The F-35 Propulsion Systems are the most powerful fighter/attack
turbofans in the world.
The Pratt & Whitney F135 family of advanced propulsion
systems utilize cutting edge technology to provide the F-35
with higher performance than conventional fighter aircraft.
The engine consists of a 3-stage fan, a 6-stage compressor,
an annular combustor, a single stage high-pressure turbine,
and a 2 stage low-pressure turbine.
The F135 is currently in the SDD phase.
The F135 is using the lessons learned from the F119 engine
core and the JSF119 during the CDA stage to reduce risk in
SDD. During SDD the F135 test engines will undergo a range
of ground and flight tests to simulate various mission profiles.
In these tests the system demonstration engines will be run
for hours throughout various flight envelopes to ensure they
meet performance requirements. One of the vital milestone
tests occured at the end of 2003 with the first F135 engine
The first CTOL F135 engine test occurred
on 11 October 2003. The First STOVL F135 engine test occurred
on 14 April 2004. To date over 2,000 hours have been accumulated
on the F135 test engines.
Rolls-Royce Lift System
Rolls-Royce is subcontracted to Pratt &
Whitney on the F135 to provide the Lift System for the F-35.
The Lift System is comprised of the Lift Fan, Clutch, Drive
Shaft, Roll Posts and the Three Bearing Swivel Module (3BSM).
Shaft Driven Lift Fan (SDLF)
Lockheed Martin developed the idea for a Short Take-Off Vertical
Landing (STOVL) lift system that uses a vertically oriented
Shaft Driven Lift Fan (SDLF). A two-stage low-pressure turbine
on the engine provides the horsepower necessary to power the
Rolls-Royce designed Lift Fan. The Lift Fan generates a column
of cool air that provides nearly 20,000 pounds of lifting
power using variable inlet guide vanes to modulate the airflow,
along with an equivalent amount of thrust from the downward
vectored rear exhaust to lift the aircraft. The Lift Fan utilizes
a clutch that engages the shaft drive system for STOVL operations.
Because the lift fan extracts power from the engine, exhaust
temperatures are reduced by about 200 degrees compared to
traditional STOVL systems.
The SDLF concept was successfully demonstrated
through a Large Scale Powered Model (LSPM) in 1995-96 and
during the flight-testing of the X-35B during the summer of
2001. The Lift Fan, a patented Lockheed Martin concept, was
developed and produced by Rolls-Royce Corp. in Indianapolis,
Indiana and in Bristol, England.