between engineering and marketing. The following are some snippets of the items discussed.
The Cessna 172 became the ubiquitous vision of the light airplane. However, it never would have come to be if it wasn't for Piper. In 1954, an engineer started developing an experimental nose gear for the 170. A Sales Manager happened to see this, and ratted on them to the Vice President of Engineering, who immediately ordered it destroyed. The boys in engineering, being smarter than the boys in marketing, merely disassembled it and stowed it away. After all, Cessna was in the business of making tail draggers. Also, there was concern about suitability for taxiing on soft fields and in high winds, not to mention the extra drag.
Even considering all of these disadvantages, Cessna management could not deny that the Piper Tri-Pacer sales were accelerating. It seems the public was willing to take the risk. As such, the nose wheel modification was given the go-ahead and the old test nose gear was pulled out of storage. Even then, there was much development to get the nose gear to operate as well as it eventually did. Most of this development was done in secret so as not to tip their hand to other manufacturers.
The large rear window on the Cessna 150 and later 172s was opposed by engineering, as creating additional separation drag and thus reducing climb and speed performance, along with additional buffeting of the vertical tail on the slender tail cone. As it turns out, all of these fears were realized. I have even had to adjust flight test data to account for this additional drag. In the end, though, it didn't matter--the new look did wonders for sales, so it stayed.
The swept tail of later Cessnas was another marketing driven change, since it actually reduced rudder effectiveness and thus caused problems with spin recovery. A large amount of print is devoted to discussions of spin characteristics.
The drooped wing tips of later Cessnas were again thanks to marketing. While originally an engineering attempt to reduce induced drag, they resulted in no noticeable change. Again, marketing saw them and thought they looked cool. Even if they didn't reduce drag, they LOOKED like they were. So they stayed.
In addition to these stories, many things are discussed that you probably had never heard about. For instance, Cessna tried to develop a 2-control system (like the Ercoupe) without success. They had a few BLC (boundary layer control) aircraft that were built for research purposes. Did you know that at one time Cessna built helicopters? Don't look for them at the fly-ins--there were problems and eventually Cessna bought them all back and destroyed them.
In closing, a very interesting book, and especially so for anyone with
a background in flight test. If you are considering a modification to your
homebuilt, you might consider reading this book first. Cessna may have
already tried it and found it not to work.
Contents of The Leading Edge and these web pages are the viewpoints of the authors. No claim is made and no liability is assumed, expressed or implied as to the technical accuracy or safety of the material presented. The viewpoints expressed are not necessarily those of Chapter 1000 or the Experimental Aircraft Association.
Revised -- 27 June 1997