General Electric Pioneers Jet Engine Manufacturing
General Electric has been building aircraft engines since the dawn of the Jet Age.
General Electric Co. is a leading supplier of jet and turboprop engines, avionics, and electrical power and mechanical systems. Its products are used in a wide variety of commercial, military, business and general aviation aircraft.
Every two seconds, an airplane or helicopter equipped with GE engines takes off somewhere in the world. The machines have logged more than 1 billion flight hours and currently power everything from F-16 jet fighters and Apache choppers to Airbus A320 and Boeing 787 jetliners.
In 1941, General Electric built the first U.S. jet engine, which was used to power America’s first successful military jet. Since then, GE Aviation has accomplished many other lofty achievements, including the first turbojet engine to power flights at three times the speed of sound and the world’s first high-bypass turbofan engine to enter commercial service.
Today, GE Aviation continues to fly high. In 2015, the division produced 2,588 jet engines for commercial aircraft and 766 engines for military jets. All totaled, the division tallied $25 billion in gross revenue in 2015 (up 3 percent from 2014) and $6 billion in net profit (an 11 percent jump from 2014).
General Electric makes the world’s largest jet engine, now roughly 100 times more powerful than the original, which is housed at the Smithsonian Institution. The latest generation machines, such as GE9x and Leap engines, use cutting-edge materials and can be connected to the data cloud to analyze their efficiency and operations.
At the 2015 air shows in Dubai and Paris, GE Aviation garnered more than $36 billion in orders. It followed that up with more than $25 billion in new business at the 2016 Farnborough Air Show.
According to the Teal Group, a market research firm, General Electric is the largest player in the aerospace turbine industry. It accounts for 28 percent of all back-ordered turbofans, turboprops and turboshafts between now and 2025.
Despite those impressive numbers and market dominance, GE’s aerospace business has humble roots.
When the United States entered World War I, the U.S. Army Air Service searched for a company to develop an airplane engine booster. The turbo supercharger, when installed on a piston engine, would harness exhaust gases to drive an air compressor to boost power at higher altitude.
In November 1917, at the height of the war, Edwin Rice, GE’s president (and former vice president of manufacturing and engineering) received a letter from the National Advisory Committee for Aeronautics (NACA), the predecessor of NASA.
The letter inquired about a radial compressor invented by Sanford Moss, a GE engineer who worked in the company’s steam turbine department, which manufactured a line of centrifugal air compressors for steel mill blast furnaces and chemical refineries.
Turbo superchargers contained two central elements of a gas turbine: a rotary compressor and a turbine to drive it. Moss realized that if fuel could be burned in compressed air, then energy output could be increased tremendously.
“Moss was able to draw on GE’s experience in the design of high rotating-speed steam turbines, and the metallurgy of ductile tungsten and tungsten alloys used for its light bulb filaments and X-ray targets, to deal with the stresses in the turbine wheel of a turbo supercharger,” says Robert Garvin, a former GE vice president and author of Starting Something Big.
NACA challenged Moss to improve the performance of the Liberty engine, which was used in military aircraft such as the DH-4 biplane. The engine was rated 354 hp at sea level, but its output dropped by half in thin air at high altitudes. Moss believed that he could use his compressor to squeeze air before it entered the engine, making it denser and recovering the engine’s lost power.
Although General Electric accepted the challenge first, another team also requested the chance to develop the turbo supercharger. Contracts were awarded in what was the first military aircraft engine competition in the United States. Under wartime secrecy, both companies tested and developed various designs until the Army called for a test demonstration.
In the bitter atmosphere of Pikes Peak, 14,109 feet above sea level, Moss and his colleagues unveiled a 350 hp turbo supercharged Liberty V-12 aircraft engine mounted on the back of a truck.
The test proved successful and GE entered the business of making airplanes fly higher, faster and more efficiently than ever. General Electric’s first aviation-related government contract paved the way for the company to become a leading aerospace supplier.
For more than two decades, GE produced superchargers at its River Works factory in Lynn, MA. The devices continually enabled aircraft to fly higher with heavier payloads.
