Cyberwar Before There Was Cyber: Hacking WWII Electronic Bomb Fuses

we are very privileged to have Peter Goodman from New Zealand here today for our technical keynote he is a researcher in the department of computer science at the University of Auckland working on crypto he helped write the popular PGP encryption package as well and here he's going to talk today about bomb fuses and bomb disposal so let's welcome Peter Goodman to the stage thanks ok so the thinking process behind bombing is you want to cause disruption and bombing basically causes disruption also blowing stuff up is fun the general process behind it is you load the bombs and the source if rated over to destination you drop it on your destination in profit so that's the

general theory however you can revise that because you really want to cause disruption in blowing stuff up ok that's one way of causing disruption but unexploded bombs - were you expedient also cause disruption because if you've got a thousand-pound unexploded bomb under some critical installation no one can go near that and all the things been defused one example was an unexploded bomb that went under the NPL national physics lab and headington which in the UK was a critical war research establishment took 9800 man-hours to defuse this was Imperial measurements so he had yards and pounds and feet and man-hours so the fact that this thing didn't explode was at least as disruptive as if it had

exploded and during World War two and also during the Vietnam War both the Germans in the Vietnamese became very very good at repairing bomb damage very quickly so you'd bomb someplace like a runway and within 24 hours that have it patched up they paint fake bomb craters over the patches so it looked like it was still destroyed and they'd have planes taking off over the same runway so simply having bombs that detonator immediately isn't necessarily as disruptive as having bombs that sit there and don't detonate so you've got additional considerations with unexploded bombs the defenders can take as long as they want to disarm the thing so they can sit there and take whatever time they want use whatever machinery

they want to try and disarm this thing say take two approaches to combat this the first one is you make the bomb very hard to disarm and the second one is you rigged the things so it kills the people trying to disarm it traditional bomb fuses were came in all mechanical and these things go back to at least the 1890s you had these incredibly complicated mechanical contraptions and then if you look at the function of a fuse there's basically two functions the secondary purpose is you want to make the thing detonate when it's supposed to that's the secondary purpose the primary purpose is you want to make sure it doesn't feel innate when it's not supposed to you don't want the

thing detonating when you're handling it when you're loading up when it's fired or whatever you only want it to detonate once it reaches its target so during World War 2 the Japanese actually had the lowest percentage of duds because they didn't bother with safety mechanisms if you've got something that just blows up in your face then yeah it's relatively reliable and blowing up in your face whether you'd rather HIPPA blow up in someone else's face and this is great quotes if you read sort of military history books and things like that this one that's up on the screen at the moment it's not a holy sound mechanisms in some instances it was quite dangerous for the operator

this is US Army Field Manual on Japanese military equipment and so they're two main models of hand grenades the model 91 in the model 97 and in both cases have seen the italics are in the original throw immediately since action of fuses sometimes erratic so the way the Japanese fuses work if you're familiar with these basically two general types of grenades are people familiar with from films these the standard style you pull the pin out you release the spring-loaded catch you throw it and then you've got the German stick grenade you unscrew the camp and you pull this lanyard and then you throught the Japanese ones you pulled out some sort of safety pin you didn't

smash the fuse down on a rock and you throw it so one or two at one of three things would happen with these because they had really unreliable fuses you smash it down on a rock and it blows up before you can throw it killing you and if you run around you or you smash it down on a rock and you throw it and it blows up once it reaches the enemy and the third option is yeah you throw it and it doesn't blow up and the other side picks it up and throws it back at you and then it blows up killing you so one out of three isn't that bad for a for you know for a weapon like that

and then they had this guy Kaduna number who's he's been called the Japanese John Browning although I think that's a completely wrong designation because john browning designed his stuff about a hundred years ago and a lot of it's still in use today whereas nothing the sky designed was used after about august 1945 when one military historian said the sky design comically bad weapons so one of his first designs was an Ambu type 14 pistol this thing has no safety cache so what actually happened was in the late 19th century he went on a tour of Europe and looked at some of the weapons they were doing there and backed me in the state of the art was the mauser c96 pistol

also known as the broom-handle Mauser so they this was pretty much the state of the art for that time they were a bunch of experimental pistols or two-team the automatic pistols done about that time but the Mauser was the first sort of mainstream production model that was really for general use and the Chinese just built about a bazillion unlicensed copy to this thing and then probably saw the manali Express has guaranteed 100% original pistols whereas the Japanese got the sky to design his own version of it as far as I know this is the only production semi-automatic pistol ever that's been produced without a safety catch he decided he just wasn't any use for one so you could actually fire this

thing without pulling the trigger for example while carrying one of the frequent James it was also a horribly unreliable pistol so in response to this thing the principal complaint with the IJA the Imperial Japanese army was that there's no safety catch and our guys are shooting themselves trying to clear the jams and this thing you'd think that would also be a problem but apparently the main thing was a safety catch so instead of you know giving this guy a short sword and telling him to nip around the back and you know what to do with us they see designed more weapons for us based on this amazing pistol so designed us for type 94 Nambu pistol us

was the main Japanese officers pistol during World War two it is generally acknowledged as the worst production handgun ever produced that was the main Japanese side and during World War two so you know that's it's kind of an impressive feat because no two people can agree on what the beast Hank and there's no one person can agree on what the beast Hank I knows but the consensus is this is the worst handgun ever produced so the the feature that gives it that prize is its look at some of the other stuff first of all it is horribly ugly it looks like it was made by some guy with a grinder and a file and this

