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Gas Turbines

Better Than Fishing: How Friendship Stoked The Flames Of A Gas Turbine Revolution

Amy Kover
July 06, 2020

Don Brandt has always been fascinated by what makes machines tick. He worked as an apprentice in a machine shop after he graduated high school in 1949. In the U.S. Marine Corps during the Korean War, he drove himself crazy trying to fix a fleet of wonky tanks. “There was something wrong with those tanks that I just didn’t understand at the time,” Brandt says, a trace of frustration still lingering in his voice today.

His dogged determination to learn grabbed the attention of the tank manufacturer’s engineers, who recommended that Brandt study mechanical engineering at Pennsylvania State University after the war. From there, he delved deeper into the inner workings of machines, obtaining a master’s degree in material science and even pursuing, but not completing, a Ph.D. before landing at GE Power, where he poured all that curiosity into gas turbines — a field that would rapidly become one of his life’s passions. “Followed only after my great-grandchildren,” the 88-year-old says.

7F turbine Don Brandt
Don Brandt with an F-class turbine prototype. Image credit: Don Brandt.


That gaggle of kids isn’t his only progeny. Brandt is also the father of the groundbreaking F-class gas turbine at GE, the first gas turbine to hit a combined-cycle efficiency rate well above 50%, thus setting the standard for providing customers with machines that can generate more electricity with less fuel. The 7F turbine, which celebrated its 30th anniversary in June, is acknowledged as one of the most successful gas turbines ever. Nearly 1,000 are in operation around the world today, providing power to millions of homes and businesses.

The largest F-class gas turbine family — known as the 7F — came into being thanks to Brandt and his team’s unending curiosity throughout the 1970s and 1980s. After studying how materials behave under pressure, such as low cycle fatigue and linear elastic fracture mechanics, at Union College in Schenectady, New York, Brandt became GE Power’s gas turbine material science “behaviorist,” responsible for recruiting other experts to introduce new alloys and methodologies into the development of gas turbines. “As it turns out, very little of that technology was being used in the design of gas turbines at that time,” explains Brandt.

7F turbine
A copy of a letter stating GE's intent to build a gas turbine with firing temperatures as high as 2,500 degrees Fahrenheit. For comparison, the melting point of iron is about 2,800 degrees Fahrenheit. Image credit: GE Gas Power.


Word of Brandt’s smarts spread to Cincinnati, where GE Aviation’s chief engineer, Marty Hemsworth, invited him to consult on manufacturing a material for a helicopter engine in the 1970s. The two became fast friends. “He and I just hit it off as two guys who would like to go fishing together,” Brandt says. “But we never went fishing.” Instead, they talked about engineering, sharing discoveries and helping each other solve engineering problems at the two divisions.

It was around this time that Brandt began imagining how to make gas turbines more efficient and configured specifically for combined-cycle application. He knew that the key to more efficient energy is operating temperature. The higher a turbine’s firing temperature, the greater will be the cycle efficiency. Gas turbines in the 1970s ran at a firing temperature of 1,985 degrees Fahrenheit, but Brandt wanted to go to a minimum of 2,300 degrees — what could be considered a quantum leap. In fact, he asked his team to evaluate as high as 2,500 degrees in a letter dated September 5, 1979. This letter officially marked the beginning of the project that would create GE’s largest gas turbine fleet: the F class.

7F turbine
One of the first 7F turbines went to a power plant in Chesterfield, Virginia. Image credit: GE Power.


The trick was turning up the heat without melting the turbine itself. To get there, Brandt instructed his team to investigate everything from novel cooling methodologies from aircraft engines to ideal combustion configurations. But then he took things a step further by inviting Hemsworth to co-chair a corporate review board comprising scientists from GE Research, Materials & Processes Lab, and Aviation to host engineering reviews for the F class each month. Among other benefits, the collaboration led Brandt to apply Inconel 706, an alloy used for rotors in aircraft engines. He suspected the alloy could also hold up to super-hot firing temperatures, and eventually figured out how to use it for the 7F’s turbine wheel. No easy task, as Brandt points out: “[Aircraft engine rotors] weigh pounds and we were talking tons.”

The team had a few other nontechnical hurdles to leap. Brandt’s boss at the time had reservations about the project. “I really think you are going to get yourself into trouble,” he warned Brandt. They also needed to keep GE’s competitors from catching wind of this daring project. Brandt named the turbine the “F series” to make others think it was merely a few tweaks to the existing E class.

Finally, in early 1989, the first of two 7F turbine units arrived at Chesterfield Power Station in Chester, Virginia, to be guided into operation by a control specialist named Dixie Music before a crowd of what felt like a thousand onlookers. “It was a pretty dramatic moment because obviously this was a very important project to GE,” remembers Mark Bull, who oversees customer satisfaction for GE Power at Chesterfield and worked on the installation at the time. The turbines would continue to make an impression. Today, the 7F produces 756 megawatts at a thermal efficiency of 60.4%. And since going live in June 1990, there are nearly 1,000 units around the world, with more than 50 million fired hours in service.

Perhaps the 7F gas turbine’s greatest accomplishment is what its innovation has introduced. Natural gas usage increased over the last 15 years, while coal consumption has steadily declined. Power producers now demand higher efficiency from their turbines, which ultimately has helped reduce emissions.

“As a practicing engineer, I had so much fun,” says Brandt, who retired in 1996 as chief engineer for power. He then continued for another 15 years working for the chief engineer’s office as an active participant in design reviews. “But the thing that really pleases me is that we collectively worked to make the world a better place,” he says.

And so they did. Brandt and his team’s work decades ago to create the F-class gas turbine helped bring about a transformation in the gas turbine industry and GE’s latest technology — the HA gas turbine — which would build upon their work to reach new levels of performance and secure world records for efficiency.