Stealth Aircraft

The technology behind the planes

You can't hit something if you can't see it...

Introduction to Stealth Technology

Astounding leaps in airplane technology have yielded a new sort of defensive weapon: stealth. Planes capable of dropping nuclear bombs can now fly invisibly into enemy airspace, drop a payload, and fly back out without even being detected.

The way most airplane identification works is by constantly bombarding airspace with a RADAR signal. When a plane flies into the path of the RADAR, a signal bounces back to a sensor that determines the size and location of the plane. Other methods focus on measuring acoustic (sound) disturbances, visual contact, and infrared (heat) signatures.

Stealth technologies work by reducing or eliminating these telltale signals. Panels on planes are angled so that radar is scattered and no signal returns. Planes are also covered in a layer of absorbent materials that reduce any other signature the plane might leave. Shape also has a lot to do with the `invisibility' of stealth planes. Extreme aerodynamics keep air turbulence to a minimum and cut down on flying noise. The B-2 stealth bomber has a "bat-wing" shape to reduce its RADAR cross-section, as well as visual recognition, especially on the horizon. Special low-noise engines are contained inside the body of the plane. Hot fumes are then capable of being mixed with cool air before leaving the plane. This fools heat sensors on the ground. This also keeps heat seeking missiles from getting any sort of a lock on their targets.

Stealth technology was initially developed to bypass intense Soviet defense systems. Since the end of the Cold War, stealth has proved itself in various conflicts. During the Gulf War, 56 Stealth Bombers flew 1,270 missions, and were never hit.

At a cost of $2 billion each, stealth bombers are not yet available worldwide, but military forces around the world will soon begin to attempt to mimic some of the key features of stealth planes, making the skies much more dangerous.

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F-117A Nighthawk B-2 Spirit F-22 Lighning/Raptor Joint Strike Fighter SR-71 Blackbird YF-23A Black Widow II
Tacit Blue B-1B Lancer Links

F-117A Nighthawk Stealth Fighter

The Lockheed F-117A Nighthawk stealth fighter is one of the most sophisticated warplanes ever built. It is almost invisible to radar, and first operated under secrecy in 1991, then was deployed by the USAF openly in the Persian Gulf War.

The F-117A can employ a variety of weapons and is equipped with sophisticated navigation and attack systems that are integrated into a state-of-the-art digital avionics system. This system optimizes mission effectiveness and increases pilot efficiency. Detailed planning for missions into highly defended target areas is accomplished by an automated mission planning system, which specifically takes advantage of the unique capabilities of the F-117A.

The F-117A's weapons systems can hit a target 1 yard square. The radar cross-section of a stealth Nighthawk is the same as that of a seagull: one-hundredth of a square yard.

The F-117A is a single-seat low-observable strike fighter. It is powered by two non-afterburning General Electric F404-GE-F1D2 engines, each capable of delivering 10,800 pounds of thrust. The F-117A's maximum speed is Mach 1. The Nighthawk's combat range is 750 miles unrefueled with a 5,000 pound weapons payload. The stealth fighter can carry up to 5,500 pounds of munitions, including BLU-109 low-level or GBU10/GBU27 medium laser guided bombs. It also has provisions for 2 AIM-9-L air-to-air missiles.

Empty, the F-117A weighs about 3,000 pounds. Fully loaded, it weighs up to 52,500 pounds. It is 65 feet 11 inches long, 12 feet 5 inches high, and has a 43 foot 4 inch wingspan.

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B-2 Spirit Stealth Bomber

The B-2 Spirit is a multi-role bomber capable of delivering both conventional and nuclear munitions. The B-2 is able to deploy massive firepower in a short time, anywhere on the globe through previously impenetrable defenses.

The revolutionary blending of low-observable technologies with highly aerodynamic efficiency and large payload gives the B-2 important advantages over existing bombers. Its low-observability provides it with greater freedom of action at high altitudes, thus increasing its range. This also provides a better field of view for the aircraft's sensors. Its unrefueled range is approximately 6,000 nautical miles (9,600 kilometers).

The B-2's low observability is derived from a combination of reduced infrared, acoustic, electromagnetic, visual, and radar signatures. These signatures make it difficult for sophisticated defensive systems to detect, track and engage the B-2. Many aspects of the low-observability process remain classified; however, the B-2's composite materials, special coatings and flying-wing design all contribute to its "stealthiness."

The B-2 has a crew of two pilots, an aircraft commander in the left seat and mission commander in the right, compared to the B-1B's crew of four and the B-52's crew of five.

