Aviation in the Digital Age

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The Information Age is generally understood to have arrived with the Internet as it was developed through the 1970s and rolled out throughout the 1980s, and continues evolving to this day. So too the adoption of digital techniques in aviation also arrived progressively at around the same time and also continues today.

Contents

The use of digital computers in aircraft design was developed by large aerospace companies throughout the 1970s and included technique such as CAD, CAM, structural component stress analysis using FEA and for aerodynamic modelling. [1] Composite materials lend themselves better than metal to fluid "organic" aerodynamic shapes of high efficiency, and the advent of sophisticated computer-aided design and modelling has led to an expansion in the use of these materials and forms.

Digital systems also appeared in the aircraft themselves and grew steadily in sophistication. The first FADEC (Full Authority Digital Engine Control) trials took place in 1968, with the first operational system entering service in 1985. [2] [3] The first operational fully authoritative fly-by-wire system was developed for the General Dynamics F-16 Fighting Falcon and its introduction in 1978 heralded a revolution in taking over the task of ensuring stability in flight from the traditional aerodynamic stabilizers. This use of "relaxed static stability" allowed aircraft to be made more manoeuvrable and to be given an artificial "feel" to aid pilots in their main task. Meanwhile, the "glass cockpit" was replacing the traditional analogue electro-mechanical instrumentation with graphical digital displays which could display any information selected. Early glass cockpits provided less critical flight information in the form of the EFIS system, with fully glass systems appearing from 1988.

The Cold War era ended shortly after the arrival of digital technologies, bringing a marked decrease of military aviation among the major powers. More recently the rise of the Indian and Chinese economies has spurred development of military aircraft in these countries.

Aircraft

Relaxed static stability

The first operational fully authoritative fly-by-wire system was developed for the General Dynamics F-16 Fighting Falcon and its introduction in 1978 heralded a revolution in taking over the task of ensuring stability in flight from the traditional aerodynamic stabilizers. This use of "relaxed static stability" allowed aircraft to be made more manoeuvrable and to be given an artificial "feel" to aid pilots in their main task.

Composite materials

Composite materials lend themselves better than metal to fluid "organic" aerodynamic shapes of high efficiency, and the advent of sophisticated computer-aided design and modelling has led to an expansion in the use of these materials and forms.

Engines

This period has seen an upsurge in the use of electrical power systems for light aircraft and UAVs. Enabling technologies include the widespread availability and affordability of new high-performance battery technologies, high-strength rare-earth magnets in electric motors, falling costs of solar cells and sophisticated computerised control and management systems.

Meanwhile, conventional aero engines, both piston- and turbine-based, have continued the process of refinement, becoming steadily more reliable and fuel-efficient, while at the same time less polluting.

Avionics

Digital systems also appeared in the aircraft themselves and grew steadily in sophistication. Early digital systems were self-contained with limited functionality. The first FADEC (Full Authority Digital Engine Control) trials took place in 1968, with the first operational system entering service in 1985. [2] [3]

Integrated data systems require a digital data bus. The MIL-STD-1553 bus was defined in 1973. This enabled the first operational fully authoritative fly-by-wire system to be developed for the General Dynamics F-16 Fighting Falcon. The introduction of this aircraft in 1978 heralded a revolution in taking over the task of ensuring stability in flight from the traditional aerodynamic stabilizers. This use of "relaxed static stability" allowed aircraft to be made more manoeuvrable and to be given an artificial "feel" to aid pilots in their main task. Meanwhile, the "glass cockpit" was replacing the traditional analogue electro-mechanical instrumentation with graphical digital displays which could display any information selected. Early glass cockpits provided less critical flight information in the form of the EFIS system, with fully glass systems appearing from 1988.

Unmanned Aerial Vehicles

Prior to the Digital Age, unmanned aerial vehicles (UAV) or drones were of limited use, having either limited guidance capability or a vulnerable radio-control link back to a remote pilot.

The development of lightweight and low-cost sensors such as digital cameras together with mobile computing technologies has allowed UAVs to become more sophisticated and to undertake autonomous flight decisions. UAVs are being increasingly used in both civil and military roles.

UAVs are an attractive attack weapon because they combine the flexibility and firepower of a manned aircraft with the expendability of a missile. They have come to the fore through their use for air-to-ground surgical strikes in Afghanistan. However such use is controversial due to the risk of causing civilian deaths by mistake.

