LESSON PLAN

COURSE : BASIC COURSE ON ARMAMENT

SUBJECT: FUZES : Time – 90 Minutes

TOPIC : FUZE FFV 651

SL. No.

Sub Topic

Content Training Aids Time

01 General Classification

Type

End Use

Black Board

-do-

-do-

15 min

Sl. No.

Sub Topic Content Training Aids

Time

2. Construction Fuze FFV 651

Important components of fuze

Slides 30 min

3.

4.

Functioning

Proof

Fuze FFV 651

Tests on Fuze FFV 651

Proof of Fuze FFV 651

Slides

Black Board/ slides

30 min

15 min

Definition of fuze:- Fuze is a device which detonates the projectile at predetermined place and time. The fuzes can be classified as per its position in ammunition, its action, type of mechanism used.

In HEAT amn generally base type fuzes are used. Such fuzes detonates the main charge in shell from base of shell to get desired penetration at target end by Hollow Charge Principle. Fuze FFV 651 is a base type fuze used in 84 mm HEAT amn. This fuze also can be classified as Electro Mechanical Fuze.

The sub assemblies/Components of fuze are manufactured at OFAJ/Trade. The final assembly of fuze is carried out at OF Khamaria. The various test/proof facilities have been created at OF Khamaria/ LPR Khamaria.

2. CONSTRUCTION

OF FUZE FFV 651

Fuze consists of components

such as Base Screw, Fuze Base,

Rotor & Rotor Assy/Detonator N8C,

Booster Charge/Magazine charge &

Complete Electric System.

The fig. Shows the details:-

ASSEMBLY OF FUZE FFV 651

SD ASSY

Deto. N8C

The following fig. Shows the position of the fuze in shell assembly:-

FUZE FFV 651

FUZE FFV 651 FUNCTIONINGThe function of the fuze is explained in the following fig.:-

On firing due to set back forces the two safety pins get compressed rear wards which allows two balls to fall out. This releases the safety plunger which moves rear wards. Now, rotor is free to rotate. The arming spring now rotates the rotor . The movement of the rotor is controlled by the escapement. Due to 3/4th rotation of rotor the detonator is in chain of explosive train. Now the fuze is in armed condition.

On impact on hard target, the piezo crystal get crushed against the wall of base screw generating voltage.The high voltage produced creates spark & detonates the detonator which further detonates the booster charge & further themagazine & the main bursting charge.

(IMPORTANCE OF FOURLAYER DIODE )

VARIOUS TESTS ON FUZE FFV 651

X – ray testing of empty fuze to confirm non arming condition of fuze

and existence of arming. Spring , Electric Deto. Electric, Leads

between Crystal & Cap, Spring Washers, Crystal assy

Base Screw & Fuze Base – Pressure testing

Resistance Test - 60 – 350 kΩ.

Fictional Tests- Non arming, Arming, Sealing, Function at low Temp.

Tests on detonator / Complete Electric system

TESTES ON DETONATOR N8C The detonator shall function within temp. range of +60º C to – 40 º C.

The surface quality of the deto. Shall be free from scraches, dents and burrs. AQL 1.0%.

The resistance between pole & body should be between 90 ± 30 Ω. AQL 1.0%.

The deto. should not be initiated by vol. Of 10 V ± 0.5 V. (AQL 0.65%)

Function : After storage at high (+71º C) & low temp. (-40 º C), the

resistance between poles of dto shall be 60 to 250Ω. The functioning time should be 10 µsec.

Blast Effect – A steel plate 5 mm thick should have a blind hole of Dia.

2.5 mm & min depth 0.60 mm after deto. is made to function by applying vol. 100V.

Shock Test - Deto. should not function by acceleration stresses of 30000 g.

TESTS ON COMPETE ELETRIC SYSTEM

Electrical parameter tests at -40ºC & +60ºC & ambient temp.- 8 parameter tests (Capacitance, Resistance, polarity of crystal, switching vol, leakage current,forward vol, holding current,leakage current of diode

Vibration test at -40ºC & +60ºC & ambient temp. – Electric tests afar vibration test.

Jolt Test - Electric tests afar vibration test.

Temperature cycling Test at +72ºC to -54 ºC - Electric tests afar jolt test.

Shock Test/Recovery proof – To confirm withsstanding of firing stresses..

Sensitivity Proof – To confirm functioning of four layer diode.

Plate proof – To confirm functioning of CES.