Accomplishment Establishes G650 As World's Fastest Civil
Gulfstream Aerospace Corp. announced Friday that a Gulfstream
G650 recently reached Mach 0.995 as part of its 1,800-hour
flight-test program. The aircraft achieved this speed during
flutter testing, which evaluates the aircraft's damping responses
following an input from an external test device. Flutter testing is
performed at a variety of frequencies, speeds, altitudes, weights
and centers of gravity.
For the initial series of flutter tests, the aircraft achieved
clearance out to both its design dive speed (Vd) and design Mach
dive speed (Md) at altitudes ranging from 10,000 feet to up to the
aircraft's maximum certified altitude of 51,000 feet.
In order to achieve the maximum speed of Mach 0.995, Gulfstream
experimental test pilots Tom Horne and Gary Freeman along with
flight test engineer Bill Osborne took Serial Number (S/N) 6001
into a dive, pitching the aircraft's nose 16 to 18 degrees below
the horizon. During the dive, flutter exciters introduced a range
of vibration frequencies to the wing, tail and flight control
surfaces to ensure the aircraft naturally dampened out the
oscillations without further action from the pilots. Even under
such extreme circumstances, the G650 performed flawlessly.
"The airplane is very predictable," said Horne, senior
experimental test pilot, Gulfstream. "It's very easy to control and
to get precise control at those speeds. The airplane response has
matched the expectations of our engineers, and we've been able to
easily fly the test conditions and march through the test
(L-R) Tom Horne, Bill Osborne, Gary Freeman
During the flutter test missions, a team of multi-disciplinary
engineers in Gulfstream's telemetry center in Savannah monitored
the aircraft's behavior and determined real-time the damping
characteristics of the aircraft. The vibration frequencies exerted
on the aircraft ranged from 2 hertz, or twice per second, to 58
hertz, or about as fast as a fluorescent light flickers.
"We're doing very well," said Pres Henne, senior vice president
of Programs, Engineering and Test, Gulfstream. "The demonstrated
flutter margins met or exceeded our expectations out to maximum
speeds. That's a good sign."
As S/N 6001 continued with flutter
testing, S/N 6005 completed initial phase manufacturing and began
engine testing. S/N 6005 is the fifth and final aircraft in the
G650 flight-test program. Each aircraft in the program has a
specific purpose, with S/N 6001 focused on envelope expansion, air
data calibration, flutter, in-flight performance and flight
controls. S/N 6002 is used to evaluate the aircraft's systems as
well as its takeoff and landing performance, while S/N 6003 tests
the avionics, in-flight load measurement and ice protection system.
S/N 6004 will be the first G650 outfitted and tested with a full
interior, which is currently being installed. S/N 6005 will
participate in the reduced vertical separation minimum testing.
The G650 flight-test program officially began on Nov. 25, 2009.
Through Aug. 25, the four airplanes currently flying in the program
have completed more than 170 flights and 575 flight-test hours.