The B-2 Spirit is powered by 4 General Electric F-118-Ge-100 engines. Each engine can provide 17,300 pounds of thrust. The B-2 is 69 feet long, 17 feet high, and 172 feet in wingspan. It can reach high subsonic speeds and its ceiling is 50,000 feet. A typical bomber weighs 336,500 pounds. The B-2 has an intercontinental range and can carry a weapons payload of nuclear or conventional munitions. The bomber can carry 40,000 pounds and a crew of 2, with provisions for a third crew member. The cost of a single bomber is $2 billion dollars.

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F-22 Lightning/Raptor Stealth Fighter

The F-22 Raptor is a relatively new plane, chosen by the USAF in April 1997 to replace the aging F-15 fleet. The F-22 Raptor employs a 'stealthy' design, the ability to cruise over long ranges at supersonic speed without afterburning, a very high level of aerial agility and STOL capability with the aid of a two-dimensional thrust vectoring system, a fly-by-light control system for a relaxed stability airframe, and an advanced nav/attack system using artificial intelligence to filter data and reduce the pilot's workload while improving his grasp of the tactical situation.

Key features of the design are an angular but clean external shape with jagged edges on any portion that could reflect electromagnetic energy back toward a hostile radar, three internal weapon bays in place of external hardpoints, and a state-of-the-art avionics suite. It also includes a VHSIC computer system (operating on the artificial intelligence principles of the Pilot's Associate system) offering three times the memory and 16 times the operating speed of the F-15's system.

The Raptor is an advanced tactical fighter powered by 2 15876kg afterburning Pratt & Whitney F-119-P-108 turbofans. Its maximum takeoff weight is 27,216kg. The fighter is 18.92 meters long, 5 meters high, and has a 13.56 meter wingspan. The Raptor is armed with one 20-mm M61A1 Vulcan six-barrel cannon, as well as bays for AIM-120 AMRAAM, AIM-9's.

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Joint Strike Fighter (JSF)

The Joint Strike Fighter is a short vertical takeoff and landing stealth fighter. It has been designed, but not actually produced. The design specifications have not yet been publicly released. Northrop Grumman is teamed with McDonnell Douglas and British Aerospace in the competition to build the next-generation Joint Strike Fighter for the United States and the UK. The McDonnell Douglas/Northrop Grumman/British Aerospace team has developed an affordable design to meet the needs of the U.S. Air Force, Navy, Marine Corps and the Royal Navy well into the next century.

The team has selected the Lift + Lift/Cruise concept for the STOVL variant to be used by the Marine Corps and the Royal Navy. In this concept, a separate forward engine will provide lift, while the rear cruise engine will provide rear lift and conventional forward thrust. For development of the lift engine, the team is partnered with General Electric and Allison. The benefits of this propulsion system include minimizing the size of the inlet and main engine bay, maximizing the weapons bring-back potential, and simplifying the manufacture of the JSF.

Since the McDonnell Douglas/Northrop Grumman/British Aerospace team uses the same engine developed for the F-22 -- the Pratt & Whitney F119 -- with only minimal changes, this design minimizes main engine development cost and schedule risk. The design also could have growth potential. Northrop Grumman has received JSF awards worth more than $78 million for work including the Weapons System Concept, Avionics Virtual Systems Engineering and Prototyping, and the Affordable Weapons Delivery System contracts. In February 1996, the company's Electronic Sensors and Systems Division received a $48 million contract to design, build and flight test the Multifunction Integrated Radio Frequency System.

The first JSF could enter service as early as the year 2008. The aircraft will replace aging F-16's, F/A-18's, A-10's, F/A-2'sand AV-8B's. As many as 3,000 JSF's could be built, bringing a new age stealth fighter into the USAF.

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SR-71 Blackbird Reconnaissance Plane

Thirty years after its first flight, the SR-71 Blackbird is still unmatched in height and speed. The Blackbird can fly at an altitude of 100,000 or more and can go as fast as Mach 3.5 or 2,500 MPH.

The SR-71 is the fastest known aircraft. It was the only aircraft that could fly its entire mission at supersonic speeds. The only aircraft that even approaches the Blackbird's speed is the Mig 25, and it can only sustain Mach 3 for a few minutes. The Anglo-French Concorde is the only civilian aircraft that can sustain supersonic flight for hours at a time.

The Blackbird operates at the extreme edge of Earth's atmosphere and pilots are required to wear space suits like astronauts in the event of an emergency. The Blackbird's paint is highly sophisticated: it is formulated to radiate excess heat as well as to disrupt incoming radar energy. It changes to blue at operating temperatures and altitudes. The Blackbird's tires are filled with nitrogen and impregnated with powdered aluminum to enable them to withstand heat. The Blackbird's airframe is 90% titanium to withstand the friction generated at Mach 3. The friction can cause the Blackbird's skin to heat up to 400 degrees Fahrenheit.

