British Ordnance Collectors Network
This is a sample guest message. Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
MD1 Fuze - Pub Quiz
- Thread starter Bonnex
- Start date
Nismosonic
Well-Known Member
depth charge fuze ?
Nismosonic
Well-Known Member
Depth charge that looked like a beer keg fuze ?? hence pub quiz ?? :tinysmile_twink_t: LOL
Butterfly takes it with JW (Johnny Walker of whisky fame). All with Tirpitz connections deserve a point as do the first principle guys with their explanations involving underwater exploits.
TimG kindly opted out and he can now explain how it works
I have attached a couple of newly discovered drawings and another photograph from the MD1 glass plates which shows the location of the fuze. I believe the fuze was designed by Albert Midgely but input from Jefferis can't be ruled out. Midgely developed the 'W' bomb (mentioned by Darryl) with MD1 (or MIR(c) as it was at that time). The Midgely-Harmer Co made a considerable number of A/C bomb fuzes.
I'll add a drawing of the fuze unless Tim beats me to it (please).
See last year's deliberations at http://www.bocn.co.uk/vbforum/johnny-walker-bomb-t28752.html
[Apologies if this assumes knowledge of MD1 and its personalities. Feel free to ask questions.]
TimG kindly opted out and he can now explain how it works
I have attached a couple of newly discovered drawings and another photograph from the MD1 glass plates which shows the location of the fuze. I believe the fuze was designed by Albert Midgely but input from Jefferis can't be ruled out. Midgely developed the 'W' bomb (mentioned by Darryl) with MD1 (or MIR(c) as it was at that time). The Midgely-Harmer Co made a considerable number of A/C bomb fuzes.
I'll add a drawing of the fuze unless Tim beats me to it (please).
See last year's deliberations at http://www.bocn.co.uk/vbforum/johnny-walker-bomb-t28752.html
[Apologies if this assumes knowledge of MD1 and its personalities. Feel free to ask questions.]
Attachments
MD1 Fuze
Hello, the patterns seems to be british, so I think on a british bomb of course. And I think more in the direction of the "dambusters" bomb. Isn't it ?
Hello, the patterns seems to be british, so I think on a british bomb of course. And I think more in the direction of the "dambusters" bomb. Isn't it ?
Nice Photo's and documents Bonnex, Thanks for posting
Maybe the same bomb nearly 50 years later being dealt with by Norwegian EOD.
OK wishful thinking but this is one of those used on the operation to attack Tirpitz and is likely the one in the museum (see thread of last year). To quote from Arthur Hogben's excellent book 'Bombs Gone':
"As far as can be determined the JW Bomb was only deployed operationally on one occasion and that during an attack upon the TIRPITZ as she lay in the Kaa Fjord in Northern Norway. The attack took place on 15 September 1944 when 27 Lancasters of 9 and 617 Squadrons [...] dropped 12000lb Tallboys and JW Bombs.
Of the 27 aircraft, seven carried 12 JW Bombs each."
OK wishful thinking but this is one of those used on the operation to attack Tirpitz and is likely the one in the museum (see thread of last year). To quote from Arthur Hogben's excellent book 'Bombs Gone':
"As far as can be determined the JW Bomb was only deployed operationally on one occasion and that during an attack upon the TIRPITZ as she lay in the Kaa Fjord in Northern Norway. The attack took place on 15 September 1944 when 27 Lancasters of 9 and 617 Squadrons [...] dropped 12000lb Tallboys and JW Bombs.
Of the 27 aircraft, seven carried 12 JW Bombs each."
Attachments
Last edited:
The following is a edited description of how the bomb and fuze function. Unfortunately, at the moment the only diagram I have avaialabe is a .pdf and it exceeds the maximum upload size.
MOST SECRET
J.W. Bomb
Advance Instructions for Use
(S.B.44057)
3] Description
The J.W. Bomb is designed on the principal of the oscillating mine for the attack on enemy shipping. The bomb is of almost exactly the same density as sea water. At one end of it is a small buoyancy chamber which is alternately flooded and blown at intervals of about one minute by means of a compressed gas system described in para. 4 below. The bomb weighs about 400 lb. And contains about 90 lb. Of Torpex in the form of a shaped charge with a heavy cone; this is at least as effective as a solid charge of 120 lb. Weight. The trim of the bomb is so adjusted that it moves sideways as well as vertically. If it hits the bottom of a ship on its upward path it will fire, (See fig.7 for calculated details of performance).
The fuze employed incorporates direct action and also a self destruction device to blow the bomb up when all the gas is exhausted. If it is washed ashore, or any attempt is made to unfuze it after it has been dropped Live. It is possible for this device not to function if the bomb is at the bottom of its travel when the gas is almost exhausted: in this case it will probably remain on the bottom, but if it is washed ashore or removed from the water it will immediately fire.
