Mortars Detail Study

Question 1

60mm illum M721 operation from fuze functioning?

Answer 1

At a pre set time the fuze functions in flight.
The expulsion charge ignites and ejects the candle assembly.
A spring ejects the parachute from tail cone.
The parachute opens, slowing the decent of burning candle which illuminates the target for at least 32 seconds at a minimum of 250,000 candle power.
M721 has a height of burst of between 300 or 400m above ground level for charges 1 and 4 respectively

Question 2

PD Prac M775 functioning of the fuze? (60mm)

Answer 2

safety pin is removed immediately before loading into M224/M224A1.
Upon firing, the acceleration moves the setback pin.
Rearward against a spring, releasing a slider.
Which holds the striker In its rearward position once the striker is released, it travels upward allowing the ball bearings to be forced into central alignment between the striker and the primer.
Upon impact, the striker is driven into the ball bearings which initiate the primer, igniting the pyrotechnic smoke cartridge.
The pyrotechnic smoke cartridge in the fuze produces a flash, audible sound and cloud of smoke, to simulate the HE function.
Upon functioning, the hole plugs are expelled from the holes in the base of the projectile, allowing the smoke cloud to vent through the holes

Question 3

81mm illum M853A1 MTSQ M772 from fuze functioning?

Answer 3

Commencing the fuze arming sequence.
The fuze has a minimum arming delay time of 0.8 seconds and will not arm at a distance of less then 40m.
On achieving the preselected flight time, the fuze functions resulting in the initiation of the fuze booster.
Internal pressure build up as a result of the function of the fuze booster causes separation of the front and tail cone sections of the mortar body by fracturing the shear pins.
On separation of the mortar body, the M853A1 illuminating assembly is ejected rearwards from the front section of the mortar body.
Simultaneously, the function of the fuze booster initiates the ignition system of the illuminant canister.
Deployment of the parachute assembly controls the rate of decent of the illuminant canister.
The illuminant canister burns a minimum period of 50 seconds generating a minimum luminosity of 525,000 candela and provides an effective area of illumination of approximately 1 200m diameter

Question 4

Cart 81mm illum M853A1 / fuze MTSQ M772 candela and burn time?

Answer 4

525,000

50 seconds

Question 5

81mm IR illuminating M816 fuzed MTSQ M772 watts and burn time?

Answer 5

50 watts/steradian

60 seconds

Question 6

Fuze MTSQ M772 goes with what natures?

Answer 6

81mm smoke & phosphorus
81mm illum
81mm IR

Question 7

Fuze MTSQ M776 goes with what nature?

Answer 7

60mm illum

Question 8

Fuze PD M935 what nature?

Answer 8

81mm HE M889A1

81mm HE M0221A1

Question 9

Fuze PD M751 goes with?

Answer 9

81mm prac

Question 10

Fuze PD M935 settings?

Answer 10

SQ

Delay

Question 11

Fuze M734A1 goes?

Answer 11

81mm HE M821A2

Question 12

Fuze MO M734A1 settings?

Answer 12

Prox 60/81 & 120
Impact
Delay

Question 13

M783 settings?

Answer 13

PD
Delay
Dummy prox/ NSB

Question 14

Time setting of a fuze MTSQ M772 the use of a what spammer?

Answer 14

1 3/4 inch AF Fuse setting spanned

Question 15

Actions prior to and during firing?

Answer 15

Remove the propelling charge assembly protector.
Set the fuze MTSQ M772 timing mechanism.
Remove the safety pin prior to loading.
Load the mortar.
On striking the firing pin, the percussion primer functions ignition cartridge.
Ignition cartridge subsequently ignites propelling charge assemblies via the flash holes located in the tail fin.
Rapidly expanding gases generated by the burning propellant propel the mortar cartridge toward the targeted area

Question 16

What is the problem with firing charge 1 in IR?

Answer 16

Tendency to illuminate the mortar position and potentially expose the mortar crew to hostile forces