Did You Fly The Vulcan?? (Merged)
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Bomb Fuzing
I have just published the following text (on request) on a different forum and am cross posting here for completion. It relates to supposition that the last Black Buck raid dropped its bombs in airburst mode. It explains how the bomb fuzing was selected etc.
<<RAF Conventional bombs have exploder pockets in the nose and the tail. Initially pistols were fitted to each pocket namely a Number 76 Nose and a Number 75 tail. An alternative tail pistol was the Number 79 delayed action pistol. These were all ‘impact’ fused systems albeit the detonator could incorporate a delay, short in the case of the 76/75 and up to 48 hours or more for the No 79.
The fusing was initiated in the by the selection of a two-way switch. The default (off) position was TAIL with the up position as NOSE and TAIL. This enabled airborne selection of impact fusing (nose) and tail (backup) or delay (tail) and nose inactive.
The pistols were carried safe with a safety pin in the arming vane and a fusing lanyard. With the appropriate fusing selected an electro-magnetic fusing unit (EMFU) was activated which locked the fusing lanyard. When the bombs dropped the fusing lantard would pull the safety pin from the pistol, the arming vane would rotate, and after a safe separation and fusing unit (SAFU) period the pistol striker would be free to start the explosive train.
In the 50s a new fusing system, the 900 series, variable time (VT) fuse was developed to allow air burst fusing. This fuse, with an integral detonator, was initiated in much the same way but also required an electrical pulse through a ‘Churchill’ plug. A second fusing switch was then added to the armament panel next to the Nose/Tail - Tail switch; this was the VT on/off.
To drop a stick of bombs with airburst function the switches would be set to Nose/Tail and the other to VT. To drop the stick with only Tail impact the VT would be left off. Now we get a problem.
A later bomb fuse, the 947, was developed for the tail fusing pocket. For this fuse to function the VT function had to be selected.
In the case of the Falklands the correct selection for an airburst would have been Nose/Tail and VT. For an impact detonation the selection would be Tail and VT. If the airburst fuse, say the 952, failed then the tail fuse, the 947, should have worked. However whether or not a nose fuse was fitted, it would be essential to select VT. If VT was not selected then neither a nose nor a tail function would work.
Now I am speculating but I do not think there was any intention to drop the bombs in airburst mode. In that case only the tail fuse would have been fitted. Fusing selection should have been Tail and VT ie the VT should have been selected UP.
The stick that failed to explode would have caused as much chaos and disruption as the one that did. Bombs that do not explode my be delayed action with delays from 30 minutes to 48 hours or even possible 96 hours. As they failed to explode the first task would have been to identify the impact area and impose a quarantine over an area at least 1600 x 500 yards and that only after you had located bombs 1 and X. I imagine there would have been a shortage of volunteers doing the initial survey!
Amended to update fuses and facts.
<<RAF Conventional bombs have exploder pockets in the nose and the tail. Initially pistols were fitted to each pocket namely a Number 76 Nose and a Number 75 tail. An alternative tail pistol was the Number 79 delayed action pistol. These were all ‘impact’ fused systems albeit the detonator could incorporate a delay, short in the case of the 76/75 and up to 48 hours or more for the No 79.
The fusing was initiated in the by the selection of a two-way switch. The default (off) position was TAIL with the up position as NOSE and TAIL. This enabled airborne selection of impact fusing (nose) and tail (backup) or delay (tail) and nose inactive.
The pistols were carried safe with a safety pin in the arming vane and a fusing lanyard. With the appropriate fusing selected an electro-magnetic fusing unit (EMFU) was activated which locked the fusing lanyard. When the bombs dropped the fusing lantard would pull the safety pin from the pistol, the arming vane would rotate, and after a safe separation and fusing unit (SAFU) period the pistol striker would be free to start the explosive train.
In the 50s a new fusing system, the 900 series, variable time (VT) fuse was developed to allow air burst fusing. This fuse, with an integral detonator, was initiated in much the same way but also required an electrical pulse through a ‘Churchill’ plug. A second fusing switch was then added to the armament panel next to the Nose/Tail - Tail switch; this was the VT on/off.
To drop a stick of bombs with airburst function the switches would be set to Nose/Tail and the other to VT. To drop the stick with only Tail impact the VT would be left off. Now we get a problem.
A later bomb fuse, the 947, was developed for the tail fusing pocket. For this fuse to function the VT function had to be selected.
In the case of the Falklands the correct selection for an airburst would have been Nose/Tail and VT. For an impact detonation the selection would be Tail and VT. If the airburst fuse, say the 952, failed then the tail fuse, the 947, should have worked. However whether or not a nose fuse was fitted, it would be essential to select VT. If VT was not selected then neither a nose nor a tail function would work.