In 1921, a new world altitude record of 40,800 feet was set by John Macready, an Army Air Service pilot. Sixteen years later, Howard Hughes set a transcontinental air record flying from Los Angeles to Newark, NJ, in his H-1 monoplane equipped with a GE supercharger.
During World War II, General Electric supplied 300,000 turbo superchargers for use in fighter and bomber engines. In fact, that experience and expertise is why the U.S. Army Air Corps’ selected GE to develop the nation’s first jet engine during the darkest days of the war.
In October 1941, while the London Blitz was raging, a group of General Electric engineers in Lynn received a secret present from King George VI. Stacked inside several crates were parts of the first jet engine successfully built and flown by the Allies. The engineers’ task was to improve on the handmade machine and bring it to mass production.
The U.S. War Department and Army Air Corps commissioned GE to rebuild and commercialize the engine invented by British engineer Frank Whittle. Because they were given a short time window to redesign the engine, the American engineers worked nonstop, guided by Whittle’s blueprints.
The U.S. government selected GE for the project because of its knowledge of the high-temperature metals needed to withstand the heat inside the engine, and its expertise in building superchargers for high-altitude bombers, and turbines for power plants and battleships.
Earlier this year, Joseph Sorota, the last surviving member of the World War II-era team that designed the first U.S. jet engine, died. He was 96.
Sorota was still an engineering student at Northeastern University in Boston when he joined GE and started working on the top-secret project.
“Our colleagues called us the Hush-Hush Boys,” Sorota told GE Reports last year. “We couldn’t talk to anyone about our work. They told us that we could be shot.”
One day, on his way home, Sorota says he was approached by a man he had never met before. The stranger asked him questions, such as “did I have a girlfriend or did I have a drink at a bar?” Sorota recalled. “When he identified himself as a man from the FBI, I almost died. I didn’t do anything wrong, but I thought he was there maybe to arrest me.”
The mysterious man told Sorota to follow another stranger to a small building with a tall brick smokestack at the back of the Lynn River Works’ industrial lot. “The FBI man warned me that if I gave away any secrets, the penalty was death,” Sorota said. He joined the project as employee No. 5.
The high-priority effort was so secret that team members had to pick up jackhammers, knock down walls and modify the workshop by themselves.
The team, which eventually counted several hundred engineers and technicians, worked around the clock designing new components and testing them at a secret facility located behind the production halls inside the factory. It took them just five months to develop the first prototype and another five months to ready it for the first flight.
But, problems quickly popped up after they unpacked the British engine from its box. “We didn’t have the right tools,” Sorota recalled. “Our wrenches didn’t fit the nuts and bolts, because they were on the metric system. We had to grind them open a little more to get inside.”
There were 15 people on Sorota’s shift. His job was to design the paths that channeled air inside the engine. Occasionally, he would take trips to other secret sites and study jets salvaged from the German V-2 rocket bombs that were falling on England.
In March 1942, just five months into the project, the Hush-Hush Boys wheeled their prototype inside a concrete bunker for a test. The cell opened into an old brick smokestack to channel exhaust and mask the tests.
However, the engine stalled. The engineers went back to their drawing boards, redesigned the compressor and started achieving higher thrust.
In the summer of 1942, the engineers loaded the first pair of working jet engines, each producing 1,300 pounds of thrust, onto a railcar and shipped them to Muroc Army Air Field in California’s Mojave Desert. Three GE engineers accompanied the top-secret cargo on its cross-country trip, along with five U.S. Army security guards.
Aircraft designer Larry Bell had been working in parallel with the GE team and building America’s first jet, the XP-59. On Oct. 2, 1942, the plane, equipped with engine I-A, soared to 6,000 feet and ushered in the Jet Age.
The first GE engines used a radial (centrifugal) turbine to compress air streaming inside the machine and help it generate thrust. It was similar in design to older technology GE was using for turbo superchargers.
Back at the River Works plant, Sorota and his colleagues started to work on an engine with an axial turbine that pushed air through the engine along its axis.
“The Whittle engine, when we took apart the compressor, was like a vacuum cleaner compressor,” he recalled. “It had a two-sided impeller that was very inefficient. Our engineers developed what now is known as the axial flow compressor.” This compressor is still being used in practically every modern jet engine and gas turbine today.
