Many of the features seen in the Ercoupe originate from an earlier design in response to a US Bureau of Air Commerce sponsored design competition in the mid 1930's to build an easy to fly, safe aircraft. At that time most small aircraft were biplanes made from wood and fabric, had heavy controls and would stall and spin easily. But most deaths occurred during or after landing as these planes were tail draggers, requiring real skill during final touchdown and small crosswind gusts could set off a ground loop.
Fred Weick and a group of co-workers at the National Advisory Committee for Aeronautics (NACA) came up with a design in their spare time in 1934, paying for it themselves! This design, the W-1, featured tricycle undercarriage to stop nose-over landings but had a high wing and a pusher propeller.
Weick left NACA and joined aircraft fabrication tools company ERCO in 1936 to design their first aircraft. Many of the ideas tried out in the design of the W-1 became incorporated in the Ercoupe, which now featured low wing and twin rudders. By careful design it was incapable of stalling and spinning. The elevator could only move up 13 degrees, preventing a high angle of attack being obtained. In addition the aircraft had no rudder pedals, the rudders being operated by the yoke and coordinated with the ailerons. With no rudder pedals the Ercoupe is landed in a crabbed attitude in a crosswind, with the undercarriage being built strong enough to withstand this. The aircraft automatically straightened itself on landing. Although Fred Weick expected around half the Ercoupes sold to have rudder pedals, the marketing department decided otherwise, rating the simplicity of the Ercoupe with no pedals as a major selling point.
Just after production started the second world war broke out and supplies of aluminium used throughout the airframe became scarce, halting production. A few trial Ercoupes were made with wood.
The Ercoupe was selected by the US Air Corps for the first trials of rocket-assisted take-off. Unfortunately there are no FAA approved upgrades for this to be applied to civilian machines!
At the end of the war the manufacturers of light aircraft believed that the large number of returning war pilots would want their own planes and with growing affluence the market would be huge. Erco ramped up production and in 1946 produced 4,311 aircraft that were for sale at $2,665. At peak production 34 aircraft were manufactured each day in three shifts.
Unfortunately the market was not as large as everyone hoped, and all of the small aircraft manufacturers ran into problems. In fact the only companies to survive had 4 seat aircraft in production as well as 2 seat. Novel marketing techniques were brought in to sell the Ercoupes, including in-store displays in Macys and demonstration landings in shopping mall car parks. Over enthusiastic sales teams boasted that the Ercoupe was so easy to fly you could solo after one or two hours.
However, although the Ercoupe cannot stall or spin it, if flown slowly a high sink rate can develop. If this happens on final approach there can be insufficient time to regain speed by lowering the nose and opening the throttle due to the high drag. Somehow this warning didn't feature in the sales material!
In the mid-50’s Forney bought the rights to the Ercoupe and produced an upgraded model called the Aircoupe. In the ‘60’s Alon improved the ‘coupe still further with a new canopy and instrument panel and made planes for 3 years, followed by Mooney. However, it had gained an image of being too easy to fly. A real man's aircraft had rudder pedals and could stall and spin you into the ground. It was much harder to do yourself damage in an Ercoupe, a sissies plane.
Later models had conventional controls with rudder pedals, although they don't do much and you still can't stall or spin. After Mooney took over production in 1967 they redesigned the fuselage incorporating a conventional tail. The Mooney Cadet could spin, but sales were poor against the standard training aircraft from Cessna and Piper.
Viewed from the front the fuselage has an inverted triangle section. Originally the section was designed narrow and deep to accommodate the planned engine, an in-house design with in-line inverted cylinders. When Continental offered the C-65 at half the price Erco could make an engine the upper part of the cowl was redesigned to accommodate the horizontally-opposed flat four engine, resulting in the triangular shape.
Of the 5,685 built, 76% of those were constructed in 1946. 1,758 are still on the FAA register, 1,314 with a valid certificate.
Additional comments from Ed Burkhead:
In all, most of the Ercoupe’s innovations have been incorporated into most aircraft design. The tricycle landing gear has become the normal gear. Differential ailerons are now common. Many aircraft are designed to have benign stall behaviour and many are incapable of spinning when flown within the specified centre of gravity limits but they’re not certificated as such probably because that would be difficult and expensive.
Many or most modern aircraft have the wing and wing root designed to produce a controlled stall burble at the wing root while leaving the outer panels flying cleanly to maintain control. And, many also use an interlink between the ailerons and rudder, usually done through soft links by bungee or spring so they may be overridden.
Many modern planes have the engine canted to the right and down like Fred’s Ercoupe design to minimize P-factor on takeoff.
Still, few have gone as far to minimize the effects of power changes on aircraft trim as did the Ercoupe. The twin tail was to prevent the corkscrewing slipstream from pushing on the side of a vertical stabilizer a push that changes with power changes. Similarly, planes with conventional tails also are unable to match the pitch stability with power changes that’s given by the “split” elevator in the models from the E onward.
Aircraft design has adopted most of Fred Weick’s innovations to develop aircraft that rarely bite their pilots. But, as Fred Weick observed, the effects of pilot judgement are even more important.