Stealth Technology
In the late 1950’s the American CIA began sending
Lockheed U2 ’spy-planes’ over the Soviet Union to take intelligence
photographs. The U2’s flew at 80,000ft (24,000m) to be out of range of
anti-aircraft fire, but it then became clear that radar was not
detecting them.
These extraordinary planes were little more than
jet-powered gliders built of plastic and plywood. On takeoff they
jettisoned their small outrigger wheels from the ends of their wings
... and they landed on their main, retractable wheels in the centre.
It was not until May 1960, after more than four years of
overflights, that the Russians shot one down using new radar equipment
belonging to SA-2 surface-to-air missiles. And even then the U-2 did
not receive a direct hit. A missile exploded close enough to put the
fragile aircraft into an uncontrollable dive, and the pilot, Gary
Powers, had to eject.
The success of the U-2s led to highly classified
research work in the US, known as ’Stealth’, to create a military
aircraft that was invisible to radar. The U-2 had gone undetected for
so long because it was made of non-metallic materials which absorbed
radar waves rather than reflecting them back to the radar ground
station, as normally happens.
The Stealth programme aimed at designing
high-performance military aircraft incorporating, among other
features, a minimum of metal and with the exterior clad in highly
absorbent tiles. The aircraft would be almost invisible to radar and
could make most radar-controlled anti-aircraft systems obsolete.
After being developed under a blanket of secrecy, the
high-tech B-2 Stealth bomber was unveiled at the Northrop company’s
manufacturing plant in Palmdale, California, in November 1988. An
audience of invited guests and journalists was kept well away from the
plane ... which was designed to slip through enemy radar defences
without being detected and then drop up to 16 nuclear bombs on key
targets.
To help achieve radar invisibility, the bomber is coated
with radar-absorbent paint on its leading edge. A similar technology
is used underwater to foil sonar detection. Modern submarines are
coated in a thick layer of a top-secret resin which is highly
absorbent acoustically, and reflects only a minute amount of the
energy transmitted by sonar detectors.
Another technique used by aircraft to avoid radar is to
fly at very low levels where there is a great deal of ’ground clutter’
... radar reflections given off by buildings and other objects.
Low-level aircraft can go undetected by most radar systems. But the
latest, most sophisticated ground-defence systems are designed to
discriminate between ground-clutter and hostile planes. In addition,
ground-clutter is partly avoided by using ’look down’ radar systems,
which track aircraft from other aircraft flying above.
In the Gulf War, you may have seen on TV, the Baghdad
AAA - they were getting bombed, but they didn’t know by what, they
were shooting all over the sky hoping for a hit .... kinda pathetic
last resort ... but cruise missiles used then .... fun fun fun.
The skeleton of the F-117 is made mainly of aluminium.
The aircrafts skin, by contrast, is mostly composite RAM (Radar
Absorbent Material). The twin butterfly (\/) tail obscures the exhaust
plume from infrared sensors aboard pursuing fighters. The Nighthawk’s
twin General Electric engines are buried deep in the fuselage. That
have shallow "platypus"
exhausts, which cool and deflect the exhaust gases upward to minimise
heat emissions. The edges of the F-177’s cockpit canopy, like all
surfaces, have no right angles (right angles are strong radar
reflectors). The Stealth can be refueled in flight. But rumors about
the handling of the F-117, said it was somewhat ’erratic’, especially
when refueling ... as a result, one of the first nicknames for the
plane was "Wobblin’ Goblin".
Forty F-117’s were deployed to the Gulf. Only 59
production F-117s were built, yet the total cost of the program is
over six billion dollars!
F-117 Nighthawk Specs:
Type: Single-seat low-observable strike fighter.
Powerplant: Two non-afterburning General Electric
F404-GE-F1D2 engines, each delivering 10,800lb thrust.
Max Speed: Mach 1 (estimated)
Combat Radius: 750 mi. Unrefueled, with 5000lb weapon
load.
Service ceiling: Not revealed (perhaps one of you
people know?)
Weapons: Up to 5,500lb. Carried Internally. Principle
weapons are BLU-109 low-level or GBU10/GBU 27 medium-level
laser-guided bombs. Provision for two AIM-9L air-to-air missiles.
Weights: Empty 30,000lb; loaded 52,500lb.
Dimensions:
Nighthawk Engagement Profile:
The Stealth fighter/bomber detects its targets via the
forward looking infrared turret, called FLIR, embedded in its nose.
This provides a good picture of the target from several miles away, on
even the darkest of nights.
Bombing from medium altitude, the F-117’s fire-control
computer calculates the proper release point for the weapons to reach
the general target vicinity. Weapons release will generally be a a
range of one or two miles.
Closer to the target, control is switched to the
downward looking infrared turret, or DLIR. This is equipped with a
laser designator.
As the weapon approaches the target, the laser
designator is fired. Sensors in the nose of the weapon now steer it
toward to radar reflection, where it detonates with devastating
accuracy. (You could see shots through the camera on TV, quite
regular during the Gulf War).
Source: Unknown