The Jet Age Begins
General Electric management decided to double down and invest in more jet engine research. They referred to the decade between 1942 and 1952 as “the fastest 10 years in history.”
New engines, such as the centrifugal flow J33 and the axial flow J35, continued to push the envelope. The J35 was the first turbojet engine to incorporate an axial-flow compressor, which has been used in all GE engines since then.
They used a radial turbine to compress air, similar to the design that Moss developed for his turbo superchargers. However, mass-production was handled by General Motors’ Allison division in Indianapolis (today, part of Rolls-Royce).
In 1945, the Lynn supercharger department was disbanded and replaced by the aircraft gas turbine division. Harold Kelsey was named managing engineer of the unit and set GE on an upward course it would follow for several decades.
Years later, Kelsey, who was promoted to executive vice president of GE in 1955, said, “My biggest contribution was to get General Electric into engine production…I made the decision to drop centrifugal engines and concentrate on the axial flow type.”
Soon, GE engineers started to develop the J47 engine. It eventually powered everything from fighter jets, such as the F-86 Sabre, to the Convair B-36 strategic bomber.
Large portions of the Lynn River Works were converted to jet engine production. The Everett, MA, plant, which had been producing superchargers since 1941, began to manufacture jet engine components. The first engine rolled off the Lynn assembly line in 1948. Each engine contained 8,859 parts.
General Electric eventually assembled more than 30,000 J47 engines, making it the most produced jet engine in history. Another 5,000 were built under license by companies such as Studebaker-Packard Corp.
“At one stroke, GE absolutely dominated the U.S. market for military jet engines,” says Garvin. “The peak production period during the Korean War was more than 1,000 engines per month. GE made only about 15 percent of the parts, procuring others from a huge network of suppliers.”
Because of that large demand, the Lynn plant couldn’t keep up with production rates. So, GE management looked around for a second factory.
They selected a federally owned plant near Cincinnati, where Wright Aeronautical piston engines had been produced during World War II. GE formally opened the second J47 assembly line at the Lockland Plant on Feb. 28, 1949 (the complex, now known as Evendale, is GE Aviation’s world headquarters).
In 20 months, employment exploded from 1,200 to 10,000 people, requiring a tripling of manufacturing space. And, for many years, Building 700 held the title of the world’s largest single-story building under one roof.
With the Korean War boosting demand, more than 35,000 J47 engines were delivered by the end of the 1950s. The engine set two milestones. It was the first turbojet certified for use by the U.S. Civil Aeronautics Administration and the first jet engine to use an electronically controlled afterburner to boost its thrust.
An average of 400 J47 engines were assembled monthly. Facing a problem with compressor rotor instability in early models, GE engineers decided to assemble the engines vertically to ensure integrity and stability during buildup.
To speed up production, engineers also installed an automated assembly line at the Lockland plant.
“GE current assembly practice is to run engines through a ‘green’ assembly, test them, tear them down, inspect, and reassemble on the final lines,” said an article in the April 14, 1952, issue of Aviation Week. “After final assembly, they are again run and shipped.
“The engines are assembled vertically on the green lines and fixtures are designed to stand the engine on its nose,” added the article. “[The major reason for this] is to eliminate the small sag in the long frame resulting from horizontal assembly. Secondary advantages are space-saving and accessibility. The final line uses horizontal assembly.”
The new J47 assembly line was called a “grape arbor” because the engines hung from an overhead conveyor. According to Cramer LaPierre, vice president and general manager of GE’s aircraft gas turbine division, “this probably is the first completely mechanized jet engine conveyor system in the country.
“The new system has abolished the wasted motion of moving engines from operation to operation manually,” added LaPierre. “The ‘industrial grape arbor’ innovation permits automatic engine movement from station to station, allowing workers to concentrate fully on assembling the engine parts.”
General Electric also conceived what became known as the Lockland Plan, a production philosophy under which the thousands of components used in the jet engines were produced by specialized manufacturers all over the United States. The parts flowed to a large central point (Lockland) for final assembly.
At the time, more than 260 manufacturers were part of the complex supply chain. The Lockland Plan was one of the pioneers of big business-small business cooperation for mutual benefit. It was the forerunner of the three-tiered supply chains widely used today in the automotive and aerospace industries.