Now I am speculating but I do not think there was any intention to drop the bombs in airburst mode. In that case only the tail fuse would have been fitted. Fusing selection should have been Tail and VT ie the VT should have been selected UP.
The stick that failed to explode would have caused as much chaos and disruption as the one that did. Bombs that do not explode my be delayed action with delays from 30 minutes to 48 hours or even possible 96 hours. As they failed to explode the first task would have been to identify the impact area and impose a quarantine over an area at least 1600 x 500 yards and that only after you had located bombs 1 and X. I imagine there would have been a shortage of volunteers doing the initial survey!
Amended to update fuses and facts.
Last edited by Pontius Navigator; 22nd Mar 2007 at 17:36.
I don't own this space under my name. I should have leased it while I still could
ZH, you are of course correct, however I did not say they did have nose VT fuses fitted; I was describing how the original VT fuse was a nose fuse.
There was a presumption that bombs intended for impact would have had the 76 Nose and 75 Tail pistols.
There is also the possibility that the aircraft was loaded for both airburst and ground burst options. It all depends on how the bombs were preped and loaded as the fitment of the nose fuses would have been done in the bomb dump and not on the aircraft.
The 90-way bomb distribution system and the fusing and isolation switch options were at once incredibly simple and overly complicated depending upon ones training. For crews who had only trained for a nuclear mission the switch to conventional operations would have been very rapid. Dilution rates among Navs Rad was high in the late 60s and 70s so long term memory would have been fading.
There was a presumption that bombs intended for impact would have had the 76 Nose and 75 Tail pistols.
There is also the possibility that the aircraft was loaded for both airburst and ground burst options. It all depends on how the bombs were preped and loaded as the fitment of the nose fuses would have been done in the bomb dump and not on the aircraft.
The 90-way bomb distribution system and the fusing and isolation switch options were at once incredibly simple and overly complicated depending upon ones training. For crews who had only trained for a nuclear mission the switch to conventional operations would have been very rapid. Dilution rates among Navs Rad was high in the late 60s and 70s so long term memory would have been fading.
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In my 2000 Vulcan hours I never dropped anything heavier than the 28lb practice bomb. On the rare occasions we came near a 90 way my Nav Rad claimed it meant 89 possible ways of getting the wrong result.
Time to get back on the front page.....
Time to get back on the front page.....
I don't own this space under my name. I should have leased it while I still could
50+, clearly you weren't in Cyprus.
We got to chuck several tons of HE into the oggin. I believe that notices to mariners were issued but a 100 of so tons of HE going off over an hour of so must have echoed as far as Israel and Egypt.
We dropped free-fall from 2500 feet with, I believe, 10 millisecond delay pistols tail pistols. I don't remember any nose pistols. It was both spectacular and beautiful.
Running in at 500 feet we could see the target 'bloom' as the bombs from the aircraft 10 miles ahead detonated. I used to wonder what it would be like with a stream attack on an airfield with 4 aircraft at 30 seconds interval.
As each explosion developed it would throw up a mass of water magenta in colour. You could see the difference in yield, bomb to bomb. I don't recall a dud.
The first stick I remember feeling in the aircraft. Later sticks I only remember seeing them. It is possible they had longer delays.
On a later demo in Epi Bay our flight commander dropped 21 retards from 300 feet - very impresive. Great blue grey water spouts reaching up to the clouds above the Vulcan.
We got to chuck several tons of HE into the oggin. I believe that notices to mariners were issued but a 100 of so tons of HE going off over an hour of so must have echoed as far as Israel and Egypt.
We dropped free-fall from 2500 feet with, I believe, 10 millisecond delay pistols tail pistols. I don't remember any nose pistols. It was both spectacular and beautiful.
Running in at 500 feet we could see the target 'bloom' as the bombs from the aircraft 10 miles ahead detonated. I used to wonder what it would be like with a stream attack on an airfield with 4 aircraft at 30 seconds interval.
As each explosion developed it would throw up a mass of water magenta in colour. You could see the difference in yield, bomb to bomb. I don't recall a dud.
The first stick I remember feeling in the aircraft. Later sticks I only remember seeing them. It is possible they had longer delays.
On a later demo in Epi Bay our flight commander dropped 21 retards from 300 feet - very impresive. Great blue grey water spouts reaching up to the clouds above the Vulcan.
Thread Starter
It beggared belief to learn that the navigators had been flown thousands of miles from ASI only to screw up the 90-way switch.....
Surely they should have been practising the switchery until it was second nature to them?
Surely they should have been practising the switchery until it was second nature to them?
