Hellfire Meets Predator

How the drone was cleared to shoot.

In 2000, Predators began reconnaissance missions for the CIA in Afghanistan. After 9/11, they flew armed, becoming the most controversial weapon since the atom bomb. (Lt. Col. Leslie Pratt/USAF)
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The Hellfire’s software would have to be modified too, to launch the missile properly from the Predator’s normal operating altitude of about 15,000 feet, for the AGM-114 was designed to be launched at tanks by helicopters flying 2,000 feet or less above the ground. Test firings—first from the ground, then in the air—would be necessary.

Beyond all that, the engineers would have to integrate the missile’s circuitry and software with the Predator’s flight control computer and a new sensor turret, or modified Kosovo ball, which Raytheon Corporation was developing. The new turret would add the daylight camera lacking in the laser ball used in Kosovo.

On July 28, Big Safari received formal approval from Headquarters Air Force to do what Jumper wanted, but the instruction said no Predators were to be modified until the service got both Congressional approval and a ruling that arming the drone was acceptable under the INF Treaty. Under the circumstances, the Big Safari team did as much analysis and made as many modifications as they could.

Engineers at Wright-Patterson analyzed the Hellfire’s rocket plume and came up with encouraging results. Because the Hellfire would get away from the Predator so fast—within 250 milliseconds it would be 16 feet past the drone’s nose—and its rocket plume was so compact, the aircraft’s tail would only “see” (in engineering jargon) a high temperature of 440 degrees Fahrenheit as the missile departed, and that only briefly. The wing and fuselage would see only 170 degrees, and the air pressure change around the plume would present no problems.

General Atomics, meanwhile, conducted analyses showing that a Hellfire could indeed be launched from a Predator without breaking the aircraft apart or throwing it into a spin.

Engineers at the General Atomics factory in California began writing the software needed to wed the Hellfire to the Predator. They also designed new ribs and cross brackets to go inside the Predator’s wings at their hardpoints, allowing them to carry a single-rail launcher derived from a multi-rail launcher that Big Safari had quickly gotten from the Navy. The engineers were still barred, though, from making any changes to the aircraft chosen to become the first armed Predator, tail no. 97-3034. 

On August 30, Air Force lawyers issued a legal opinion forbidding all “touch labor” to arm the Predator prior to getting approval from Congress. Now the team working on Jumper’s project was barred from modifying not only Predator 3034 but also any of the other equipment needed for the project. All they could do was look and analyze, not act.

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Parked on the concrete floor of a hangar at General Atomics’ flight test facility at El Mirage, California, the rubber wheels of its three-legged landing gear locked in bright yellow chocks, was Predator 3034. A dozen feet to either side, sitting atop aluminum wing stands—trestles akin to sawhorses—were the Predator’s unattached wings.

Midway along the underside of one wing hung a single rail cut from what once was a four-rail M299 Hellfire launcher. Hung from the rail was a black Hellfire. The missile was what Big Safari called a House Mouse. Not only did this Hellfire carry no propellant to create thrust and make it fly, it also lacked the shaped explosive charge a live missile would carry, a charge that could generate a jet of heat and pressure powerful enough to drill through a heavy tank’s armor on impact. The mock Hellfire, however, held all the same electronics as a live one. Running from the launcher where the House Mouse hung on the unattached wing to the socket where the wing was meant to fit into Predator 3034’s fuselage was a collection of gray wires.

This unorthodox sight had resulted from a phone call received by the Big Safari office at General Atomics on September 21. The Air Force had secured Congressional approval to spend money arming the Predator, so touch labor would now be allowed. But the state department general counsel’s “initial opinion,” as a senior Air Force procurement officer reported in an email to Jumper and others, was that a “weaponized Predator constitutes a cruise missile, hence an INF Treaty problem.” Lieutenant General Stephen Plummer added that the defense department’s general counsel was “working with them to change that opinion.” But until the issue was resolved, no missile could be mounted on a flyable Predator.

Big Safari’s solution, meanwhile, was to put the missile launcher on a detached wing and then wire it to the flight control computer in the Predator’s fuselage to check whether the systems would work together once the wing was reinstalled. The tactic was legal, for a Predator unable to fly was clearly outside the INF Treaty definition of a cruise missile as “an unmanned, self-propelled vehicle that sustains flight.”

On January 2, Predator 3034 got its wings back in the General Atomics hangar at El Mirage. Government treaty experts had decided that a lethal drone was permissible under the INF Treaty, according to the simple logic that a cruise missile, by definition, had a warhead, and the Predator didn’t. The Predator was merely a platform, a UAV that had landing gear and was designed to return to base after a mission.

At El Mirage, each of 3034’s wings held a single gray launch rail, and each rail angled down five degrees from its wing’s leading edge. With the wings in place, a small group of engineers and technicians fitted the drone with a Forty-Four ball, the same laser designator turret used on the Predators flown over Kosovo in 1999. Then, after three weeks of ground and test flights of various kinds, the team trucked 3034, a ground control station, and other equipment 90 miles north to the test range at China Lake Naval Air Weapons Station to start shooting missiles.

***

Now Predator 3034 had its wings and nose, but its tires were missing. At China Lake, it would be put through a static ground launch of a Hellfire to see, before trying it in the air, what a missile rocketing off the drone’s wing would do to the aircraft. Under each of 3034’s shiny new white wings hung a 64-inch-long inert Hellfire.

Only one of these inert Hellfires would be launched in the test, but each had white stripes along its black skin, the better to help high-speed film and video cameras see the missile’s aerodynamics in flight. The stresses on the drone from the heat and thrust of the Hellfire’s rocket plume would be measured by thermal, strain, and pressure gauges, and by temperature-indicating crayons applied to the laser ball, tails, and leading edges of the wings.

Chained to its test pad, 3034 sat with its nose pointed northwest and nine degrees upward. Behind the drone and its Hellfires was a hill 40 feet higher, with two big antennas on its summit, one to stream the Predator’s video, the other to communicate with a ground-based laser designator sitting beside a control van a couple of miles downrange. A crew manning the second laser designator would shine a laser beam to guide the inert Hellfire to a mock target, a dusty, defunct green tank sitting in the desert three miles straight ahead of the Predator.

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