CHAPTER 2 AIRCRAFT ROCKETS AND ROCKET LAUNCHERS The  history  of  rockets  covers  a  span  of  eight centuries, but their use in aircraft armament began during World War II. Rockets answered the need for a large missile that could be fired without recoil from an aircraft. Since the airborne rocket is usually launched at close  range  and  measured  in  yards  or  meters,  its accuracy  as  a  propelled  projectile  is  higher  than  a free-falling bomb dropped from high altitude. AIRCRAFT ROCKETS LEARNING   OBJECTIVE:   State   the principles  of  rocket  propulsion.  Identify  rocket components to include motors, warheads, and fuzes. Identify the purpose and use of service rocket  assemblies  to  include  the  2.75-inch folding-fin aircraft rocket (FFAR), the low-spin folding-fin aircraft rocket (LSFFAR), and the 5.00-inch FFAR. There are two rockets currently used by the Navy. The first is the 2.75-inch, folding-fin aircraft rocket (FFAR) known as the Mighty Mouse. The second, a 5.0-inch,  folding-fin  rocket  known  as  the  Zuni.  The Mighty Mouse and the Zuni are discussed in detail later in this chapter. ROCKET AND ROCKET FUZE TERMINOLOGY Some of the more common terms peculiar to rockets and  rocket  components  used  in  this  chapter  are  defined as  follows: Acceleration/deceleration.  These terms apply to fuzes that use a gear timing device in conjunction with the   setback   principle. Prolonged  acceleration completes  arming  the  fuze,  and  deceleration  or proximity  initiates  detonation. Igniter.  The  initiating  device  that  ignites  the propellant  grain.  It  is  usually  an  assembly  consisting  of an electric squib, match composition, black powder, and magnesium   powder. Hangfire. A misfire that later fires from delayed ignition. Misfire.  A  rocket  does  not  fire  when  the  firing circuit is energized. Motor.  The  propulsive  component  of  a  rocket. It  consists  of  the  propellant,  the  igniter,  and  the nozzle(s). Propellant grain.  The solid fuel used in a rocket motor, which, upon burning, generates a volume of hot gases that stream from the nozzle and propel the rocket (also known as the propellant or propellant powder grain). Rocket.  A  missile  propelled  by  the  sustained reaction of a discharging jet of gas against the container of gas. Setback. This term is applied when internal parts react to the acceleration of the rocket. Setback is a safety  feature  designed  into  those  fuzes  that  use  a  gear timing  device. Thrust. The force exerted by the gases produced by the  burning  of  the  rocket  motor  propellant. PRINCIPLES OF ROCKET PROPULSION Rockets are propelled by the rearward expulsion of expanding gases from the nozzle of the motor. The necessary gas forces are produced by burning a mass of propellant  at  high  pressure  inside  the  motor  tube. Rockets function even in a vacuum. The propellant contains its own oxidizers to provide the necessary oxygen during burning. 2-1