I don't own this space under my name. I should have leased it while I still could
BEagle, some years earlier we used to fly mixed loads of 8x25 and 8x100.
The mantra that all Nav Rads were taught was "zero press - zero press" on the 90-way; this would ensure the first bomb release pulse was sent to the first available bomb.
Now the 25 lbs had to be dropped from low level and the 100 lber from high level. If the bombs were loaded so that the 25lbs were first and the 100lbs second, but the crew planned the high level drops first, the Nav Rad would have to 'step through' the 25s so that the first firing pulse went to bomb number 9. This evolution was deemed too intellectually challenging by the powers that be, probably pilots, so we would arrange for the bombs to be loaded with the 100lbs set to go first.
Carefully briefed the Nav Rad went on the sortie. All he had to do was zero-press etc and drop 8 x 100lbs. If he did not drop all 8 I seem to remember that he was supposed to bring all remaining bombs home.
Well, on this occasion he had the load correctly set for the mission - which, this time, was 25lbs first and 100lbs second. Off he goes and carefully steps through all 8 25lbs and proceeds to drop 8 100lbs at Wainfleet at low level. Predictably 8 unexpolded bombs although he got 8 scores.
Then off to Jurby for the high level phase. Once again he dropped all 8 25lbers that were susceptible to spinning and other sins and proceeded to get a very large and irregular bomb pattern.
And back to the fusing. In practice bombing fuse selection was an irrelevance. Our unofficial mantra then was 'train as you would for the best scores.' By 1982 a large degree of corporate memory had gone. Dilution levels would have been high.
Even in the 60s training shortcuts were taken. Some crews, to 'discharge' the nuclear bomb response simulator away from the target area. Bomb doors would be opened and the requisite number of firing sequences would be done before the serious business of actually doing the practice or simulated drops.
The mantra that all Nav Rads were taught was "zero press - zero press" on the 90-way; this would ensure the first bomb release pulse was sent to the first available bomb.
Now the 25 lbs had to be dropped from low level and the 100 lber from high level. If the bombs were loaded so that the 25lbs were first and the 100lbs second, but the crew planned the high level drops first, the Nav Rad would have to 'step through' the 25s so that the first firing pulse went to bomb number 9. This evolution was deemed too intellectually challenging by the powers that be, probably pilots, so we would arrange for the bombs to be loaded with the 100lbs set to go first.
Carefully briefed the Nav Rad went on the sortie. All he had to do was zero-press etc and drop 8 x 100lbs. If he did not drop all 8 I seem to remember that he was supposed to bring all remaining bombs home.
Well, on this occasion he had the load correctly set for the mission - which, this time, was 25lbs first and 100lbs second. Off he goes and carefully steps through all 8 25lbs and proceeds to drop 8 100lbs at Wainfleet at low level. Predictably 8 unexpolded bombs although he got 8 scores.
Then off to Jurby for the high level phase. Once again he dropped all 8 25lbers that were susceptible to spinning and other sins and proceeded to get a very large and irregular bomb pattern.
And back to the fusing. In practice bombing fuse selection was an irrelevance. Our unofficial mantra then was 'train as you would for the best scores.' By 1982 a large degree of corporate memory had gone. Dilution levels would have been high.
Even in the 60s training shortcuts were taken. Some crews, to 'discharge' the nuclear bomb response simulator away from the target area. Bomb doors would be opened and the requisite number of firing sequences would be done before the serious business of actually doing the practice or simulated drops.
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On a later demo in Epi Bay our flight commander dropped 21 retards from 300 feet - very impresive
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Most Flying hours?
I've been reading the thread on most Canberra hours; who do we think had the most Vulcan hours, Dave Thomas, Joe L'Estrange, John Willy, Jon Tye?
Only 1700 for me in two tours.
Also, what ever happened to "Bombay" Peach?
3P
Only 1700 for me in two tours.
Also, what ever happened to "Bombay" Peach?
3P
"Bombay" Peach
Also, what ever happened to "Bombay" Peach?
YS
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Vulcan Mk1 Weapon Bay and Bomb Separations.
Clearances for weapon releases from the Mk1 Vulcan (XA892 mostly) involved dropping enormous numbers of duds into Lyme Bay. All sorts of combinations of test releases preceded service approvals.
The airflows around the Vulcan weapons bay seemed to be particularly benign although some close jostling of bombs was occasionally observed.
Dropped the first big blunt 10,000 pounder at 0.98 IMN and watched it on closed circuit TV disappear with a slight pitching oscillation. The release was hardly perceptible.
Did we at Boscombe Down do a satisfactory job or were there any occurrences of damage to a Vulcan or cases of dangerous live bomb jostling ?
Some releases from other platforms can be terrifying and close to terminal.
