It was 1980 and turbine capacity was measured in kilowatts. The big names in manufacturing included Boeing and Alcoa. And UTC's Hamilton Standard aerospace subsidiary had just built a 3MW prototype in Sweden. It then won a $5.9 million US Interior Department contract to build an even larger machine, known as the WTS-4.
By 1982 the turbine's two 40-metre blades were turning in Medicine Bow, Wyoming - producing power until the right-wing Republican administration of Ronald Reagan gutted federal wind power support as the decade unfolded. That lack of support, along with a worldwide oil glut, scuttled plans to deliver 20 of the machines to Hawaii for an 80MW project.
As the domestic wind industry began to recover in the 1990s, turbine sizes hovered well under 1MW for many years. They still averaged less than 1.75MW in the US as recently as 2009. So in 2005, as Clipper readied its innovative 2.5MW turbine that included four generators and a distributed drive train, the machine was seen by many as an unpromising departure from the modest-sized norm - not unlike the WTS-4.
But although Hamilton exited from wind and eventually became known as Hamilton Sundstrand, the company continues making advances in aerospace technology. And last year, as UTC began forming a due-diligence team in advance of its $0.25 billion bid to partner with Clipper, it called upon a pair of long-time Hamilton engineers who had worked on the WTS-4.
"They worked on the Hamilton wind project and they continued at Hamilton since then, doing other things related to gearboxes and blades," says Mauricio Quintana, Clipper's new CEO. "They're both excellent. That's why a lot of people were sceptical about the Clipper design, whereas UTC saw a lot of innovation."
Clipper founder Jim Dehlsen was among those keenly aware of the Hamilton Standard WTS-4 back in the day. A book he read in the 1980s delved into the topic and he visited the Medicine Bow test site in the mid-1990s. "The machine had been abandoned and I thought I could probably buy it for about $25,000," Dehlsen says. "As it turns out, there's an engineer who actually did buy it and worked on it and, I think, got it back operating. It was a really amazing machine for its time."
Dehlsen believes the WTS-4 was dismantled sometime in the late '90s or early '00s. But the overall experience made an impression and years later, when Clipper sought a test site for its prototype machine, Medicine Bow became the logical destination. Clipper's 2.5MW test turbine was erected in 2005 - five or ten rotor diameters from where the WTS-4 had stood, says Dehlsen.
Over the years, California-based Clipper and UTC crossed paths. Somewhere around 2002, Dehlsen visited UTC's base in Connecticut to explore licensing the company's retractable-blade technology and applying it to wind power - an idea that still intrigues Dehlsen. "There've been some intersections that are kind of interesting," he says. "I think I've had UTC in my blood for a long time."