GE Aviation reveres Gerhard (“Herman the German”) Neumann as a jet engine pioneer and the architect of the company’s dramatic rise in the 1970s to become the worldwide jet propulsion leader across commercial and military aircraft, as well as marine and industrial applications. But the picture was hardly that rosy when Neumann took over the top job in 1961.
The outlook in the early 1960s was, to put it bluntly, bleak: GE’s first engine for jetliners, the CJ805, was a financial bust on the poor-selling Convair 800 and 900; the government-funded “atomic engine” turbojet program was cancelled by President John F. Kennedy; and the company’s highly innovative J93 military turbojet for the XB-70 bomber failed to become a production program. What’s more, GE’s 1950s military fighter-engine mainstay, the J79, lacked the legs to satisfy future propulsion requirements. Meanwhile, Pratt & Whitney’s dual-shaft compressor turbojets powered more than 80 percent of the western world’s commercial jetliners and continued to gain ground on military aircraft, including powering the new U.S. Air Force C-141 transport.
Neumann, who joined GE in 1948 and soared up the ranks after introducing variable-stator vane compressor technology to jet propulsion, turned to his leadership team in 1962 with a simple, if emphatic, declaration: “I’m tired of losing.”
A dramatic refocus of efforts was needed. With support from his mentor and boss, GE Vice Chairman Jack Parker, Neumann and his team set out to establish a technological roadmap to protect and position the company’s jet propulsion franchise. In 1962, Parker and Neumann focused on what became known as the GE1 “Building Block” demonstrator engine program. It was arguably the most important technology undertaking in the company’s history.
GE didn’t lack in advanced technologies but the company needed a strategy for packaging them better for future military and commercial aircraft requirements. The GE1 was the catalyst. It incorporated a scaled compressor with variable stator vanes, an innovative annular combustor, turbine-cooling technologies, and advanced materials developed for several government R&D programs. In short order, the GE1 program bolstered GE’s jet engine portfolio and greatly enhanced its ability to compete for future commercial jetliner business.
The program expanded in several directions. It was the antecedent of the GE4 engine, which helped the company win a short-lived U.S. government-sponsored supersonic transport program later in the decade (eventually cancelled in 1971), and it spawned the GE1/6 demonstrator engine, which featured the core “hot section” technology that gave birth to a new generation of GE military and commercial high-bypass turbofan engines.
The “building block” approach proved masterful and GE’s corporate commitment to the GE1 generated tremendous enthusiasm within Evendale’s technical community. Several propulsion leaders, including Peter Kappus, Fred MacFee, Jim Worsham, and Brian Rowe, helped to create a technology roadmap for the GE1. “With such an efficient core design as the GE1, we could add a fan or an afterburner or a thrust-vectoring device to satisfy any number of future applications,” wrote Rowe, who succeeded Neumann as the leader of GE Aviation. (Worsham later led Douglas Aircraft and revitalized McDonnell Douglas.)
Perhaps the most important engine line that the GE1 led to was the TF39—a major leap in design that offered record thrust and fuel efficiency.
Selected in 1965 to power the U.S. Air Force’s massive C-5 Galaxy transport, the sporty features of the TF39 drew heavily from GE1 hot-section core technology to drive the industry’s largest front fan (97 inches in diameter). The fan required unprecedented compressor efficiencies and turbine temperatures to turn it. To accomplish this, the engine’s hot section was equipped with a two-stage high-pressure turbine (HPT) driving a variable-stator compressor with a 16:1 pressure ratio. A six-stage, low-pressure turbine (LPT) powered the fan.
The result: An unprecedented 8:1 front-fan bypass ratio, a 25:1 overall pressure ratio, and turbine temperatures at 2,366 degrees Fahrenheit. The TF39 introduced new high-temperature alloys and an improved system for providing a cooling film of air over the HPT blades. This air shielded the blades from temperatures that exceed their melting point.
It was a turning point for GE and jet propulsion. The TF39 operated 25 percent more efficiently than all turbofans at the time—a stunning achievement that kicked off a new era in aviation, enabling high-bypass turbofans to power enormous aircraft for very long distances.
The TF39 win over P&W’s lower-bypass JTF14E turbofan set the stage for a showdown between the two engine titans in the commercial jetliner arena. Months after the August 1965 selection of the TF39, GE announced plans to create a commercial variant, the CTF39, to pursue future Douglas, Lockheed, and Boeing jetliners.
The CTF39 would evolve into GE’s CF6 commercial turbofan family, the most popular high-thrust engine for commercial jetliners for three decades, powering a dozen aircraft, including the Airbus A300, A310, and A330, the Boeing 747 and 767, and the Douglas D-10 and McDonnell Douglas MD-11.
The GE1 building block program went on to create huge dividends in the military world. In 1970, the U.S. Air Force selected the GE F101 engine to power the B-1 bomber. The dual-shaft F101, GE’s first afterburning turbofan, built upon the GE1 and GE9 demonstrators, along with metallurgical advances from the X370 demonstrator. Amazingly, the F101 was the twentieth version of the GE1 to reach hardware stage. In the 30,000-pound thrust class, the F101 was as powerful as the J79 with 25 percent better fuel efficiency.
As the decade rolled on, the F101’s importance extended beyond the B-1. Its highly efficient and compact core (with two bearings versus three) paired an efficient nine-stage compressor with a highly-loaded, single-stage high-pressure turbine, making it the natural fit for a number of new military engines—the F110 family for the F-16 and F-15; and the F118 for the B-2 bomber and U2 spy plane.
By the mid-1970s, the F101 core would be married to the engine low-pressure system from Safran Aircraft Engines, resulting in the record-selling CFM56 commercial engine family for CFM International.
None of these successes would have unfolded without Neumann’s GE1 “Building Block” demonstrator engine. Indeed, GE Aviation’s crusty old veterans will tell you the GE1 was the greatest GE jet engine to never power an aircraft. With that kind of track record, it’s hard to argue.