Aircraft

F-117A Nighthawk

This is my F-117A Nighthawk Stealth Fighter Attack Aircraft site. You will find information and facts about the F-117A Nighthawk.

Hover over the links below for a description of that page.

Check out http://airliners.net/ for about 270 pictures of the F-117A Nighthawk.

Background

Designing an aircraft that is nearly invisible to enemy radar may seem more like a dream than reality. However, in 1975, Skunk Works (slang for Lockheed's Advanced Development Projects Unit) set out to do just that. How do you accomplish such a task and still make it aerodynamic and able to fight as a military weapon? It took engineers three years to come up with a prototype. Because of their radical design, it was too risky and expensive to construct a full size aircraft to see if the avionics low radar profile would work. Under contract by Defense Advanced Research Projects Agency (DARPA) the team built two 60% scale models to test their design. "Have Blue" was born in 1978.

Have Blue was the codename for the scale aircraft. After the Air Force System Command took control of the project, it was highly classified. The F-117A wasn't released to the public until 1988; and only after full production models existed. In order to save time and money, the prototypes were made with off the shelf parts including non-afterburning General Electric J85s that were enclosed on top of the wings. Other pieces were taken from existing aircraft including the F-16, Northrop A-5, and a Fairchild Republic A-10. They had no weapon bays or tactical equipment of any kind. The fly-by-wire system which was adopted from the F-16 had to be modified as the Have Blue prototype was aeronautically unstable about all three axis, where as the F-16 was only unstable about the pitch axis. Even with the off the shelf parts, they cost $37 million.

The first prototype was completed in November 1977. It was shipped to the remote Groom Lake Test Facility in Nevada to help preserve its secret status. It flew in January or February of 1978 (the exact date is still classified) for the first time. The Have Blue had a very high landing speed (160 knots) because of the lack of speed brakes and spoilers. On May 4, 1978 disaster struck. Most test flights went without incident, but this time it hit the ground excessively hard jamming the right main landing gear. The pilot, Bill Park, pulled the aircraft up to try to get the gear to fully extend. After three unsucessful attempts, he was ordered to take the aircraft up and eject from it. He hit is head and became unconscious; as a result, he suffered serious back injury and had to retire from flying. The wreckage was buried in the Nevada desert.

The second Have Blue arrived at the test site shortly after the first one crashed. This one was built to test the stealth design of the aircraft. After several flights it was determined that to keep the aircraft the most stealthy, it would have to fly straight toward the radar station, head on. It was invisible to all airborne radar except the Boeing E-3 AWACS, and only then at close range. Most ground based missile tracking radar could tract the Have Blue, but only when it was within the minimum range of the surface-to-air missiles. In other words, it was only visible when it was practically on top of them. During its 52nd flight, one of the engines caught on fire, the pilot, Lt.Col. Dyson, was forced to eject. It too was buried in the desert. Despite these two losses, the aircraft and thus, their designs and concepts, proved their worth.

Built mainly of aluminum, the F-117A was extremely complicated to build. In order to keep its radar protection at a maximum, the tooling of the aircraft had to be 10 times more accurate than that of other aircraft.

The engines are a pair of non-afterburning General Electric F404-GE-F1D2 turbofans, derivatives of the afterburning engines that power the F/A-18 Hornet.

Like the Have Blue, the aircraft was unstable about all three axes. The fly-by-wire system that was incorporated into the Have Blue and the F-117A intercepted all flight controls from the pilot. The computer then made small adjustments to the control surfaces of the plane. To further insure the pilots safety this system is quadruple redundant. All four of the fly-by-wire systems are constantly compared with each other. If one does not agree with the other three, it is assumed faulty and shut down. It is very unlikely that all four will fail, but if they do the aircraft would be unable to fly and the pilot must eject.

Since it has no flaps, the F-117A has a high landing speed at 185 mph. As a result, a parachute is deployed when it touches down to slow the aircraft.

Nighthawk, Wobblin' Goblin, Black Jet, and Frisbee are just a few of the nicknames this aircraft has received. Although it has no official name, Nighthawk is the one most commonly used.

Presently the F-117A are under control of the 49th Fighter Group at Holloman Air Force Base near Alamogordo, NM. Sometimes when driving back and forth between my house and my parent's house you can see them fly overhead and fairly close over the highway. They are very majestic.

Stealth Technology

Unlike its distant cousin, the B-2 Spirit, the F-117A incorporates a technique called faceting. Looking at pictures of the plane you can see that there are really no curved surfaces. The surface of the plane is composed of triangle shapes and angles. The idea is that if the radar wave hits the aircraft, it will be reflected away, and in effect scattered, from the radar station.

