Don Dahler
Author, Journalist
Stealth Fighters - Almost Invisible

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 February 8, 2003

F-117 Nighthawks are considered “stealthy” because of two technologies, both considered top-secret until fairly recently. 
One is the radar-absorbing material that coats every exterior surface, and in fact, has to be re-applied to screw-tops or scratches after every flight. The actual chemical makeup of the RAM is still classified but in his non-fiction book, “Fighter Wing,” author Tom Clancy describes it as “a mixture of metal or metal-oxide particles or fibers embedded in synthetic resin.” The original substance was highly toxic, so the Stealth pilots nicknamed the ground crewmen who touch up the jets “Martians” for the bulky chemical-protection suits they were forced to wear. There is reason to believe the Air Force has developed a less-dangerous compound that can now be applied without the awkward precautions. 
Even though the black jets got their nickname from the color of their surface and the fact that they almost exclusively operate at night, some pilots believe they’d be even more invisible if they were painted dark grey; the theory being a grey shape, slightly lighter in color than the surrounding sky and stars, doesn’t warrant a second look, as it would -- again, theoretically -- register on the human eye as a faint cloud. But, these pilots say, a totally black shape is unnatural, and as the delta-winged craft quietly slices through the night sky, especially at lower altitudes, its movement is slightly visible against a field of stars. At any rate, talk to any F-117 pilot and they’ll express nothing short of awe and respect for the black jet’s design.
The other technology that gives the F-117 an almost invisible profile to radar and infrared tracking systems is the shape of the jet itself. Lockheed Advanced Development Projects, working in the famous “Skunk Works” in Burbank, California, designed a delta-wing airframe without a single right-angle surface, since radar works by bouncing into solid objects and then noting the presence of its own reflection. Just as a radar signal sent into empty space produces no reflection, radar signals dispersed into a thousand directions reads as no radar signal at all.
Likewise, the heat-signature of the jet’s exhaust, which would show up like a spotlight on a moonless night to infrared systems, is lessened by channeling the fumes over heat-dispersing materials and hiding the glow of the exhaust from almost every angle. 
The fighters’ dual General Electric F404 engines do not have afterburners, a device common in other fighter jets that injects fuel into the rear part of an engine to add a burst of thrust. The Nighthawks don’t have them because, in the words of F-117 pilot, call-sign “Robo” (the Air Force requests no last names be used for pilots currently in-theater) “if you got a passing gear, you’d be tempted to use it.” Using them could be deadly on a Stealth mission; afterburners are very bright and very loud. 
But the lack of such a punch of speed makes the Stealth fighters relatively slow and defenseless. In fact, the designation of “fighter” is almost a misnomer; unlike all other American fighter jets, F-117s have no way of taking part in aerial combat against other aircraft – no air-to-air missiles, no M-61 Vulcan canon, no chaff to distract enemy missiles, and they’re not built to out-maneuver a conventional jet. 
Their only defense is invisibility. So the black jets are a jumble of oblique angles, like a cubist rendering of a large bat. 
Col. Jim Hunt, wing commander of the 49th Fighter Wing, home of the Stealth fighters, was one of the first pilots allowed to view the top-secret jets back in the early 1980’s. “I was just amazed. I was amazed first at how the thing could actually fly, cause it didn’t look like an airplane. And then I was probably equally amazed or even more amazed at who could have invented this. Who could’ve thought up this thing and make it do what it did.” 
His first instinct proved right; the answer to the question of how the F-117…then still known by the code-name, Have Blue… could actually fly turned out to be, frankly, it can’t. Not by human hands, anyway. In the air, the Stealth fighter is unstable in all three axes, that is, it wants to pitch, yaw, and roll all at the same time. In lay-terms that means it flies about as well as a crystal ash-tray. But four super-computers, working in quadundancy – are able to control the jet with instantaneous micro-adjustments of the flight surfaces, much faster than the human brain is capable of. As “Robo” says, “From weapons systems all the way to the flight control computers, there’s a lot of magic in that plane.”
After the mission briefing, a detailed flight plan is entered onto a hard-drive back at base, which is then plugged directly into the avionics system of the plane.  The jet takes off, flies a complicated, precise pattern to the objective that is designed to steer clear of anti-aircraft threats, then zeroes in on the selected targets with laser-guidance and/or gps coordinates. This leaves the pilot free to concentrate on the mission objectives and crucial systems checks, such as comparing the target acquisition input with visual references, like streets or bridges. The Air Force says there are at least two, and usually three, separate packets of information that helps the pilot make sure he’s on the right target. 
Despite this space-age technology, Stealth pilots say that aspect alone, the double-and-triple checking of targets before releasing the bombs, makes the presence of a human pilot in the cockpit still an irreplaceable failsafe. 
In the coming weeks or months ahead, if the U.S. once again goes to war and American warplanes once again take to the night skies over Iraq, their mission is expected to be one in which accuracy is paramount, and wide-spread death and destruction avoided. 
A role the U.S. Air Force says is custom-made for the black jets. 

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Stealth Fighters - Almost Invisible