was a you know a newly model which was a mess production when towards the end of the war they probably were made with a grinder and a file it's chambered for this underpowered 8 millimeter de round also designed by Nambu so he was an incompetent weapons designer and an incompetent ammunition designer I had a six round clip so it was the same as a revolver it was mechanically clunky it was unreliable it was badly engineered it was just an awful weapon but the thing that the gives it the prize of the worst handgun ever designed is actually I go back a bit if you look above the monitor obvious it is above the pistol is that

body which isn't exposed see a bar so if you press down on that the pistol fires without pulling the trigger there's lots of demos of this people love to demonstrate this because it you know you should have make fun of this thing so that's someone firing the pistol will this finger no be near the trigger so if you've got this thing and it's loaded and you holster it or will you put it down on your table on the table or you're cleaning it already about you can fire it this is a persistent but as far as going to a completely unfounded rumor that calls it a suicide pistol because Japanese officers when they were surrendering they would hand it over to

Americans like vests and the American would then pick it up and press down on the sear and shoot someone similar examples of stuff this Takai design i'll get back when to bomb fuses in a minute but just this is this is something else he designed it's a type of leave in machine gun it looks like a cross between like a combine have a stone a sewing machine it's just it's an unbelievable weapon if you interested in this either talk to me afterwards we'll go and look at it on youtube it's it's no one's ever designed anything like this before since but the main point is you really do want safety features on your weapon do you do not want you know

someone we can shoot yourself in the foot some people put by putting it down on the table or holstering a pistol some mechanical fuse designs are really really difficult to make both reliable and safe you want something that detonates once it reaches its target but not when it's being fired or when it's being handled and in the case of this for example this is a gym and when I can infuse a 30 millimeter fuse so this is going to be used in air to air combat typically over Germany so you want something that doesn't detonate when it's fired it detonates if it hits its target but if the thing then falls onto the ground over one your cities you

don't want all these 30 millimeter shells detonating all over your city and so what this one does it's got this incredible series of mechanical safety features I'm not sure how obvious it is from their diagram how have as on that but the two things are right at the top is the ring of six ball bearings so as the shell is fired it starts spinning and the force that they're spinning then forces these six ball bearings outwards and so they've free the path for the firing pin and down below there that sort of dark those two dark bands that's a collar that's also forced open by the force of the spinning so once the things in flight at spinning

at high speed these two sets of mechanical interlocks are moved out of the way the firing pin can then be pushed down when it hits the target if it misses the target the force back down to earth that stops spinning there's mechanical interlocks locked back into place and once it hits the ground it can't detonate anymore it's a pretty ingenious design you know it's a purely mechanical fuse which makes sure that that will the thing will detonate on impact with a target by point D tonight when it hits the ground however this thing is being fired out of a cannon and it's been accelerated at hundreds of G's so you've got all these very fine mechanical devices which may

or may not function reliably with that kind of shot that's a larger more modern for use used in an artillery shell again entirely mechanical that's got a bunch of safety features so first of all it's got a cap over the top so before you actually fire the thing you remove the cap so if you accidentally hit the fuse if a firing pin or anything like that there's no problem and this is because it's largely you've got more safety features in it so in again I don't sure how obvious it is on the diagram but let's fire this is frangible link in the top that share that breaks away from the firing shock such chatters and that frees the firing

pin so I can travel down and it's got a second to meet you down at the base these two cams also activated by the shell spinning and the cannon rotates the primer into place beneath the firing pin so if it's not fired if you simply drop it the primer is no way near the firing pin even if the firing pin somehow gets to push down it's not gonna hit the primer once that's spinning becames rotating to place in the primers then underneath the firing pin when it impacts on the target at D tomates but again you've got all these very fine mechanical components that have to deal with a massive amount of shock when they

fired and also being spun at an insanely high speed and not fall apart or shatter or break so it is very very difficult to rely but to build both reliable shells and ones that are safe in World War one America Sheltie american-supplied under lend-lease about one third of all and she'll supply to the British were duds because they couldn't actually just build them safely so generally carried an extensive electronic our trials on fuses in 1931 and 32 by the Treaty of Versailles though forbidden from developing a whole bunch of different weapons including this kind of stuff so starters on secret in 1926 and they did the testing in secret in Russia so Russia was at that

time was Bolshevik Russia and they had no friends anywhere because they were Bolsheviks and they wouldn't like them and so it the Treaty of Rapallo with Russia and because Germany was basically a pariah and Russia was a pariah they collaborated in doing this weapons testing so the one place where Germany could safely keep weapons was in Soviet Russia and that he stood 250 mechanical fuses and 250 electronic fuses and they found the electronic fuses were vastly superior and they also had the advantage that they had their Spanish Civil War where they assisted assisted Franco and they're basically stages of testing ground for diffusers so they had a few school the type 15 fuse which was the

precursor to the one they used during World War two and got to test it extensively and it was a relatively benign war because they weren't fighting anyone with significant military capabilities and they'd say EF yields and I could go in and retrieve diffusers and see what happened so basically the life testing if he fuses during the Spanish Civil War so traditional bomb fuse is in the nose of the bomb with an electric fuse you don't need to do that anymore there's no mechanical connection even you don't rely on the fuse actually impacting the ground you can have at the side of the bomb and so what they did there is they have huge fuse pockets in the side of