However, GE continued to produce some key components in-house, such as control panels, electronics and generators. Among many other innovations, the company unveiled the first hermetically sealed microminiature relay for aerospace applications in 1955.
Cold War Warriors
GE Aviation’s long tradition of building upon previous technology, knowledge and experience goes back to its first generation of engineers. One of their more secretive projects involved nuclear-powered aircraft.
In 1951, General Electric was awarded a joint contract by the Atomic Energy Commission and the U.S. Air Force to develop an engine and airframe for a bomber dubbed the WS-125. Most of the R&D work was carried out in GE’s top-secret aircraft nuclear propulsion department. The plan called for two gas-turbine jet engines coupled to an airborne nuclear reactor.
The engine project, called the X211, featured twin turbojet engines equipped with afterburners. The unique power plant was 41 feet long and was capable of producing 34,600 pounds of thrust. In the late 1950s, the Air Force terminated the project before an actual aircraft flew.
During the early days of the Cold War, the Century Series fighters, which would fly at more than twice the speed of sound, made a huge leap in technical advancements, including aerodynamics and engine design. It also marked a paradigm shift in manufacturing techniques and forced engineers to find new ways to join exotic materials, such as titanium.
As the jets became faster, GE engineers were tasked with developing more powerful engines. They responded with one of the most important developments for the J79 turbojet—a variable stator. The movable stator vanes in the engine helped the compressor cope with the huge internal variations in airflow from takeoff to high supersonic speeds.
More than 17,000 J79s were built over a 30-year period, powering fighters such as the F-4 Phantom II. A J79-powered F-104 Starfighter became the first aircraft to achieve Mach 2 flight in 1958.
For the Convair 880/990 series airliner, the CJ805 derivative of the J79 engine marked GE’s entry into uncharted territory—the commercial airliner market. The new engine included a thrust reverser and a sound suppressor.
“The Convair 880 was lighter and faster than the Boeing 707 and the Douglas DC-8,” claims Garvin. “The lightweight CJ805 contributed to its high performance.
“The Convair 990 was the first American jetliner with a turbofan engine to increase thrust and reduce specific fuel consumption and noise,” adds Garvin. Engineers attached an aft-fan to the rear of the gas generator, behind a three-stage turbine that drove a 17-stage compressor.
Despite its advantages, the Convair jetliners failed to attract a big market. Convair ended up losing more than $500 million on the project, which at the time was the single largest corporate disaster in American business history. GE lost $80 million and exited the commercial aircraft sector.
“In terms of sales, the CJ805 program was a small country cousin to GE’s big and profitable military engine business and a considerable cost drag,” says Garvin. “Although the program was not a commercial success, without it GE would not be in the airline engine business today. The company demonstrated that it was prepared to back up its product, listen to the airlines and respond to their needs.”
General Electric engineers were also busy in the mid-1950s developing a new gas turbine that would transform helicopter capability. The 800-hp T58 turboshaft engine powered a Sikorsky HSS-1F in the first turbine-powered helicopter flight.
In 1964, GE introduced the T64 free-turbine turboshaft-turboprop engine. It featured technical innovations, such as corrosion-resistant, high-temperature coatings that contributed to the development of very heavy lift helicopters, such as the Sikorsky CH-53 Sea Stallion.
The Evendale, OH, manufacturing complex was eventually designated as GE’s production facility for large jet engines, while its sister plant in Lynn, MA, focused on developing and producing small jet engines. However, the two factories evolved into vastly dissimilar operations.
“They were separated not only by a distance of 800 miles, but also by philosophical and technical differences that frequently hindered the growth and progress of GE’s aircraft engine business,” according to Eight Decades of Progress. “A rivalry had developed over the years between Lynn (the “mother chapter”) and Evendale (the “offspring”) that had grown considerably larger than its parent.
“Not invented here” factors often resulted in the two locations competing directly with each other. Management recognition that GE’s aircraft engines comprised one business serving one set of customers—aircraft manufacturers, the federal government and airlines—led to a “one world” initiative that unified the aviation unit.
General Electric established small, tightly knit “projects” to manage each product line. Each project and product was supported by division-wide “functional” organizations, such as engineering and manufacturing, which ensured effective utilization of manpower and facilities.
