The Pratt & Whitney TF33 military turbofan engine and its commercial variant, the JT3D, celebrated its 55th anniversary in June. Bec...
The Pratt & Whitney TF33 military turbofan engine and its commercial variant, the JT3D, celebrated its 55th anniversary in June. Because the TF33's performance has been so exceptional for so long, its durability is something that's being studied and utilized in the design of the company's future propulsion systems.
The JT3D was the first turbofan engine designed and produced by Pratt & Whitney, developed from the JT3C turbojet. When it was introduced, the engine had approximately 50 percent more take-off thrust, 25 percent more climbing power and 20 percent greater power at maximum cruise than previous engines.
The versatile engine had powered high-altitude, reconnaissance aircraft; bombers; and aircraft doing low-level aerial delivery.
It was a low-bypass-ratio engine built around the J57's service-proven core. The JT3 made its first flight on a Boeing 707-120 aircraft on June 22, 1960. Shortly thereafter, McDonnell Douglas selected it for versions of the DC-8.
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| Eight of these engines power the USAF B-52H Strategic bomber |
Over the past six decades, it also powered the Lockheed C-141 Starlifter, Boeing C-135B Stratolifter. EC-135, RB-57 and KC-135, as well as the VC-135, which served U.S. presidents as Air Force One from Richard Nixon to George W. Bush.
The TF33 is expected to remain active on the B-52H fleet until 2045, and that obsolescence issues are being worked to extend its life out until 2070.
The production spanned from 1959-1985, producing around 8600 engines. Still, with approximately 1,100 engines in use – more than 800 in the B-52H fleet – the ability of suppliers to make parts for the engine remains a critical component.
"It's one of our biggest challenges, ensuring we have the parts to keep the engines running," said Gary Ransom, customer support engineer, Military Engines. "It can be a challenge to make a part from a drawing that's more than 50 years old.
"I'm constantly getting asked questions about TF33 engine performance. They're interested in such things as knowing why the engine performs so well in severe conditions, like ice build-up" he added.
Weighting around 2 ton, the 6.2 metre long and 1 metre diameter engine has a maximum thrust of 17,000 lbf (75.6 kN).
These engines enable the 488,000 pounds B-52H to fly at a maximum speed of 650 mph, to more than 10,000 miles, carrying a maximum weapon payload of 27 tonnes.