In the 21st century, civilian UAVs such as the quadcopter are increasingly being used for recreational purposes and for aerial observation via a digital camera.

A micro-UAV is small enough for several to be carried at once, and these are finding applications in military reconnaissance and scientific research.

Civil aviation

During this period, civil aviation continued to expand. Airliners and engines grew larger and more fuel-efficient, while digital systems progressively took over the flight control and other avionics. Modern jet airliners have glass cockpits, full-authority digital engine and fly-by-wire computerised flight controls and, most recently, Mobile Internet communications connectivity.

Major disruptions to air travel in the 21st century included the closing of U.S. airspace due to the September 11 attacks, and the closing of most of European airspace after the 2010 eruption of Eyjafjallajökull.

General aviation

Ultralight and microlight aircraft have grown in popularity, along with other sporting activities such as paragliding.

In 1986 Dick Rutan and Jeana Yeager flew the Rutan Voyager around the world non-stop and with no aerial refuelling.

In 1999 Bertrand Piccard became the first person to circle the earth in a balloon.

Military aviation

The use of digital fly-by-wire systems and relaxed static stability gave military aircraft increased manoeuvrability without sacrificing safety or flyability. Advanced tactical manoeuvres such as Pugachev's Cobra became possible.

Missiles

Digital technology allowed missile guidance systems to shrink in size and to compute and correct their flight path en route. The use of onboard maps, video processing and terrain comparison (TERCOM) software gave cruise missiles unprecedented accuracy.

Stealth

During the postwar period, radar detection was a constant threat to the attacker. Attack aircraft developed the tactic of flying at low level, "under the radar" where they were hidden by hills and other obstacles from the radar stations. The advent of low-level radar chains, as a defence against cruise missiles, made this tactic increasingly difficult. At the same time, advances in electromagnetic radiation-absorbent materials (RAM) and electromagnetic modelling techniques offered the opportunity to develop "stealthy" aircraft which would be invisible to the defending radar. The first stealthy attack aircraft, the Lockheed F-117 Nighthawk entered service in 1983. Today, stealth is a requirement for any advanced attack aircraft.[ citation needed ]

Ground activities

The U.S. Centennial of Flight Commission was established in 1999 to encourage the broadest national and international participation in the celebration of 100 years of powered flight. [4] It publicized and encouraged a number of programs, projects and events intended to educate people about the history of aviation.

Manufacturing

The widespread use of digital techniques throughout design and manufacture has led to a revolution in aircraft design. Now, a designer can create an aircraft, model its aerodynamic and mechanical characteristics, design the production components and have them manufactured on the shop floor, all within a single end-to-end digital domain.

The increasing use of fibre composite materials has also led to ever-larger autoclaves for applying and curing the resin which binds the structural fibres in place. Novel test and inspection techniques have also had to be developed, as the failure modes and symptoms of composite components tend to be very different from those made of metal. For example, layers of fibre can delaminate within a multi-layer component, weakening it with no outward visible sign of cracking. Where a metal skin tends to conduct the current from a lightning strike in all directions and to shield sensitive components, carbon fibre tends to conduct along the fibres and to allow more of the energy into the interior, requiring more careful design to protect critical flight components from lightning EMP.

The increasing sophistication of avionics systems has led to longer development times. In particular the use of digital flight systems such as fly-by-wire has led to an ever-increasing sophistication and complexity of the control software, which can take many years to develop and validate. During this period, any change to the aircraft's physical design may require revision and revalidation of the associated software.

Air traffic control

As computers became more sophisticated in the 2000s, they began to take over routine aspects of the air traffic controller's task. Up until then all air traffic in nearby airspace was tracked and displayed, with the air traffic controller responsible for monitoring its position and assessing any need for action. Modern computerised systems are capable of monitoring the flight paths of many more aircraft at a given time, allowing the controller to manage more aircraft and to focus on the decision-making and follow-up processes.

See also

Related Research Articles

Avionics Electronic systems used on aircraft, artificial satellites, and spacecraft

Avionics are the electronic systems used on aircraft, artificial satellites, and spacecraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fitted to aircraft to perform individual functions. These can be as simple as a searchlight for a police helicopter or as complicated as the tactical system for an airborne early warning platform.

Fly-by-wire Electronic flight control system

Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires, and flight control computers determine how to move the actuators at each control surface to provide the ordered response. It can use mechanical flight control backup systems or use fully fly-by-wire controls.

