RKT 2.75inch

Question 1

Describe the functioning of the Rocket Motor 2.75inch FZ90 MOD .2/S

Answer 1

• Firing current is applied to the RKT and Fuze head
• Fuze head causes black powder to ignite
• Ignites propellant grain which burns internally
• Produces large quantity of gas that ruptures closure disc and foil seals
• Rocket is pushed down tube towards target
• Gas exits deflects causing RKT to spin
• Fins deploy under spring tension after leaving the tube
• Fin and Spin imparted to RKT provide stability
• Fins maintain spin for remainder of trajectory

Question 2

The MK 352 mod FZ 5 PD consists of four main components, list them:

Answer 2

• Fuze Body
• Safe and Arming Device
• Nose Cap Assembly
• Booster Assembly

Question 3

What are the current in-service 2.75inch warheads that can be fitted to the Rocket motor 2.75” FZ90 MOD .2/S?

Answer 3

• Warhead 2.75inch HE FZ 71
• Warhead 2.75inch Flash FZ 181
• Warhead 2.75inch Prac FZ 120

Question 4

How many devices lock the rotor in place to provide safety on the Fuze Mk 352 Mod FZ 5?

Answer 4

Two devices lock the rotor in the unarmed position

Question 5

Can the shortening clip be removed from rocket motor when its unpacked from its packaging?

Answer 5

No, only immediately prior loading into launcher

Question 6

The FZ90 is authorised for use in what?

Answer 6

• LAU FZ 225 Nineteen Shot Rocket Pod

- LAU FZ 233 Seven Shot Rocket Pod

Question 7

What are the main components of the Rocket motor 2.75 Inch FZ90 MOD.2/S?

Answer 7

• Rocket Motor Tube
• RF Igniter assembly
• Propellant Grain
• Nozzle and Fin Assembly

Question 8

What is the propellant grain?

Answer 8

Double Based Propellant

Question 9

What are the FZ 90 Mod .2/s operating limits?

Answer 9

-46 Degrees C to +66 Degrees C

Question 10

Main components of the Warhead 2.75inch HE FZ 71?

Answer 10

• Body (Contains 1.05kg of comp B)

- Fuze

Question 11

How does the Warhead 2.75inch HE FZ 71 Fuze MK 352 function?

Answer 11

• During initial thrust, weights in S&A move rearwards (1st lock)
• Spring loaded 2nd lock rotates on its axis
• Centrifugal force moves second lock by rotating it and freeing the rotor
• Rotor turns under control of the escarpment mech
• Rotor moves into position, locked in place by the index and second lock
• On impact, firing pin is pushed back onto the primer which functions the det
• Explosive train of det, booster, main fill
• casing splinters

Question 12

Components of the Warhead 2.75inch Flash FZ 181

Answer 12

• Body
• Fuze
• Flash charge

Question 13

Components of the Warhead 2.75inch Prac FZ 12

Answer 13

-Body