8 Revolutionary Engines That Changed Aviation Forever

Crewed flight is unquestionably one of the greatest achievements of the 20^th century. Not only did it significantly expand the scope of what we, as humans, can achieve, but it also revolutionized the way we trade, the way we communicate, and of course, the way we travel. While much is said about the pioneers and aircraft that represented successive generations of aviation evolution, without the internal combustion engine (which later included jet engine technology), none of it — quite literally — would have gotten off the ground.

There are relatively few players in the aircraft engine manufacturing industry, dominated by U.S. and European brands. Some even form alliances to get the best results. In commercial aviation, success is usually measured by how safely and economically an aircraft can transport goods and passengers, paying close attention to emission levels and engine noise, while in military service and space travel, their functions are more task-specific. One thing all have in common, however, is that the engine is the beating heart of each aircraft, and through the years, it has played a pivotal role in the development of this modern technological marvel.

The following are the engines that made the biggest waves in aviation, revolutionizing not just the industry itself but also the way we live our lives and view the world around us. From a field in Ohio to the outer reaches of the solar system, these machines tell the story of how we ascended to the skies.

As aviation became mainstream, light aircraft began taking on roles as passenger vehicles and freight carriers, such as mail planes, and being used for business and personal use. Most engine development in the mid-20^th century focused on heavy radial engines and prioritized speed and payload, and there was a requirement for smaller engines for smaller craft. The Continental motor company started producing the A40, a four-cylinder, air-cooled engine that was a perfect fit for light planes, including the new Taylor Cub design, as it weighed just 155 pounds and produced 40 horsepower.

The Taylor Cub was a precursor to the Piper Cub, which became highly popular in the 1930s, with production accelerating during World War Two. Cubs were the primary training aircraft used in the Civilian Pilot Training Program at the outbreak of the war, and they were used in military service as reconnaissance, transport, and spotting planes. A Cub was built every 20 minutes to facilitate this, and the Continental Motors company was thriving.

Larger variants of the successful A40 were required as the demands of the aviation industry changed over time, and the 90-horsepower C-90 and 200-horsepower A-200 were also popular units for Continental. So successful and reliable were these engines that they still serve as the basis for most modern light aircraft engines, with these smaller planes promoting flying as a hobby as it became less of an elitist pursuit. In this regard, the A40 made piloting aircraft more widely available to the masses.

Jet engine technology wasn't practical until the mid-1930s, before which it was deemed too inefficient for long-haul subsonic flight. While jet engines were not widely used during World War Two, development accelerated after 1939 with the invention of the Heinkel He178, the first successful jet aircraft upon which most jet engines were subsequently based, including the Pratt & Whitney JT3.

The JT3 family of turbofan engines was first developed in 1950. It was soon given the U.S. Airforce designation TF133, and in 1955 it was installed on perhaps its most notorious aircraft, the B52 long-range heavy bomber. Eight JT3 engines power the B52, which is still in service today, having clocked over 72 million flight hours.

Later, commercial aircraft fitted the JT3, including the Lockheed C-141 Starlifter and the Boeing 707. It was favored for its low noise, low emissions, and low fuel consumption. It occupied a sweet spot between the turboprop and turbojet engines of its day, and was ideal for fast, economical subsonic flight but eliminated the scream of the turboprop's compressor and the deafening note of the turbojet's exhaust. Instead, the JT3's turbofan sent enough air through the engine to provide enough thrust but rerouted a quantity around the engines; hence the turbofan became known as a "bypass engine." This practicality led the turbofan family of engines, including the Pratt & Whitney JT3, to become today's dominant commercial jet engine. It evolved to produce supersonic variants, some of which are used in military aviation.

The Rolls-Royce Trent family of engines has been in service for over a quarter of a century and continues to go from strength to strength. Just as its namesake British river is subject to intense yearly flooding, the Trent engine has flooded the market as the turbofan power unit installed on some of today's most popular widebody aircraft, including the Boeing 777 and 787, and the Airbus A330, A340, A350, and A380.

This is another high-bypass turbofan engine, much like the Pratt & Whitney JT3, whereby air is routed around the engine, making it quieter and more efficient, compared to a zero-bypass engine where all air is delivered through the turbine. Also, like the General Electric CF6, it has been produced in several variants for different applications, including non-aircraft industrial and marine purposes.

Rolls-Royce is second only to General Electric among the biggest providers of aircraft engines, with Pratt and Whitney coming in third. But thanks to the versatility and long-range capability of its Trent engines, it has revolutionized international travel, as it allows providers to fly in diverse conditions from intense desert heat to sub-zero arctic environments and to navigate longer routes. These include the longest commercial flight currently in operation, from New York's JFK to Singapore International Airport, at 18 hours and 50 minutes.

Following the Space Race of the 1950s and 1960s, a requirement was identified for a reusable low-orbit spacecraft that could launch satellites, service other spacecraft, and act as a laboratory. This would become known as the Space Shuttle. One of its defining features was its Reusable Solid Rocket Booster. Unlike previous rocket engines, which were discarded and hit the ocean at great speed before sinking, the Space Shuttle's engines could be recovered, having parachuted gently to a safe splashdown not far from the launch site.

Variously manufactured by Pratt and Whitney and an alliance of Lockheed Martin and Boeing, this 149-foot-long behemoth produced 6.6 million pounds of thrust and reached peak power in two-tenths of a second. It required over 1,000,000 pounds of propellant and would burn for two minutes — the time it took to reach an altitude of 28 miles at 3,100 miles per hour. Once the fuel was expended, it would be separated from the Space Shuttle's external tank using electrically fired explosions before deploying three 136-foot wide parachutes after re-entry.

Space travel became continuous with the construction of the International Space Station. Over time, the Space Shuttle's primary role became servicing the Space Station. The last three orbiters, Endeavor, Atlantis, and Discovery, were decommissioned in 2011, with commercial spacecraft such as the SpaceX Dragon 2 and Boeing Starliner filling the role. Meanwhile, NASA's Orion spacecraft will use lessons learned from the Shuttle Program to take humans further into space than ever before.