ALLIED BOMBS AND FUZES

DESIGNATION

PRINCIPAL MARKING

(A) No. 28 Mark I/A/

(A) No. 28

(B) No. 28A Mark II

Mark I/A/

(C) No. 28D Mark II

(B) No. 28A

CLASSIFICATION

Pyrotechnic Nose Time

Mark II

TYPE OF MISSILE

Flare

(C) No. 28D

Mark II

MARKINGS AND

BOMBS USED IN:

SUBSIDIARY

(A) & (B) - Flare, Aircraft,

MARKINGS:

Reconnaissance, 4 inch, Mark I.

(C) - Flare, Aircraft, Reconnaissance,

8 inch, 4 minute, Mark I and II.

OPERATION

When the flare is dropped from the plane, the arming rod (Q) is withdrawn, freeing the spring loaded detonator holder (P) which moves forward in its channel to impact the striker (5). The flash from the detonator passes through an opening (F) in the fuze body to the upper time ring, in which the direction of burning is counter-clockwise. After a time interval, determined by the prior setting of the lower movable ring in rela-tion to the upper ring, the flash passes down a channel (H) to the lower time ring, in which the direction of burning is clockwise. In the meantime, the arming vanes have rotated, withdrawing the arming stem until the shoulder of the spring loaded valve rod (M) bears against the inner face of the arming stem bushing. The valve is then raised, which permits passage of the flash from the lower time ring to the powder pellet (K). The powder pellet (K) them ignites the magazine pellet (N) through the passage (Y), and (N) then fires the magazine (O).

Data

(A)

(B)

(C)

1

COLOR

2

OVERALL LENGTH

3

OVERALL WITDH

Vanes 4.3 inches

Vanes 6.9 inches

4

MATERIAL OF CONSTRUCTION

5

DESCRIPTION

The fuze consists of a body containing a mechanism for igniting time rings; a valve mechanism for preventing pre- mature action; a magazine for igniting the ejection charge of the flare; and, around the stem of the fuze, two time rings, one of which is capable of being rotated for setting purposes.

Safety Devices:– The arming rod (Q) is retained in SAFE position by spring loaded ball (V), thus preventing the ar- ming vane spindle from rotating until the arming vane spin- dle from rotating until the flare is released from the carrier. The safety pin (C) prevents the arming vane spindle and firing rod from moving during transit. The valve (M) pre- vents the fuze from functioning until the flare has dropped a safe distance below the aircraft. The setting of the time ring to SAFE, thus marking the pellet (K), also prevents the fuze from functioning.

6

POSITION AND METHOD OF FIXING IN BOMB

Screwed into nose and secured by a locking ring.

7

FUZES LIKELY TO BE FOUND WITH

None.

None.

None.

8

COMPONENTS OF EXPLOSIVE TRAIN

9

ARMING TIME

10

REMARKS

1. The No. 28A and No. 28D fuzes differ from each other only in respect of the size of their arming vanes.

2. The No. 28A and 28D fuzes differ from the No. 28 Mark I/A/ in the following constructional details:–

(a) A retaining plate is fitted on the top of the body against which the threads of the arming vane spindle engage, when the valve has been lifted from its seating. This ensures the valve assembly being held in positive engagement with the fuze body.

(b) Althrough the minimum possible setting is 4, which is limited by a stop, no setting below 7 is to be employed owing to the risk of blinds.