DonHollway.com: STEALTH SECRETS OF THE F-117 NIGHTHAWK

	Stealth Secrets of the F-117 Nighthawk
	by Don Hollway
	Originally published in AVIATION HISTORY, March 1996

Its development was kept under wraps for 14 years, but by 1991 the F-117 Nighthawk had become a household word.

Though few of them realized it at the time, television viewers tuned to the Cable News Network around 7 PM Eastern Time on the evening of January 16, 1991 were treated to a rare, live preview of wars to come. Broadcasting live from their room in Baghdad’s Al-Rashid Hotel, correspondents Bernard Shaw and Peter Arnett were covering the state of alert of Saddam Hussein’s Iraq. 5 1/2 months after Iraqi forces invaded the neighboring emirate of Kuwait—and seventeen hours after the deadline for their withdrawal set by the military coalition opposing them—Baghdad had taken shelter beneath the strongest concentration of air defenses in the world, including 76 surface-to-air missile (SAM) launchers and nearly 3,000 antiaircraft artillery (AAA or “triple-A”) guns. Iraqi radar operators scoured the moonless skies for the first intimation of approaching aircraft, but they saw nothing. “We haven’t heard any planes yet,” noted Shaw, wondering aloud whether Boeing B-52 bombers flew so high they couldn’t be heard. Surely no manned aircraft could brave these defenses.

650 miles almost due south, at Khamis Mushayt in southwestern Saudi Arabia, pilots of the 37th Tactical Fighter Wing were anxiously watching the CNN newscast. Two hours earlier their squadron mates had departed King Khalid Air Base on the first air strike of the war. One of their targets, on the west bank of the Tigris River, was the 370-foot Al-Kark Communications Tower, through which CNN’s TV signal passed to the outside world. Now, as the estimated time-on-target approached, each man at King Khalid kept one eye on CNN and one on his watch, counting down. If all had gone according to schedule, the network would go off the air...now!

The need for an aircraft which could penetrate modern air-defense systems had actually arisen from another Middle Eastern conflict almost 20 years earlier. In the 1973 Yom Kippur War, Israeli-flown McDonnell-Douglas F-4 Phantom fighters suffered heavily from Egypt’s radar-guided SA-6 SAMs. Over Vietnam the U.S. Air Force was already devoting more than half the aircraft in each “strike package” to radar suppression rather than bombing. Plainly they were on the wrong side of the cost-effect equation.

The first real answer came in 1975 from the most likely source: the Advanced Projects Division of Lockheed-California—the famous “Skunk Works.” Engineers there reasoned that curved surfaces reflect energy in many directions, the way a soap bubble reflects sunlight. If an aircraft’s surfaces were flat, like the facets of a diamond, reflections could be limited to directions of the designers’ choice—namely, away from enemy receivers. Models tested outdoors at Lockheed’s Palmdale facility bore out the hypothesis; even a bird perching on one model caused its radar cross-section (RCS) to “bloom.”

But faceting caused handling problems, so Skunk Works team leader Ben Rich—a close associate of Lockheed’s brilliant chief Kelly Johnson and a veteran of the firm’s U-2 and SR-71 spy plane programs—secured government funding for two full-size, flying prototypes under the appropriately meaningless code-name “Have Blue.” Skinned with large sheets of flexible radar-absorbent material (RAM), they featured sharply-raked wings and twin fins canted sharply inward, not for supersonic capability but to avoid bouncing reflected signals back to their source. For the same reason cockpit-canopy, access-panel, and landing-gear doors required jagged, sawtooth edges, which had to fit perfectly flush when closed. Since just the reflection of the pilot’s helmet would outshine the rest of the plane put together, the canopy was also given a transparent coating, probably of gold or indium-tin, to render it impenetrable to radar. Similarly, since modern radars can look down engine inlets to view highly reflective compressor faces (and in many cases identify them by counting the rotating blades), the engine inlets were covered with a fine, radar-opaque mesh. Even screw heads were redesigned; at one point, just three which had been insufficiently tightened caused the jet’s RCS to bloom.

Radar, however, is not the only popular method of aircraft detection. To reduce their vulnerability to heat-seeking missiles the prototypes used slit-like exhausts, shielded from beneath by a wide, flat, “platypus” tail. Exhaust emerged in cool, diffuse fans rather than hot, concentrated streams. The canted fins were also intended to further screen the exhausts from enemy fighters looking down from above.