If manufacturing one type of component was more efficient at a specific plant, all parts of that type were produced there. The commonality of manufacture and the cross-fertilization of concepts finally achieved in 1966 resulted in substantial productivity increases that continued during the 1980s, when GE had more than 20 different gas turbine engines in production at the same time.
One success story from that time period was the Lynn-manufactured J85 turbojet engine. Contracted by the USAF to build a low-cost air-combat aircraft, Northrop built the F-5 Freedom Fighter around the J85 engine. The F-5 soon became the standard air defense aircraft for more than 30 nations.
Advances in compressor, combustor and turbine knowledge in the 1960s led to the decision to propose a more compact core engine with a single-stage turbine and only two bearing areas vs. three, resulting in the GE F101 engine, which was selected for the U.S. Air Force’s groundbreaking B-1 bomber.
In the early 1970s, the U.S. Army turned to GE for an improved turboshaft engine to power its new generation of helicopters. The result was the legendary T700. Capitalizing on the lessons of the Vietnam War, the T700 provided the Army with an exceptionally reliable engine built using a revolutionary modular architecture.
The T700 was designed for field maintainability to drive down costs and improve Army helicopter readiness rates. Since then, more than 20,000 T700s have been built, logging more than 100 million flight hours.
General Electric engineers also developed the J93 engine to power the world’s largest, highest flying and fastest bomber, the experimental XB-70 Valkyrie. In 1965, it became the first aircraft to achieve Mach 3 flight.
Six 28,800-pound-thrust turbojets propelled the 500,000 pound aircraft to three times the speed sound at an altitude of 74,000 feet. Many technologies pioneered on the J93 are still used in today’s military and commercial engines.
One of the most significant technical achievements was a new technique for electrolytically drilling longitudinal air cooling holes in the engine’s large turbine blades. A noncontact process called shaped-tube electrochemical machining (STEM) is still used today to drill small, deep holes in electrically conductive materials.
During the defense buildup of the 1980s, GE military engines continued to play an important role. In 1984, the U.S. Air Force selected the highly reliable F110 engine, which was based on the F101 design, for the F-16C/D fighter.
Also in the 1980s, the F404 engine for the F/A-18 Hornet entered production. The F404 is the world’s most ubiquitous fighter engine, with more than 3,700 powering 10 aircraft types worldwide.
In 1964, General Electric competed with Pratt & Whitney for a contract to build engines for the U.S. Air Force’s new strategic airlifter, dubbed the C5-A. It set the company on track to eventually become a leader in the cut-throat commercial jetliner sector.
“The engines would have to be bigger, more powerful and more efficient than any built to date, and they were going to be ordered under a novel form of contract,” says Garvin. “The contract would be a ‘total package procurement,’ one lump sum for development and production years into the future, shifting the risk of [huge cost] overruns from the U.S. Department of Defense to the manufacturers.
“GE saw this as an opportunity to define engine technology for the next 50 years and took a giant gamble,” claims Garvin. “The highest bypass ratio until then had been just under 3-to-1. GE proposed a radical thermodynamic cycle for the new engine—a bypass ratio of 8–to-1, which offered a quantum improvement in propulsive efficiency.”
In 1965, General Electric received a contract to build the TF39 engine.
“This was GE’s first real dual-rotor front fan engine, with variable stator vanes on the high-pressure compressor,” adds Garvin. “From that time on, all of GE’s large military and commercial engines were of [this] configuration.
“GE designed the TF39 to military specifications, while keeping in mind the needs of U.S. airlines with whom the design had also been reviewed,” Garvin points out. “The technical success of the TF39 set a performance benchmark for turbofan engines and gave GE credibility as a designer and manufacturer of commercial engines.”
Building on the technology of the TF39 military engine, GE moved aggressively into the commercial aerospace sector in 1971 with a derivative engine, the CF6-6 high bypass turbofan, for the new Douglas DC-10.
General Electric engineers persuaded the airframe maker that a three-engine aircraft would be better than a twin-engine version. Among other things, they calculated that a trijet design could generate as much as 6 percent additional revenue for airlines by allowing the plane to hold more passengers.
