5.0-inch A.R. with 5-inch motor7.2-inch H.E. "Mouse Trap" and 2.5-inch Practice
U.S. EXPLOSIVE ORDNANCE
PART 2 - ROCKET AND ROCKET FUZES
Chapter 5 - ROCKET BODIES
Section 4 - NAVY ROCKETS

5-inch S.S.S.R.

General: The General-Purpose and Common rounds are particularly adapted for repel-ling PT-boat attacks at ranges less than 11,000 yards. The High-Capacity rockets are suitable for barrages at 1,250 to 5,000 yards. These rockets must be used in the speci-ally designed Launchers Mk 50 Mod 0 and 1 and Mk 51 Mods 0 and 1; and in Launcher Assemblies Mk 101 Mod 0 or Mk 102 Mod 0.

Data

 

General Purpose

Common

H.C. (5,000 yds.)

H.C. (2,500 yds.)

H.C. (1,250 yds.)

Head

5.0" Mk 7

5.0" Mk 8

5.0" Mk 10

5.0" Mk 12

5.0" Mk 13

 

All Mods

All Mods

All Mods

All Mods

All Mods

Motor 5.0" Mk 3 5.0" Mk 3 5.0" Mk 4 5.0" Mk 5 5.0" Mk 6
 

All Mods

All Mods

All Mods

Mod 1

Mod 0

Propellant grain Mk 21 Mod 0 Mk 21 Mod 0 Mk 22 Mod 0 Mk 24 Mod 0 Mk 25 Mod 0
Igniter Mk 17 Mod 0 Mk 17 Mod 0 Mk 18 Mod 0 Mk 20 Mod 0 Mk 20 Mod 0
Motor length 22.5" 22.5" 15.28" 10.50" 8.845"
Over-all length 31.5" 28.8" 32.2" 32.2" 32.2"
Head weight 20 lb. 20 lb. 24.6 lb. 31.4 lb. 34.35 lb.
Filler TNT Explosive "D" TNT TNT TNT

Weight

1.75 lb. 1.68 lb. 9.6 lb. 12.4 lb. 13.6 lb.
Total weight 49.1 lb. 50.8 lb. 50.2 lb. --- ---
Fuzes:          

Nose

Mk 100 Mod 0 None Mk 30 Mod 3 Mk 30 Mod 3 Mk 30 Mod 3
     

or Mk 173

or Mk 173

or Mk 173

Base

None Mk 31 Mod 0 None None None

Aux. Det.

Mk 44 Mod 2 None Mk 44 Mod 1 Mk 44 Mods 1 Mk 44 Mods 1
       

and 2

and 2

Range 11,000 yd. 11,000 yd. 5,250 yd. 2,500 yd. 1,250 yd.

Velocity

1,530 ft./sec.

1,600 ft./sec.

830 ft./sec.

475 ft./sec.

340 ft./sec.

Heads

5.0-inch Head Mk 7 - General Purpose: This head is threaded externally at the after end to accommodate the motor. It is threaded internally at the forward end to ac-commodate the fuze adapter for Rocket Fuze Mk 100 and Mods. Two spanner holes are located in the after end of the head spaced 180° apart to facilitate assembly. The fuze adapter is internally threaded for Auxiliary Detonator Fuze Mk 44 Mod 2. The Nose Fuze Mk 100, all Mods, is screwed in over the Auxiliary Detonating Fuzes. (The fuze adapter and an Auxiliary Detonator Mk 44 Mod 2 are shipped installed in the head.)

Figure 133. 5.0-inch S.S.S.R. (Head Mk 7 Mod 1)

5.0-inch Head Mk 8 and Mods - Common: This head is internally threaded at the after end to take Base Fuze Mk 31. It has two spanner holes 180° apart to facilities as-sembly operations.

Figure 134. 5-0-inch S.S.S.R. (Head Mk 8 Mod 1)

5.0-inch Head Mk 10 and Mods - High Capacity: The nose of this head is internally threaded to fit Nose Fuze Mk 30 Mod 3 and a fuze adapter. It has two spanner holes 180° apart near the base end to facilitate assembly operations. The fuze adapter is in-ternally threaded to hold Auxiliary Detonator Mk 44 Mod 1, and the Nose Fuze Mk 30 Mod 3 fits over the auxiliary detonator.

Figure 135. 5.0-inch S.S.S.R. (Head Mk 10 Mod 1)

5.0-inch Head Mk 12 and Mods - High Capacity: The 5.0-inch Head Mk 12 and Mods is 3.125 inches longer than the 5" Mk 10 head used in the 5,000-yard round. It carries about 2.8 pounds more TNT than the Head Mk 10.

5.0-inch Head Mk 13 and Mods - High Capacity: The 5.0-inch Head Mk 13 and Mods is 4.78-inches longer then the 5.0-inch Head Mk 10. It also carries about four pounds more TNT.

Motors

5.0-inch Motor Mk 3 and Mods: The motor tube is a seamless steel tube with inter-nal threads at both ends. It is machined with a bourrelet ring at each end. The front clo-sure is a steel disc pressed in position near the front end of the motor tube. It seals the front end from moisture, dirt, etc., and retains the igniter and propellant grain in place. A thin felt pad cushions any contact between the front closure and the igniter. The Igniter Mk 17 Mod 0 consists of a flat tin case containing 35 grams of black powder and an elec-tric squib. A felt disc one inch thick protects the grain from accidental shock. It has an eccentrically placed hole which houses and forms a snug fit for the igniter case. The pro-pellant is an inhibited, cruciform grain weighing approximately ten pounds. The nozzle plate assembly consists of eignt nozzles and a grid mounted on a nozzle plate. The cylin-drical T-shaped steel grid is pressed into place and peened in position in a center hole in the nozzle plate. It acts as a spacer between the grain and the nozzle plate, creating a chamber which equalizes the pressure to all nozzles during burning. The nozzles are press fitted into the plate and are canted 12° to give a clockwise rotation. The nozzle-plate ring assembly consists of a nozzle-plate ring and the insulated contact ring. The contact ring is a steel band around the nozzle-plate ring and is insulated from it. The plate ring and contact ring are the two terminals of the ignited electrical circuit. The rings are short circuited by a band. The short-circuiting band must be removed when preparing the rocket for firing. The rear closure is a thin aluminium cup cemented in place in the after end of the motor, and blows out after the motor pressure builds up.

5.0-inch Motor Mk 4 and Mods: The 5.0-inch Rocket Motor Mk 4 is similar to the Mk 3 discussed above, except that the motor tube is seven inches shorter than the Motor Mk 3. The Igniter Mk 18 with shorter leads is used. Propellant Grain Mk 22 Mod 0, shorter and weighing approximately 5.5 pounds, is used. The nozzle in the nozzle plate assembly has a smaller throat diameter.

5.0-inch Motor Mk 5 Mod 1: The Mk 5 Mod 1 is similar to the Mk 4, except that it is 3.125 inches shorter of eight nozzles. This shorter motor gives a range of 2,500 yards and a maximum velocity of 475 ft./sec., which is suitable for barrage purposes.

5.0-inch Motor Mk 6 Mod 0: The Mk 6 Mod 0 is also similar to the Mk 4 and Mods, except that it is 4.78 inches shorter and the nozzle plate has only four nozzles. The cant of these nozzles has been increased to insure stable flight of the round at slower veloci-ties. This shorter motor gives a range of 1,250 yards and a maximum velocity of 340 ft./ sec., which is suitable for barrage purposes.

5.0-inch A.R. with 5-inch motor7.2-inch H.E. "Mouse Trap" and 2.5-inch Practice