JDW: JSF engine design changes cause knock-on effect
Design changes that helped to reduce a weight growth problem two years ago are now resulting in problems for the propulsion system of the F-35B Joint Strike Fighter (JSF).
The Pratt & Whitney F135 engine for the short-takeoff-and-vertical-landing variant is running at about five per cent, or 190°F (87.7°C), higher than the system's limit in tests, according to programme officials. Around half of the temperature increase, or 100°F, is being attributed as an inadvertent consequence of the programme's 2004 decision to compensate for the aircraft's overall weight growth by raising engine thrust levels.
The new turbine vane design is set to be introduced sometime in mid-2006, and that fix alone should solve more than half of the temperature problem, said Rob Burnes, chief of the JSF joint programme office's propulsion directorate.