Radar and Stealth Technology in Aerospace Engineering

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Stealth Technology referred as “VLO” i.e., “VERY LOW OBSERVABLE TECHNOLOGY” in aerospace engineering.

The goal of stealth technology is to make an airplane invisible to radar. There are two different ways to create invisibility:

  1. The airplane can be shaped so that any radar signals it reflects are reflected away from the radar equipment.
  2. The airplane can be covered in materials that absorb radar signals.

Most conventional aircraft have a rounded shape. This shape makes them aerodynamic, but it also creates a very efficient radar reflector.The round shape means that no matter where the radar signal hits the plane, some of the signal gets reflected back.

A stealth aircraft, on the other hand, is made up of completely flat surfaces and very sharp edges, When a radar signal hits a stealth plane, the signal reflects away at an angle, The overall result is that a stealth aircraft like an F-117A can have the radar signature of a small bird rather than an airplane.

In aerospace engineering fighter planes are made so they are harder to be detected by the radar and other devices.

The first combat use of stealth aircraft was in December 1989 during Operation Just Cause in Panama

  • Well known examples include the United States’ F-117 Nighthawk (1980-2008), the B-2 Spirit “Stealth Bomber,” and the F-22 Raptor.

HISTORY OF STEALTH TECHNOLOGY

  1. The first true “stealth” aircraft may have been the Horten  Ho 229 flying wing fighter-bomber, developed in Germany during the last years of WWII.

4-View-Horten-Ho-229-Flying-Wing-Fighter-Bomber-Rendering

2.  SR 71 the first Stealth airplane launched. It is well known as ‘black bird’. Lockheed_SR-71_Blackbird

RAM AND RAS IN AEROSPACE ENGINEERING

  1.  RAM  Refers  to “RADAR ABSORBENT MATERIALS”.
  2. RAS reffers to “RADAR ABSORBENT STRUCTURE”.

Most such material consists of an active ingredient—a dielectric, such as carbon, or magnetic ferrites—which is moulded into a non-loss dielectric matrix, usually a plastic of some kind.

To achieve a high degree of absorption over a wide bandwidth is to use “honeycomb “ structure.

PLASMA STEALTH

Plasma stealth is a proposed process that uses ionized gas (plasma) to reduce the radar cross section (RCS) of an aircraft. Conductivity of the plasma allows it to interact strongly with the incoming radio wave, but the wave can be absorbed and converted into thermal energy rather than reflected.

plasma might also be used to modify the reflected waves to confuse the opponent’s radar system.

DETECTION BY INFRARED RADIATION

Passive IR detection devices rely on the fact that every atom of matter, including clouds and rain, continuously sends out electromagnetic radiation at an IR wavelength which corresponds to its temperature.

For aircraft detection, IR seekers look for contrasts between hot parts on the airframe.

In engine exhausts, carbon dioxide produces most of the IR signature at 4.2 microns.

IR sensors can ‘see’ at two different wavelengths, (medium: 3-5 microns and long:8-14 microns) to provide good target discrimination.

INFRARED STEALTH

To degrading the performance of IRST systems is to ensure that the exhaust dissipates as quickly as possible after leaving the aircraft.

Some of the techniques are follows:

1.Engines  can be fitted with flow mixers to blend the cold bypass air with the hot air that passes through the combustor and the turbine.

2.The exhausts geometry can be adapted to a wide and flat shape.

3.Interaction between the exhaust stream and the airflow over the aircraft can be engineered to create an additional vortex which further promotes mixing.

USE OF STEALTH AIRCRAFT

stealth aircraft have been used in conflicts, including Operation Desert Storm, Operation Allied Force and the 2003 invasion of Iraq. Thus in aerospace engineering, the stealth technology  is employed to strike high-value targets.

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Hello, I am an aircraft structural analyst with industrial experience and a master degree on aerospace structures. Currently working for an aerospace company as a stress
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