Air to Air Missiles : An Introduction

Tuesday, February 16, 2010

At the time of outbreak of World War II, electronics was gaining momentum. Its role in war ended as radio equipment for communication and detection of enemy in a particular topography.The use of electronics in combat technologies increased only after World War II. Today, the military has electronic surveillance equipments like UAV’s, radars, jamming devices, GPS navigation systems, and precision weapons like guided missiles and smart bombs that are far more accurate than any other weapon. This article elucidates the technology behind air-launched anti-aircraft guided missiles with advanced guidance technologies and their basic design concepts.

Introduction:-

The use of electronics has increased after World War II. Today, military has electronic surveillance devices, jamming devices, GPS (Global positioning System) and precision weapons like guided missiles and smart bombs or GBUs (Guided Bomb Unit) which are more accurate in attacking their target then any other weapon.

Guided missiles are self-propelled air borne projectiles carrying explosive charge and guided in flight towards the target.

Classification:-

Missiles are broadly classified on the basis of:-

· Launch Environment Used

· Guidance Used

Launched Environment Used:

1) Air-launched Missiles

a)Air-to-Air Missile

b)Air-to-Ground Missile

2) Surface-launched Missiles

a) Surface-to-Air Missiles

b) Surface-to-Surface Missiles

Guidance Used:

1 Radar Command Guidance

2 Radio Command Guidance

3 Wire Guidance

4 Inertial Guidance

5 Astro Guidance

6 Terrain Comparison Guidance (TERCOM)

Air-Launched Anti-aircraft Missile:

The air-launched anti-aircraft missile is launched from an airborne aircraft to wipe out its target.

Various parts of this missile are:-

·

Rocket Motor - Provides thrust to the missile by burning solid propellant material.

Target-Seeker - Searches for the target.

Electronic Guidance Control (EGC) - Guides the missile.

Control Actuation - Adjust the fins on the instruction received from EGC.

Warhead - Explosive device which destroy the target.

Battery - Provides power to the missile onboard electronics.

Umbilical Cable - Connects the missile onboard electronics with the computer of the aircraft called as ‘avionics’.

Working:-

Before the launch, the pilot designates a target. The data goes to the missile guidance control. As soon as the missile is launched the target seeker is activated and it searches for the target. The rocket motor burns the solid propellant material which provides thrust to the missile. The wing of the missile provides the necessary lift and the electronic guidance control guides the missile towards the target.

Three types of guidance system are used in general:

Semi-active Radar Homing Guidance

Target has to be illuminated by a radar transmitter from parent radar. The reflected waves are received by the receiver in the nose of the aircraft.

Active Radar Homing Guidance

The missile carries it own target seeking radar. The inbuilt radar hunts for the target. This system is costlier and bulkier and is used in long range missiles also called as ‘beyond visual-range missile’ or BVR missile.

Infrared Homing Guidance

The infrared homing guidance system is mainly designed to destroy the target using infrared homing. It seeks infrared radiations available and are also called as ‘heat seeking’ missiles.

Infrared Tracking:-

The target image appears as bright and dark shining spots which indicate the hotter and colder regions of the target. This image is called as the ‘infrared signature’ of the target. The infrared sensor array is coupled with a mechanical scanning system which scans a larger section of the sky. It continuously moves reflectors and lens to feed light to the sensors.

The guidance control system figures out position of the target based on the fluctuations in the detected infrared light.

Guidance System:-

· The Target Seeker.

The infrared sensor that will respond to the wavelength of IR radiation from aircraft are placed in a circular matrix arrangement and grouped into four arrays. An array is one sector of circle.

· Positional Information

If the infrared image falls exactly on the centre of the nose of missile, all the arrays will get IR radiations with equal intensity. When signal from any one array is stronger than other it indicates target has changed the position.

· Speed Information

If target is moving from right to left, right array will receive the image which will generate a pulse. Then the left array will receive the image and will generate a pulse. Measuring the time interval between the two pulses and calculating it with pre-calibrated values speed of target can be known.