To further reduce the chance of radar picking it up, the plane is covered in radar absorbent material (RAM).The exact composition of this material is classified, although it is believed to be a matrix of magnetic particles held in place by a polymer. It originally came in large sheets, but later when it went into production, the RAM was sprayed on in a facility controlled by computers. The F-117A is turned on a spit while spray guns spray the aircraft.

The application of this RAM was very important. All seems and joints had to be inspected and filled with a RAM like material before each flight to ensure maximum stealthness. Even one loose screw could make it look like a truck flying in, instead of a small bird, which is what the F-117A usually looks like on radar.

The air intakes for the engines are covered in a fine grating, where the gaps are smaller than most radar waves. The grates are also covered in RAM material. The purpose is to prevent radar waves traveling down the air intakes and bouncing off the fans of the engines. The inside of the air intakes are also covered in RAM to further reduce the radar signature. Since the air intakes are so small they are fitted with electrical heaters to prevent the buildup of ice. In addition, because they restrict airflow two large blow-in doors are fitted over both intakes for low speed operations, like taxiing, takeoffs, or low-speed flight.

As complicated as the intake is, the exhaust is even more complicated. They are mounted on top to prevent infrared (heat) detection from the ground. Narrow and wide, they spread out the exhaust cooling it quickly and presenting as low an infrared signature as possible. The ducts are round when they exit the engines but are flatted out into a plume at the end of the plane. At the end of the exhaust are more grated openings 12, each about 6 inches square. The gratings in the exhaust function in the same way they do at the intakes. In addition, heat-reflecting tiles are used to further reduce the aircraft's heat signature. Air is also bypassed around the engines to help cool them as well. As a source of persistent maintenance problems, the exhaust was redesigned in 1991 with different airflow paths, better heat shields, and better seals.

Even the windows have been designed to reduce the aircraft's radar signature. They are covered in a thin gold layer to prevent the pilot's helmet from showing up on the radar (a problem that plagued engineers during early tests).

The Nighthawk cannot use any radar to navigate or to feed to the fly-by-wire system, for that would greatly increase its radar signature. Instead, four probes extend out of the nose of the aircraft. They have tiny holes in them that allow the plane to determine its airspeed and angle of attack. It was yet another very difficult problem for engineers to solve. Like most aircraft, it is also fitted with an inertial guidance system. Later the navigation systems were upgraded to include GPS tracking ability.

In addition , the canopy, weapon bay doors, and landing gear doors, have serrated edges to conceal the joints when they are folded shut.

The stealth technology of the F-117A is so good, that it is undetectable by conventional radar system until 16 miles, and even then it looks like a small bird.

Weapons

All weapons must be concealed internally for stealthness. Inside the bay, it can carry 5,000lbs of ordinance.

Some of the loads which can be accommodated in the F-117A's weapons bay include two laser-guided MK84 2000-pound bombs, two laser-guided GBU-10 Paveway II 2000-pound bombs, two laser-guided GBU-12 Paveway II 500-pound bombs, two laser-guided GBU-27 Paveway III 2000-pound bombs, two BLU 109 deep-penetration bombs, or two AGM 130s. The GBU-10 Paveway II laser-guided bomb consists of a special nose and tail section attached to a standard 2000-pound Mk 84 high-explosive bomb. The tail section of the bomb consists of a set of folding aerodynamic surfaces which permit the bomb to glide, whereas the nose section includes a laser light seeker, guidance electronics, and control fins. The GBU-24 Paveway III is a more advanced version of the Paveway II with a larger tail surface and a more efficient guidance system which permits it to be used at lower altitudes and at greater distances from the target. The BLU-109 deep-penetration bomb has a forged casing of hardened steel which permits it to pierce more than six feet of reinforced concrete before exploding. When dropped on softer targets, the BLU-109 can bury itself deep into the ground before exploding, destroying its target by sending earthquake-like shock waves rippling through the ground. The F-117A can also carry up to two Mark 61 nuclear weapons, although the aircraft does not actually have an assigned nuclear mission. For long-range ferry flights, fuel tanks can be installed in the weapons bays in the place of bombs. -Joe Baugher

Despite its fighter designation, the F-117A has no air-to-air capability.

Since it cannot rely on radar for weapon aiming, infrared was used instead. The forward looking infrared (FLIR) and downward looking infrared (DLIR) are also coupled with lasers to illuminate the target for weapons. These systems together create the infrared acquisition and designation system (IRADS). The laser creates a spot on the ground 12 to 18 inches in diameter. Therefore, it is only switched on approximately ten seconds before the bomb impacts its target. These systems are so accurate that the F-117A can hit a target on a clear night one meter in size from an altitude of 25,000 feet.