The prototypes were shipped to the top-secret facility at Groom Dry Lake, in the Switzerland-sized Nellis Air Base range north of Las Vegas, Nevada. Home to the both the U-2 and SR-71 testing programs—as well as the “Red Hat” squadron, the Air Force’s top-secret stable of captured MiG fighters—Groom was the natural choice for its newest “black” (top-secret) program.

The first prototype flew in early 1978. Naturally unstable, airborne only by virtue of computerized, quadruply-redundant fly-by-wire controls, it exhibited rapid speed loss in nose-up attitudes, a high landing speed and sink rate. This ultimately proved its undoing when Lockheed test pilot Bill Park bounced it off the ground, jamming the right gear halfway up. Unable to land or even belly in, he burned off his excess fuel and ejected from 10,000 feet over the Nevada desert. The prototype was destroyed and Park, injured in the ejection, never flew again.

The second prototype, however, proved to all practical purposes invisible to radar. It showed at most a low-intensity, nebulous radar sparkle, nearly indistinguishable from background noise, until well within the missile’s minimum launch range. Only the massive airborne antenna of the Boeing E-3 Sentry “AWACS” and some ground-based low-frequency and very-high-frequency radars had success, but because of their large antennae these last are unsuitable for battlefield use.

Offered virtual immunity to radar, the Air Force quickly underwrote production of full-scale development (FSD) aircraft. The new design reflected lessons learned during the “Have Blue” program. Engine power was increased, the inlets and exhausts baffled and soundproofed to minimize noise—emitting, instead of the typical jet-turbine scream, a high-pitched whine said to set dogs barking before the plane itself appeared. The prototypes’ inward-canted fins had actually acted to reflect the exhausts’ heat emissions, so the FSD’s fins were canted outward in a V-shaped “butterfly” tail.

The demands of combat, as modified by the requirements of stealth, dictated the rest of the redesign. First of all, and contrary to most military aircraft designs since the 1950s, the FSD would carry no radar. Even an inactive radar acts as a reflector; for the FSD to beam microwaves about was tantamount to shining a beacon on a dark night. Even the normal radio antennae which stud conventional aircraft were made to retract beneath the FSD’s skin when not in use. Also, since external fuel tanks and weapons would spoil the plane’s RCS, all fuel and munitions would be carried internally. The limited capacity of inboard fuel tanks could be overcome with aerial refueling, and that of an internal bomb bay was not seen as serious, given the new plane’s perceived mission. Instead of scattering tons of conventional bombs in hopes of a hit it would deliver just one or two laser-guided “smart” bombs. Essentially seeker heads and fins attached to a standard “dumb” bombs, LGBs home on invisible, infrared laser light shined on the target by the attacking aircraft, yielding a circular-error probable (CEP, the distance around the target in which the bomb is likely to strike) measurable in inches.

Having (temporarily) lost its new Boeing B-1 bomber to government cutbacks, the Air Force was anxious for a new aircraft to fill the void. Naturally speculation in the aviation press centered around a full-sized Advanced Technology Bomber. The FSD might have escaped attention altogether except that in 1980 the White House intentionally alluded to its existence. Whether this was an election-year ploy remains open to question, but the new aircraft—now popularly known as the “stealth fighter,” as opposed to the “stealth bomber”—was over the course of the next decade to become the hottest topic in aviation.

Given a new code name, “Senior Trend,” the new airplane was also given the deceptive designation of F-117. The American “Century Series” of fighter aircraft, beginning with the North American F-100 Super Sabre, supposedly ended with the General Dynamics F-111. In October of 1962, in the interest of cross-service commonalty, the Department of Defense began renumbering its combat aircraft, starting with F-1. After the Northrop YF-17 (which became the Northrop/McDonnell-Douglas F/A-18 Hornet) came the Northrop F-20 Tigershark; aviation journalists naturally guessed the stealth fighter was designated F-19. In fact the origin of the F-117 designation is somewhat of a mystery. Were the “Century Series” designations passed on to the MiG fighters of the Red Hat squadron—F-112 for the MiG-15, F-113 for the MiG-17, F-114 for the MiG-19, F-115 for the MiG-21, and F-116 for the MiG-23? At any rate the F-117 designation started turning up on Lockheed documents regarding “Senior Trend,” and the Air Force saw no reason to change it. At the very least it enabled government spokespeople to plausibly deny the existence of an “F-19.”