· Distance Information

The strength of the signal diminishes as the distance between the missile and target increases. So, measuring the signal strength and comparing it with pre-calibrated values distance of target is obtained.

After calculating speed, position, distance, EGC designates control to fin actuator. Fin actuators are used to actuate the fins to steer the missile.

Merits:

· Ready to fire missile

· Highly Precise

· Cost Effective

· Could be shoulder launched

Demerits:

· Low Range

· Get deflected by Flares

By - Vishal Bhatnagar

The Blackbird: An interesting story

Lockheed-Martin SR-71 Blackbird

(story by a USAF pilot of SR-71 Blackbird)

Interesting history lesson for those of you so inclined

In April 1986, following an attack on American soldiers in a Berlin disco, President Reagan ordered the bombing of Muammad Qaddafi's terrorist camps in Libya . My duty was to fly over Libya and take photos recording the damage our F-111's had inflicted.. Qaddafi had established a 'line of death,' a territorial marking across the Gulf of Sidra , swearing to shoot down any intruder that crossed the boundary. On the morning of April 15, I rocketed past the line at 2,125 mph.

I was piloting the SR-71 spy plane, the world's fastest jet, accompanied by a Marine Major (Walt), the aircraft's reconnaissance systems officer (RSO).We had crossed into Libya and were approaching our final turn over the bleak desert landscape when Walt informed me that he was receiving missile launch signals. I quickly increased our speed, calculating the time it would take for the weapons-most likely SA-2 and SA-4 surface-to-air missiles capable of Mach 5 - to reach our altitude. I estimated that we could beat the rocket-powered missiles to the turn and stayed our course, betting our lives on the plane's performance.

After several agonizingly long seconds, we made the turn and blasted toward the Mediterranean . 'You might want to pull it back,' Walt suggested. It was then that I noticed I still had the throttles full forward. The plane was flying a mile every 1.6 seconds, well above our Mach 3.2 limit. It was the fastest we would ever fly. I pulled the throttles to idle just south of Sicily , but we still overran the refueling tanker awaiting us over Gibraltar.

Scores of significant aircraft have been produced in the 100 years of flight, following the achievements of the Wright brothers, which we celebrate in December. Aircraft such as the Boeing 707, the F-86 Sabre Jet, and the P-51 Mustang are among the important machines that have flown our skies. But the SR-71, also known as the Blackbird, stands alone as a significant contributor to Cold War victory and as the fastest plane ever-and only 93 Air Force pilots ever steered the 'sled,' as we called our aircraft.

The SR-71 was the brainchild of Kelly Johnson, the famed Lockheed designer who created the P-38, the F-104 Starfighter, and the U-2. After the Soviets shot down Gary Powers' U-2 in 1960, Johnson began to develop an aircraft that would fly three miles higher and five times faster than the spy plane-and still be capable of photographing your license plate. However, flying at 2,000 mph would create intense heat on the aircraft's skin. Lockheed engineers used a titanium alloy to construct more than 90 percent of the SR-71, creating special tools and manufacturing procedures to hand-build each of the 40 planes. Special heat-resistant fuel, oil, and hydraulic fluids that would function at 85,000 feet and higher also had to be developed.

In 1962, the first Blackbird successfully flew, and in 1966, the same year I graduated from high school,the Air Force began flying operational SR-71 missions. I came to the program in 1983 with a sterling record and a recommendation from my commander, completing the weeklong interview and meeting Walt, my partner for the next four years He would ride four feet behind me, working all the cameras, radios, and electronic jamming equipment. I joked that if we were ever captured, he was the spy and I was just the driver. He told me to keep the pointyend forward..

We trained for a year, flying out of Beale AFB in California , Kadena Airbase in Okinawa , and RAF Mildenhall in England . On a typical training mission, we would take off near Sacramento , refuel over Nevada, accelerate into Montana , obtain high Mach over Colorado , turn right over New Mexico , speed across the Los Angeles Basin , run up the West Coast, turn right at Seattle , then return to Beale. Total flight time: two hours and 40 minutes.