4 Functioning
On release from the aircraft the parachute is opened by the static cord and the flexible fuzing link is withdrawn from the fuze. This latter releases the fuze shutter which flies into the live position.
On impact with the water the parachute releases and falls away. In doing so it pulls the flexible wire from the gas starting valve, see (fig.1) and the gas starts to flow.
High pressure gas flows to the fuze and cocks the self-destruction device. Gas also flows through the pressure reducing valve, see fig.1, to the buoyancy chamber.
The bomb first descends to a depth of about 40 ft. as it loses its striking velocity, then rises and commences to function as follows. The hydrostatic valve opens when the bomb has risen to a depth of about 20 ft. and floods the buoyancy chamber. The bomb puts its nose down and glides off at an angle of about 30* to the vertical, the gas flowing steadily at a constant rate independent of depth into the front buoyancy chamber expelling the water. The bomb thus becomes steadily lighter by the nose and glides more horizontally, thus giving it sideways travel. At a depth of about 70 ft. the bomb is buoyant by the nose and ascends nearly vertically nose up. When it reaches a depth of about 20 ft. the hydrostatic valve opened and the cycle recommences.
If the bomb hits the bottom of a ship on its upward path the striker is driven in and fires the fuze. On its downward path, when the bomb is pointing fuze downwards, the ball in the fuze between the striker and the striker spindle (see Fig.4) rolls out of the way, so that even if the bomb strikes an obstruction and the striker is driven in, the fuze will not fire.
If the gas is exhausted without the bomb having fired, the reduction of pressure allows the bolt of the self-destruction mechanism (see Fig.4) in the fuze to fly back and release the hammer on to the striker. The same thing happens if any attempt is made to disconnect the fuze after the self-destruction device is cocked.
MOST SECRET
J.W. Bomb
Advance Instructions for Use
(S.B.44057)
3] Description
The J.W. Bomb is designed on the principal of the oscillating mine for the attack on enemy shipping. The bomb is of almost exactly the same density as sea water. At one end of it is a small buoyancy chamber which is alternately flooded and blown at intervals of about one minute by means of a compressed gas system described in para. 4 below. The bomb weighs about 400 lb. And contains about 90 lb. Of Torpex in the form of a shaped charge with a heavy cone; this is at least as effective as a solid charge of 120 lb. Weight. The trim of the bomb is so adjusted that it moves sideways as well as vertically. If it hits the bottom of a ship on its upward path it will fire, (See fig.7 for calculated details of performance).
The fuze employed incorporates direct action and also a self destruction device to blow the bomb up when all the gas is exhausted. If it is washed ashore, or any attempt is made to unfuze it after it has been dropped Live. It is possible for this device not to function if the bomb is at the bottom of its travel when the gas is almost exhausted: in this case it will probably remain on the bottom, but if it is washed ashore or removed from the water it will immediately fire.
4 Functioning
On release from the aircraft the parachute is opened by the static cord and the flexible fuzing link is withdrawn from the fuze. This latter releases the fuze shutter which flies into the live position.
On impact with the water the parachute releases and falls away. In doing so it pulls the flexible wire from the gas starting valve, see (fig.1) and the gas starts to flow.
High pressure gas flows to the fuze and cocks the self-destruction device. Gas also flows through the pressure reducing valve, see fig.1, to the buoyancy chamber.
The bomb first descends to a depth of about 40 ft. as it loses its striking velocity, then rises and commences to function as follows. The hydrostatic valve opens when the bomb has risen to a depth of about 20 ft. and floods the buoyancy chamber. The bomb puts its nose down and glides off at an angle of about 30* to the vertical, the gas flowing steadily at a constant rate independent of depth into the front buoyancy chamber expelling the water. The bomb thus becomes steadily lighter by the nose and glides more horizontally, thus giving it sideways travel. At a depth of about 70 ft. the bomb is buoyant by the nose and ascends nearly vertically nose up. When it reaches a depth of about 20 ft. the hydrostatic valve opened and the cycle recommences.
If the bomb hits the bottom of a ship on its upward path the striker is driven in and fires the fuze. On its downward path, when the bomb is pointing fuze downwards, the ball in the fuze between the striker and the striker spindle (see Fig.4) rolls out of the way, so that even if the bomb strikes an obstruction and the striker is driven in, the fuze will not fire.
If the gas is exhausted without the bomb having fired, the reduction of pressure allows the bolt of the self-destruction mechanism (see Fig.4) in the fuze to fly back and release the hammer on to the striker. The same thing happens if any attempt is made to disconnect the fuze after the self-destruction device is cocked.
Thanks Tim :tinysmile_grin_t: