The Defense Advanced Research Projects Agency (DARPA)
Tactical Technology Office (TTO) and the Naval Air Systems
Command (NAVAIR) Air Combat Electronics Program Office (PMA-209)
today announced the successful completion of a joint flight
demonstration of an advanced navigation set on an F/A-18.
Personnel from the Naval Air Warfare Center, Aircraft Division
(NAWCAD), Patuxant River, Md., provided engineering and
integration of the navigation set into the aircraft.
They also
provided the aircraft itself and the ground and flight crews.
Flight testing was conducted Nov. 26 - Dec. 17, 1996.
DARPA provided a Phase 1 Global Positioning System (GPS)
Guidance Package (GGP) for the tests.
The GGP consists of a
miniature inertial navigation set (INS), a 10-channel receiver
capable of processing GPS precision position service signals and
a navigation computer.
The GPS receiver and INS are tightly
coupled, which allows them to aid each other, depending on GPS
signal conditions and the air alignment mode.
The objectives of the flight demonstrations were threefold:
to demonstrate GGP performance under highly dynamic conditions
(e.g., 7.5g acceleration); to demonstrate the advantages of a
tightly coupled architecture; and to demonstrate various modes of
operation.
The modes include blended GPS/INS navigation;
inertial-only navigation, simulated periodic jam-out of GPS
signals and inflight alignment of the INS.
For the tests, the GGP was mounted in the nose of the F/A-18
and a single GPS antenna was mounted on the top of the aircraft.
Instrumentation included data recording equipment and a
differential GPS reference receiver for ground truth.
Recorded
data enabled the calculation of GGP performance in position,
velocity, and GPS satellite tracking.
Prominent among the flight profiles were a diamond pattern
and simulated bombing and combat maneuvers, e.g., air-to-air
combat.
The diamond profile had relatively long legs and
tested both blended GPS/INS and INS-only navigation.
The bombing
and combat maneuvers included up to 7.5g turns and rapid changes
in altitude and airspeed.
Barrel rolls, Immelmans and split
maneuvers were included in some flights.
This took the top-
mounted GPS antenna out of line-of-sight to GPS satellites.
The
high value of tightly coupled INS aiding was thus demonstrated.
The INS navigated when the GPS receiver had no signals, and
enabled reacquisition of GPS signals within seconds once the
aircraft rolled level.
The DARPA GGP program manager, Air Force Lt. Col. Beth
Kaspar, said, The flight tests really put the GGP through its
paces -- one of our so-called benign flights had barrel rolls and
touch-and-goes.
We certainly met our demonstration goals,
especially in showing the value of tight coupling and navigation
in high dynamics conditions.
I have high praise for the splendid
cooperation and performance by all Government and industry
participants.
GGP Phase 1 was developed under DARPA sponsorship by Litton
Industries, Woodland Hills, Calif., and Rockwell International
Collins Avionics and Communications Division, Cedar Rapids, Iowa.
The program is now in its second phase, during which navigation
performance will be increased, and size, weight and power will be
significantly reduced.
Litton Industries and Honeywell Inc. are
leading the teams competing in the Phase 2 development phase.
