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By: - 8th January 2018 at 00:47 Permalink - Edited 1st January 1970 at 01:00
Good question...
William Thompson (long time Cessna engineer and test pilot) doesn't have an answer in his exhaustive book Cessna, Wings for the World, The Single-Engine Development Story, one of three volumes covering the maker.
Likewise, Juptner's ATC series and Phillips' Cessna history don't say.
My guess is as the first Cessna post war type, they wanted a "modern" or new numbering system. The less expensive and basic 120 received its ATC a week before the 140...but that doesn't answer anything...why not call it the 100 or 110?
Even the even-odd theory goes out the window when the four seat 170 appeared.
To further confuse things, the prototype 190 was the P-780.
Either they had some clever master plan (leaving 150 free for the eventual replacement of the 120/140) or they just got lucky.
By: - 9th January 2018 at 14:14 Permalink - Edited 1st January 1970 at 01:00
I do remember reading in an interview with a Cessna engineer that the idea for a center thrust twin (push pull) came from the Dornier 335 hence the Cessna 336 and 337
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By: Stepwilk - 7th January 2018 at 22:14
I'm doing a magazine article on the full restoration of the number-one production Cessna 172, which won the Vintage Contemporary category as Oshkosh last summer.
Which got me wondering: How did Cessna come up with the designations 120, 140, 170, 172 and others of the 100-series single-engine aircraft? (No need to get into the 200s, 300s, 400s...) The only semi-logical explanation I've ever heard is that 172 is the square footage of the wing area, but in fact the wing area is 174 square feet, and they never called the Skyhawk a 174.
Did Cessna just pull these numbers out of...thin air? When car manufacturers come up with numeric and alphanumeric designators, there is always some relationship to displacement, number of cylinders or doors, or something of the sort, but I can't imagine what Cessna's rationale was. Certainly they're not engineering-model designators, like what Porsche uses.
Any thoughts?