Content PageIdentification Of Business Jet2 Types Of SystemsFly-By-Wire System Introduction “Old” Flight Control SystemDescriptionWhy Fly-By-Wire is useful?AdvantagesHow It WorksFlight Control SurfacesFlight Control System (Boeing) Envelope Limiting/ProtectionMulti-Scan Weather Radar (Rockwell Collins)IntroductionHow it operates Why Is It NecessaryAdvantagesDisadvantagesInstallation Locations (Boeing)Potential installation challengesReferences          Identification of Business JetEmbraer Legacy 450COST15,250,000 – 15,250,000 USDRANGE4,260 kmTOP SPEED1,017 km/hrHighlightsFastest jet in mid-light segmentFull digital flight controls, unique in its segmentLargest-in-class cabin: 6 feet tall with flat floorCapable of taking off and landing on shorter runwaysExcellent cabin altitude 2. Recommended Avionics SystemFly By Wire Multi-Scan Weather RadarFly-By-Wire3.1 IntroductionName: Fly-By-Wire SystemWhere: Cost: Cheaper maintenance costs.Components Used in Fly-By-Wire System: 3.2 “Old” Flight Control SystemThe old flight control systems consisted of the control stick, pulleys, cable, push rod and elevator. 3.3 DescriptionFly-by-Wire (FBW) is the commonly accepted term for flight control systems that use computers to process the flight control inputs made by the pilot or autopilot and sends the corresponding electrical signals to the flight control surface actuators. This arrangement replaces mechanical linkage which means that the pilot inputs do not directly move the control surfaces. Instead, inputs are read by a computer that in turn determines how to move the control surfaces to best achieve what the pilot wants in accordance to which Flight Control Law is active.3.4 Why is the Fly-By-Wire System useful?The first ever aircraft to have the Fly-By-Wire System was the F-16 back in 1973. This system had its advantages such as it being lighter, damage tolerant (to a certain extent) and having more effective control over a necessarily highly maneuverable aircraft. The Fly-By-Wire system has the capability to ensure that unintended increases in the angle of attack are detected and resolved by marginally deflecting the control surfaces in the opposite way while the problem is still small.                                                                                                    3.5 Challenges of InstallationThere are more things needed in the installation of the Fly-By-Wire system compared to the old flight control system. This is because the Fly-By-Wire system has more components than the older flight control system which only consists of a control stick, pulleys, cable, push rod and elevators. Thus this makes the installation of the Fly-By-Wire system more challenging as the engineers that are installing this system have to make ensure that all the components of this Fly-By-Wire system are functioning properly and well.3.6 AdvantagesThe main advantage of this is that this system is less vulnerable (you can easily make it redundant) and it takes less space and is easier to route through the airframe (in the traditional cable/pulley system you have steel cables under tension going from the cockpit to all control surfaces). Another advantage of this system is that it makes flights safer as the flight computers can be programmed to carry out adjustments to control surfaces automatically. This helps keep the flight much more stable, as the plane is to some extent, “flying by itself”. Another advantage of this system is that it reduces pilot workload as it provides a more usable interface and takes over some computations that previously would have to be carried out by the pilots. Next, with this system, there is weight reduction. By reducing the mechanical linkage, a significant amount of weight (and hence, fuel), is saved. 3.7 DisadvantagesOne of the little disadvantage is that the Fly-By-Wire system is costly. While this does not apply in most planes, it will still cost a ton for low-budget aircraft manufacturing companies. Another disadvantage is that, since this Fly-By-Wire system is electrical, the failure of its electrical system, such as short circuits, could lead to a complete system shutdown. Third, there are no real input feel for the pilot since his movement of the stick is not physically connected to each other. This means that the co-pilot might be making control movements the captain might not know about. 3.8 How it works? (Overview)Fly-By-Wire system replaces the conventional mechanical flight controls with an electronic interface. The pilot’s movements of the flight controls are converted to electrical signals, which are interpreted by the flight control computers. When a command input is made by the pilot or the autopilot, the difference between the current control surface position and the apparently desired control surface position indicated by the command is analysed by the computer and the fitting corrective signal is sent electronically to the control surface. Feedback compensation functions as error control and the flight control computer regulates the system by comparing output signals to input signals. Any error between the two becomes a command to the flight control surface until output equals input. In an FBW system the signal route from FCC to control surface is called the forward path while the signal route