Parts of an aircraft


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Parts of an aircraft

  1. 1. Parts of an AircraftCan you please explain the different parts of an aircraft, such as thewing, horizontal tail, vertical tail, and fuselage?ORWhat is the fuselage?The types of questions we are asked at this site span the whole range,from the very broad and simple to the very detailed and specific. So wethought it would be a good idea to take a step back and define somebasic terminology about the components that make up a typical aircraft.Explaining these definitions will hopefully level the playing field a bitand allow our regular visitors to better understand some of the morecomplex subjects we routinely deal with on this site.Lets start by first looking at a very basic schematic of a traditionalaircraft layout, and we will add more complexity as we go.:Basic ComponentsBasic components of an aircraft
  2. 2. fuselageThe fuselage is that portion of the aircraft that usually contains the crewand payload, either passengers, cargo, or weapons. Most fuselages arelong, cylindrical tubes or sometimes rectangular box shapes. All of theother major components of the aircraft are attached to thefuselage. Empennage is another term sometimes used to refer to the aftportion of the fuselage plus the horizontal and vertical tails.wingThe wing is the most important part of an aircraft since it produces thelift that allows a plane to fly. The wing is made up of two halves, left andright, when viewed from behind. These halves are connected to eachother by means of the fuselage. A wing produces liftbecause of itsspecial shape, a shape called an airfoil. If we were to cut through a wingand look at its cross-section, as illustrated below, we would see that atraditional airfoil has a rounded leading edge and a sharp trailing edge.Definition of an airfoilengineThe other key component that makes an airplane go is its engine, or
  3. 3. engines. Aircraft use several different kinds of engines, but they can allbe classified in two major categories. Early aircraft from the Wright Flyeruntil World War II used propeller-driven piston engines, and these arestill common today on light general aviation planes. But most modernaircraft now use some form of a jet engine. Many aircraft house theengine(s) within the fuselage itself. Most larger planes, however, havetheir engines mounted in separate pods hanging below the wing orsometimes attached to the fuselage. These pods are called nacelles.horizontal stabilizerIf an aircraft consists of only a wing or a wing and fuselage, it isinherently unstable. Stability is defined as the tendency of an aircraft toreturn to its initial state following a disturbance from that state. Thehorizontal stabilizer, also known as the horizontal tail, performs thisfunction when an aircraft is disturbed in pitch. In other words, if somedisturbance forces the nose up or down, the horizontal stabilizerproduces a counteracting force to push the nose in the oppositedirection and restore equilibrium. When in equilibirum, we say that anaircraft is in its trim condition. The horizontal tail is essentially aminiature wing since it is also made up of an airfoil cross-section. Thetail produces a force similar to lift that balances out the lift of the wing tokeep the plane in equilibrium. To do so, the tail usually needs toproduce a force pointed downward, a quantity called downforce.vertical stabilizerThe vertical stabilizer, or vertical tail, functions in the same way as thehorizintal tail, except that it provides stability for a disturbance in yaw.Yaw is the side-to-side motion of the nose, so if a disturbance causesthe nose to deflect to one side, the vertical tail produces a counteractingforce that pushes the nose in the opposite direction to restoreequilibrium. The vertical tail is also made of an airfoil cross-section andproduces forces just like a wing or horizontal tail. The difference is thata wing or horizontal tail produces lift or downforce, forces that arepointed up or down from the aircraft. Meanwhile the vertical tailproduces a force pointed to one side of the aircraft. This force is calledside-force.Basic Control SurfacesIn addition to the wing and tail surfaces, aircraft need some additionalcomponents that give the pilot the ability to control the direction of theplane. We call these items control surfaces.
  4. 4. Aircraft control surfaces and axes of motionelevatorThe elevator is located on the horizontal stabilizer. It can be deflected upor down to produce a change in the downforce produced by thehorizontal tail. The angle of deflection is considered positive when thetrailing edge of the elevator is deflected upward. Such a deflectionincreases the downforce produced by the horizontal tail causing thenose to pitch upward.rudderThe rudder is located on the vertical stabilizer. It can be deflected toeither side to produce a change in the side-force produced by thevertical tail. The angle of deflection is usually considered positive whenthe trailing edge of the rudder is deflected towards the right wing. Sucha deflection creates a side-force to the left which causes the nose to yawto the right.aileron
  5. 5. Ailerons are located on the tips of each wing. They are deflected inopposite directions (one goes trailing edge up, the other trailing edgedown) to produce a change in the lift produced by each wing. On thewing with the aileron deflected downward, the lift increases whereas thelift decreases on the other wing whose aileron is deflected upward. Thewing with more lift rolls upward causing the aircraft to go into a bank.The angle of deflection is usually considered positive when the aileronon the left wing deflects downward and that on the right wing deflectsupward. The greater lift generated on the left wing causes the aircraft toroll to the right.The effects of these control surfaces and the conventions for positivedeflection angles are summarized in the following diagram.Aircraft control surfaces and positive deflection anglesAdditional ComponentsWeve already seen the major parts of a typical plane, but a fewimportant items were left out for simplicity. Lets go back and discuss afew of these items.
  6. 6. Components of an aircraftflapFlaps are usually located along the trailing edge of both the left andright wing, typically inboard of the ailerons and close to the fuselage.Flaps are similar to ailerons in that they affect the amount of lift createdby the wings. However, flaps only deflect downward to increase the liftproduced by both wings simultaneously. Flaps are most often usedduring takeoff and landing to increase the lift the wings generate at agiven speed. This effect allows a plane to takeoff or land at a slowerspeed than would be possible without the flaps. In addition to flaps onthe trailing edge of a wing, a second major category is flaps on theleading edge. These leading-edge flaps, more often called slats, are alsoused to increase lift. More information on slats and flapsis available here.cabin & cockpitSometimes these two terms are used synonymously, but most of the
  7. 7. time the term cockpit is applied to a compartment at the front of thefuselage where the pilots and flight crew sit. This compartment containsthe control yolks (or sticks) and equipment the crew use to sendcommands to the control surfaces and engines as well as to monitor theoperation of the vehicle. Meanwhile, a cabin is typically a compartmentwithin the fuselage where passengers are seated.nose & main gearThe landing gear is used during takeoff, landing, and to taxi on theground. Most planes today use what is called a tricycle landing geararrangement. This system has two large main gear units located nearthe middle of the plane and a single smaller nose gear unit near thenose of the aircraft.trim tabThe above diagram illustrates a "trim tab" located on the elevator. Thesecontrol tabs may be located on other surfaces as well, such as a ruddercontrol tab or a balance tab on the aileron. Nonetheless, the purpose ofall these tabs is the same. In the previous section, we discussed that thehorizontal stabilizer and elevator are used to provide stability andcontrol in pitch. In order to keep a plane in a steady, level orientation,the elevator usually has to be deflected by some small amount. Since itwould be very tiring for a pilot to physically hold the control stick inposition to keep the elevator at that deflection angle for an entire flight,the elevator is fitted with a small "tab" that creates that elevatordeflection automatically. The trim tab can be thought of almost as a"mini-elevator." By deflecting the tab up or down, it increases ordecreases the downforce created by the elevator and forces the elevatorto a certain position. The pilot can set the deflection of the trim tabwhich will cause the elevator to remain at the deflection required toremain trimmed.