A representative fuze from each class is discussed in the following paragraphs. The fuzes currently in use and their primary application are listed in table 2-3. For more detailed information on fuzes, refer to  Aircraft Rocket  Systems  2.75-inch  and  5.0-inch  NAV- AIR 11-75A-92. REVIEW NUMBER 2 ANSWERS A1. High-explosive  rocket  warheads  are  painted olive  drab  and  may  have  a  narrow  yellow band around the nose. A2. HE-FRAG warheads are used against personnel and light material targets, such as trucks and parked aircraft. A3. The    AT/APERS    warhead    is    an    effective combination   of   the   HE-FRAG   and   HEAT warheads. A4. The    flechette    warhead    contains    a    large number of small, arrow-shaped projectiles. A5. Smoke warheads produce a volume of heavy smoke for target marking. A6. The   flare   warhead   is   used   to   illuminate tactical operations. IMPACT FIRING FUZES.—Impact firing fuzes (fig. 2-12) function when the rocket strikes a target that offers sufficient resistance to cause crushing or other disarrangement of actuating parts. All current impact firing rocket fuzes have the same type   of   safety/arming   mechanism.   This   mechanism consists  of  an  unbalanced  rotor,  which,  under  setback forces,   drives   a   gear-train   timing   system.   A   given minimum  acceleration  over  a  given  length  of  time  is required   to   complete   the   arming   cycle.   If   rocket acceleration  is  too  low  or  extends  over  too  short  a period  of  time,  the  arming  mechanism  returns  to  the unarmed condition. The timing mechanism provides a safe   separation   distance   from   the   launcher   before arming. When  located  in  the  nose  of  the  warhead,  impact firing fuzes are known as point-detonating (PD) fuzes. If they are located in the base of the warhead, they are known  as  base-detonating  (BD)  fuzes.  Nose  and  base fuzes  function  either  instantaneously  or  after  a  short delay that gives the warhead time to penetrate the target before functioning. MECHANICAL   TIME   FUZES.—Mechanical time   fuzes   (fig.   2-13)   function   by   the   action   of   a mechanical timer. These fuzes contain a safety/arming device and a clock mechanism. The arming mechanism is   similar   to   those   in   impact   detonating   fuzes   and requires  a  minimum  acceleration  over  a  given  time  to complete the arming cycle. Upon arming, the mechanical timer is started, and after a set elapsed time, the fuze initiates the firing train. The  Mk  193  Mod  0  is  the  only  mechanical  time rocket fuze currently in use. It is permanently installed in the nose of the Mk 33 Mod 1 flare warhead. 2-10 FUZE CLASSIFICATION APPLICATION Mk 188 Mod 0 Mk 352 Mod 2 FMU-90/B M423 M427 Mk 191 Mk 193 Mod 0 Model 113A Mk 93 Mod 0/M414A1 Nose impact (PD) Nose impact (PD) Nose impact (PD) Nose impact (PD) Nose impact (PD) Base detonating impact (BD) Mechanical time Acceleration-deceleration Proximity 5.0-inch 2.75-inch and 5.0-inch (Note 1) 5.0-inch (Note 1) 2.75-inch (Note 2) 2.75-inch 5.0-inch 5.0-inch 2.75-inch 5.0-inch Note 1: Requires use of BBU-15/B adapter booster for 5.0-inch configurations. Note 2: Designed for use with 2.75-inch LSFFARs only. Table 2-3.—Rocket Fuzes