90 Years of General Aviation
Powered by the Continental A-40 Engine

Mark W. Stewart
EAA# 412692
VAA# 22984

A-40 Cutaway

When the Continental A-40 engine was introduced in 1931, it changed everything in general aviation. Few people know of the A-40 engine nor of the pivotal role it played. This little engine gave birth to general aviation as we know it today. The 37 hp A-40 completely changed the cost of flying. It was now economical for flight schools to purchase, operate, and maintain these little engines. As the world’s very first horizontally opposed four-cylinder engine, it launched a whole new engine design platform, that is still in production today. The compact design of the A-40 also allowed aircraft designers to reduce the drag of the engine and streamline the entire aircraft to achieve 200 mph for a four-place airplane.

Prior to the A-40, flight schools were few and far between because they were not profitable. Flying heavy and expensive radial engine powered planes was only for the rich, especially in the early 1930’s and the Great Depression. The light weight, low-cost A-40 engine, paired with the introduction of light weight aircraft, changed all of that. Now, for the first-time flight schools could be profitable and the average person could not only afford flying lessons, but could also afford to buy their own airplane.

Not only did the A-40 make flying affordable for general public, but it started a whole new engine design platform, the horizontally opposed four-cylinder engine. The A-40 was the cornerstone engine for all light weight aircraft engines that followed. Think of the hundreds of thousands of horizontally opposed four-cylinder engines that have been built over the past nine decades and they all owe their start to the A-40. Manufacturers like Piper, Beech, Cessna, Aeronca, Mooney and many more all used flat four-cylinder horizontally opposed engines on their aircraft, from engine makers like Continental, Lycoming, Franklin, and Manasco. Whether four-cylinder, six-cylinder, or even the 400 hp, eight-cylinder horizontally opposed engine, the A-40 is the grandfather of them all.

The A-40 was “the little engine that could” and it did, giving birth to general aviation with 2,500 airplanes in the 1930’s. The unique design of the A-40 completely eliminated all other engine designs. The other engines include: the three, five, and seven-cylinder radial engines, the in-line four-cylinder engines, the inverted in-line four-cylinder engines, and the two-cylinder horizontally opposed engines. They all disappeared from the light weight aircraft general aviation market by the early 1950’s.

Aircraft design was radically changed by the A-40 as well. The four-cylinder horizontally opposed engine was a natural fit for the side-by-side seating in airplanes. The design provided an unobstructed view out the front, reduced the drag of the aircraft, and offered a practical environment for flight instruction. Can you picture a five-cylinder radial engine on the nose of a Cessna 172? The inline engines of the day made the nose of the airplane very long, like the inverted 200 hp Ranger on a Fairchild 24. The compact and light weight design meant that the aircraft designer could substantially shrink the nose area, and the cabin width thereby streamlining the aircraft. These design changes also led to the aerodynamic pressure cowling that is ubiquitous on aircraft today. This pressure cowling enables a four-place airplane to cruise at 200 mph, while burning just 18 gph.

Several aircraft makers used the A-40 to power their planes, but none more than Piper Aircraft. Piper, including the Taylor Aircraft Company’s planes, built over 1800 aircraft with the A-40 engine from 1931 to mid-1938. Taylor, started the Taylorcraft Aviation Company and produced 606 Taylorcraft Model A’s powered by the A-40. In total, Continental manufactured over 2,600 engines which launched the light weight aircraft industry that we know today.

Stop in the Vintage Hangar and see a cut away of the A-40 engine and learn more about its history. Also, be sure and walk through the first row of Vintage Aircraft parking and inspect more than a dozen A-40 powered aircraft from the 1930’s, Cubs, Taylorcrafts and Heaths, all flown into Oshkosh for your enjoyment.


1935 E2 Piper Cub

A-40 Head