the bomb the fuses went into that the other thing is because it's now now electronic fuse you haven't got the single point of contact with the bomb hits the ground so you can put in multiple fuses so a lot of the bombs had to fuse pockets for two different types of users and you can mix and match different fuses so the general form of a bomb fuse it's about the size of a fuse to give you a scale for that sort of thing so when the witness was inserted in the fuse pocket so you hit a pocket on the side of the bomb was about that thickness so the armorer would take the fuse this is a effectively turn in a

fuse this is purely the electronic side of things so the way the detonation chain worked the bomb itself would swell with amytal which is the standard military explosive it's a mixture of ammonium nitrate and TNT and it's a perfect military explosive it's in sense that if it doesn't degrade it doesn't absorb moisture it's very shock immune so you can for example fire a bullet into it and it shouldn't be donated you can see it fire to it you can do all sorts of stuff and it's very very safe to handle but because it was so hard to detonate you need a very strong explosive pledge to actually detonate the thing so the way the fuse works you've got the basic fuse

that's the electronic component you've even got something called a primary explosive which is a very sensitive explosive which is why you don't generally use this in your main bombs and that screws into the base of the standard fuse so that's detonated by the fuse that's about the same explosive charges a hand grenade so the fuse fires the primary explosive the primary explosive is easy to see it off but relatively weak so around there you've got a second or booster explosive which amplifies the shock of the primary enough to actually detonate the TNT which is relatively immune to shock so you've got these three stages of the explosive train so what the armorer would do is they would this is called

the gain so that would it which amplifies the explosive charge so they would take this drop in the attract acid which is the booster explosive drop this into the fuse pocket and screw down a locking ring and at that point the bomb is armed so we've got two parts of the arming mechanism the top part is the bomb wreck in the aircraft and the lower part is the actual fuse which goes into the bomb and the it's electrically armed so the you've got on it you've got two selector switch in the cockpit where they can select the fuse delay and a bunch of other things so the thing but this is the army context are only

engaged once the Bombers leave the bomb wreck what that diagram shows it zigzag thing at the top is these arming contacts which are held in place like this and once the bomb drops down out of a few Zurich and it's lift that so it once has dropped the bomb rack it makes momentary contact and puts a pulse of electrical energy into the bomb so the feature with this is with a standard bomb you can get an armed bomb sitting in your feet and your bomb rack and it's stuck one of the lugs hasn't attached and saving his plane your aircraft with an armed bomb in the aircraft and that has happened and aircraft have been

destroyed by particularly Japanese aircraft were notorious for this again because they had no safety mechanisms you basically ended up with a kamikaze aircraft because you couldn't safely land this thing so you've pretty much had to crash it into something in order to D to get rid of the bomb so again that was an impressive safety feature if you compete us with mechanical fuses you were guaranteed that this thing was only armed once it had already dropped out of the bomb racks so you we were pretty much we're not going to hear the case we've got an armed bomb sitting in a bomb wreck and the last section of the mechanism is diffusing the bomb so this is a

two-stage thing initially when you get this passive current before going into the spawn it goes into storage capacitors so they absorb the initial current post you've then got resistors that it leaks through into arming capacitors and there's a certain delay while it leaks through those resistors which is the arming time of the bomb again you don't want this bomb to be live the manner that leaves the bomb wreck you want to have a couple of stick in to delay slightly it's well clear of the plane before it goes live they didn't go into the firing capacitors in the firing capacitors these trembler switches in there so when it hits the ground the chamber switches courses are

short and then it fires the actual fuse yes so the time for the charge to leak from the initial storage capacitors into the army capacitors is the arming time and the igniters themselves is three different igniter switch can speak by the armored us so there's is a screw in here where when the Bombers actually initially said you can set the screw to allow it to detonate immediately or have a delayed detonation because you don't necessarily want to do tonight immediately on this if it deviates as soon as it hits the surface here's a huge amount of blast but not much damage he wanted to do tonight once it's penetrated under the ground and destroy the structure that it says

so most of the circuitry in this thing is actually to prevent accidental detonation not to ensure detonation these fuses are incredibly safe the bombs could actually be transported in the armed state that's a nice T 250 which is a 250 kilogram bomb and the theatric on the side means it's armed so that's a fully armed bomb being tripped in its case because the fuse is safe enough you can a transported in that state but the mechanical fuse there's no way you could ever do then this is the standard fuse used throughout the war it's about 225 B so that's that's the mainstream fuse used everywhere this is a development of the type 15 fuse so the 15 was the one that they