from the control surface to the FCC is called the feedback loop or path. Gain is the amplification or attenuation which is applied to the forward signal to achieve the desired aircraft response. A filter may be used to block feedback of signals or motion which occur at an undesirably frequent interval.The Fly-By-Wire System has three modes of operation. (refer to 2.9)Normal mode provides full functionality. Secondary mode provides reduced functionality due to failures in the system. The plane can fly but cannot be dispatched. Finally, there is the direct mode. This mode ignores PFC and uses pilot command directly. This is due to major failures in the system or pilot selection. Diagram 1: Overview on how Fly-By-Wire works3.9 Flight Control SurfacesThere are three main aircraft control surfaces which are elevators, ailerons and rudder. 3.9.1 ElevatorsAs the name implies, the elevator helps “elevate” the aircraft. It is usually located on the tail of the aircraft and serves two purposes. The first is to provide stability by producing a downward force on the tail. Airplanes are traditionally nose-heavy and this downward force is required to compensate for that. The seco6668nd is to direct the nose of the aircraft either upwards or downwards, known as pitch, in order to make the airplane climb and descend.3.9.2 AileronsThe ailerons are located at the rear of the wing, one on each side. They work opposite to each other, so when one is raised, the other is lowered. Their job is to increase the lift on one wing, while reducing the lift on the other. By doing this, they roll the aircraft sideways, which allows the aircraft to turn. This is the primary method of steering a fixed-wing aircraft.3.9.3 RuddersThe rudder is located on the tail of the aircraft. It works identically to a rudder on a boat, steering the nose of the aircraft left and right. Unlike the boat however, it is not the primary method of steering. Its main purpose is to counteract the drag caused by the lowered aileron during a turn. This adverse yaw, as it is known, causes the nose of the airplane to point away, or outwards, from the direction of the turn. The rudder helps to correct this by pushing the nose in the correct direction, maintaining what is known as coordinated flight.3.10 Flight Control Systems (Boeing) The principles of the Boeing approach to fly-by-wire electronic flight control systems were established with the Boeing 777. The design principle adopted is to provide a system that responds similarly to a mechanically controlled flight control system. Because the B777 system is controlled electronically, it is also able to provide flight envelope protection. The electronic system operates on two levels – there are 4 Actuator Control Electronics (ACE) units and 3 Primary Flight Computers (PFC). The ACEs control actuators (from those on pilot controls to control surface controls and the PFC) and the PFC determines the applicable control laws and provide feedback forces, pilot information and warnings.3.10.1 Standard Protections and AugmentationsThe 777 flight control system is designed to restrict control authority beyond certain range by increasing the back pressure once the desired limit is reached. This is done via electronically controlled backdrive actuators (controlled by the ACE). The protections and augmentations are: bank angle protection, turn compensation, stall protection, over-speed protection, pitch control, stability augmentation and thrust asymmetry compensation. The design philosophy is: “to inform the pilot that the command being given would put the aircraft outside of its normal operating envelope, but the ability to do so is not precluded.” In other words, the flight envelope protection system provides crew awareness of envelope margins and limitations by means of tactile, visual and aural cues and warnings. However, the protection functions of the system do not reduce or limit pilot control authority.Normal ModeIn Normal mode during manual flight, the ACEs receive pilot control inputs and send these signals to the three PFCs. The PFCs verify these signals and utilise information from other airplane systems in order to compute control surface commands. These commands are then sent back to the ACEs which then send the enhanced signals to the flight control surface actuators which convert them into analog servo commands. Full functionality is provided including all enhanced performance, envelope protection and ride quality features.When the autopilot is engaged, the autopilot system sends commands to the PFCs. The PFCs generate control surface commands which are sent to the ACEs in the same manner as pilot control inputs. The autopilot commands move the flight deck controls to provide autopilot feedback to the pilots. If a pilot overrides the autopilot with control inputs, the PFCs will disengage the autopilot and utilise the pilot control inputs. Note that the autopilot is not available should reversion to Secondary or Direct mode occur.Secondary ModeBoeing Secondary mode is somewhat similar to the Airbus Alternate Law. When the PFCs can not support Normal mode operation due to internal faults or to loss of information from other aircraft systems, they automatically revert to Secondary mode. Reversion to Secondary mode results in the loss