Dewdz,
Stuff for the whistleblowers group. This looks like some good shit.
Way cool--Pentagon gettin' zapped!
F-117A Nighthawk ("Stealth") Program--Summary
Construction
The primary RAM and infrared-reflecting material used on the F-117A
Nighthawk, also known as the Stealth Fighter, is Dow Chemical's Fibaloy
(Lockheed Memorandum TK-523). Fibaloy is used for structural airframe parts
in the F-117A and for skin panels, spars, ribs, and 1ongerons. Only 10
percent of the airframe's structural weight is from metal. Reinforced
carbon fiber, developed by the Air Force Materials Laboratory at Wright
Patterson AFB in Dayton, Ohio, is another important RAM used on the F-117A.
This material not only absorbs radar energy, but dissipates it as well and
helps reduce the F-117A's infrared signature. It is used primarily for
high-temperature areas like outer skin panels near the engines, and wing
and vertical-fin leading edges.
The F-117A's unique shape is one factor that contributes to RCS reduction.
Edges are rounded, and skins are made of Fibaloy in a secret and difficult
manufacturing process. These skins are built in multiple layers that are
filled with bubbles and tiny fibers oriented in a specific alignment,
spacing, and density for maximum RCS reduction. This process is the most
secret element of stealth technology. Parts are formed using super-plastics
and are joined with strong adhesives. Kevlar 49 and Silag are used in key
crossbar struts.
Internal structural architecture of the F-117A has an even greater effect
on RCS reduction. A design called cut-diamond, which employs several
thousand flat surfaces, is used on the F-117A. Each of the small, flat
surfaces is angled so it does not share a common radar reflective angle
with any other small, flat surface. When a radar beam strikes the F-117A,
only one or two of the flat surfaces reflects the incoming radar energy,
while the adjacent surfaces present too high an incident angle to reflect
the radar energy back to the radar receiver.
The cut-diamond structure is covered by a layer of Fibaloy and Retinyl
Schiff base salt materials that is able to absorb 98.7 percent of all
radiated energy. Like the SR-71, internal plastic radar -absorbing
triangular inserts are fitted to the F-117A's vertical-fin and wing leading
edges. Iron ball RAM (supplied by TDK Magnetics, cf. Import Waivers) is
applied to external surfaces and to some internal metal parts. All gear
doors and access panels are specially shaped and tightly fitted to maintain
the airframe's low RCS.
To enhance its low visual signature, the F-117A employs both active and
passive background-masking camouflage techniques that enable it to change
color to match the background. Two camouflage colors are used: flat-black
for night missions, and dull gray for day missions.
The active camouflage technique is "background-clutter signal to aircraft
RCS matching." This technique makes use of the F-117's extensive ECM/ESM
suite and does not require any changes to the aircraft's structure. With
this technique, an F-117A flying at low level protects itself from
look-down interceptor radars by matching its overall RCS (as detected from
above) with that of the terrain below. This ability makes the F-117A show
up as ground clutter on the interceptor's radar, provided the F-117A's RCS
precisely matches that of the terrain below it, and the hostile radars
would simply reject the clutter and the F-117A masked in the clutter, and
never detect the F-117A.
ECM/ESM equipment is housed in smart skins, or portions of the F-117A's
airframe that incorporate microcircuitry, thus avoiding the need to install
antennae or sensors that might have a high RCS on the outside of the
airframe. This feature has the combined benefit of saving space on the
inside of the airframe and permitting the airframe to be lighter and
smaller.
Reconnaissance/weapons systems include a forward-looking laser radar used
for both terrain-following navigation (TERCOM) and for attacking targets. A
forward-looking infrared (FLIR) system is installed, as well as a low light
level TV and a head-up display. Its weapons suite includes the optically
guided AGM-65 missile and the AGM-45 Shrike antiradiation missile. The
AGM-88A high-speed antiradiation missile (HARM) is also included. An
advanced gun system developed by Hughes called the in-weather survivable
gun system/covert is installed, and all weapons are carried internally.
Another weapon that is planned for deployment in FY 93 is the AGM-I36A
Tacit Rainbow antiradiation drone missile. This weapon can loiter after
release and protect the F-117A from hostile radar tracking by detecting and
destroying hostile radars. The Tacit Rainbow is small enough that four can
be carried internally by the F-117A.
In one recent test of the F-117A's weapon aiming and guidance system, a
500-lb bomb was dropped from altitude of 10,000 feet, and the bomb scored,
going right into the top of its target, a 55-gallon drum. Results are
similar to the Gulf War experience.
Lear Siegler has developed a quadruple redundant electronic fly-by-wire
system for the F-117A that eliminates the need for control cables, thus
saving weight and simplifying construction. The pilot controls the F-117A
with a side-stick controller mounted on the right side of the cockpit.
The F-117A pilot sits on an ACES ejection seat. The pilot's canopy has flat
surfaces, and should be coated with an optically transparent RAM to prevent
radar reflection from the pilot or cockpit equipment. Landing gear is
designed for rough-field operations, and each gear leg has a single wheel.