Morley's tested during the Spanish Civil War on the twenty five PT was his standard fuse so the selector fuse and the switch which was set by the armory enables or delays a short delay circuits so you've got these detonation delay options there's an instantaneous which typically isn't used this short one second so basically penetrates some distance into the structure and then is a relatively long when seventeen seconds so it's it's the unit comes to rest and then a theater nights and some of these things you can also do things for example if you're doing low-level bombing you don't want instantaneous detonation because you're going to knock out the aircraft so in that case you'll see at the 17

second delay so the aircraft has got time to get clear before the bomb detonates and again this is the the flexibility of these electronic fuses and you could set them to do all sorts of interesting things but what wasn't so easy with mechanical fuses the physical layout was you've got trembler switches which actually activate the thing and I've already mentioned things like this so that's the gain which contains a nitro Penta it's still used today in primacord ellic which is a fuse cord and I mentioned the explosive treinta triggers the purgation HED generates of tnt and the electronics are pitted and Benjamin so in a tall pace of components so there's no transistors there's no

valves there's nothing like that in the purely passive components and the extremely shocked and sensitive because the whole thing's potted and bitumen there were half a century later that was kind of a state-of-the-art infusers the mark 376th electronic fuse the thing about this is this is basically a Markku the first one developed was the type 15 they hit a few teething problems they developed the type 25 B and that was you know the second development of the fuse this one the Mac 370 sixties 376 revisions that they went through of this fuse to get into that state the problem with that it basically does exactly the same thing as a 25 B but they use transistors and all sorts

of other fancy components and the problem is you've now got these you know sensitive components and you've had safety circuitry to deal with the fact that these transistors can't deal with over-voltage and under-voltage and you know electrical shorts and other things then you have to add even more circuitry to add redundancy in case one of the transistors fails and so on so you've got this huge amount of complexity that exists solely because you've added more complexity and it just breeds even more complex so I can't really see anything in there that isn't already in the 25 B which has purely passive components and was 50 years but before then as an aside how do you mail a bond fuse so this came to me

as I was an intellectual component well the thing is you know you don't really want to label seeing something and label a bomb fuse because if everyone knows that a bomb fuses like some sticks of TNT with wires and the clock attached to it and this isn't that so you just label is in the literal mind and it is completely inert in passive it's not like I'm seeing something dangerous you know you could shut these things fully armed because there was nothing in the air that well it's just a bunch of capacitors and resistors alternatively you can get it seen from someone like the Ukraine where you can just post anything and they don't really care what

you post him anyway how did he fuse these things so I've mentioned that these things were charged electrically and they then go into the Army capacitors so in the same way that you can charge them and equally ignore so he doesn't charge them so there's something called a Crabtree discharger it just goes into these two brass contacts pushes down on them completes the circuit the charge leaks back out of the arming capacitors and at that point the thing is completely safe and completely inert so this isn't this is in the cases of bombs that don't detonate so some of these things didn't detonate because again it's affecting the ground there's this enormous mechanical shock and so in

some cases they you know they didn't do tonight and again this isn't necessarily a bad thing because an unexploded bomb was at least as bad as one that exploded so basically wait for the charge to leak back out of the arming context and been the thing is safe at that point the theory is if you read the manuals it sees your toy landed around the fuse and you stand well back can you pull the fuse out the problem is the bomb has impacted the ground with a massive amount of force in typically the fuse pocket is deformed the fuse is now stuck in the fuse pocket inside you basically attack it with the chisel and a hammer a

device that here's trembler context on it that detonated teeny shock and this only worked on the type 15 fuses so they had a whole bunch of type 15s leftover from the Spanish Civil War and they used those initially and then what they did is because the civilians were worried about these bombs being dropped on when they published all these feel-good stories and newspapers saying you know so the problems we can defuse these things if you've got a bomb in your bed yeah don't worry about it we'll come in and we'll defuse it for you and the idea was to raise morale the problem is the Germans are also reading these papers and they said okay you know

they know how to defuse these things well we designed the fuses so they can't do this anymore the extreme example of a supposed type 50 fuse which I'll get onto a bit later so once they had the type 25 which you couldn't use the Crabtree on anymore they had the brass liquid discharge so what you do in that case is you put the screw this brass container over the top of this this has got all these amazing screw lugs on it so you can just screw on this discharger it's filled with meats with salt in it so it's a conductive liquid the in force event force it into the fuse under pressure so you've got a bicycle pump

and you pump this thing up it forces this liquid in there because it's conductive it shorts out the capacitors the thing discharges and then you're fine again and it required about a thirty minute wait so you're sitting the on top he's sitting it with a spawn you pump you look put into it you retire to a safe distance after thirty minutes you come back and you take it with a cold chisel and a hammer and hope that it's not gonna see it up we see it off there's another fuse called the type 17 clockwork fuse so this is the sort of the detonate on impact or don't detonate and kill the diffusor fuse in combination with that there's a type 17

clock worth of use so this is a standard electronic impact fused in the upper portion so it's basically the same as the 25 billion what that does is it being triggers a clockwork mechanism which counts down so rather than firing the igniter immediately it starts as clockwork mechanism and there's a delay of between 2 hours and 80 hours after being armed and at that point it detonates so this is kind of the canonical ticking bomb and this was often used as a secondary fuse alongside the primary fuse so the problem with this is you can take you tell what delay has been set it's a 2 to 80 hours you have no idea how long that thing's going

to keep ticking before it detonates so a standard approach was you wait 96 hours before you start messing with the bomb however the type 17 fuse head to particularly nasty failure modes the first one and again remember you've got this mechanical this very sensitive mechanical clockwork device that's being subject to a mess of shock as it impacts the ground so one of them is it stops on impact with the ground it counts down to zero and stops and then as soon as you disturb the thing at detonates and the second one is it stops on impact with the ground and then it restarts so these things aren't necessarily you know sitting on the ground with the bomb with

