A bit of background about the "K"
Bare with me on this layout, as I pulled this information from a fairly old document. I cleaned it up a bit so some areas may not make sense.
Aeronca Model K and Model L
By mid-1935, Aeronca, a contraction of Aeronautical Corporation of America, had pretty well weathered the worst of the Depression. Earlier in the year, Taylor Stanley stepped down as President of the company, when Walter Friedlander bought controlling
interest in the firm for his sons, Carl and John. Stanley remained on the Board of Directors.
Walter Friedlander was an alert, progressive businessman having gained considerable wealth and business experience dealing in
real estate. He long wanted to get into the manufactur-ing business. His sons were to "learn-the-ropes" by pulling the Aeronca Aircraft Corporation together and putting it on top in the aviation field. Unlike the earlier Taft-Roche-Dietz regime, the Friedlanders were at the plant every day and with their genuine interest and per-sonal drive, Aeronca began to undertake more progres-sive policies.
The company's first aircraft, the C-2 and C-3 series used a unique wire bracing system for the wings. But Civil Aeronautics Authority Airworthiness Require-ments, Bulletin U-A, Section 22, October 1, 1934, made this type of wing bracing rather difficult to use and meet new, more stringent requirements. This stemmed from several accidents involving aircraft featuring this method of wing bracing (Aeroncas and Buhl Bullpups) as discussed earlier. Accident reports pointed to pilot error in over stressing the wings far beyond design load limits. Placards and verbal admonishments to pilots did little good.
Aeronca was also getting more competition from other lightplane manufacturers, particularly Taylor Aircraft Company (Piper) who was using new, albeit troublesome, four-cylinder 40-hp opposed Continental A-40 engines. This engine had the potential of doubling its power in succeeding years of development. The Aeronca E-113, two-cylinder engine, even in its final development was limited in growth.
In addition, in the autumn of 1935 under the direction of Walter Jamouneau, Taylor Aircraft had dressed up their squared-off, boxy Taylor E-2 Cub into the more stream-lined Taylor J-2 Cub configuration. The public was going for the change.
The handwriting was on the wall.
If Aeronca was to survive, a new airplane was needed. The Approved Type Certificate (ATC No. 396) for the wire-braced C-3 Master remained valid for the life of the production run, but that would be the end. The year 1935 was pretty good for the C-3 model, 128 Masters being built and sold. Production continued throughout 1936, with 122 units delivered and flying.
The Friedlanders moved forward boldly. Before the leaves of 1935 began to turn into their annual array of artistic colors, not one but two new aircraft designs were initiated. The first was a high wing cabin model, essentially an extension of the earlier Aeroncas. The
second, a radical departure, an enclosed cabin, can-tilever low wing aircraft. Both planes would use the Aeronca E-113C engine and plans were made to intro-duce them to the public in the spring of 1936. Unfortunately, many unforeseen problems and rebellion by nature plagued their plans and schedules. Design and engineering of the new planes was turned over to Aeronca's chief engineer, Roger
Schlemmer, and he had a lot to contend with in light of new government regulations and the new management's initiation into the world of flying machines.
Jean Roche, father of the original Aeronca and still on the Board of Directors, was strongly against using struts to brace the high wing airplane. He wanted to retain the wire bracing method and felt that sales and appearance was the prime reason for going to struts. Roche was still working at Wright Field and rarely at the Aeronca plant. He regularly voted down any inno- vation or new trend in design of construction in the Aeronca line.
The CAA regulation was decisive though and whether the Model K developed because of this or by choice, the design work commenced in August 1935.
Why the designation "K" when they were only at the letter "C"? -::Walter Friedlander said that the next letter after "C" that could be easily understood over the tele-phone was "K." And that was it. This would be followed in natural sequence with "L," low wing model.
Design and general arrangement of it started in October 1935. It would seem that the Model K would be an easy task, while the Model L might pose a problem. In real-ity the reverse was true. Design started within a month of each other. The two prototypes were constructed at the same time, virtually right alongside of each other.
