USNBD, British Bombs and Fuzes, Pyrotechnics, Detonators; Section II - Fuzes & Pistols: Tail Pistols No. 28 und No. 30

U.S.N.B.D. - BRITISH BOMBS AND FUZES; PYROTECHNICS; DETONATORS

BRITISH FUZES & PISTOLS


		BRITISH TAIL PISTOLS
BOMBS USED IN		NO. 28
No. 28	G.P. 250 & 400 lb. Mk IV	NO. 28
	1000, 1900, and 4000#	*Mks II, III & IV**
	All M.C: bombs.	NO. 30
	S.A.P. 250 & 500 lb. Mk V.	NO. 30
	A.S. 100, 250 and 500 lb.	*Mks III & IV**
	Mk IV, when used for land
	bombardement.	(Service)
	L.C. 500 lb.
No. 30	A.S. 100, 250 & 500 lb.
	Mk IV; may also be used
	in any of above bombs
	when sensitive type tail
	initiation is required.
FUNCTIONING	Instantaneous impact; may be used with detonators having
	delay up to 11 sec.
ARMED CONDITION	When arming fork is less than two rotations from being com-
	pletely unthreaded from striker stem.
FUZES USED WITH	Nose Pistols No. 27, 42, or 44; tail psitol No. 28 might be
	found in A.S. 100 lb. Mk V with Nose Fuze No. 858 (These
	pistols will not necessarily be found in a bomb with nose
	pistols, since British generally fuze their bombs in the tail
	only, but might also add a nose pistol).
ARMING TIME	13 arming fork revolutions (arming fork unthreads completely
	in 15 revolutions).
MAX. BODY DIAMETER	2"
OVERALL LENGTH	3-7/8"
IDENTIFICATION	No. 28 has 5/8" knurled surface around upper part of pistol
	body; No. 30 has ¼" green groove in center of knurled sur-
	face around upper part of body.

DESCRIPTION:

These two pistols consists principally of a body with 1.1" standard threads, a striker theraded at the top end to take the arming fork, and a creep spring to prvent the stri-ker from striking the detonator until impact. The creep spring is housed in a creep spring holder which threads into the bottom of the pistol body. A tab locking device for securing the pistol in the bomb is fitted around the body just below the knurled section, and a washer is fitted just above the body threads. Unitl placed in the bomb, the arm- ing fork is prevented from rotating by a safety plate resting on two narrow recesses in-side the upper part of the body, and extends between the arming fork arms. When issued, the pistols are covered at the top by a press-cap and overseal. A guide pin threaded into the side of the lower body extension engages in one of two grooves in the striker and prevents it from rotating.

The No. 28 and No. 30 pistols are distinguished from eacher other in that the No. 28 has a blunt striker, whereas the No. 30 has a needle type striker.

MARKS NOS. COMPARED:

No. 28 Mk II* is a converted Mk II, which is obsolete, and the Mk III is of new ma-nufacture; the Mk IV is of similar construction but the body, safety plate, and creep spring holder are of moulded plastic material. Also in the Mk IV an internal projection in the central bore replaces the guide pin of the earlier marks.

No. 30 Mk III* and IV pistols are similar to the No. 28 Mk II* and III pistol execpt the striker has a long sharp point and the knurled section of the body has a green groove around it.

OPERATION:

When the bomb is loaded in the plane, the arming fork of the pistol is engaged with the arming fork in the end of the reach rod which extends through the tail unit. When the bomb is released, the arming vanes on the end of the reach rod roatet and thus unthreaded the arming fork of the pistol until it rises clear of the threaded end of the striker stem. At this point the pistol is armed, and on impact the weight of the striker body is sufficient to overcome the creep spring and forces the striker point against the cap in the detonator, which may be instantaneous acting or have a short delay up to 11 sec.

REMARKS:

The No. 30 pistol, through originally intended primarily for use in the A.S. bombs, is gradually replacing the No. 28 in other types of bombs in which a sensitive type tail ini-tiation might pistol be required. The No. 30, then, is now considered the standard British tail pistol.