Flight Control System PDF

ESA 272: Aircraft Sub-systems Element Flight Control System Dr. Nurul Musfirah Mazlan  About Aircraft An aircraft is a machine that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. It counters the force of gravity by using either sta...

ESA 272: Aircraft Sub-systems Element Flight Control System Dr. Nurul Musfirah Mazlan  About Aircraft An aircraft is a machine that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines  Type of Aircraft AIRCRAFT Powered & Fixed & Rotary Unpowered Wing Manned & Manual, Unmanned Autonomous, Remote Control Parts of an Aircraft Wing Design Wing Tip Design Wing Position Tail designs Aircraft Motions  Control Surfaces Primary Flight Control Elevator Aileron Rudder Secondary Flight Control Flap Slat Speed-brakes Spoiler  Roll Motion Controlled by ailerons  Pitching Controlled by elevators Yawing Controlled by rudder Rudders turn the aircraft right or left Control Column  How they work? Pitch control – move the control column fore and aft; push column forward – aircraft pitch down, pull column – pitch up Roll control – move the control column side to side; push to the right drops the right wing and vice versa Yaw control – push the rudder pedals to the left will yaw the aircraft to the left and vice versa Elevator Control System  Active Learning (Note Checking) Student individually write down notes from an article given in class – 7 minutes When finished, compare your notes with a partner that sits beside you In pair, summarize the most important information from the notes Identify any sticking points in the notes and clarify if possible Share in class Trim Feel  Mechanical Flight Control System Basic method of controlling the aircraft Control devices with the pilot are connected directly to the control surfaces of the aircraft by a system of rods, levers, cables and pulleys Two types of mechanical systems were employed: push-pull rods and cable-pulley  Read & Explain Pairs Work in pair (A and B) Both students read all the headings to get overview Both students silently read the first paragraph Initially set student A as summarizer and B as accuracy checker. Rotate roles after each paragraph Summarizer summarizes in own words content of the paragraph to partner Accuracy checker listens carefully, corrects any misstatements and adds anything left out. Move to the next paragraph. Switch roles and repeat procedures. Continue until finished. Summarize and agree on overall meaning of the entire material Push-pull control rod systems Cable and pulley systems Hydro-mechanical Flight Control System Combination of two parts: – Mechanical circuit – similar as in mechanical control system – Hydraulic circuit - When a pilot moves the hydro mechanical controls, the circuit operates and the servo valve in the hydraulic circuit opens. This type of control is often used in older jets as well as high performance airplanes – E. g: Boeing 707 (hydraulic), Boeing 727 and 737, Airbus A300 (hydro-mechanical) Hydro-mechanical Flight Control System  Fly-by-wire Flight Control System Replaced the conventional manual flight controls of an aircraft with an electronic interface The movements of flight controls are converted to electronic signals and transmitted by wires Allows automatic signals sent by the aircraft's computers to perform functions without the pilot's input, as in systems that automatically help stabilize the aircraft Fly-by-wire Flight Control System Fly-by-wire Flight Control System Data:  Pitch, roll, yaw rate and linear accelerations  Angle of attack and sideslip  Airspeed/Mach number, pressure altitude and radio altimeter indications  Stick and pedal demands  Other cabin commands (Landing gear condition, thrust level position etc)  Fly-by-wire Flight Control System Advantage: – Lighter weight due to reduction of mechanical linkages – hence save the fuel – Reduce pilot workload – the fly-by-wire provides a more usable interface a takes over some computations that previously would have to be carried out by the pilots – Airframe safety – from the control commands, the system can ensure that the pilot cannot put the aircraft into a state that stresses the airframe or stalls the aircraft  Fly-by-wire Flight Control System Disadvantage: – Electromagnetic Interference (EMI) – High Intensity Radiated Field (HIRF) Solutions: – shielded electrical cables – increase weight – optical fibre cables and optic sensors Purpose of the Components Item Purpose The cable To transmit the power Cable connector To connect the cable Turnbuckle To adjust the cable length Fairlead To guide the cable Pulley To guide the in radial direction Push pull rod To go for aft as per requirement Control stick To make orders for the remaining circuit Limitations: The complexity and weight of mechanical flight control systems increase considerably with the size and performance of the aircraft. Solution: Hydraulically powered control surfaces