The component parts of the Blackbird fit very loosely to allow for expansion at high temperatures. At rest on the ground fuel leaks out constantly, since the large tanks in the fuselage and wings only seal at operating temperatures. There is little danger of fire, however, since the fuel is very stable with an extremely high flash point.

It took a lot of effort to keep the Blackbird in the air, an estimate has put the cost of flying the Blackbird at more the $200,000 per hour. During the late 1950's, an airplane that could fly five miles(8 km) higher than any existing aircraft, cruise at a top speed of Mach 3 and be invisible to radar was barely imaginable. The plan was taken by Lockheed Aircraft Company's genius Kelly Johnson who built the F104 Starfighter (first aircraft to fly at Mach 2) and U-2.

An aircraft at Mach 3 would have to sustain a high temperature. Johnson and his team had to ignore the laws of physics and start from scratch just like the Wright brothers when they built the first aeroplane. The Blackbird would reach 326 degrees on the cockpit windshield and 426 degrees on the wing areas, which is hot enough to melt lead.

After several modifications in the design, Washington gave the go-ahead on Aug. 29,1959. The team decided to create the first titanium airplane. Titanium is as strong as stainless steel but half its weight and can withstand higher temperatures and pressures. Titanium screws and rivets were also made. At the end of the project, millions of separate spare parts were manufactured.

This caused material costs to soar, but during the Cold War, no price was too high. The electric switches and wires were gold-plated to increase conductivity at high temperatures. Tires were filled with nitrogen instead of air to prevent them from exploding as heat builds up in flight. The Blackbird was painted black to lower the temperature, as black is a good radiator. Radar asbsorbing materials were applied to the leading edges of the wings and the fuselage sloped outwards. By doing this, they were creating the first stealth aircraft, nearly invisible to radar.

The fuselage was filled with millions of ping-pong balls in case the plane exploded as a result of pumping too much air into the fuel tanks. As an additional precaution, tests were done at night.

Three Blackbirds were offered to provide surveillance over Iraq during the Gulf War but the offer was declined. By then, only 26 of the original 50 Blackbirds remained. The tooling used to make the Blackbirds were destroyed in 1970 on orders from Pentagon. The scraps were sold off. In 1990, Congress approved the decision to retire the Blackbird which in its 24 years of service had never been shot down or lost a crewman to enemy fire.

However, the Blackbird was given a final shot at glory. Lockheed and the airforce decided to use the Blackbird to attempt to break the trans-continental speed record en route from Los Angles to Washington. A Blackbird piloted by Air Force pilot Ed Yeilding took off for the East Coast at 4:30 am. The Blackbird set the record and it still stands: coast to coast in 67 min. and 54 sec.

In Sept. 1994, the Blackbird was called out of retirement. Congress granted Lockheed a $100 million dollar contract to reactivate three of the planes and return them to the USAF, where they are resuming operational duty.

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YF-23A Black Widow II Stealth Fighter

The body of the YF-23A is a blend of stealthy shapes and aerodynamic efficiency, providing a low radar cross-section without compromising performance. It is designed to cruise at supersonic speeds without afterburning. From the side, the profile of the YF-23A is reminiscent of that of the Lockheed SR-71. The general impression from other angles is that of a long, high forebodied plane with two widely-separated engine nacelles. The lengthwise variation in cross-sectional area is very smooth, minimizing transonic and supersonic drag. The forebody holds the cockpit, the nose landing gear, the electronics, and the missile bay. The inlet ducts leading to the engines curve in two dimensions, upward and inward, to shield the faces of the compressors from radar emitters coming from the forward direction.

The all-flying twin V-tails are set far apart on the rear fuselage. They are canted 50 degrees outwards in an attempt to avoid acute corners or right angles in elevation or front view. These all-flying tail sections are hinged at a single pivot. Their leading and trailing edges are parallel to the main wings but in a different plane. The all-flying canted tails double as shields for the engine exhaust in all angles except those immediately above or behind the aircraft. In the YF-23A, Northrop elected not to use thrust-vectoring for aerodynamic control. This was done in order to save weight and to help achieve better all-aspect stealth, especially from the rear.

There is a midair refuelling receptacle located on the upper fuselage behind the pilot's cockpit. Like the YF-22A, the YF-23A has a fly-by-wiresystem that controls the settings of the aerodynamic surfaces in response to inputs from the pilot.

In the pursuit of stealth, all of the weapons carried by the YF-23 were to have been housed completely internally. The forward section of the fuselage underbelly was flat, with a capacious weapons bay immediately aft of the nose gear bay. The bay could carry four AIM-120 AMRAAM air-to-air missiles. The missiles were to be launched by having the doors open and the missiles extend out into the airstream on trapezes. The missiles would then drop free and the motor would fire. The doors would then immediately shut, minimizing the amount of time that they were open and thus possibly causing more intense radar returns. It was planned that production YF-23 would have had a stretched forebody, accommodating an extra missile bay for a pair of AIM-9 Sidewinders or ASRAAM air-to-air missiles in front of the AMRAAM bay. In addition, production YF-23s would have carried a 20-mm M61 Vulcan cannon fitted inside the upper starboard fuselage just above the main weapons bay.

