End of the Relationship: Last of the QF-4s

The F-4 Phantom II fighter still flies with a number of air forces, including Egypt, Germany, Greece, Japan, South Korea, Turkey, and possibly Iran. These large 2-seat multi-role fighters were a triumph of thrust over aerodynamics, and formed the mainstay of the USAF and US Navy fleets for many years. QF-4s are former F-4s that currently sit in storage at the AMARC “Boneyard” near Tucson, AZ.

They are refurbished for flight at AMARC, then flown to BAE in Mojave, CA and fitted with remote-control equipment in a process that takes about 160 days. Once fitted for the UAV role, they are used as aerial targets and decoys for testing against air-air missiles, radars, surface-air missiles, et. al. As of April 2007, BAE Systems had converted 217 F-4s to the QF-4 configuration.

The Final Mission: The USAF’s QF-4 Target Drones

Wearing the “stars and bars” insignia of the US Air Force, an F-4 Phantom cruises in level flight. Unobserved, another USAF aircraft falls in trail behind the Phantom and fires an air-to-air missile at it. The F-4 performs an aggressive slice in hopes of evading the missile, releasing countermeasures all the while. But it’s no use – tracking unerringly, the missile cuts the F-4 in half. Debris rains from the resulting fireball, but there are no parachutes. What’s going on? Why is one US fighter being shot down by another? Strange as it sounds, this is a typical day for the 82 Aerial Target Squadron (ATRS). The 82nd flies the USAF’s last active-duty Phantoms as full-scale aerial targets (FSATs) for weapons tests.

They Shoot Airplanes, Don’t They?

Under United States law (Title 10, Section 2366 of the U.S. Code) a missile system must undergo lethality testing before it can enter full-scale production. This means it must be fired at a combat-configured target, which for air-to-air or surface-to-air missiles is a full-size, fully capable aircraft. The cost and hazards of using a manned aircraft from the active-duty inventory for this purpose are obvious. Instead, the target is an unmanned FSAT drone. As one 82 ATRS pilot summarizes it, “the F-4 is dying, to give birth to new weapons systems.” In support of U.S. test and evaluation activities, Phantom drones also act as targets for non-lethal tests of missiles, radar and other sensors, and defensive systems. They also support Air Force and Navy training, such as “Combat Archer” missile shoots. Both services also employ sub-scale target drones, which are less costly to operate than FSATs. But only a full-scale target offers the flight characteristics, performance envelope – including subsonic and supersonic flight at altitudes up to and above 50,000 feet – endurance, radar and infrared (IR) signatures, and damage resistance of a real aircraft.

The QF-4 conversion adds a digital control system for remote operation of the aircraft’s steering, throttles, flaps, landing gear, brakes, braking parachute, and tailhook. Also fitted are a vector Doppler scoring system, transponder, second autopilot, and GPS for navigation and formation-keeping in remote flight. Non-essential equipment such as the F-4E’s 20mm cannon is replaced with ballast, while unused avionics like radar are left aboard but disabled. Finally, the wingtips and tail are painted orange to distinguish the aircraft as a drone. The QF-4s are assigned to the 82nd ATRS at Tyndall, part of the 53rd Weapons Evaluation Group. The squadron operates full-scale and sub-scale drones over Tyndall’s air weapons range in the Gulf of Mexico. Detachment 1 of the 82 ATRS, based at Holloman AFB, New Mexico, provides target services for the Army and civilian contractors over the Army’s White Sands Missile Range (WSMR).

Flying the QF-4

Both 82 ATRS and Det 1 maintain a few “primary flier” aircraft for manned flight, approved for up to 300 flight hours. Other FSATs are cleared for 100 hours, and are kept ready for unmanned flight with non-essential items like ejection seats removed, or held in non-flying storage. Despite having over 60 aircraft on strength, 82 ATRS has a small military staff: six USAF pilots split between the two bases and a few sergeants to oversee maintenance. All other personnel are civilians employed by Lockheed Martin, including pilots, ground controllers, and maintainers. All are ex-military with a tremendous level of expertise – for example, contract pilots typically have over 1000 F-4 flying hours.

QF-4s are almost always flown with a pilot aboard, unless a weapons launch will occur. Usually he does not touch the controls but stands ready to take over if ground control is lost or the aircraft departs. The pilots fly the aircraft themselves on chase missions and to maintain proficiency.

The aircraft are controlled remotely by the Gulf Range Drone Control System (GRDCS) at Tyndall or the Drone Formation Control System (DFCS) at WSMR. Drone controllers have a flight instrument display on a monitor, but no direct visual contact with the aircraft. A controller may fly, using a joystick and keyboard instead of stick, throttles, and rudder pedals; however, most test and evaluation flights are steered by computer. This allows a test to be flown within exact parameters and repeated exactly if necessary. Up to six QF-4 aircraft can be controlled in formation, using GPS to maintain each in position relative to the flight track.

The programmed flight track may include an automatic landing, but if the telemetry signal is degraded or the aircraft is damaged, a Ground Mobile Control System (GMCS) is used to perform a visual landing. GMCS is a panel van with two control positions on the roof. It is parked by end of the runway so the controllers can watch the aircraft as they steer it. One controller controls pitch and throttles, while the other controls bank and heading. Two controllers are needed due to the workload – where an onboard pilot would sense the aircraft’s attitude and speed, the controllers must interpret it from instruments.

Missile vs. Aircraft

Typically, several practice runs precede a test mission, to confirm that all test parameters are being met – many trial runs are less expensive than one failed test. If a missile will be fired at the drone, the actual test will use a NULLO aircraft – NULLO stands for “not under live local operation” but is also Latin for “zero,” the number of crew aboard. The NULLO aircraft carries a destruct charge (the warhead from an AIM-9 missile) to ensure the jet’s demise if it is damaged during the test or control is lost. Accompanied by a manned chase plane, the drone is launched from the 7,000x300-foot “droneway” at Tyndall or the 11,000x300 foot one at Holloman, heading south to avoid populated areas. At Tyndall, two DeHavilland Canada E-9A aircraft are launched as well. These converted Dash-8 airliners use sideways-looking airborne radar to establish a “shoot box” that will not endanger civilian boats on the water below the Gulf Range.