Clearances for weapon releases from the Mk1 Vulcan (XA892 mostly) involved dropping enormous numbers of duds into Lyme Bay. All sorts of combinations of test releases preceded service approvals.
The airflows around the Vulcan weapons bay seemed to be particularly benign although some close jostling of bombs was occasionally observed.
Dropped the first big blunt 10,000 pounder at 0.98 IMN and watched it on closed circuit TV disappear with a slight pitching oscillation. The release was hardly perceptible.
Did we at Boscombe Down do a satisfactory job or were there any occurrences of damage to a Vulcan or cases of dangerous live bomb jostling ?
Some releases from other platforms can be terrifying and close to terminal.
I don't own this space under my name. I should have leased it while I still could
Milt, I watched many bombs fall away clean with the bombs slowly rotating as they fell.
To minimise the risk of jostle we were limited to a minimum interval of .3 sec IIRC.
There was an incident in 1967 I think. Boscombe managed to drop 10 x 1000lb (probably inert) out of a load of 21. Only problem was the bomb doors were shut at the time.
Despite the weight of bombs, most of which imagine would have been in the middle of the bomb doors, the bomb doors did not open. I also guess the landing was particularly gentle with gentle breaking to avoid the bombs moving forward through the fueslage fuel tank.
To minimise the risk of jostle we were limited to a minimum interval of .3 sec IIRC.
There was an incident in 1967 I think. Boscombe managed to drop 10 x 1000lb (probably inert) out of a load of 21. Only problem was the bomb doors were shut at the time.
Despite the weight of bombs, most of which imagine would have been in the middle of the bomb doors, the bomb doors did not open. I also guess the landing was particularly gentle with gentle breaking to avoid the bombs moving forward through the fueslage fuel tank.
Also, XM612 on arrival on ASI (14 May 82) had a few loose bombs, as the top row of the middle carrier had released the 4 1000lb'ers, but the bottom 3 were still attached. 
This occured when the bombs were dropped to save weight (slight excess of fuel usage encountered).
Superb landing by John Reeve, used up quite a lot of the runway.
This occured when the bombs were dropped to save weight (slight excess of fuel usage encountered).Superb landing by John Reeve, used up quite a lot of the runway.
Thread Starter
So, nothing to do with 'midnight confusion' then? Or 'Caligula' not understanding how to plan from the ODM???
Both of which I have been told were probable contributory factors.
What was the landing fuel state in the end?
Both of which I have been told were probable contributory factors.
What was the landing fuel state in the end?
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According to the AOC's PSO, the b%ll&cking Caligula received had to be heard to be believed!
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Last edited by threeputt; 4th Apr 2007 at 09:10. Reason: Spieling mistak
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Pontius
Thanks for the response on bomb clearances. We TPs at BD generally flew as briefed or to flight test instructions. It would have been the boffins who issued the 0.3 second interval. Interesting.
Cannot imagine a pilot bringing back a stick of inerts on the doors. I once had a delayed release of a live 2,000 pnd target marker on to a Canberra's doors. There was no way of knowing then whether the arming wires had been pulled and it had barostatic fuzes to open a parachute and to light it up at lower altitudes. Pencil beam radar director of the Imber range talked me back to the release point where the target marker departed on opening doors. Pencil beam radar then followed the store measuring its trajectory. It was armed as I still had the arming wires and it did its thing on the way down. No significant damage to the doors.
Cannot recall whether the Vulcan had weapon bay door interlocks to prevent inadvertant drops on to closed doors. One would expect this to be a design requirement.
Thanks for the response on bomb clearances. We TPs at BD generally flew as briefed or to flight test instructions. It would have been the boffins who issued the 0.3 second interval. Interesting.
Cannot imagine a pilot bringing back a stick of inerts on the doors. I once had a delayed release of a live 2,000 pnd target marker on to a Canberra's doors. There was no way of knowing then whether the arming wires had been pulled and it had barostatic fuzes to open a parachute and to light it up at lower altitudes. Pencil beam radar director of the Imber range talked me back to the release point where the target marker departed on opening doors. Pencil beam radar then followed the store measuring its trajectory. It was armed as I still had the arming wires and it did its thing on the way down. No significant damage to the doors.
Cannot recall whether the Vulcan had weapon bay door interlocks to prevent inadvertant drops on to closed doors. One would expect this to be a design requirement.
I don't own this space under my name. I should have leased it while I still could
If you remember the Vulcan bomb doors, they were double hinged. They folded UP in the middle. If a dropped bomb was outboard of the centre hinge then the doors could not open.
I don't know how they knew they had come off - cameras?
I don't know how they knew they had come off - cameras?
