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AIRCRAFT NOMENCLATURE - 12018_278
AIRCRAFT MODEL DESIGNATIONS - 12018_280

Basic Military Requirements (BMR) - Requirement for military advancement
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takeoff or to slow the aircraft in flight or landings; ailerons that control the roll or bank of the aircraft; and trim tabs used to aerodynamically unload the control surfaces to relieve some of the pilot’s work. On the leading (front) edge of the wing may be found auxiliary lifting devices, resembling flaps, which are used to increase camber (curvature) of the wing for added lift on takeoff. Most Navy jet aircraft carry their bomb loads on pylons (called  stations) under the wings and, in some cases,  under  the  fuselage.  Some  jets  have  missile stations on the sides of the fuselage. Fuel cells are located in the wings; additional external tanks can be fitted for extra range. Larger jets may have their engines slung  beneath  the  wings  in  pods.  Some  low-wing aircraft have their main landing gear retract into the wings, while the nose wheel retracts into the fuselage. On most high-wing aircraft all gear retracts into the fuselage. EMPENNAGE.—The empennage consists of the stabilizing  fins  mounted  on  the  tail  section  of  the fuselage. These include the vertical stabilizer on which is generally mounted the rudder that is used to control yaw, or direction of the nose about the vertical axis; and the horizontal stabilizer, on the trailing edge of which are the elevators that determine the pitch (climb or dive). Some supersonic aircraft may have a full delta wing. In that  case,  there  is  no  horizontal  stabilizer  and  the elevators  and  ailerons  are  combined  into  control surfaces called  elevons. In  aircraft  with  internally  mounted  jet  engines, exhausts normally are in the tail. High-performance jets have afterburners that give additional thrust at the cost of greatly increased fuel consumption. Rudder,  ailerons,  and  elevators  are  collectively grouped as control surfaces. The “stick” or a similar device in the cockpit controls these surfaces, while foot pedals  control  the  rudder.  On  high-performance aircraft,  aerodynamic  pressures  on  these  surfaces become too great for a pilot to overcome manually; hence, all high-speed models today have power-assisted controls. Rotary-Wing Aircraft Nomenclature The  aerodynamics  of  rotary-wing  aircraft  (fig. 8-40) are considerably more complex than those of fixed-wing aircraft. A helicopter essentially consists of a fuselage, main rotor or rotors, and often a tail rotor. FUSELAGE.—As  in  fixed-wing  aircraft,  the fuselage contains the cockpit and cabin. M A I N  ROTO R . — T h e  m a i n  r o t o r  i s  t h e approximate equivalent of the wing of a fixed-wing aircraft. Each rotor blade is an airfoil, like a wing, and the lift is generated by the rotation of the assembly, which creates a flow of air over the blades. A helicopter is lifted into the air by the aerodynamic forces on the rotor and not pushed up by the downwash. Some helicopters have twin rotors in tandem at either end of the fuselage; but most have a single, main rotor with a tail rotor mounted at right angles. A few have tandem intermeshing rotors. TAIL  ROTOR.—The  tail  rotor  is  used  for directional control and stability. It is mounted at right angles to the main rotor to counteract the torque of that system. By varying the pitch of the tail rotor blades, the pilot controls yaw. Helicopter  engines  are  connected  to  the  rotor shaft(s) by a transmission, which may be disengaged. That permits the engine(s) to be operated on the ground without engaging the rotor system and also permits a mode of flight known as   autorotation. If the engines should stop while in flight, they can be disengaged; the freewheeling action of the rotor will allow a slower descent. 8-33 Figure 8-39. Fixed-wing aircraft. Student Notes:







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