of the autopilot and the pilots must control the aircraft manually. The ACEs still receive pilot control inputs and send the appropriate signals to the PFCs. However, due to the degraded mode of operation, the PFCs use “simplified” computations to generate the flight control surface commands. These commands are sent back to the ACEs from whence they are sent to the flight control surfaces in the same manner as during Normal mode operations.Aircraft handling qualities are affected by the simplified computations or PFC control laws that are utilised in Secondary mode. While all flight control surfaces remain operative, the elevator and rudder are more sensitive at some airspeeds. The following functions are inoperative or degraded during Secondary mode operations:autopilotauto speedbrakesenvelope protectiongust suppressiontail strike protectionthrust asymmetry compensationyaw damping Direct ModeThe ACEs automatically revert to Direct mode when they detect the failure of all three PFCs or when they are unable to communicate with the PFCs. Direct mode can also be manually selected by selecting the DISC position on the Primary Flight Computers Disconnect switch. In Direct mode, the PFCs no longer generate control surface commands. Pilot inputs are received by the ACEs and sent directly to the flight control surface actuators.Direct mode allows for full aircraft control while in flight and during the landing phase. Aircraft handling characteristics are very similar to those encountered while in Secondary mode. In addition to those functions lost during Secondary mode operations (as listed previously) the manual rudder trim cancel switch is inoperative.Mechanical BackupIn the event of a complete electrical system shutdown, cables from the flight deck controls to the stabiliser and selected roll spoilers allow the pilots to maintain straight and level flight until the electrical system can be restored. 3.11 System Redundancy   Rather than providing a conventional FCS for backup, the approach with commercial aircraft normally controlled wholly by FBW is to provide redundancy for the FCCs and sensors by installing more of them. When all components are operative, an FCS is commonly said to be operating in normal law. Limited failures usually cause auto reversion to some degraded, but still computed, FCS mode. The lowest level of FBW backup mode normally features analog electronic signals that bypass the FCCs and go directly to the flight control actuators – Direct Law. Under Direct Law, there is no feedback control and there may be fixed gains aimed at providing acceptable control forces proportional to control surface deflection. The gain selected may optimise control forces for the landing configuration, or might provide different gains for cruise and landing, switched, for example, through the flap selector. 3.12 Envelope LimitingEnvelope Limiting prevents the Pilot or Co-Pilot from exceeding the limits that have been set for the plane. This would mean that the pilots would not be able to yank to the extent that it would overstress the airframe and endanger the safety of the aircraft. However this also means that in the case of an emergency the pilot does not have to fear about exerting too much force on the control panel such that it would endanger the plane. This is possible with the help of the envelope limiting. With it, the pilots are less uncertain and thus can get the plane out of the emergency as fast as the plane allows. 3.12.1 Envelope ProtectionEnvelope Protection deters the exceeding of limits but it does not prohibit the pilots from exceeding those limits. This would mean that the Pilots are able to overcome the limits that have been set on the plane if they exert a higher force than the limit. An example of this would be the Pitching Limit of the plane. If the pilot were to exert a higher force on the control panel, the pilot would be able to exceed the limit. 4.  MultiScan Weather Radar(Rockwell Collins)Model Number: RTA-4100Part Number:  523-08167974.1  IntroductionThe Rockwell Collins RTA-4100 MultiScan Weather Radar delivers comprehensive weather analysis and threat detection capability to pilots. Capabilities such as MultiScan automatic operation, Geographic Weather Correlation, OverFlight™ protection and turbulence detection accurately depict weather and weather related hazard events at any location around the globe. The system provides a 300 nm ‘clutter-free’ weather display and enhanced effectiveness as a threat detector. Turbulence detection provides the flight crew with turbulence detection and alerting capability out to 40 nautical miles.4.2  How it operates?Weather radar operates on the principles of reflectivity. Thunderstorm reflectivity can be divided into three parts. See the figure below.The bottom third of the storm below the freezing level is composed entirely of water and is the part of the storm that most efficiently reflects radar energy. The middle third of the storm is composed of a combination of supercooled water and ice crystals. Reflectivity in this part of the storm begins to diminish since ice crystals are very poor radar reflectors. The top third of the storm is composed entirely of ice crystals and is almost invisible to radar.Most airborne weather radars operate in the X-Band and are specifically