a fuse pocket face upwards it might be face down and mud so you've got to rotate the thing you rotate the thing and suddenly the bomb starts ticking you have no idea how long it's going to take before it kills you there were bombs detonated more than a year after they were they fell so that when these bombs fell they had signed the various priorities but fell into some very high priority area like under a Gas Works or a railway line or the example of the NPL and Teddington there are priority one that he fused them immediately and then they were lower in lower priority one so some of the really low priority ones it's you know at the farm somewhere they

they've didn't bother defusing them because it just wasn't worth doing it because they had more agent bombs to defuse is there some of these degenerated more than a year later they hit some sort of mechanical shock or something the timer would suddenly start countdown again and the bomb would detonate so the thing was the type 17 is it contains metal components so it's bronze and steel so the way you stop you defuse this thing is user making it a collar that goes around the bomb in lots of steel components in place so what you do is you turn down to where the bombers and that's an actual photo of a bomb being diffused so you tunnel down to

where the Bombers you clamp on this gigantic meat metal collar you activate the magnets and you certainly with a stethoscope and hope the ticking stops so this is think what the clock stock also known as the Q coil and it was this 90 kilogram thing feed from hundred and forty volt DC batteries he lowered this gigantic a heavy thing around the bomb tape that over we the fuse was a mere listen to it with the stethoscope and it's all the ticking stopped at that point the type 17 fuse has been wounded inert and you can then take the bomb away and move it to a safe location and work on it there either to detonate or

to this various other way other way to defusing this thing we don't forget on to in a minute another fuse after the original blitz so he was the main blitz 1942 41 and there's something with the baby blitz in 1943 and at that point they'd improved the techniques so they injected a urea formaldehyde resin which was a primitive type of plastic and other things so they drilled into it injected plastic reason it solidified and stopped the thing from moving so that was that was in the main fuse this was the 17 and 25 and then they were being diffused so the Germans came up with us count activist so 1940 a bomb penetrated under an oil storage tank in

a picture refinery in Swansea this was a this is a priority-one bomb it's a petrol refinery you've got to stop these bombs detonating because the fuel is kind of precious they finally extracted the bomb there were other bombs going off so the guy who did this was in the middle of piles of burning petrol with bombs going off around them and somehow got this thing out and the bomb had split open and it was something else under the under the underneath of the game that wasn't normally there and was called a 240 and so what the stud is it was under here and there was a firing pin the spring-loaded firing pin that was held

in place by the game when you pulled this out the firing pin shot across and detonated the bomb so they've gone to a strategy to of this bombing which was you rigged things to kill the defenders you can't withdraw the main fuse the minute you put door the main fuse when you defusing it it detonates the bomb so any fuses not just the type 17 the type 25 any other fuse that was used could potentially have one of these things inserted underneath it so as soon as you do as soon as you remove the fuse to defuse the bomb detonates and kills the crystal diffuser so the counter heck with us was she'd rely upon the case of

the bomb and I've mission that aim at all is it's a really good military explosive it's been used since before World War one it's still used today because it has these amazing properties that it's really insensitive it's really safe so you drill open the case of the bomb and you remove the aim at all and the standard way of doing this is use high pressure steam because it's so intense if it's perfectly fine to do that it melts the amytal Union get the sludge of amytal and water that pours out on the side of the bomb and at that point you still have again left in there but that's about the Paley explosive charge of a hand grenade so it's not that much

damage if it does detonate and some of these bombs the biggest bomb was a bomb called the satan which was over a ton of explosives and that could take quite a while to actually sit there next to this bomb with a few still on it's steaming out a ton of explosive and it was also used for discharging fuse capacitors so you for steam under the thing capacitors then malfunction and don't still recharge anymore and then you can pull the fuse out a slightly more alarming method is you can set fire to the amytal and again it's perfectly safe to do that it will burn so you thermite to burn open the case of the bomb and you set

fire to the M at all and you simply burn the whole lot and because M at all as I mentioned it's extremely insensitive you can burn happily at Point D tonight so you can you can take a block of TNT and set fire to it and use it to brew tea if you're out in the field now virtually it detonates once the burning reaches the fuse it will detonate but by then most of the amytal is gone so again you get a very small explosion rather than a gigantic explosion of all the ammeter all going up so the response to this was to type 50 fuse this is really nasty so the Germans apparently had despised

within the bomb defuser community and knew all the tricks that they were using so they come up with the type 50 fuse this had a split plunger so with a Crabtree discharger you push this thing in any discharge up I said a split plunger so once you remake contact if it's really been armed you push the plunger and the bomb will detonate immediately it also had circuitry where if you use the mistress alternate method matures out and also D tonight's immediately and then they added some extra features it had an extremely long arming delay so instead of arming instead of arming you know while it was still in the air it armed after the bomber came to come to reached and have

been at least for quite some time it wasn't the DITA they don't impact right bomb that was because the trigger was an extremely sensitive spring contact it was so sensitive that tapping the case of the bomb with the pencil was enough to set it off that's why you had to have this long arming delay to make sure it was totally at rest so if anyone tried to dig down to this bomb or sneeze near it or harsh words or anything the bomb will detonate the sole purpose of the type 50 fuse was to kill bomb diffusers and it was typically paired with a type 17 fuse so you've got a fuse that detonates if you sneeze near it

