As with many things in technological development, identifying the most revolutionary designs depends in part on what aspects one wants to stress. And when it comes to commercial aircraft engines, it also depends on what is counted as a commercial aircraft engine. For this article, they will include early piston engines, turboprops, and jet engines. As the future generation of aero engines is now starting to take shape, something can be said about where the next revolution is increasingly likely to take place.

When ranking the most revolutionary engines, it’s worth keeping in mind that an engine can be a technology demonstrator and not that successful in itself. As an aircraft example, the Douglas DC-1 was a revolutionary design, even though only a single aircraft was ever built. The DC-1 enabled the development of the DC-3, which revolutionized the aviation industry. Here are some things to know about the most revolutionary commercial engines, including technology demonstrators and mass-produced models.

Wright J-4/J-5 « Whirlwind » Piston Engine

First introduced in the 1920s

The Wright Whirlwind family of air-cooled radial aircraft engines produced the first truly reliable commercial powerplants for aircraft. The series was built by Wright Aeronautical, which became a division of Curtiss-Wright. The engines, and especially the J-5, were some of the first aircraft piston engines that were considered reliable enough to make commercial passenger flying practical.

Previously, earlier airliners had to contend with aircraft that frequently experienced engine failures. The Whirlwind series drastically reduced operational risks for airliners. They were air-cooled, didn’t overheat, and boasted higher reliability. The engine powered early mail/passenger aircraft like the Fokker F.VII and the Ford Trimotor. The Ford Trimotor represented Ford Motor Company’s foray into building airplanes before exiting and returning to focus on cars.

Engines like the Pratt & Whitney Wasp series and the Wright Cyclone series later succeeded the Whirlwind series. These engines were also air-cooled radial aero engines, although they were more powerful. Before the Whirlwind, one of the major issues with aero engines was their tendency to overheat. Most famously, Charles Lindbergh’s Spirit of St. Louis nonstop crossing of the Atlantic was powered by the J-5.

Pratt & Whitney Wasp Series

First introduced in the 1920s

Following the Wright Whirlwind series, one of the most impactful engines was the Pratt & Whitney Wasp series of air-cooled, radial piston engines. The series was first developed in the 1920s, and developments ran into the 1940s. It was one of the first products that catapulted Pratt & Whitney to its status as a major aero engine developer. The company had been founded in 1925 by Frederick B. Rentschler, who had been president of Wright Aeronautical.

Rentschler brought some of Wright’s best engineers and developed the R-1340 Wasp as the first design. Later, the P&W R-1830 variant would become one of the most produced radial engines in history. It became the backbone of commercial aviation in the 1930s and 1940s. The two-row radial design improved power, but did not add excessive complexity or weight.

The Wasp series proved the perfect engine for the ubiquitous Douglas DC-3 airliner. The DC-3 was built as a commercial airliner, but then became the most important Allied transport of WWII. Post-war, it practically launched the modern airliner industry. The engine was able to operate in everything from Arctic to tropical conditions, and the DC-3 only required two engines.

Rolls-Royce RB.53 Dart

First introduced in 1948

The Rolls-Royce RB.53 Dart first ran in 1946, and it powered the Vickers Viscount on its maiden flight in 1948. That flight flew from Northolt to Paris-Le Bourget Airport carrying 14 paying passengers and marked the first regularly scheduled airline flight by a turbine-powered aircraft. The Viscount was the first turboprop-powered aircraft to enter airline service.

The engine proved that turboprops could be efficient and quiet compared with aero piston engines. They offered smoother vibration levels, lower cabin noise, and faster cruise speeds. Turboprop engines remain a mainstay of regional airliners. The Dart was able to introduce a whole new engine for the aviation industry, allowing it to move away from piston engines.

The Rolls-Royce Dart’s testbed aircraft were the British WWII military aircraft, the Lancaster (1947), and the Dakota (1949). The Dart went on to power the Argosy, Herald, Friendship, Andover, and Convair 600 and remained in production until 1987. The Dart was known to be durable, and the last examples were built to power the Fokker F27 Friendships and Hawker Siddeley HS 748s.

Pratt & Whitney Canada PT6

First introduced in 1964

Pratt & Whitney Canada boasts, « The PT6A engine family is the world’s most popular engine in its class and is one of Pratt & Whitney’s greatest success stories. » It adds, « Experience gained from the PT6A has helped spawn many of the engine families that have made Pratt & Whitney a world leader in the gas turbine engine market.« 

Arguably, this is no exaggeration. The Pratt & Whitney Canada PT6 was first designed in 1958, flew in 1961 and entered service in 1964. Updated variants of the PT6 remain in production. Not only has the family powered smaller aircraft like the de Havilland Canada Dash 7, de Havilland Twin Otter, King Air, and Pilatus PC-12, but it has also powered helicopters, land vehicles, hovercraft, and boats.

The P&W Canada PT6 features a reverse-flow architecture where air enters at the rear, reverses course, and then moves forward through the turbine. This gave it unmatched accessibility for maintenance and made it exceptionally compact. Its ruggedness allowed it to operate on poorly prepared aircraft and made it a great option for regional aviation, including accessing remote communities.

Pratt & Whitney JT9D

First introduced in 1970

The Pratt & Whitney JT9D is listed here, even though the General Electric TF39 was the first high-bypass jet engine. General Electric may have been able to develop its TF39 first, but its application was the military Lockheed C-5 Galaxy. Meanwhile, P&W’s JT9D made the Boeing 747 Jumbo possible.

The Pratt & Whitney JT9D was the first high-bypass turbofan able to produce the enormous amount of thrust needed for the world’s massive Jumbos. It achieved a bypass ratio of around 5:1 and offered significant reductions in fuel burn and noise compared with older low-bypass engines. It also powered the DC-10 and A300, and was a keystone to the global air-travel boom of the 1970s.

The General Electric TF39 gained more significance as it was developed into the General Electric CF6 and General Electric LM2500. The CF6 is the world’s most successful widebody engine and is still made for the Boeing 767-300F freighters being produced. The LM2500 is the naval variant powering many of the world’s NATO and NATO-friendly naval warships.

General Electric GE90

Entered service in 1995

The General Electric GE90 is notable for shattering several records. It was the first engine to produce over 100,000 lbf (the GE90-115B is certified at 127,900 lbf). It came with a record 123-128 inch fan diameter and introduced the highest bypass ratio of around 9:1. Other innovations included composite fan blades on a large scale, very high turbine temperatures, swept wide-chord blades, and more.

The GE90 was able to redefine ultra-long-range networks with the Boeing 777-200LR and Boeing 777-300ER, as well as the Boeing 777F. The GE90 remains in production for the remaining Boeing 777Fs being produced, while it also directly aided the development of the GEnx, most famously powering the Boeing 787 Dreamliner and the upcoming Boeing 777X with the GE9X.

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The GE9X is even larger than the GE90, with a fan diameter of 134 inches. The GE90’s family’s modern rival is the Rolls-Royce Trent series, which is also an excellent engine powering the A330neo, the A350, and is an option for the Boeing 787 Dreamliner. The Trent series was the first bleedless architecture on a large engine and made a bunch of other technological leaps. The GE90 is listed instead of the Trent because it is seen as the single biggest « shock » moment in the widebody aero engine market in the 1990s-2000s.

CFM International RISE

Expected in the late 2030s

This last listing is somewhat speculative, but the picture of the next-generation aero engines is now starting to take shape. Safran and GE Aerospace, through their CFM International joint venture, believe the next revolution in commercial engines for narrowbody airliners will be open-fan engines. Central to this is the Revolutionary Innovation for Sustainable Engines (RISE) that was first unveiled in 2021.

The CFM RISE is being developed for Airbus’ next-generation successor to the Airbus A320 narrowbody family. GE Aerospace says, « The RISE program is advancing technologies to support a future aircraft engine that aims to be 20% more fuel-efficient, with 20% lower carbon emissions, than current commercial engines. »

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The plan is for the open-fan CFM RISE engine to be ready in the second half of the 2030s. Meanwhile, Rolls-Royce has built the massive UltraFan to develop a next-generation turbofan. Another area of development is the use of Hydrogen Fuel Cells, including hybrid electric aircraft. Honeywell has gone so far as to say, « We anticipate the use of conventional jet aviation fuel will go away in the next 20-30 years. »