designed to both penetrate and reflect weather. In the figure below, the reflection of light rain can be equated with green on the radar display. Moderate rain can be equated with yellow and heavy rain can be equated with red. In order to be able to penetrate heavy rain, the radar will not be able to detect fog, very light rain or relatively dry clouds. On the other end of the spectrum, the radar’s ability to reflect light rain may prevent the radar beam from penetrating heavy rain and thus may mask weather behind a storm cell.The technology is intended to provide a better overall view of storms that is free of ground clutter by using two radar beams aimed at slightly different angles. This system operates automatically and gives pilots a complete picture of the weather while eliminating the requirement to manually adjust the radar. The system automatically scans ahead of the aircraft and combines the returns through advanced digital processing and analysis algorithms to display not just precipitation rates but the actual weather threats. The result is a more accurate depiction of weather and turbulence hazards while significantly reducing flight deck workload and training for pilots. 4.3  Why is it necessary?Accurately depicting the weather is critical to safety and comfort. Without the weather radar, pilots will not be able to know what is ahead. With a means to know what the weather is like ahead, pilots will be able to avoid the impending danger. The weather radar will depict a more accurate information such as weather and turbulence hazard while significantly reducing flight deck workload and training for pilots. The advanced weather radar solutions enhances pilot’s situational awareness with advanced weather avoidance technology, so that pilots are always aware of potential weather threats. With detection ranges of up to 320 nm and available Doppler™ turbulence detection at ranges of up to 50 nm, the weather radars give pilots real-time information on the smoothest, most efficient routes around dangerous weather systems. 4.3.1 AdvantagesThe operation is fully automatic and it is active gain in all modes therefore making it highly reliable. The system also provides alerts that allows the pilots to avoid penetrating thunderstorm tops, which account for a large portion of serious turbulence encounters. The key to MultiScan operation is the radar’s ability to look down towards the lower reflective portion of a storm cell and automatically eliminate the ground clutter using digital signal-processing techniques pioneered by Rockwell Collins. Ground clutters are unwanted echoes.  Such echoes are typically returned from ground, sea, rain, animals/insects, chaff and atmospheric turbulences, and can cause serious performance issues with radar systems.The weather radar is unlike conventional airborne weather radar systems which merely sweep the skies ahead and paint a picture of what’s returned but instead, the multiscan technique makes multiple passes of the sky at varying tilt angles and stores all the data in its memory. When the pilots select a desired range, the information from each of the scans is rearranged and merged in a single, coherent picture on the radar display. 4.3.2 Disadvantages One of the weather radar limitations is that it indicates only the presence of liquid water. The consequence is that a thunderstorm does not have the same reactivity over its altitude range because the quantity of liquid water in the atmosphere decreases with the altitude. Yet, the convective cloud and associated threats may extend significantly above the upper detection limit of the weather radar (called ‘radar top’). This means that reactivity is not directly proportional to the level of risk that may be encountered: a convective cloud may be dangerous, even if the radar echo is weak. This is particularly true for equatorial overland regions where converging winds produce large scale uplifts of dry air. The resulting weather cells have much less reactivity than mid-latitude convective cells. However, turbulence in or above such clouds may have a higher intensity than indicated by the image on the weather radar display. On the other hand, air close to the sea can be very humid. In this case, thermal convection will produce clouds that are full of water: these clouds will have a high reactivity, but may not necessarily be a high threat. As such, the weather radar can only detect rainfall, windshear and wet turbulence but is unable to detect clear turbulence, cloud, fog, sandstorm, lighting etc. 4.4  Installation LocationsThe antenna on a pedestal is located at the nose of the aeroplane while the receiver, transmitter, and processor is located at the main equipment centre which will process the information. The cockpit is where the weather radar control panel and weather information will be displayed, on the Navigation Display. 4.5 Identification of potential installation challengesThe weather radar generates very high microwave energy to do what they do and, without proper care, that energy can be hazardous to the user and others around the airplane . Also, there is no ramp test equipment to assist in troubleshooting the unit and user is unable to determine whether it is bad or not.

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