next to a timed fuse that detonates after certain amount of time with an optional tools 40 next to it which detonates if you try and pull the fuse out the other thing was that because this thing had these really sensitive chamber switches if you use the clock stopper on the type 17 fuse it's like 50 fuse next to it will be detonated by their magnetic field so every single defusing mechanism had at that point apart from steaming out the explosive was rendered void they also had naval mines which was just a scary they had this thing called the beam 1000 which was a one ton naval mine so they have magnetic fuse to detonate it making it extends this to detonate it

when a ship went nearby it also hit the standard ealerts which is the the the standard 25 impact view so if it dropped on land instead of going into the water it would didn't anyone impact it also had a hydrostatic valve to detonate it so because these things were dropped into the ocean and they were under the surface if you pulled it to the surface to defuse it it would detonate and 20 had a photoelectric sensor inside it so if you drilled open the case and shun the light inside always post it to any kind of light it would also detonation so the thing with this was I mentioned earlier the type 376 fuse was overly complex you

had all this extra compensating circuitry to deal with the fact that this initially complex circuitry would fail and that's exactly what happened with the beam 1000 it was intended for the Clyde which which was that we have a scholarship yards were in an overshot and came down near Dumbarton the first guy the first bomb defuser that encountered this I'd never seen one of these things before so I cut the side open and Seana torchin on to the photoelectric cells however because of all this extra complexity the wires are come loose because of the shock of the impact and start never actually detonated and it saved his life yeah because the more complex the thing is

the more things there are to go wrong so basically that the the only approach it was left while still steaming out the explosive because all the other diffusing mechanisms had been bypassed so then the Jim has introduced something even nastier called the type 50 B or the Y fuse so this wasn't in the main bullet sisters and the baby boots in 1943 and again they had that same problem that it's you know because it's electronic you can add all these cool features but it's now very complicated and so there's a lot more things to go wrong so it's again it's sustained a type 20 few 550 fuse which is already a horrible enough used to deal with anyway

but underneath that were batteries and Mercury killed switches in the XY and z direction so I've already mentioned that year the bomb could have come caressed face down or fuse pocket down in some mud so if you rotate this thing the tilt switches are activated in the bomb detonates and kills you it's also got an eighty withdraw collar on the base so these things it's a completely smooth thing so you drop it into the fuse pocket you can pull it straight back out again afterwards this head and Auntie was draw like in Kalos so once this thing was in the fuse pocket there's no way you can get it back out again there was a fuse captured the winner

under the Bakerloo line which was a main railway line in London again it's a type 1 priority so that had top priority to be defused the secondary circuit was inactive because by this time they were using effectively slave labor to make these things and these guys weren't terribly motivated to help the German war effort site they often sabotage the stuff that they were manufacturing the secondary circuit on this was completely inactive so presumably due to sabotage by the by the guys he was supposed to be sealing it and actually saved he defused his life because he used he assumed it was a standard pipe fitters charger on it and that would have killed him but

because it had been sabotage it doesn't work so in this case what you do is you target the batteries and the thing about the thing about these fuses is you know if you look at this is a black box it's it's kind of an interesting black box you know you charge to fling a minifiers but what you do is you look at the individual components that make this up so you've already targeted the capacitors the capacitor has certain physical characteristics so you move outside the physical operating range that it's designed for the same thing with the batteries you don't just assume it's a black box with with tilt switches it's got batteries and those batteries

have certain characteristics so you target those and what you do is you freeze them to the point where they no longer function as batteries assuming that mucking around with the bomb and that manner hasn't already caused it to do tonight so what you do is you build a clay or pasta scene dam around the fuse pocket and then you pour liquid oxygen into it until this is purely rule of thumb until you've got a 1 1 foot dam at a frost ring all the way around the outside of the bomb and that tells you that the batteries have been hopefully been frozen solid sufficiently that they're not working anymore and at that point you can you sustain the

techniques of getting rid of a fuse so typically it takes about 2 hours so you're sitting there next to this bomb for 2 hours pouring liquid oxygen out of a deep earth flask onto the thing until you've got your frost ring around the outside of it and then you crowbar out the fuse so the locking thing you know makes it more difficult to to get out but you know it's a standard thing with brute force of brute force doesn't work you're not using enough of it so you just apply a crowbar and eventually your leverage outputs of the fuse so the problem with us was liquid oxygen wasn't very portable again this was the initial response to the stuck on

the while to figure this out they used liquid oxygen so later they use dry ice which you can make on-site and right at the end of the war there was what was left of the Luftwaffe used an improved wife used which had been a low temperature batteries again because they had spies inside the bomb defusing section they knew what they were doing so they used beater low temperature batteries and so dry ice wasn't sufficient to call them that went back to liquid oxygen but however that didn't half the amount of time they had so with liquid oxygen at about 20 minutes before the battery started functioning again would these be debate you said about 10

minutes to get the fuse out with a crowbar naval mine fusing was slightly different but they had the same kind of arms race with that so these didn't use contact mines it's they called Hertz horns these are really World War one meet used a lot more sophisticated fusing so one of the things they used was I've already mentioned the beam 1000 here the magnetic mine so it detected iron objects passing nearby so it wasn't based on the ship bumping into it it's simply a ship going close to it was enough to detonate it so the heck for this was you had these towed electromagnetic emitters these when they fitted to an aircraft so you flew this aircraft at low altitude