The Model K flew first but didn't go into production for nearly a year afterward. The Model L flew second and went into production within six weeks of its first flight. There were a number of reasons for this. The Model K ran into engineering snags from the outset and then, just as the green light for production was turned on, near dis-aster struck the Aeronca plant. The twist of fate accounts for the low wing being in production for about a year (1936) while the high wing, late in production, was built for nearly three years, the last one being delivered in April 1939.
The Model K
While the Aeronca K had about the same overall dimensions and appearance as the C-3, it was an entirely new airplane. In view of the fact that the 37/40-hp E-113C engine was to be used, Roger ScWemmer had to keep the power to weight ratio in balance and yet come up with a plane that would exceed the C-3 in comfort, eye appeal, and performance. With newer, more modern materials to work with this was within reach, providing customers or the sales department did not demand too many innovations and extras.
In brief: the decision was made to retain the basic aft Aeronca triangular fuselage, widen the forward cabin area for more comfortable side-by-side seating, strut brace the wings and lengthen the landing gear for easier maneuvering on rough ground and tall grass. The fuselage was faired with wood bulkheads and stringers and fabric covered. The nose and engine area was formed aluminum. The vertical tail was of welded chrome-molybdenum tubing and an integral part of the fuselage. The horizontal tail surfaces were of similar construction. A trim tab, controlled from the cockpit, was inset on the left elevator, negating the use of an adjustable elevator. This was the first Aeronca to feature the trim tab and it became a standard feature on all succeeding designs. The gravity-fed tank was located in the fuselage just aft of the engine firewall. Capacity was increased 25% to 10 gallons over previous C-3 models.
The Clark Y airfoil section was retained for the wing and the tip was angled up to a maximum. This had an effect of increasing efficiency and stability, while retaining a minimal dihedral angle throughout the span. The entire wing was new. With the use of struts for bracing, the structure could be made much simpler, yet stronger than the C-3 wing. The main structure was spruce wood, the ailerons were metal framework and of semi-Frize balance.
The Model K ran into several major stumbling blocks that delayed production. The first came with the landing gear. Elimination of drag was of prime importance. Schlemmer was faced with using the same powers the C-3 yet having to use a longer landing gear strut because it was essential to get the belly of the plane higher off the ground for easier and safer ground handling. The gear on the C-3 was extremely short, snuggled up against the fuselage. With the K, more strut would be exposed, creating drag and robbing engine power.
The original landing gear devised was a relatively short, rigid structure, each leg containing an oleo strut and braced in the conventional tripod manner. Flight tests, however, showed that a higher angle of attack was needed for better takeoff and landing characteristics. Either the wing itself or the whole plane had to have more angle of attack. This was easily remedied by lengthening the landing gear. However, the powers that be in management wanted to "dress-up" this feature and called for a "simpler" more modern arrangement, eliminating the V-strut bracing between the main wheel bearing struts. Roger would have liked to have come up with a simple monostrut arrangement similar to that used by Cessna on their Airmaster series but this proved too expensive for the Model K concept. This idea, and a couple others, fur-ther delayed final design and production readiness of the plane.
Another problem involved the designing of dual wheel control system. During test flights of the prototype it was found that the entire elevator control system was out of balance, causing the plane to oscillate in the vertical plane. It was determined the use of a heavy vertical control column had more of a bearing on balance than realized. The actual position of the column's e.G., in relation to its pivot point caused the moment to add or detract from flying loads on the tail. Various bearings and positions of the control column and horizontal tail surfaces were tried until this had no effect on any of the plane's flight attitudes.
Other nagging and persistent matters kept the Model K from the marketplace beyond the schedule planned. Nothing seemed to be going smoothly. Test flights were sporadic. Because of the time factors, attention was turned to the more progressive low wing design and the Model K development languished throughout the spring and summer. Aeronca wasn't ready to apply for an Approved Type Certificate on the Model K until the winter of 1936. Management decided not to offer it until January 1937 when it would be officially demonstrated and shown to the public at the National Aviation Show at North Beach Airport and the Grand Central Palace in New York.
:isadizzy:
