Aircraft Engines: Definition, Function, Types, Differences, History

An aircraft engine is the power unit of the aircraft propulsion system and is referred to as an aero engine generating thrust by converting fuel into kinetic energy. The earliest practical form was the piston engine, an internal combustion heat engine that turns a propeller to move the aircraft. Later, the turbojet engine became the first type of gas turbine engine, initiating the jet era in which a reaction engine directly accelerates a stream of air and combustion products rearward.

In modern flight, the spectrum extends from the simple air-breathing ramjet, which needs no rotating parts, to the non-air-breathing rocket engine that carries both its own oxidizer and its own fuel. More recently, the electric aircraft has emerged, the propulsion provided only by electric motors powered by stored energy. Each of these propulsion systems reflects a distinct approach to converting fuel or electrical energy into thrust, and together they trace the history of flight from the propeller airplane to supersonic jets and the edge of space.

Expert behind this article

Jim Goodrich

Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.

What is an aircraft engine?

An aircraft engine is the part of the propulsion system for an aircraft that generates mechanical power. Aircraft engines are almost always either lightweight piston engines or gas turbines.

An aircraft engine, often called an aero engine or powerplant, is any engine installed or manufactured for installation in an aircraft to produce thrust. It is a heat engine that converts fuel into heat energy, turns that heat into mechanical energy, and then uses the mechanical energy to propel the aircraft. Aircraft engines also include turbosuperchargers, appurtenances, and accessories necessary for its functioning, though not propellers.

The purpose of an aircraft engine is to generate reliable mechanical power so the powerplant can produce thrust to propel the aircraft. Reliability is defined as the ability to perform at specified ratings in widely varying flight attitudes and in extreme weather conditions. In service, an aircraft engine operates at a relatively high percentage of its maximum power output throughout its service and is at full power output whenever takeoff is made. Whatever the flight phase, the engine must function efficiently through all variations in atmospheric conditions encountered in widespread operations while meeting exacting requirements of efficiency, economy, and reliability.

How does an airplane engine work?

Airplane engine working starts when air is drawn into the engine through the front intake. A fan at the front of a turbofan sucks in air and compresses a portion of it. Variable inlet guide vanes direct this compressed air into the compressor, which increases the pressure and temperature of the air. The compressed air then enters the combustion chamber, where fuel is sprayed and ignited, producing high-energy gases. These gases pass through the turbine, which extracts energy to drive the compressor, making the engine cycle continuous. Bypass air, accelerated by the fan around the engine core, produces the majority of thrust.

In turbofan engines, a low-pressure turbine drives the large fan, adding momentum to bypass air and generating additional thrust. The core exhaust passes through a turbine, spins the blades, and exits through an exhaust nozzle, pushing the aircraft forward. While the fan pushes a large amount of air around the core, most thrust comes from bypass air. The aerodynamic principle behind thrust generation relies on Newton's third law: high-speed exhaust gases leave the engine in one direction, propelling the airplane forward in the opposite direction. Compared with turboprop engines, where the turbine engine supplies brake horsepower (bhp) through a rotating shaft that turns a propeller converting bhp into thrust horsepower, turbofan engines operate quietly because the bypass flow produces thrust by accelerating a large mass of air to a lower velocity.

Jet engines, like scramjets, maintain supersonic airflow throughout the engine. Shock waves compress incoming air, enabling the ramjet to use the aircraft's forward motion to compress air without moving parts. In turbojets, air intake compression reduces air velocity to subsonic before combustion occurs. Fuel ignition raises the temperature of the air, and the combustion process further increases energy. The mixer sometimes combines hot combusted core air with cold bypass air before the exhaust gases exit the nozzle, boosting thrust production. Engine heat dissipates primarily through the exhaust, but losses also occur due to friction and internal processes. Overall, turbine engines efficiently convert fuel into mechanical energy, driving compressors and fans to propel aircraft forward through aerodynamic thrust.

How powerful is an airplane engine?

Airplane engine power varies. A 1,000 pound (453.6 kg) airplane with a 100 horsepower (74.6 kW) engine has a power loading of 10 pounds per horsepower (22.05 N/kW). At full power that same 100 horsepower (74.6 kW) aircraft engine burns about 6 gallons (22.7 L) of avgas per hour; when properly leaned in flight an air-cooled aircraft engine uses about 0.06 gallons (0.227 L) of avgas per horsepower. Large reciprocating giants like the Hughes H-4 Hercules, driven by 8 Pratt & Whitney R-4350 Wasp Major engines at 3,000 bhp each, give 24,000 bhp at full throttle.

Jet power is measured in pounds-force of thrust. From the 1950s to the 1990s thrust of a typical jetliner engine went from 5,000 lbf (de Havilland Ghost turbojet) to 115,000 lbf (General Electric GE90 turbofan). The GE90-115B is the current record holder for most powerful jet engine, generating 127,000 lbf (594 kN) of thrust, often said to have 110,000 shaft horsepower. Two GE90 engines produce approximately 61,700 horsepower; at takeoff speed and full thrust the engine gives around 55,000 HP. Two engines of a fully loaded Boeing 777 on a cruise flight generate approximately 46 Megawatts of power, equivalent to about 61,700 mechanical horsepower since one megawatt equals 1,341 mechanical horsepower.

The largest and most powerful commercial aircraft engine ever built is the GE9X, designed for the Boeing 777X family. It is certified to operate at 105,000 lbf (467 kN) and during testing generated 134,300 pounds-force (597 kN) of thrust, holding the Guinness World Record for most thrust ever achieved by a commercial jet engine. Four engines on a fully loaded Airbus A380 produce approximately 224 Megawatts of power at takeoff, equal to nearly 300,000 horsepower. Most powerful turbofan engines in production today produce in excess of 120,000 lb (533,790 N) of thrust, and jet engines can produce over 30,000 horsepower (22,371 kW).

What are the types of aircraft engines?

The types of aircraft engines are listed below.

• Turbojet aircraft engines
• Turbofan aircraft engines
• Gas turbine based aircraft engines
• Turboprop aircraft engines
• Ramjet aircraft engines
• Piston aircraft engines
• Diesel aircraft engines
• Reciprocating piston aircraft engines
• Spark ignition aircraft engines
• Air cooled aircraft engines
• Turboshaft aircraft engines
• Water cooled aircraft engines
• Rocket aircraft engines
• Four cycle aircraft engines
• Rotary aircraft engines
• Two cycle aircraft engines

Aircraft engines come in many different types, categorized into two main groups: air-breathing and non-air-breathing. Most aircraft engines are internal combustion types, where the combustion process takes place inside the engine. Air-breathing engines include piston, turboprop, turbojet, turbofan, turboshaft, and ramjet engines. Among gas turbine engines, four types are used to propel and power aircraft: turbofan, turboprop, turboshaft, and turbojet. Turbofan engines, common in modern commercial aviation, are used on large passenger aircraft like the Boeing 747, Boeing 777, and Airbus A380. They combine the best of turbojet and turboprop engines, using a ducted fan that bypasses some intake air around the core. They are quieter than turbojets but inefficient at very high altitudes.

Turboprop engines, a mix of turbine and propeller-driven aircraft, turn a propeller through a speed reduction gearbox. They use a portion of exhaust energy to drive the propeller and are highly fuel-efficient, effective at moderate speeds, and most efficient at mid-range altitudes of 18,000-30,000 feet (5,486-9,144 meters) and speeds between 250-400 knots (128.6-205.8 meters per second). Turboprop engines are used on regional and cargo routes and are found in aircraft like the King Air and Dash 8. However, they have heavy gearing systems that break down and limited forward airspeed.

Turbojet engines, the first type of gas turbine engine invented, are used in commercial aircraft and private jets. They have high-speed performance and take up little space but are noisy and have poor performance at slow speeds, high fuel consumption, and are largely replaced in modern commercial aviation. Turboshaft engines, primarily used on helicopters like the Bell 206 and Sikorsky UH-60 Black Hawk, provide mechanical output and onboard power for larger aircraft when grounded. They are typically smaller than piston engines but have loud, intricate gear systems that are heavy and break down.

Non-air-breathing engines include rocket and electric motors. Some aircraft have been rocket powered, and many small UAVs have used electric motors, representing the future of aircraft propulsion. Additional manufacturers dominate the global market for aircraft engines, including GE Aerospace, Safran, Rolls-Royce, and MTU Aero Engines.

What is a jet engine?

A jet engine is an internal combustion air-breathing engine that discharges a fast-moving jet of heated gas. Examples include turbojet, turbofan, ramjet, scramjet, and pulse jet engines.

A jet engine is a type of reaction engine that provides propulsion by expelling a reaction mass. It is an internal-combustion engine whose exhaust gases flow directly into the atmosphere, generating thrust by jet propulsion. Most jet engines used in aviation are air-breathing, drawing in air through an intake, compressing it, mixing it with fuel, and igniting the mixture. The resulting high-speed exhaust gases exit through a nozzle, creating thrust according to Newton's third law of motion.

In commercial aviation, a commercial jet engine is designed to produce power for fuel efficiency. It typically uses a high-bypass turbofan, which accelerates large volumes of air and produces a lower-velocity exhaust stream, refining fuel economy and reducing noise. Commercial engines operate at high bypass ratios and do not have the same size constraints as fighter jet engines.

In general aviation, turbojet engines are used for trainers, while turbofan engines are common in business jets. Turboprop engines, which use a portion of exhaust energy to drive a propeller, are widely used in smaller aircraft due to their efficiency at lower speeds and altitudes.

Jet engines are primarily used in military and civil aviation. Military aircraft use low-bypass turbofans for tactical aircraft, turbojets for trainers, and ramjets or scramjets for missiles and hypersonic vehicles. Ramjets operate best at supersonic speeds around Mach 3 and can reach speeds up to Mach 6, but they cannot operate under static conditions. Afterburners are used to augment thrust in fighter jets.

Examples of jet engines include the turbofan engine, which bypasses a portion of air around the core and has a large fan at the front, the turbojet engine, which powered aircraft like the Lockheed F-104 Starfighter, and the turboshaft engine, which generates power for a drive shaft and is used in helicopters.

How does a jet engine work?

Jet engines work by sucking air into the front intake with a fan, compressing it, and then mixing fuel with the compressed air in combustors where the mixture burns and gases expand, according to the continuous Brayton cycle of intake, compression, combustion, and exhaust. The turbine, powered by the hot, rapidly expanding gases, drives the rotating air compressor and fan, while the remaining hot gases are expelled through a nozzle to create the forward pushing thrust.

What are the specifications of jet engines?

The specifications of jet engines vary with model. The CFM56 family supplies 18,500-32,000 lbf, the GE9X delivers 597 kN (134,000 lbf), and geared turbofan engines sit in the 14,000-33,000 lbf bracket. Fan diameter sets the physical size: GE9X measures 134 inches (340.4 cm), Trent XWB-97 uses 118 inches (299.7 cm), PW1100G-JM and PW1500G measure 6.7 ft (204.2 cm) and 6.1 ft (185.9 cm) respectively, while geared turbofan models share the same 6.1-6.7 ft (185.9-204.2 cm) window. Bypass ratio governs capacity and efficiency; GE9X achieves 10:1, PW1100G-JM and PW1500G reach 12.5:1, and the overall pressure ratio of the GE9X climbs to 60:1, with a core pressure ratio at 27:1.

Internal capacity is measured in mass flow: in high-bypass designs the fan draws up to 1,000 pounds per second (453.6 kilograms per second), and the core contains ten high-pressure compressor stages. Specific fuel consumption expresses the rate of fuel use; the lower limit is 0.336 pound per hour per horsepower (0.152 kg per hour per kilowatt) for shaft power and 0.207 kg per hour per kilowatt (0.456 pound per hour per horsepower) for gas horsepower. Thrust-to-weight ratio is mostly a function of engine construction technology and varies with scale, weight reduction and carbon-fiber composite fan cases refine this ratio while maintaining structural integrity.

Rotational speed divides between fan speed N1 and core speed N2, both monitored in rpm. Time Between Overhaul for a more-typical turbine engine ranges 3,500-6,000 hours, and Electronic Engine Control (EEC), now in its fourth generation, improves reliability, fault detection, and data storage. Materials include ceramic matrix composites in the GE9X and fourth-generation composite fan blades that maximize airflow and minimize drag, all contributing to a quieter, more efficient, and lower-emission powerplant.

What are jet engine advantages and disadvantages?

Jet engine advantages are that they offer high-altitude capabilities, longer range, and higher speed, making them faster and quieter than many alternatives. High-speed capability is the main advantage of turbojet engines which is useful for supersonic flight, giving militaries an edge in air combat and strategic operations. Turbofan engines provide higher speed and greater fuel efficiency over long distances, are more fuel-efficient at lower airspeeds, and are relatively quieter, reducing overall environmental impact. Bypass air enhances fuel efficiency and reduces noise levels.

Jet engine disadvantages include less efficient and less cost-effective performance for short distances. Turbojet engines consume a lot of fuel, are very noisy, and have problems with noise and fuel consumption in the speed range that airliners fly (0.8 Mach). They are relatively inefficient for subsonic flight and have very little to no use in modern aircraft due to these issues. Turbofan engines require more maintenance due to additional components that add complexity and maintenance requirements. Wing-mounted engines are easier to maintain but are more susceptible to foreign object damage and make aircraft more difficult to control in an engine failure event.

What are the parts of a jet engine?

The parts of a jet engine are listed below.

• Compressor
• Combustion chamber
• Turbines
• Air intake
• Fuel system
• Diffuser
• Axial compressor
• Cold section
• Propelling nozzle
• Hot section
• Centrifugal compressor
• Exhaust
• Fan
• Bleed air system
• Drive shaft
• Accessory gearbox
• Lubrication system
• Cooling system
• Bypass ducts
• Impeller
• Igniter
• Nose bullet
• Hydraulic system

The cold section includes the air intake, fan, diffuser, compressor, bypass ducts and drive shaft. Air intake is the gateway that captures, smooths and directs incoming air, gives a pressure boost and helps prevent compressor surging. In high-bypass turbofan engines the fan is the first part to meet the incoming air - it pushes part of the air into the core and bypasses the rest around the sides of the engine. The compressor, whether axial or centrifugal, squeezes the incoming air to high pressure. It is located in the cold section and is driven by the turbine through the main rotating shaft. The diffuser, located in the cold section, uses stator vanes to lower flow velocity and increase pressure before the air reaches the combustor. The hot section starts at the combustion chamber and contains the combustor, high-pressure turbine, low-pressure turbine, afterburner, exhaust and propelling nozzle.

Inside the combustion chamber, fuel is injected by fuel nozzles and igniters. The mixture burns and produces high-energy gas. The turbine extracts energy from these hot gases; the high-pressure turbine drives the high-pressure compressor, the low-pressure turbine drives the fan and the low-pressure compressor, while the main rotating shaft links the compressor wheel at the front to the turbine wheel at the back. After the turbines, the accelerating gases pass through the exhaust and propelling nozzle to generate thrust. An optional afterburner injects extra fuel into the exhaust for additional thrust. Accessory drives, gearboxes, bearings, seals, fuel pumps, bleed-air systems, lubrication and cooling systems, hydraulic systems, starter, FADEC, EICAS and the streamlined nacelle that encloses the engine complete the assembly.

What are the types of jet engines?

The basic types of jet engines are turbojet, turbofan, turboprop, and turboshaft. Turbojet engine was the first type of jet engine ever developed and the first type of gas turbine engine invented. Turbojet engines are used in military aircraft and early commercial jets, and they powered the Lockheed F-104 Starfighter. Turbojet engines generate thrust through a propelling nozzle, accelerate a smaller quantity of air through a large velocity change, and are capable of very high speeds. Turbojet engines incorporate a turbine-driven compressor, have a relatively simple design, and take up little space. Turbojet engines are noisy, have high fuel consumption, and show poor performance at slow speeds.

Most airbreathing jet engines that are in use are turbofan jet engines. Turbofan engines have a large fan at the front, bypass air for additional thrust, and give good efficiency at speeds just below the speed of sound. Turbofan engines are quieter than turbojets, are heavier than turbojets, and have a larger frontal area than turbojets. Turbofan engines are used in commercial airliners, business jets, and modern aviation, and they provide better fuel efficiency. Turbofan engines are inefficient at very high altitudes.

Turboprop engines are efficient at lower speeds, are effective at moderate speeds with propeller-driven thrust, and are very fuel efficient. Turboprop engines are quieter than turbojets and have a larger frontal area. Turboprop engines have limited forward airspeed, have gear systems connected to the shaft that are intricate and break down, and are most efficient at mid-range altitudes of 18,000-30,000 feet (5,486-9,144 m). Turboshaft engines have independent engine and rotor speeds. Ramjet engines rely on forward motion for compression, have no moving parts, and cannot operate under static conditions. Ramjet engines are efficient at supersonic speeds and are used in experimental aircraft.

What is a piston aircraft engine?

An aircraft piston engine is an internal combustion engine that operates on the same principles as the engines found in most automobiles, and it uses one or more reciprocating pistons. Aircraft piston engines are most commonly fueled with AVGAS and are connected to a propeller.

A piston aircraft engine is a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. It is a type of internal combustion engine that drives the propeller. Piston engines operate on the four-stroke five-event-cycle principle, known as the Otto cycle. The four-stroke cycle consists of intake, compression, power, and exhaust strokes. The intake stroke draws the fuel-air mixture into the cylinder. The compression stroke compresses the fuel-air mixture. The power stroke occurs when the spark plug ignites the fuel-air mixture, forcing the piston down. The exhaust stroke expels the spent gases.

Piston engines are most commonly fueled with avgas, although diesel fuels are becoming more common in light aircraft. The majority of aircraft engine pistons are machined from aluminum alloy forgings. Cylinders - four to six - are arranged in a horizontally opposed configuration. Horizontally opposed engines have cylinders arranged opposite each other, providing a low weight-to-horsepower ratio. Cylinders contain steel cylinder barrels hardened to resist wear. Engines use air-cooled cylinders in the majority of piston engine aircraft. Air-cooled engines transfer heat directly from cylinders to air, with fins to increase heat dissipation.

Engine accessories include magnetos, carburetors, fuel pump, oil pump, vacuum pump, generator, tachometer drive, and starter. Engines use two magnetos for redundancy. Magnetos generate current when spun close to a coil of wire, providing spark to spark plugs without battery power. Spark plugs ignite the fuel-air mixture at top dead center. The ignition system includes magnetos, spark plugs, timing device, and distribution mechanism. Booster magnetos or high tension booster coils provide a strong spark when starting.

The number of sparks required for each complete cycle of the engine is equal to one-half the number of cylinders in the engine. Engines have four, six, or eight cylinders. Lycoming produces four-, six-, and eight-cylinder piston engines. Lycoming XR-7755 was the largest piston aircraft engine ever built in the United States, with 36 cylinders. Piston engines are used for the light aircraft market. Engine weight influences power-to-weight ratio. Engine performance is affected by density altitude. Propeller performance is affected by flight conditions. The propeller is driven by the crankshaft which translates piston linear motion to rotational work. The crankshaft is bolted directly to the propeller. The propeller provides thrust to move the aircraft.

What is the aircraft engine displacement?

Aircraft engine displacement is a measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is measured in cubic centimeters on small import engines or in cubic inches on American engines.

Aircraft engine displacement is the internal size of the engine, defined as the total volume of air-fuel mixture all pistons can draw in during one complete cycle. For a reciprocating piston engine this total is found by multiplying together three measured values: the distance the piston travels (stroke length), the circular area of one cylinder, and the number of cylinders in the whole engine. The result is normally stated in cubic inches on American engines, in cubic centimeters on small imported types, or in liters on larger import engines. Thus a 1.6-liter engine displaces about 96 cubic inches while the 5- to 10-liter class is common on single- and twin-engine propeller aircraft.

The Lycoming O-235 carries 235 cubic inches (3,851 cc), the Continental IO-550 used in many 300 hp installations displaces 550 cubic inches (9,013 cc), the V-1710 designation indicates 1,710 cubic inches (27,994 cc), and the Lycoming XR-7755 with 36 cylinders totals about 5,900 cc (359.9 cubic inches) or 5.9 liters (359.9 cubic inches). Because engineers need to know how effectively the engine fills that volume, they compare actual charge density to theoretical displacement. At standard sea-level conditions volumetric efficiency is about 85 percent, meaning the real charge is only 85 percent of the calculated piston displacement.

What are the types of piston engines used in planes?

The types of piston engines used in planes are listed below.

• V-Type reciprocating piston engines
• Horizontally Opposed reciprocating piston engines
• Radial reciprocating piston engines
• In-Line piston engines
• Rotary reciprocating piston engines

The first common type of piston engine used in aircraft was the rotary engine. In-line, radial and flat engines are three primary reciprocating-piston types. The rotary and radial types have given way to horizontally-opposed ‘boxer’ engines that are also called flat engines. A radial engine has fixed, non-rotating cylinders arranged in a circle around the crankshaft. It consists of rows of cylinders arranged radially about a central crankcase and uses a master-and-articulated rod assembly. Otto-cycle engines, called four-stroke or four-cycle engines, contain a cylinder fitted with a piston and were invented by Nikolaus August Otto in 1876.

Flat reciprocating engines feature horizontally aligned cylinders, while in-line engines feature banks of cylinders. Crankshafts are bolted directly to the propeller in most airplane applications. Reciprocating piston internal-combustion engines drive propellers but cannot produce thrust on their own. Small general-aviation aircraft and bush planes use mostly horizontally-opposed reciprocating piston engines. These engines power private and commercial airplanes that typically fly below 15,000 feet (4,572 meters).

Lycoming, Teledyne Continental, and Rotax produce piston engines suitable for aircraft. Lycoming 0-360, Lycoming 0-540, Lycoming 0-720, Teledyne Continental 0-470, Pratt & Whitney R-1340, Pratt & Whitney R-985, and Vedeneyev M-14P are common bush-plane piston engines. Piston engine nomenclature includes O = opposed, I = fuel injected, T or TS = turbocharged, G = geared, H or V or HV = helicopter or vertical installation, and R = radial. Radial reciprocating piston engines remain rugged and dependable, but their use is now very limited. Pulse jets have very little to no use in modern aircraft. The Wankel engine is a good choice for high power-to-weight ratio and is an internal-combustion engine.

Jim Goodrich

Pilot, Airplane Broker and Founder of Tsunami Air

What is the difference between jet engines and piston engines?

The differences between jet engines and piston engines are given in the table below.

Jet engine operates continuously, while piston engine operates with discrete cycles. Reciprocating engines have a set of pistons, whereas jet engines do not have pistons. Internal combustion defines both devices, yet the crankshaft converts the reciprocating linear motion of the piston into rotating motion inside a piston engine. Jet engines do not have pistons and instead rely on a rotary driven fan that derives energy from fluid flow.

What is the difference between a jet engine and a gas turbine?

A jet engine and a land-based gas turbine function in the same manner, but they have different end products. In a land-based gas turbine, the turning rotors spin the shaft on a power turbine to create electricity. The difference between the turbofan and turbojet is the addition of large fan blades and a nacelle around the jet engine. A turbofan engine is powered by an aviation gas turbine engine. All turbofan engines have a large ducted fan powered by an aviation gas turbine engine. Turbofan engines are much better at lower airspeeds.

Turboshaft engines are essentially turbojet engines with a large shaft connected to the back of it. The biggest difference between turboshafts and turbojets is that turboshaft engines use the majority of their power to turn a turbine rather than produce thrust out the back of the engine.

What is the history of aircraft engine development?

The history of aircraft engine development begins with the aeolipile described by the Hero of Alexandria in 1st-century Egypt. It demonstrated rudimentary jet power centuries before practical flight. Early aviation relied on piston engines. The Wright Flyer first flew in 1903 powered by a four-cylinder, water-cooled, inline gasoline engine built by Orville and Wilbur Wright. The first practical rotary engine was the Gnome Omega designed by the Seguin brothers and first flown in 1909. Lycoming began developing aviation aircraft engines inspired by Charles Lindbergh's trans-Atlantic flight. Lycoming developed its first aircraft engine, the R-680 nine-cylinder radial in 1929, first used on a TravelAir biplane on April 3 1929. The first airplane engine ‘booster’ search by the U.S. government in 1917 sought a turbo-supercharger that used exhaust gases to drive an air compressor for high-altitude boost.

Sir Frank Whittle registered a patent for the turbojet engine in 1930, yet Hans von Ohain from Germany developed the world's first jet plane - the experimental Heinkel He 178 - which made the first jet-powered aircraft flight on August 27 1939 with his He S 3 engine. Maxime Guillaume filed the first patent for using a gas turbine to power an aircraft in 1921. The first jet-engine development by Frank Whittle was the W1X in 1940, followed by the W2B model air-tested in 1941 powering the Gloster E.28/39, his first flight test occurred in 1941. Anselm Franz of Junkers introduced the axial-flow compressor in the jet engine suitable for the Messerschmitt Me 262, the first operational jet fighter that entered service in April 1944 alongside the Gloster Meteor in July 1944. The first U.S. jet-engine test flight was in the Bell P-59A in October 1942. GE developed the nation's first jet engine, the I-16 in 1944 and the I-40 after World War II.

Jim Goodrich

Pilot, Airplane Broker and Founder of Tsunami Air

World War II accelerated research into jet engine development. Adoption of the turbofan engine marked the 1960s, gaining economy by having much of its thrust pass around the engine core. The first production turbofan engine was the CFM56 in the 1970s. GE and Safran formed CFM International in 1974, which became one of the greatest success stories in aviation history with more than 23,000 engines delivered. GE introduced the CF34 commercial turbofan derivative from the TF34 military engine in the 1980s. The GE90 turbofan reliability refined from 40 in-flight shutdowns per 100,000 engine flight hours to less than 1 per 100,000 in the late 1990s.