One day, high above Arizona , we were monitoring the radio traffic of all the mortal airplanes below us. First, a Cessna pilot asked the air traffic controllers to check his ground speed. 'Ninety knots,' ATC replied. A Bonanza soon made the same request.'One-twenty on the ground,' was the reply. To our surprise, a navy F-18 came over the radio with a ground speed check. I knew exactly what he was doing. Of course, he had a ground speed indicator in his cockpit, but he wanted to let all the bug-smashers in the valley know what real speed was 'Dusty 52, we show you at 620 on the ground ' , ATC responded. The situation was too ripe. I heard the click of Walt's mike button in the rear seat. In his most innocent voice, Walt startled the controller by asking for a ground speed check from 81,000 feet, clearly above controlled airspace. In a cool, professional voice, the controller replied, ' Aspen 20, I show you at 1,982 knots on the ground.' We did not hear another transmission on that frequency all the way to the coast.

The Blackbird always showed us something new, each aircraft possessing its own unique personality. In time, we realized we were flying a national treasure. When we taxied out of our revetments for takeoff, people took notice. Traffic congregated near the airfield fences, because everyone wanted to see and hear the mighty SR-71 You could not be a part of this program and not come to love the airplane. Slowly, she revealed her secrets to us as we earned her trust. One moonless night, while flying a routine training mission over the Pacific, I wondered what the sky would look like from 84,000 feet if the cockpit lighting were dark. While heading home on a straight course, I slowly turned down all of the lighting, reducing the glare and revealing the night sky. Within seconds, I turned the lights back up, fearful that the jet would know and somehow punish me. But my desire to see the sky overruled my caution, I dimmed the lighting again. To my amazement, I saw a bright light outside my window. As my eyes adjusted to the view, I realized that the brilliance was the broad expanse of the Milky Way, now a gleaming stripe across the sky.

Where dark spaces in the sky had usually existed, there were now dense clusters of sparkling stars. Shooting stars flashed across the canvas every few seconds.. It was like a fireworks display with no sound.

I knew I had to get my eyes back on the instruments, and reluctantly I brought my attention back inside.. To my surprise, with the cockpit lighting still off, I could see every gauge, lit by starlight. In the plane's mirrors, I could see the eerie shine of my gold spacesuit incandescently illuminated in a celestial glow. I stole one last glance out the window. Despite our speed, we seemed still before the heavens, humbled in the radiance of a much greater power. For those few moments, I felt a part of something far more significant than anything we were doing in the plane. The sharp sound of Walt's voice on the radio brought me back to the tasks at hand as I prepared for our descent....

San Diego Aerospace Museum

The SR-71 was an expensive aircraft to operate. The most significant cost was tanker support, and in 1990, confronted with budget cutbacks, the Air Force retired the SR-71.

The SR-71 served six presidents, protecting America for a quarter of a century. Unbeknownst to most of the country, the plane flew over North Vietnam , Red China , North Korea , the Middle East , South Africa , Cuba , Nicaragua , Iran , Libya , and the Falkland Islands . On a weekly basis, the SR-71 kept watch over every Soviet nuclear submarine and mobile missile site, and all of their troop movements. It was a key factor in winning the Cold War.

I am proud to say I flew about 500 hours in this aircraft. I knew her well. She gave way to no plane, proudly dragging her sonic boom through enemy backyards with great impunity. She defeated every missile, outran every MiG, and always brought us home. In the first 100 years of manned flight, no aircraft was more remarkable.

The Blackbird had outrun nearly 4,000 missiles, not once taking a scratch from enemy fire.

On her final flight, the Blackbird , destined for the Smithsonian National Air and Space Museum, sped from Los Angeles to Washington in 64 minutes, averaging 2,145 mph and setting four speed records.


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