across the ocean emitting this very strong magnetic field because an iron boat has a relatively weak magnetic field so you can be donate these things remotely just by projecting a strong we need may need a clear let them or you can dig out stirrups so they're not magnetic the counter Hector that was you've got a counter on it so it requires multiple activations so we're plane flying flying over at once women in it field isn't enough to activate it you need a ship that's moving towards it and you get multiple activations of the ship moving slowly towards the fuse before it will detonate counter heck to that one was the plane it's to make multiple passes and again that was kind

of effective for the Germans because instead of just flying a plane over ceiling once to clear it you had to fly the thing back and forth 15 times before you assumed that it was safe for boats to go through another one was it to take the chips the engines so not just you know any random noise but specifically the sound of a diesel engine in a shop the heck the standard heck with this was she just did the sea lanes ahead of you and hope that the shock wave detonates them all you project out some kind of noise the counter heck with this was that you require a slowly increasing volume because again a sudden pulse of noise is

not a ship a ship slowly increases in volume as it gets towards the mine once it reaches peak intensity using DNA to casino the ship's right next to you so the counter head - that was your project noise out in front of these ships so what they used was Kengo hammers which was basically pneumatic drills in this metal box welded onto the front of the ship and they hit this thing bouncing around in front of the ship so basically project had roughly the same sound as the engine and shut but at very high volume out in front of it and so the mind detonated long before the shop keeper hit it so the stats for this

were about ten thousand unexploded bombs about eight thousand would be used about 1,000 detonated in about a thousand odd probably still down there again they're out in the middle of nowhere in some farms time we're near twenty meters underground so it just wasn't worth the effort of digging them up these things are incredibly reliable and long-lived some of these things are still fully functional after 60 years there's an extra news story from the evening stained and of a bomb that was unearthed in a construction site and you know they sort of dug it up with a digger in and you know rotated it and suddenly it started ticking because I had one of these type 17 fuses that have

been stopped by the impact it started ticking and they used if you read the rest of the story they used classic World War 2 defusing techniques straight out of you know World War 2 to defuse this bomb so there's various things to help the defenders and again this is kind of interesting from a computer point of view it's you know the sort of the black box versus white box so all the fuses were very carefully labeled it's a German military manual going into excruciating detail on how these fuses had to be labeled so the bomb was labeled in minut detailed with everything it told the diffusers exactly what type of fuse was in there and there

are very specific instructions this is you know it's it's like you have to draw the letters in in a particular height in a particular font and here is the German standard for the font that defines what you know how you have to paint these leaders are on and it's like a I can actually read this thing you know 16 millimeter diameter circle with a 5 millimeter thickness and so on on a bomb that was gonna be flown over to the enemy and dropped on them the theory is no one really knows why they did this it could have been just because they were German or it could have been so that you know if a plane

came back and couldn't drop its bombs then the guy the armor would know what sort of cues was in there I don't know how that method but anyway it made it very easy for the defenders because they knew exactly what they were dealing with the numbering was you know according to one military history it was inflexibly methodical you knew that if he had a fuse and it had a zero suffix it was an 80 disturbance fuse so the 50 and 50 B it was a 5 suffix the 15 and 25 was an impact fuse the 17 was a delayed fuse and so on and so forth so the 50 B was actually marked as a 25 B T disguise it

but then I had this why after it which basically said this is markers are 25 B but it's not it's actually a 50 B fuse again why did they do this marker type 17 is a type 25 just confuse them to be really nasty so that was a not a very good idea other requirements again if you either that's kind of neat so it sees things like you know the Dean's have to be smoothed out if there's any rust on the bomb you have to scrape it off if the paint's damaged you have to repair the damaged paint because what would the english think if we dropped they a a bomb would scratch paint on

them i mean there'd be mortified would be mortified other things to help the defenders so yeah if the hidden actually carefully labeled these fuses they would have had to x-ray every fuse in the fields next she did this with the anti disturbance fuses with the wife use because they weren't quite sure what was in there so they used radon which is a radioactive radium derived radioactive gas and in basically x-ray these fuses and developed these developed photos on site so they've knew what sort of fuse was in there and again that gives an example of how high values some of these targets were and how critical it was to defuse these bombs they were running portable

x-ray apparatus and developing films of these bombs just to figure out what the fuse was so they could disarm it and that became a saint of practice for wife users because they were just too dangerous you had to know what it was you were dealing with yes so they had the inner pieces by the diffusers they were publicized this helped the other side so they stopped publishing any information about what they were doing it that didn't help that much because the Germans apparently had spies among the defuser's so they knew what they were doing but still have slowed them down to some extent and then it was just sheer blind like they discovered that there's a discovery of the two's

forty was pure like the discovery of the type fifty be fused was pure like other things with side-channel attacks from nineteen forty instead of treating the fuser as a black box treated as individual physical components and you attack the individual components rather than the black box you know heat the components you freeze them you basically move them outside the standard operating range and suddenly the thing doesn't work anymore in the way it's supposed to in the case of the attackers the decision to use electronic fuses was absolutely amazing the Allies used like chemical fuses so a time delays with a tacit eating into something enough to eventually if they donated these were relatively unreliable fuses and not very

versatile the fact that he had electronic fuses and fuse pockets on the side it a lot of versatility you could well relatively easily change the designs of the fuses to keep track in this with this arms race with the people trying to do the defusing and you hit the things like the impact changed the operating characteristics of the fuses the type seventeen was particularly bad in this so that made them sufficiently unpredictable that it was dangerous for the diffusers yeah they took advantage of the fact that the news release was publicized and they redesigned the fuses to get around that so the thing about the thing with the bomb diffusers the average lifespan of a bomb defused was

