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The selection of Lockheed
Martin and Boeing for the concept demonstration phase was
made in early 1997. McDonnell Douglas was eliminated and their
team was dissolved. In the spring of 1997 Northrop Grumman
joined the Lockheed Martin team and at the 1997 Paris Airshow,
British Aerospace was added.
The Concept Definition Phase
of the program saw the name changed to Joint Strike Fighter,
with a mandate to develop flying demonstrators for possible
production.
Between the CDP contract
award in 1996 and the first flights in 2000, literally thousands
of meetings and technical reviews took place as the Boeing
and Lockheed teams worked towards finalizing the designs for
their X demonstrator aircraft and continued refining what
would become their final program proposals.
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Boeing X-32 Test
Flights
Fred Knox, Boeing JSF Chief Test Pilot, piloted the X-32A
as it departed the runway at Palmdale on its first flight
at 10:00 am PST on 18 September 2000. During the flight, Knox
put the X-32A through some initial airworthiness tests, including
flying qualities and sub-systems checkout. The first flight
represented the X-32A's entry into a five-month flight-test
program at Edwards Air Force Base that consisted of approximately
50 test flights totaling about 100 hours to validate the X-32’s
flying qualities and performance for conventional and aircraft
carrier operations.
On 15 November 2000, the
X-32A began field carrier landing practice (FCLP) tests to
demonstrate flying and handling qualities during low-speed
aircraft carrier approach. U.S. Navy Commander Phillip “Rowdy”
Yates, the U.S. government's lead test pilot for the Boeing
JSF program, and Knox demonstrated simulated carrier landings
using a Fresnel lens to provide pilot cues during their approaches
to a simulated carrier deck outlined on a runway at Edwards
Air Force Base. The tests were successfully concluded on 2
December.
Boeing CV accomplishments
included 97 approaches and 74 actual touchdowns, as well as
numerous "wave-offs," throttle transients and integrated
test blocks including roll response and speed stability during
the FCLP tests. Flying as many as five flights a day the week
of 18 December, the X-32A successfully completed low-speed
approach CV tests, marking completion of 100% of the government-defined
CV test objectives.
The X-32B took to the air
for the first time on 29 March 2001, the pilot was Phil O'Donoughe.
The aircraft conducted a 50-minute conventional flight from
Palmdale to Edwards Air Force Base. During the flight the
X-32B was subjected to a series of initial airworthiness tests,
including flying qualities and subsystems checkout.
Following the conclusion
of several in-air STOVL tests, the X-32B was prepared for
its ferry flight to Patuxent River Naval Air Station (NAS),
MD. The X-32B departed Edwards AFB for its cross-country trip
on 4 May. While en-route to NAS Patuxent River, the X-32 made
six refueling stops, as it was not certified for air-to-air
refuelings. The X-32B arrived at Patuxent River NAS on 11
May.
On 24 June, during the aircraft's
44th flight, O’Donoghue transitioned the X-32B from
fully wingborne (conventional) to jetborne (STOVL) flight
mode and then smoothly decelerated the X-32B to a steady hover
at about 250 feet above the ground. O'Donoghue then accelerated
out of the hover and transitioned back to conventional flight
before making a "slow landing." During four other
flights the same day, the X-32B completed three additional
hovers and numerous transitions to STOVL flight. In total,
the X-32B hovered for eight minutes that day, the single longest
sustained hover covering two minutes and 42 seconds.
The final flight of the
X-32B test program occurred on July 28, 2001. The aircraft
took-off at 1547 EST, climbed to 30,000 feet and performed
a series of supersonic dashes achieving a maximum speed of
1.05 Mach. UK Royal Navy test pilot Lieutenant Commander Paul
Stone, guided the aircraft to touchdown at 1628 EST thus bringing
to a close the Boeing flight test program.
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Lockheed X-35 Test
Flights
The X-35A CTOL demonstrator successfully completed first flight
on 24 October 2000, taking off at 9:06 a.m. Pacific Daylight
Time from Palmdale. The initial flight profile included check-outs
of the on-board systems, handling characteristics and down-link
connections for the constant stream of critical data-transfer
to the flight-test technicians at Palmdale and Edwards Air
Force Base. The X-35 climbed quickly to an altitude of 10,000
feet, maintained an airspeed of 250 knots while accomplishing
a series of figure-eight maneuvers to demonstrate key handling
qualities and to validate design predictions.
The X-35A CTOL program was
completed on 22 November 2000 with all objectives achieved
or exceeded.
The X-35A (aircraft 301)
made its last flight to Palmdale, where it immediately began
conversion to the X-35B STOVL variant. The flight LiftFan
3D had just arrived at Pratt & Whitney for acceptance
testing from Rolls Royce North America.
At 9:23 a.m. PST on 16 December
2000, Lockheed test pilot Joe Sweeney launched the X-35C from
the Lockheed Martin Aeronautics plant in Palmdale, Calif.,
and flew the plane for 27 minutes before touching down at
Edwards Air Force Base. The aircraft climbed to 10,000 feet
and accelerated to 250 kt (288 mph). Sweeney cycled the landing
gear and performed aircraft flying-qualities evaluations,
including rolls, sideslips, and overall systems checks. Primary
differences from the X-35A include a larger wing and control
surfaces, the addition of ailerons and a special structure
to absorb high-impact landings. Two additional flights took
place on 19 December in preparation for commencement of FCLP
testing.
The Lockheed Martin JSF
team completed installation of the JSF X-35B’s flight-ready
propulsion system – including the shaft-driven lift
fan and engine – on May 12. Following these modifications,
the aircraft was towed to the hover pit and British Aerospace
test pilot, Simon Hargreaves began operating the flight-ready
system in the aircraft on May 24.
On 23 June 2001 at the Lockheed
Martin Skunk Works in Palmdale, the X-35B conducted its first
press-up, marking the first time in aviation history that
a shaft-driven lift fan propulsion system had lifted an aircraft
into the sky. On that day, Hargreaves took the aircraft up
to 15-20 ft for several minutes and then conducted a vertical
landing. The following day, Hargreaves again engaged the LiftFan
propulsion system, and the plane rose straight up to a stabilized
position at an altitude of about 25 ft, while Hargreaves checked
to ensure the flight controls responded properly before returning
the plane gently to the ground.
On 06 August 2001, during
the aircraft’s 66th and final test flight, Tom Morgenfeld
piloted the X-35B. The aircraft left the runway at Edwards
AFB at 1009 PST. Several test cards were performed and the
aircraft was ferried back to Palmdale for storage. The flight
lasted 3.7 hours, during which Morgenfeld went through six
aerial refuelings. Six touch and go landings were conducted
at Palmdale before Morgenfeld brought the aircraft to rest.
At the end of its testing, the total amount of flight time
on the X-35B was 48.9 hours.
Following the completion
of their flight test periods, the X-35 demonstrator aircraft
were retired to museums. The X-35A/B is now in the permanent
collection of the Smithsonian Institution and is on display
at the Stephen F. Udvar-Hazy Center near the Dulles International
Airport in Virginia. The X-35C is now in the permanent collection
of the United States Association for Naval Aviation and is
on loan to the Patuxent River Naval Air Museum in Lexington
Park, Maryland.
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