With their wings detached the first “Stealth Fighters” were flown by Lockheed C-5 Galaxy transport plane to Groom Lake, where they took to the air for the first time in June 1981. Security was, to put it mildly, tight. Unauthorized ground personnel were required to remain indoors when a stealth jet emerged from its hangar. Test flights were made mostly at night, their schedule dictated by the overflights of Soviet reconnaissance satellites. The Nellis Range is also home to the Air Force’s “Red Flag” air combat exercises, with aircraft and pilots of all American and several foreign military aviation services testing their skills by attacking most anything that flies. They were kept away from the Groom area by an airborne screen of security aircraft.

Despite its 33% increase in physical size over the prototype, the F-117’s RCS measured out between .01 and .001 square meter—about that of a small bird. Compared to, say, an F-4 Phantom typically used for “Wild Weasel” anti-radar missions and with a head-on RCS of six meters, the F-117 was able to get 90% closer to ground-based search radars, and 98% closer to airborne radars, before being detected.

Testing was still underway when the Air Force ordered an entire wing of the definitive, production version of “Senior Trend”: the F-117A Nighthawk. Until delivery of their F-117As the pilots trained in Vought A-7D Corsair IIs. The first military pilot to fly a Nighthawk was Lt. Col. Alton C. Whitley, a Vietnam vet with combat experience in the A-7 and the North American F-100 Super Sabre, and former commander of the Air Force’s Aggressor squadron. ‘Star Wars’ type of aircraft. I thought, ‘Boy, is this the 21st century!’”

Having outgrown the Groom Lake facilities, the stealth unit—now officially the 4450th Tactical Group—operated out of the Tonopah Test Range airfield in the northwest corner of the Nellis Range. Though overlooked by public land, the TTR was some 40 desert miles from the nearest town—sufficiently remote to discourage all but the most persistent observers. 4450th pilots flew into Tonopah each Monday aboard a government-chartered airliner for four nights of intensive training before returning home Friday afternoons. It seems likely the grueling body-clock changes, rather than any inherent flaws in the F-117A itself, accounted for the ensuing pilot/aircraft losses.

By this time the second “Have Blue” prototype had caught fire in midair and crashed, and the first F-117A was retired after going inverted and backwards on takeoff. Both test pilots survived; the first incident was attributed to a broken fuel line and the second to inadvertently cross-connected pitch and yaw controls. (Normally the Nighthawk’s fly-by-wire system so compensates for its instability that when one jet lost an entire rudder in mid-air and at high speed, the pilot had to be informed of the fact by the chase plane, after which he landed safely.) With low wing-loading and gee-limits comparable to the F-4, the F-117 handles well; the widely-reported nickname “Wobbly Goblin” apparently derives from its “departure” characteristics—once out of control, it can’t be recovered.

In June 1986 and again in October 1987 pilots flew their Nighthawks into the ground. Both incidents were attributed to pilot fatigue and disorientation. Despite USAF efforts to the contrary word filtered to the outside world. Public interest in the stealth fighter had been renewed in July 1986, when Testor Corporation released a curvaceous plastic model of an “F-19,” insisting it was 80% accurate. Finally, in November 1988, the Pentagon publicly revealed a grainy, heavily-retouched photo notable mostly for how little it revealed of the F-117.

By then the 4450th, now activated as the 37th Tactical Fighter Wing (the “Defenders of the Crossroads”) and consisting of the 415th and 416th Tactical Fighter Squadrons (the “Nightstalkers” and “Ghost Riders” respectively) and the 417th Tactical Fighter Training Squadron (the “Bandits”), was combat-ready. Twice stealth fighters were within an hour of taking off to bomb targets in Libya, only to have their missions scrubbed to avoid revealing their existence. Not until December 1989 and the U.S. invasion of Panama—Operation “Just Cause”—did the F-117A see action.

Refueling in mid-air, six Nighthawks made their way to Panama via Texas and the Caribbean Sea. Two of these were backup aircraft, which turned back unneeded; two more assigned to support special-forces troops attempting to kidnap dictator Gen. Manuel Noriega turned back when their mission was scrubbed. Confusion over the last-minute change resulted in a mix-up over the remaining target, a barracks housing two battalions of élite enemy troops. The intent was not to kill but to stun; the lead F-117A did just that, and with a single 2,000-lb. Mark 84 bomb. Colloquially known as “the Hammer,” the bomb—with a lethal radius of 400 feet and capable of blowing out eardrums half a mile away—landed in a field next to the barracks, throwing the Panamanians into confusion. The second stealth jet also hit its aim point, which turned out to be in error. Despite the 50% hit rate the Air Force declared the mission a success. After all, the stealth jets had gone unnoticed on Panamanian radar. But the real test was less than a year in coming.

On August 17th, 1990, the 37th T.F.W. received a new commanding officer—none other than Al Whitley, the F-117A’s first military pilot. “Four hours later,” the colonel recalls, “the word came in to deploy our first squadron.” The U.S. and its allies planned to get Saddam Hussein’s Iraqis out of Kuwait, by force if necessary, and the Nightstalkers of the 415th T.F.S. were among the first allied units to deploy to Saudi Arabia.

Located 6,500 feet up in the mountains near the Red Sea, King Khalid Air Base—”Tonopah East”—had been built in the late 1970s in return for delivery of McDonnell-Douglas F-15 Eagle fighters and AWACS airborne sentries to Saudi Arabia. It was beyond the reach of Iraqi Scud-B ballistic missiles, but the stealth jets would require three midair refuelings each in order to reach their main target—downtown Baghdad.

“I generally put the F-117s against the Baghdad targets,” admitted the Air Force’s chief mission planner, Brig. Gen. Buster C. Glosson, “...where we would have lost [conventional] airplanes.” 37th T.F.W. personnel included just three combat veterans—Whitley, his deputy commander, and one “Just Cause” pilot. But five months later the incessant training above the barren Nevada desert paid off as the Nightstalkers and Ghost Riders lugged two tons of bombs apiece across more than 1,000 miles of nighted desert. Shortly before 3AM local time, January 17th, eight black jets rose batlike, lights-out and radio-silent, above Baghdad.

It was Capt. Marcel Kerdavid who was assigned to bomb the Al-Kark tower. “Even though I felt very well prepared with my training, I was somewhat apprehensive about the aircraft,” he admitted later. “Its stealthiness had not been tested in combat, and everyone wondered whether or not this stealth stuff really worked.”

Anticipating a pilot-rattling sleet of antiaircraft fire, mission planners had assigned a second stealth jet to mark Kerdavid’s target and lighten his workload. (In fact the prior arrival of several Tomahawk cruise missiles had spurred a flurry of triple-A, but a few minutes before the stealth jets arrived overhead the Iraqi crews actually ceased fire to cool their overworked guns.) As the laser touched down on the Al-Kark’s dome-shaped roof a forward-looking infrared scope (FLIR) in the nose of Kerdavid’s plane picked up the signal and displayed it in the cockpit’s eight-inch video display. Using a fingertip control on his throttle stick, Kerdavid locked his aim point onto the laser glint and his weapons system projected an imaginary “basket” above it, into which it would have to drop the bomb for a successful strike.

Ten seconds before release, Kerdavid hit the “pickle” button to enable his weapons system. The Nighthawk’s bomb-bay snapped open and lowered its lethal load into the slipstream: a one-ton GBU-27A/B guided bomb, designed especially for use by the F-117A. Based on the BLU-109 “penetrator” munition, extra-streamlined and case-hardened (a design which in prewar tests had penetrated up to 12 feet of reinforced concrete before exploding), its pop-out wings and microprocessor-equipped laser seeker—specially bobbed to fit in the F-117A’s bomb bay—provided for loft-bombing from treetop height and long standoff range.

Freed of the necessity of dodging antiaircraft fire, however, Kerdavid (who was awarded a Silver Star for his feat) was able to drop his bomb from relatively high above and near the Al-Kark. He immediately veered away north toward his secondary target, a command bunker in the Taji suburbs. The second F-117 loitered on station a little longer, using its belly-mounted, downward-looking infrared (DLIR) laser designator to mark the target for Kerdavid’s bomb.

In their room in the Al-Rashid Hotel, CNN’s microphones picked up the rising moan of an air-raid warning. “Now the sirens are sounding for the first time,” noted Peter Arnett. “The Iraqis have informed us—”

In that instant, as if out of nowhere, Kerdavid’s GBU-27 slammed into the Al-Kark like the fist of Allah, drilling halfway down the tower before exploding. The entire building snapped in half—a spectacle lost to CNN viewers and personnel at King Khalid, as the network went promptly black. A surviving audio-only land link allowed Arnett to verbally describe the blind spray of return fire rising above the Baghdad skyline. The Iraqi gunners had no idea where to aim; their radars told them no aircraft were above them.

But seconds later another F-117A’s GBU-27 impacted directly across the Tigris from the Al-Kark, through the roof of the 12-story Baghdad International Telephone Exchange, known to Air Force mission planners as the “AT&T Building” and the only target in the city slated for a double hit. One of those planners was the 415th’s Major Jerry Leatherman, who 60 seconds after the first strike circled in from the northeast to drop a pair of high-blast Mk. 84 homers from three miles up through the hole in the building’s roof. The first went a little low, but the second was dead on and together they demolished the top four floors.

In quick succession three waves of stealth jets singled out their objectives with a precision at once merciful and merciless: the Iraqi Air Force and Ba’ath Party headquarters, air-defense control centers, Rashid Airfield, and other high-value targets including two of Saddam Hussein’s presidential palaces. A half-hour after the initial attacks the city blacked out, probably not because of Iraqi precautions but because their power grid was destroyed. But Baghdad remained well-lit by the storm of triple-A fire above it.

“It was a giant 4th of July display from the surface to 15,000 or 20,000 feet in every direction,” recalled Al Whitley, who led the Ghost Riders on the second wave and could see the glow from 100 miles away. “They knew we were up there; they just didn’t know where.”

Back at King Khalid the ground crews anxiously counted the returning aircraft, the last of which didn’t touch down until after dawn. Miraculously, not only did every Nighthawk come back, but none of them bore so much as a scratch—an achievement which was to stand throughout the entire conflict.

In the first 24 hours of the war the 42 stealth fighters at King Khalid—just 2.5% of the total allied aircraft deployed in the Gulf—accounted for 31% of the targets attacked. Damage estimates were lower than expected, partially due to a low layer of mist that obscured Baghdad toward dawn. Not only did cloud cover—three times the seasonal average during the course of the war—interfere with subsequent operations, it compromised the black jets’ invisibility.

“If you’re just above a cloud deck, with the moon reflecting off it, you can really stick out,” explained Leatherman. At one point an F-117A was shadowed by what appeared to be an Iraqi Mirage F1 fighter, shining a landing light or spotlight in order to visually acquire the stealth jet. A gentle turn, however, broke whatever lock the Iraqi had; this was the closest any Nighthawk came to a dogfight over Iraq.

Throughout the Gulf war the black jets were consistently assigned the most dangerous, high-priority targets: radar sites, SAM and Scud launchers, enemy command/control/communications facilities, bridges, hardened aircraft shelters and bunkers. Their data recorders provided some spectacular video footage for Air Force publicists: a hardened Scud storage facility destroyed by a laser-guided bomb dropping through an air duct; one bomb blowing in the door of an ammunition bunker and a second flying though to explode inside; a GBU-27 flying down an elevator shaft to detonate deep within the Iraqi Air Force Headquarters, blowing out all four walls. Given clear weather, Whitley stated, the combination of stealth fighter and laser-guided bomb was so accurate that, let alone targeting a building, “you can want the men’s room or you can want the ladies’ room.”

Ultimately the greatest purpose served by Nighthawks’ surgical strikes, as opposed to indiscriminate bombing, was the saving of lives on both sides. By handling more than 40% of the coalition forces’ strategic targets and relegating formerly strategic bombers like the B-52 to tactical, front-line objectives, they led the USAF to completely reorganize after the war in order to adapt to the new technology and tactics. The 37th Tactical Fighter Wing, redesignated the 49th T.F.W., relocated from Tonopah to Holloman Air Force Base, New Mexico. Its planes are expected to serve well into the next century; Air Force analysts have so far found no way stealth technology can be compromised in the foreseeable future.

Whatever developments arise, the F-117A Nighthawk, the Skunk Works and Ben Rich are assured their place in aviation history. “We guaranteed to deliver an aircraft which would have stealth characteristics, be virtually undetectable by today’s known radar technologies, and be able to deliver a weapons system with unprecedented accuracy,” said Rich. “We’ve done that. Our accomplishments speak for themselves.”

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