about ten weeks so if you were the person who actually did the defusing rather than the guy who dug down to the bomb you were made officer grade because he had to have the ability to order around the guys who were doing the other work however you were never put through Officer Training School because you would be dead before we could actually use your officer training and you know think about that for a second that's kind of a scary thing we will appoint you as an officer but we're not going to bother training you as an officer because you won't live to be able to use that capability if you want some reading material on this stuff is an annual fuse

conference which is now in its 56th year and it's everything you never wanted to know about fuses the recent highlights is use of lead-free solder and fuses because you've got to apparently be RoHS compliant so you know that you know if you're talking about being maimed by trasto munitions and stuff at least you know that it's lead-free shrapnel rather than lead at retinal and finally your chances are meaning up on watchlists due to my research activity for this talk is probably close to 100% okay we've got a couple of minutes for questions do we have any questions when I be here you didn't show the ticking down red letters when did they get added the red letter is ticking

down ten nine eight when did that get added yeah only movie bombs this is what they actually look like not dynamite in red letters just a question here your marked on the regulations about dealing with paint scratches and scratches to the to the metal in the bomb casing that kind of thing that seems likely to be more than purely cosmetic I would have expected that that regulation would exist due to increased risk for corrosion of the mild steel casing do you think that's possible or is that actually purely cosmetic cosmetic I'm actually getting almost 100% a car up on the stage we'll just try that question one more time all right one more time sorry yeah do you actually think that

the the regulations about paint scratches and scratches on the steel of the bomb casing was for cosmetic reasons or do you think it might be to prevent accelerated corrosion and possibly premature detonation well so that the paint wasn't the bombs were painted and it was fine but it was the lettering wasn't for protection it was purely for labeling the bomb and the instructions specifically said that you know you hit your correct the lettering and even for rust you'd only noticed the rust as you're loading the bomb out of the plane and it's gonna be you know it's they got a half-life of a couple of hours before it gets dropped so I don't understand and you know I've read military history

books where they also say we don't know why they did this I think they were just being German I caught a question around the users that use transistors can you use EMP to defuse those so that the Mac 376 was one of the last of the transistorized fuses they now all use integrated circuits which makes them even more flaky because they're more you know there's even more complexity and things to go wrong one would assume you could however to generate the amount of EMP you need to deal with a shell and flight towards you it's not really practical to do that in the field there's a really interesting history I've still got a couple minutes

on this here's an interesting history if you read the history of the development of proximity fuses during World War two they basically sent out a what would now be called radar but it was a lot of frequency pulse and if it was reflected back into the fuse they knew that they were close to an object and would detonate and the way they were worried that the Germans would capture these things and reverse-engineer them and build their own so developed a way of jamming them which broadcasts a radio pulse back at the fuse so that's not necessarily EMP but there was a way of dealing with the very early proximity fuses which had no you know sit pattern

they just if they got a radio pulse back they would do tonight so early procs fuses could be detonated that by later procs fuses they know that they've seen out the specific waveform the specific series of pulses and they can't be fooled that easily so yes straight EMP it's not really practical and for effectively jamming the fuses they're designed with anti jamming capabilities so you can't really do that either I'll take your question over here hi and you mentioned that an unexploded bomb is almost as dangerous as one that has actually detonated presumably it's much cheaper to manufacture something that looks like a bomb but doesn't well it's never gonna detonate and do you think

that's a reasonable strategy for an out force to do - nope one in five or one in ten they are just things that look like bombs so that you cut down your operating costs so most of most of the cost of the bomb was sort of machining the casing in the fins and all the other stuff so you've still got you know the amytal is relatively cheap and they produce thousands of tons of this stuff and having something that's completely inert you still want to fill up with explosive so it possibly detonates at some point I don't really know if it's if it's worth the effort because it might be that cheap and you still want some explosive in it to do

some damage at some point and another question here so they took a few examples I suppose of each of these bombs to to figure out how to diffuse them how many examples did it take them to figure out those procedures and how reliable were they once they figured that out did they improve over time repeated showings or did they still have repeated failures that's kind of a long a chance that they had it's probably best if I do it later because that would be a small token itself how they figured this out they had a bunch of people like he was a guy called the other Suffolk who was the stadia for bomb defuser he was it was

like the canonical mad scientist he hit this big stately home and he get these bombs wheel into the middle of his almost palace and start mucking around with him in the basement figure out these techniques so some of it was you know rigorous research and some were what was just these eccentric geniuses who figured out some of the stuff he mean she got killed defusing some new type of bomb that he had encountered before so it was it was a very British way of doing things they just got anybody they could think of anyone who could coup could come in and say don't have a go out looking at this got thrown at it and yes some of it was like some

of was expertise like the other sufferer got better and better over time he went from the simple fuses to the more complicated ones and that's like computer hacking you know if people hacking 20 years ago you had relatively simple attacks in SDS the defense's got me to the attackers adapted their techniques and got better and better so with the simple fuses the lis diffusers got trained up on this and once they the experience were the easy fuses that could work onto how diffusers that were deployed later but that that's a very short version of a much longer answer there anymore are there any more questions well let's thank Peter Goodman for is such a great keynote

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