Used in:

Mk 159 Mod 0 in 5.0-inch Rocket Head Mk 6 Mod 0 (General Purpose)

Mk 159 Mod 1 in 5.0-inch Rocket Head Mk 6 Mod 1 (General Purpose)

Overall dimensions and weight of fuze:

Length:

5.812 inches (Mod 0)

5.813 inches (Mod 1)

Diameter (maximum):

2.965 inches (Mod 0)

3.200 inches (Mod 1)

Body threads

Weight:

3.4 lbs. approx. (Mod 0)

3.5 lbs. approx. (Mod 1)

Applicable specification: OS 3585

General arrangement drawing:

422550 (Mod 0)

439631 (Mod 1)

Sketch list of drawing & specs:

109605 (Mod 0)

165124 (Mod 1)

Explosive components:

Delay detonator assembly (adapted from the delay detonator assembly of Fuze Mk 157. The assembly consists of a mercury fulminate Percussion Primer Mk 106, an ex-pansion space, the 0.015 second black powder delay element and the Relay Detonator Mk 31 Mod 0 (lead azide) assembled in a single case closed by a crimp contained shutter.

Booster lead-in charge (tetryl) contained in the lead-in disc.

Booster charge (approximately 12 grams tetryl) contained in magazine.

General. Fuze Mk 159 is a modification of Fuze Mk 157 to satisfy the fuze require-ments for a higher velocity fin-stabilized rocket employing a 5.0-inch rocket motor and a 5.0-inch rocket head. Accordingly the arming constants were adjusted to the burning characteristics of the 5.0-inch Rocket Motor Mk 1 and 2. The major changes incorporat-ed in Fuze Mk 159 are as follows:

1. Diameter of inlet orifice – 0.0145 inches.

2. Diameter of shear wire – 0.064 inches.

3. Grooved inlet-washer used instead of screen.

4. Fuze must arm between 325 and 375 psi.

5. Delay of 0.015 second.

Fuze Mk 159 Mod 0 is sealed in the rocket head by a copper gasket under the fuze head flange. Fuze Mk 159 Mod 1 has the flange head diameter increased to 3.2 inches and a projectile type gas check is used.

Use. Fuze Mk 159 Mod 0 is used in the 5.0-inch General Purpose Fin Stabilized Aircraft Rocket (Complete Round) Mk 4 Mod 0 (see OP 1415). Fuze Mk 159 Mod 1 is used in the 5.0-inch General Purpose Fin Stabilized Aircraft Rockets (Complete Rounds) Mk 4 Mod 0 and Mk 26 Mod 0 (see OP 1415). Just prior to assembly of the round on aircraft, a Nose Fuze Mk 149 is usually installed in the head. The latter fuze can be fired instantaneous or safe, depending upon the target. This permits the use of a round with selective fuze action (instantaneous or 0.015 second delay) at the time of firing. The above rockets are used against light fortifications, tanks, locomotives, and similar targets.

Functioning mechanism. Same as Fuze Mk 157 except as previously noted above.

Figure 36 – Base Fuze Mk 159 Mod 0, Cross Section View,
Armed and Unarmed Position

Arming. Arming is identical with Fuze Mk 157.

Firing. Firing upon impact is identical with Fuze Mk 157.

Acceptance test data. These fuzes selected for functional test are assembled in the proper rocket head fitted with a flat nose shipping plug and a 5.0-inch Rocket Motor Mk 2 and fired from a surface launcher at 15 degrees elevation for water impact. Accep-tance is based on a cumulative test plan designed to accept (95% of the time) lots in which 95% of the fuzes function satisfactorily; lot poorer than 95% will be subject to re-jection with lots 80% effective being rejected 90% of the time.

Sensitivity limits. The sensitivity of Fuze Mk 159 is the same as for the Fuze Mk 159.

Figure 37 – Base Fuze Mk 159 Mod 1, Unarmed Position Showing Gas Checking

Same as Fuze Mk 157.

Same as Fuze Mk 157.

Same as Fuze Mk 157.

Same as Fuze Mk 157.