In the 1980s, the CF6 family of engines emerged as the most popular engines powering wide-body aircraft, including the Airbus A300, the Boeing 747 and the McDonnell Douglas MD-11.
In 1971, a French aerospace manufacturer called Snecma (today, it’s known as Safran Aircraft Engines) selected GE as a partner in the development of a smaller commercial turbofan engine for the short-to-medium-range aircraft market. The joint venture, known as CFM International, would eventually become one of the greatest success stories in aviation history.
The collaborative effort created an engine called the CFM56, which was based on Snecma’s fan technology and the core technology of GE’s F101 engine. Today, the engine powers more than 550 commercial and military aircraft worldwide, including the Airbus A320 and the Boeing 737.
In 2008, CFM International launched Leap-X, an entirely new baseline turbofan engine to power future replacements for current narrow-body aircraft. It incorporates cutting-edge technologies that provide better fuel efficiency.
The first version of the Leap engine entered service on the Airbus A320neo in January 2016. It will also be used on the Boeing 737MAX and the Comac C919.
Production is currently ramping up at a new 225,000-square-foot facility in Lafayette, IN. After producing 100 engines last year, the plant expects to assemble 500 units this year, followed by 1,100 in 2018 and 2,000 by 2020.
The state-of-the-art assembly line features an automated vision inspection system and radio frequency parts management to track components on the plant floor. The Leap engine is also assembled at a GE plant in Durham, NC.
In addition to CFM, GE Aviation formed a joint venture with Honda Motor Co. in 2004. GE Honda Aero Engines builds HF120 turbofans for business aircraft such as the HondaJet.
General Electric engineers are currently in the process of testing the GE9X, which will power Boeing’s next-generation 777X jetliner in a few years. The goal is the achieve FAA Part 33 clearance by the end of next year.
With a 134-inch fan diameter, it’s the largest aircraft engine ever made. The GE9x engine will produce 105,000 pounds of thrust and will eventually become GE’s flagship product. It will feature 16 fourth-generation carbon-fiber composite fan blades; a third-generation combustor for high efficiency and low emissions; and ceramic matrix composite (CMC) materials in the combustor and turbine.
CMCs consist of silicon carbide ceramic fibers and ceramic matrix enhanced with proprietary coatings. With one-third the density of metal alloys, the ultra-lightweight material can help improve fuel efficiency and durability.
General Electric predicts that demand for CMCs will grow tenfold over the next decade. That’s why it’s currently investing more than $200 to build a pair of factories in Huntsville, AL, that will open next year.
“The use of CMCs in the hot section of jet engines is a significant breakthrough in the aviation industry,” says Ted Ingling, GE9X general manager at GE Aviation. “CMCs are also more heat resistant than metal alloys, allowing the diversion of less cooling air into an engine’s hot section. By using this cooling air in the engine flow path, an engine runs more efficiently at higher temperature.”
GE Aviation is also in the process of building a new assembly plant in Eastern Europe that’s scheduled to open in 2022. The Czech Republic facility will produce the world’s first 3D-printed turboprop engine. General Electric is spending $400 million to develop the engine, which will power the new Cessna Denali, a single-engine, six-seat aircraft.
Additive manufacturing technology will play a key role in the engine. For instance, it will allow engineers to consolidate 845 parts into just 11 components. Although the engine will still contain hundreds of parts, the reduction in complexity will help speed up production, reduce fuel burn by up to 20 percent, achieve 10 percent more power and lower the engine’s weight.
“The physics is simple,” says Milan Slapak, a turboprop program manager at GE Aviation in Prague. “The more metal you have in the air, the more money you need to spend on the material itself and on the fuel to keep it flying. Also, an engine with fewer components reduces the number of parts you need to design, certify, inspect and make. [Additive manufacturing] really is a game changer and it will totally change the way traditional supply chains operate, and simplify them massively.”
GE Aviation engineers have been working on the turboprop engine for more than three years. They’re already using 3D-printed fuel nozzles in the machine.
“It will be a different world 10 years from now from a manufacturing perspective,” claims Slapak. “Additive [technology] will enable us to make parts with complex shapes that are currently either impossible to achieve using conventional technologies or are simply too expensive to make.”