Infrared signature is reduced by mixing fan-bypass air and air from cooling
baffles with exhaust gases. Mixing of air with exhaust also has the benefit
of reducing the acoustic signature. Because infrared homing missiles track
aircraft by the heat of their exhaust nozzles, not the heat of the exhaust
gas, the nozzles are made of materials that keep the infrared signature
low. Cooling baffles and special coatings also help reduce the infrared
signature from hot engine-exhaust nozzles. Newer infrared homing missiles
with all-aspect launch angles can track only the exhaust plume, but the
work done to cool exhaust nozzles and cool exhaust gases on the F-117A (and
other stealth aircraft) makes infrared lock-on by these kinds of missiles
highly unlikely.
Two modified nonafterburning 12,500-1b General Electric F404-HB turbofan
engines power the F-117A. Two-dimensional thrust-vectoring exhaust nozzles,
which can vector thrust in various vertical and horizontal positions, are
installed; however, the nozzles are only two-dimensional in shape, with no
vectoring capability.
Material around the engine bays is a matrix sandwich of polymers and
pyramidic noise-absorbing structures. The sound-proofing is so effective
that the F-117A makes only a medium-level (53 dB) humming noise at a
distance of 100 feet, and on takeoff a slight whine (61 dB) is heard. The
F-117A uses a Benson-designed Rotorduct system that provides additional
cold thrust from the engines. The Rotorduct system is connected to the
forward and aft sections of the engines.
During night operations, the F-117A flies lights out, with no navigation,
strobe,
or position lights of any kind. F-117As are equipped for all-weather
operations without any outside assistance. All guidance systems are
passive, except for the laser radar, but that gives no signals that could
be detected. Guidance systems include a ring-laser gyro based inertial
navigation system and global positioning system receiver, both of which are
passive navigation systems.
Performance
Although the F-117A can fly at supersonic speeds (Mach 1.73), most of its
flying is done below the speed of sound close to the ground to take
advantage of terrain-masking of hostile radar installations. High-speed
flight at low levels also protects the F-117A from infrared-guided weapons
or infrared detection systems. At higher altitudes, the F-117A would be
exposed to such systems for longer periods of time, while at low levels,
the F-117A is not over one area long enough for weapons systems to lock on.
Even if the weapons could lock on briefly, the F-117A flies so quickly that
it would be long gone before the weapon could shoot it down.
Operating at high speeds and low levels makes the F-117A somewhat unstable
due to its large wing/fuselage planform. USAF cites this as one reason,
among others, for one or two of the four operational crashes. The F-117A
uses small ride-control vanes similar to those on the nose of the B-I
bomber. These are known as impedance-loaded flow-control vanes, and they
alleviate the often bumpy ride encountered during low-level and high-speed
flight.
Supersonic flight in the F-117A is inefficient because of the materials
from which it is built. Some of the materials, while excellent at reducing
detectability signatures, have a rough finish that add to the F-117A's
parasite drag.
F-117A Operational Basing
An F-117A unit is permanently based at Tonopah Base (Area 30, also known as
Sandia Strip and Mellon Strip) in the northwest corner of the highly secret
Nellis
Test Range about 170 miles from Las Vegas, in Nevada. Tonopah Base has 72
hangars and was refurbished in 1979 by the U.S. Air Force. (It hadn't been
used since World War II.) The unit is known as Team One--Furtim Vigilans
(covert
vigilantes), and there are 95 F-117As based there. (The term literally
means "vigilant by stealth" or "stealthily vigilant" in Latin.) The
full-service F-117A wing gained initial operational capability in 1983 at
Tonopah Base.
There are F-117A temporary-duty (TDY) detachments at Elmendorf AFB and
Shemya AFB in Alaska, Kadena Air Base in Japan, and in the United Kingdom. The
F-117A also has been active in the Middle East and in Latin America, used
in the Gulf War and in covert drug trafficking survellance operations.
The U.S. Air Force uses the F-117A in various roles and has integrated F-117A
operations with those of the rapid-deployment forces and with the new special
operations command. Two of the F-117A's known missions are covert
reconnaissance and covert surgical strikes on preselected targets. In
operational tests, this effective stealth aircraft has flown within 17
miles of actual Soviet-manned radar stations without being detected, and
Soviet-manned Iraqi radar stations detected fewer than 3 of the F-117As in
753 different sorties over Iraq.
F-117A Nighthawk Specifications
Length 56.43 ft
Height 15.72 ft
Wingspan 40.20 ft
Empty weight 19,674 lb
Maximum takeoff weight 34,120 lb
Cruise speed Mach 0.93
Maximum speed Mach 1.12 at 36,000 ft
Powerplant two 12,700 lb GE F404-HB nonafterburning turbofans highly
modified. Composites used in engine construction
Combat radius 498 miles
