ALLIED BOMBS AND FUZES

DESIGNATION

PRINCIPAL MARKING

(A) D.A. No. 19 Mark I

(A) D.A. No. 19

(B) D.A. No. 20 Mark I, II or III

Mark I

(C) D.A. No. 27 Mark I

(B) D.A. No. 20

CLASSIFICATION

Mechanical Nose Impact

Mark I, II or III

TYPE OF MISSILE

H.E. Bombs

(C) D.A. No. 27

Mark II

MARKINGS AND

BOMBS USED IN:

SUBSIDIARY

(A) 50, 120, 250 & 500 lb. G.P. Mark I

MARKINGS:

bombs; 520 & 550 lb. R.A.F. Mark I

bombs; 112 lb. R.L. Mark VI & VII; and

250 lb. R.L. Mark II.

(B) 112 lb. R.L. Mark V and 250, 520 &

550 lb. R.L. Mark I.

(C) 250 & 500 lb. G.P. Mark IV

OPERATION

When the bomb is released from the plane, the fuzing wire retains the pressure plate stop (C) and the arming vanes are then free to rotate. The vanes unscrew and fall during flight. On impact, the pressure plate forces the striker inward, shearing the shear wire and in turn piercing the cap of the detonator.

DATA

(A)

(B)

(C)

1

COLOR

Brass

Brass

Brass

2

OVERALL LENGTH
(less booster)

4.1 inches

5.3 inches

4.2 inches

3

OVERALL WIDTH

Body - 2.0 inches
Vanes - 3.0 inches

Body - 1.9 inches
Vanes - 4.0 inches

4

MATERIAL OF CONSTRUCTION

Brass bodies, steel plungers and aluminum vanes.

5

DESCRIPTION

These fuzes consist of a brass body (E) with standard parallel nose threads or admiralty taper threads, and the lower portion threaded for the exploder. Plunger (K), made of steel, passes centrally through the body, the lower end terminating in the striker (F). The upper end is threaded, and onto this is screwed the pres-sure plate (J). The upper surface of the pressure plate is rounded and has eight semi-circular notches cut in the periphery of it. The brass shear wire (D) is 5/32 inches in diameter. The arming vanes consist of five aluminum vanes permanently attached to the dome (H), which has two diametrically opposed openings in its lower surface, giving of the arming vane dome is a small stud and dome stop pin (G). The arming vanes fit over the arming vane nut (A) and are secured by a pin. This nut screws onto the threaded extension of the plunger (K). The pressure plate stop (C) is roughly horse-shoe in shape. The longer arms are bored trans-versely to take the safety pin (L). A U-shaped spring clip is rivetted onto the pressure plate stop which clips around the plunger, thus holding the pressure plate stop in place after the safety pin is removed.

6

POSITION AND METHOD OF FIXING IN BOMB

Screwed into adapter at nose of bomb using spanner wrench on flats

Screwed into adapter at nose of bomb and secured by a spring locking collar

7

FUZES LIKELY TO BE FOUND WITH

Tail No. 5B Mk. I or II, No. 21 Mk. I or II and No. 22 Mk. I or II.

Tail No. 5B Mk. I or II.

No. 28 Mk. I, tail pistol (fuze) can be used either a tail plug or a tail fuze.

8

COMPONENTS OF EXPLOSIVE TRAIN

Cartrigde type with cap, screwed on bottom of fuze.

Cartridge type with cap.

9

ARMING TIME

10

REMARKS

1. Fuzes D.A. No. 19 Mark I or II are conversions of old stocks of D.A. No. 8 Mark I to a design which permitted the alternative use of cast iron for the body.

2. Fuzes D.A. No. 20 Mark I, II or III are similar to the D.A. No. 19 Mark I or II ex-cept that they have admiralty taper nose threads instead of the standard parallel threads.

3. Fuze, Aircraft Bomb D.A. No. 20 Mark I is a converserion of old stocks of Fuze, Aircraft Bomb D.A. No. 9 Mark I.

4. Aricraft bombs fitted with these fuzes should not be dropped SAFE from heights in excess of 3000 feet.