Page 26 - Nov 2015 Volume 9, Number 11

The prototype Model 18A was refurbished and sold to the Ethyl Gasoline Corporation, which was one of the earliest operators of Beechcraft airplanes, including the Model 17R1 shown here. The company took delivery of the bullish Beechcraft in 1934, but in December 1935
it was destroyed when it crashed into a mountain in New York.
(EDWARD H. PHILLIPS COLLECTION)
in August 1935, provided that impetus. According to an article printed by the Bureau, the request for bids was intended to “...bring into being a small transport airplane for its own airline inspectors,” thereby paving the way for “small operators to purchase similar types from the industry without having to shoulder the initial engineering and development expenses that are involved in all new airplane design projects.2
Among the companies intending to bid were the Lockheed Aircraft Company, led by former Travel Air designer Lloyd C. Stearman; Monocoach, the Stinson Aircraft Company, Barkley-Grow and the Kinner Aircraft Company. Of these, the Monocoach, Kinner and Stinson designs featured a single vertical stabilizer. Ted Wells and Walter Beech were familiar with these competitors, and were particularly impressed by the sleek Lockheed Model 12 transport that featured two vertical stabilizers, as did the Barkley-Grow design.3
The chief reason the next-generation Beechcraft featured twin vertical stabilizers can be traced to the evolving science of stress analysis, which in the mid- 1930s was still not fully understood when applied to all-metal, semi-monocoque airframe structures. Wells had learned about the pitfalls of analysis from a series of errors he made during certification of the Model 17R1 biplane in 1932. When he submitted documentation on the empennage showing how the calculations were made for various forces acting on the welded steel tube structure, his work was criticized in a letter to Walter Beech written by officials of the Bureau of Air Commerce
24 • KING AIR MAGAZINE
(a division of the Department of Commerce). They alleged that Wells’ work bordered on incompetence and ordered him to resubmit the analysis. Ted’s 10 years of experience working with welded steel tube airframes were of little help when faced with determining stresses imposed during flight on an all-metal airframe.
In the wake of that experience, Wells decided to build the new Beechcraft’s aluminum alloy fuselage around a welded steel tube frame. He considered designing the twin-engine transport with a single vertical stabilizer, but there was a problem: torsional stresses imposed on the aft fuselage during flight with one engine inoperative would be difficult to calculate (such analysis was not fully understood by many aeronautical engineers of that era). Ted’s solution was to design the airplane with two vertical stabilizers, analyzing each one separately as a single structure. In addition, mounting the two vertical surfaces outboard on the horizontal stabilizer had the advantage of retaining the total area required for adequate directional control under flight with one engine inoperative.
Walter Beech was known for taking calculated risks that were necessary in the capricious business aircraft industry, but before a final decision was made to proceed with design and construction of a twin-engine monoplane, he used a tactic that had proven useful during the halcyon days of the Travel Air Company. In 1928, he directed a massive marketing campaign to determine whether aviation-minded businessmen would buy a single-engine monoplane whose main feature was an enclosed cabin seating up to eight people.
His efforts were rewarded with a positive endorsement from the marketplace, and design of the Type 6000 was approved. Beech’s risk soon paid off handsomely. By late 1929, the Type 6000B and more powerful A6000A
NOVEMBER 2015