The YF-23 is 67 feet 5 inches long, 13 feet 11 inches high, and has a 43 foot 7 inch wingspan. Its maximum takeoff weight is 64,000 pounds. The YF-23 can reach Mach 2 and has a range of 700-800 nautical miles unrefueled. It is armed with 4 AIM-9 Sidewinder missiles and 4 AIM-120 AMRAAM missiles all stored in internal bays. The YF-23A is flown by 1 pilot.

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Tacit Blue

The U.S. Air Force unveiled the Tacit Blue Technology Demonstration Program on April 30, 1996, at the Pentagon. Tacit Blue was created to demonstrate that a low observable surveillance aircraft with a low probability of intercept radar and other sensors could operate close to the forward line of battle with a high degree of survivability. Such an aircraft could continuously monitor the ground situation behind the battlefield and provide targeting information in real-time to a ground command center. Tacit Blue validated a number of innovative stealth technology advances.

Tacit Blue featured a straight tapered wing with a V-tail mounted on an oversized fuselage with a curved shape. The aircraft has a wingspan of 48.2 feet and a length of 55.8 feet and weighed 30,000 pounds. A single flush inlet on the top of the fuselage provided air to two high-bypass turbofan engines. Tacit Blue employed a quadruply redundant, digital fly by wire flight control system to help stabilize the aircraft about the longitudinal and directional axes.

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B-1B Lancer Stealth Bomber

The B-1B is a multi-role, long-range bomber, capable of flying intercontinental missions without refueling, while penetrating sophisticated enemy defenses. It can perform a variety of missions, including that of a conventional weapons carrier for theater operations.

The B-1B's employs electronic jamming equipment, infrared countermeasures, and radar location and warning systems which complement its low-radar cross-section and form an integrated defense system for the aircraft. The swing-wing design and turbofan engines not only provide greater range and high speed at low levels but they also enhance the bomber's survivability. Wing sweep at the full-forward position allows a short takeoff roll and a fast base-escape profile for airfields under attack. Once airborne, the wings are positioned for maximum cruise distance or high-speed penetration.

The B-1B uses radar and inertial navigation equipment enabling crews to navigate globally, update mission profiles and target coordinates in-flight, and precisely carry out missions without the need for ground based navigation aids. Included in the B-1B offensive avionics are modular electronics that allow maintenance personnel to precisely identify technical difficulties and replace avionics components in a fast, efficient manner on the ground.

The aircraft's AN/ALQ 161A defensive avionics is a comprehensive electronic counter-measures package that detects and counters enemy radar threats. It also has the capability to detect and counter missiles attacking from the rear. It defends the aircraft by applying the appropriate counter-measures, such as electronic jamming or dispensing expendable chaff and flares. Similar to the offensive avionics, the defensive suite has a re-programmable design that allows in-flight changes to be made to counter new or changing threats.

The B-1B represents a major upgrade in U.S. long-range capabilities over the aging B-52 -- the main component of the previous bomber fleet. Significant advantages include a low radar cross-section to make detection considerably more difficult, the ability to fly lower and faster while carrying a larger payload, and advanced electronic countermeasures to enhance survivability. Numerous sustainment and upgrade modifications are ongoing or under study for the B-1B aircraft. A large portion of these modifications which are designed to increase the combat capability are known as the conventional mission upgrade program. This three phase program will increase the lethality, survivability and supportabilty of the B-1B fleet. Phase I of the program, completed toward the end of February 1996, added the capability to release cluster bomb unit weapons. Phases II and III will further upgrade the B-1B capability, to include the ability to deliver joint direct attack munitions and standoff weapons.

The B-1B is powered by 4 General Electric F-101-GE-102 turbofan engines with afterburners, which deliver 30,000 pounds of thrust each. It is 146 feet long, 34 feet high, and has a 79-137 foot wingspan. It weighs about 190,000 pounds empty, and its maximum takeoff weight is 477,000 pounds. The Lancer can reach +900 mph, and has an intercontinental range unrefueled. The bomber's ceiling is +30,000 feet. The B-1B carries a crew of 4: aircraft commander, pilot, and an offensive and defensive systems officer. It is armed with up to 84 Mark 82 conventional 500-pound bombs, 30 CBU-87/89/97's, and can be reconfigured to carry a wide variety of nuclear weapons. A single bomber costs +$200 million.


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