Fixed-wing aircraft Heavier-than-air aircraft with fixed wings generating aerodynamic lift

A fixed-wing aircraft is a heavier-than-air flying machine, such as an airplane, which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distinct from rotary-wing aircraft, and ornithopters. The wings of a fixed-wing aircraft are not necessarily rigid; kites, hang gliders, variable-sweep wing aircraft and airplanes that use wing morphing are all examples of fixed-wing aircraft.

Unmanned aerial vehicle Aircraft without any human pilot or passengers on board

An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without any human pilot, crew, or passengers on board. UAVs are a component of an unmanned aircraft system (UAS), which includes adding a ground-based controller and a system of communications with the UAV. The flight of UAVs may operate under remote control by a human operator, as remotely-piloted aircraft (RPA), or with various degrees of autonomy, such as autopilot assistance, up to fully autonomous aircraft that have no provision for human intervention.

Fourth-generation fighter

The fourth-generation fighter is a class of jet fighters in service from around 1980 to the present, and represents design concepts of the 1970s. Fourth-generation designs are heavily influenced by lessons learned from the previous generation of combat aircraft. Third-generation fighters were often designed primarily as interceptors, being built around speed and air-to-air missiles. While exceptionally fast in a straight line, many third-generation fighters severely lacked in manoeuvrability, as doctrine held that traditional dogfighting would be impossible at supersonic speeds. In practice, air-to-air missiles of the time, despite being responsible for the vast majority of air-to-air victories, were relatively unreliable, and combat would quickly become subsonic and close-range. This would leave third-generation fighters vulnerable and ill-equipped, renewing an interest in manoeuvrability for the fourth generation of fighters. Meanwhile, the growing costs of military aircraft in general and the demonstrated success of aircraft such as the F-4 Phantom II gave rise to the popularity of multirole combat aircraft in parallel with the advances marking the so-called fourth generation.

Stealth aircraft Aircraft which use stealth technology to avoid detection

Stealth aircraft are designed to avoid detection using a variety of technologies that reduce reflection/emission of radar, infrared, visible light, radio frequency (RF) spectrum, and audio, collectively known as stealth technology. The F-117 Nighthawk was the first operational aircraft specifically designed around stealth technology. Other examples of stealth aircraft include the B-2 Spirit, the F-22 Raptor, the F-35 Lightning II, the Chengdu J-20, and the Sukhoi Su-57.

Glass cockpit Aircraft instrumentation system consisting primarily of multi-function electronic displays

A glass cockpit is an aircraft cockpit that features electronic (digital) flight instrument displays, typically large LCD screens, rather than the traditional style of analog dials and gauges. While a traditional cockpit relies on numerous mechanical gauges to display information, a glass cockpit uses several multi-function displays driven by flight management systems, that can be adjusted to display flight information as needed. This simplifies aircraft operation and navigation and allows pilots to focus only on the most pertinent information. They are also popular with airline companies as they usually eliminate the need for a flight engineer, saving costs. In recent years the technology has also become widely available in small aircraft.

Elevon

Elevons or tailerons are aircraft control surfaces that combine the functions of the elevator and the aileron, hence the name. They are frequently used on tailless aircraft such as flying wings. An elevon that is not part of the main wing, but instead is a separate tail surface, is a stabilator.

Aircraft flight control system How aircraft are controlled

A conventional fixed-wing aircraft flight control system consists of flight control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight. Aircraft engine controls are also considered as flight controls as they change speed.

HAL Tejas Indian lightweight multirole fighter

The HAL Tejas is an Indian, single engine, delta wing, multirole light fighter designed by the Aeronautical Development Agency (ADA) in collaboration with Aircraft Research and Design Centre (ARDC) of Hindustan Aeronautics Limited (HAL) for the Indian Air Force and Indian Navy. It came from the Light Combat Aircraft (LCA) programme, which began in the 1980s to replace India's ageing MiG-21 fighters but later became part of a general fleet modernisation programme. In 2003, the LCA was officially named "Tejas". It is the smallest and lightest in its class of contemporary supersonic combat aircraft.

Trainer aircraft Aircraft designed for training of pilots and aircrew

A trainer is a class of aircraft designed specifically to facilitate flight training of pilots and aircrews. The use of a dedicated trainer aircraft with additional safety features—such as tandem flight controls, forgiving flight characteristics and a simplified cockpit arrangement—allows pilots-in-training to safely advance their skills in a more forgiving aircraft.

