"The positive attributes of the GCLF were its extensive risk
reduction during the ASTOVL program, and better up and
away performance. Its negative attributes included its large
size, adverse temperature ranges and pressure environments
for the ducts, and the required cost of engine development for
higher airflow."
"From JAST to JSF: The Evolution of the Joint Strike Fighter"
by Ian A. Maddock
"Although the Gas Coupled Lift Fan (GCLF) system did not add as much concentrated
weight as a Shaft Driven Lift-Fan (SDLF) or a lift engine, it required more volume for the ducting of engine gas
forward to the lift fan, which decreased the fineness ratio of the aircraft and, thereby, supersonic efficiency. Under
the JAST program, McDonnell realized they would need to leverage development of the F119 engine – then being
readied for production, in contrast to the F120. The lower volume of fan air, coupled with the increased payload
requirements for JAST, meant that the gas-couple fan could not produce sufficient thrust. Unable to team with
Allison for the shaft driven lift fan being developed for the Lockheed concept, McDonnell decided to adopt
Northrop’s lift plus lift/cruise configuration.
...
Construction of their GCLF LSP PM propulsion system (without the airframe) was begun in 1994 at GE’s
Peebles, Ohio test facility. Full-scale p propulsion system testing using a GE YF120 engine and d a lift fan using GE
F101 components was conducted. The engine with a slave nozzle was first run in February 199 95. After 22 hours of
check-out and calibration tests, the bifurcated air induction system and the lift fan were installed led the next month for
a further 9 hours of tests, which concluded in May 1995. The test rig with the inlet system is sh hown in Figure 5; the
lift fan inlet is covered with screens to prevent anything falling or getting sucked in.
The MDA/NGC/BAe team did not test a complete LSPM due to the change in STOVL concept. When they
abandoned the GCLF approach, construction of the LSPM was discontinued since it was no longer relevant to their
selected concept. However, the experien ience with the aft lift module consisting of the diverter valve and the aft lift
nozzles was directly applicable to their L+L/C concept. Although the lift fan concept was dropped, the duct
blocker/lift nozzle feature was maintained in the L+LC design. Interestingly, it would have beeen a GE/Allison built
Aft Lift Module between the P&W engine and the P&W nozzle.
McDonnell Douglas was notified ied in November 1996 that it was not selected to continue to the Concept
Demonstration Phase (CDP).
The Quest for Stable Jet Borne Vertical Lift: ASTOVL to F-35 STOVL
Ian A. Maddock
Jacobs Technology, Arlington, Virginia 20112
and
Michael J. Hirschberg
American Helicopter Society International, Alexandria, Virginia 22314
AIAA 2011-6999
AIAA Centennial of Naval Aviation Forum "100 Years of Achievement and Progress"
21 - 22 September 2011, Virginia Beach, VA
