snubber holds the hook down and prevents it from bouncing when it strikes the carrier deck. CATAPULT EQUIPMENT Carrier aircraft have built-in equipment for catapulting off the aircraft carrier. Older aircraft had hooks on the airframe that attached to the cable bridle. The bridle hooks the aircraft to the ship's catapult. Newer aircraft have a launch bar built into the nose landing gear assembly. See figure 4-16. The holdback assembly allows the aircraft to be secured to the carrier deck for full-power turnup of the engine prior to takeoff. For nose gear equipment, a track attaches to the deck to guide the nosewheel into position. The track has provisions for attaching the nose gear to the catapult shuttle and for holdback. NOTE: The holdback tension bar separates when the catapult is fired, allowing the aircraft to be launched with the engine at full power. Q4-9. In fuselage construction, what are the three classes of monocoque design? Q4-10. Points on the fuselage are located by what method? Q4-11. In an aircraft, what are the main structural members of the wing? Q4-12. What does the term “wet wing” mean? Q4-13. The stabilizing surfaces of an aircraft consist of what two airfoils? Q4-14. What are the three groups of flight control surfaces? Q4-15. What is the purpose of speed brakes on an aircraft? Q4-16. Most present-day Navy aircraft are equipped with what type of landing gear? ROTARY-WING AIRCRAFT LEARNING OBJECTIVE: Identify the construction features of the rotary-wing aircraft and recognize the fundamental differences between rotary-wing and fixed-wing aircraft. Within the past 20 years, helicopters have become a reality, and are found throughout the world. They perform countless tasks suited to their unique capabilities. A helicopter has one or more power-driven horizontal airscrews (rotors) to develop lift and propulsion. If a single main rotor is used, it is necessary to employ a means to counteract torque. If more than one main rotor (or tandem) is used, torque is eliminated by turning each main rotor in opposite directions. The fundamental advantage the helicopter has over fixed-wing  aircraft  is  that  lift  and  control  are independent of forward speed. A helicopter can fly forward, backward, or sideways, or it can remain in stationary flight (hover) above the ground. No runway is required for a helicopter to take off or land. For example, the roof of an office building is an adequate landing area. The helicopter is considered a safe aircraft because the takeoff and landing speed is zero, and it has autorotational capabilities. This allows a controlled descent with rotors turning in case of engine failure in flight. FUSELAGE Like the fuselage of a fixed-wing aircraft, the helicopter fuselage may be welded truss or some form of monocoque construction. Many Navy helicopters are of the monocoque design. 4-13 ANf0415 Figure 4-15.—Arresting gear installation.