AAI Corporation

AAI Corporation is an aerospace and defense development and manufacturing firm, located in Hunt Valley, Maryland, US. Formerly a wholly owned subsidiary of United Industrial Corporation, AAI was acquired by Textron in 2007. It currently operates as a unit of Textron Systems and employs more than 2,000.

Mikoyan Project 1.44 Fighter technology demonstrator aircraft

The Mikoyan Project 1.44/1.42 was a technology demonstrator developed by the Mikoyan design bureau. It was the Soviet Union's answer to the U.S.'s Advanced Tactical Fighter (ATF), incorporating many fifth-generation jet fighter aspects such as advanced avionics, stealth technology, supermaneuverability, and supercruise. The design's development was a protracted one, characterised by repeated and lengthy postponements due to a chronic lack of funds; the MiG 1.44 made its maiden flight in February 2000, nine years behind schedule, and was cancelled later that year.

IAI Lavi Israeli prototype jet fighter

The IAI Lavi was a single-engined fourth-generation multirole jet fighter developed in Israel, by Israel Aircraft Industries (IAI), during the 1980s. The decision to develop the Lavi was controversial, both with the Israeli public, due to the enormous associated costs, and particularly with the U.S. government due to competition with American jets on the export market. By 1984 Israel, with a population of 4 million, had the world's highest military expenditure as a proportion of GDP, at 24%, a rate of spending considered unsustainable. These issues contributed to the ultimate cancellation of the aircraft, by the Israeli government, during the flight-test phase of development in August 1987.

Icing conditions Atmospheric conditions that can lead to the formation of ice on aircraft surfaces

In aviation, icing conditions are atmospheric conditions that can lead to the formation of water ice on an aircraft. Ice accretion can affect the external surfaces of an aircraft – in which case it is referred to as airframe icing – or the engine, resulting in carburetor icing, air inlet icing or more generically engine icing. These phenomena do not necessarily occur together. Both airframe and engine icing have resulted in numerous fatal accidents in aviation history.

PZL-230 Skorpion

The PZL-230 Skorpion (scorpion) was a proposed Polish low-cost attack aircraft. It was being developed by Polish manufacturer PZL Warszawa-Okecie in the late 1980s and early 1990s.

Flight envelope protection

Flight envelope protection is a human machine interface extension of an aircraft's control system that prevents the pilot of an aircraft from making control commands that would force the aircraft to exceed its structural and aerodynamic operating limits. It is used in some form in all modern commercial fly-by-wire aircraft. The professed advantage of flight envelope protection systems is that they restrict a pilot's excessive control inputs, whether in surprise reaction to emergencies or otherwise, from translating into excessive flight control surface movements. Notionally, this allows pilots to react quickly to an emergency while blunting the effect of an excessive control input resulting from "startle," by electronically limiting excessive control surface movements that could over-stress the airframe and endanger the safety of the aircraft.

General Atomics MQ-20 Avenger Unmanned combat aircraft demonstrator built by General Atomics

The General Atomics MQ-20 Avenger is a developmental unmanned combat air vehicle built by General Atomics Aeronautical Systems for the U.S. military.

The HAL HJT 39, aka CAT , was an Advanced Jet Trainer (AJT) project proposal by Hindustan Aeronautics Limited (HAL) for the Indian Air Force. HAL HJT 39 CAT Programme was Announced at Aero India, February 2005, with mockup of front fuselage and cockpit shown. It was projected to fly within three and a half years of go-ahead with airframe and engine commonality with HAL HJT-36 Sitara, avionics comparable with those of HJT-36 and HAL Tejas.

The period between 1945 and 1979 is sometimes called the post-war era or the period of the post-war political consensus. During this period, aviation was dominated by the arrival of the jet age. In civil aviation the jet engine allowed a huge expansion of commercial air travel, while in military aviation it led to the widespread introduction of supersonic aircraft.

References

  1. Introduction to Finite Element Analysis Archived 2011-05-14 at the Wayback Machine , Laboratory for Scientific Visual Analysis (recovered 21 February 2014).
  2. 1 2 "1968 | 2110 | Flight Archive". www.flightglobal.com. Archived from the original on 2013-12-31.
  3. 1 2 Gunston (1990) Avionics: The story and technology of aviation electronics Patrick Stephens Ltd, Wellingborough UK. 254pp, ISBN   1-85260-133-7
  4. Executive Summary, U.S. Centennial of Flight Commission, archived from the original on 2006-09-24