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Deep Penetration bombs


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#1 Wuzak

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Posted 14 July 2007 - 12:07 AM

During WW2 there were only two truly deep penetration bombs used, the 12,000lb Tallboy and the 22,000lb Grand Slam.

Because of the size and weight of these they could only be carried by specially modified Lancasters (and also B-29s later). The target drop altitudes could not be met by the Lancaster, but the altitude it could reach were deemed to be sufficient for the task.

This is the 12,000lb Tallboy bomb

Posted Image

And this is the 22,000lb Grand Slam bomb

Posted Image

You will notice that in front of the Grand Slam bomb is an example of the 4,000lb ballistics test bomb, used to test and prove the theory of deep penetrating bombs.

Looking at the test bomb I got to wondering how useful a weapon that might have been. It would have been packed with 35-45% of its weight in explosives (Tallboy 43.3%, Grand Slam 41.5%).

In terms of numbers used these bombs were not significant. About 850 Tallboys and 41 Grand Slams were used.

It is doubtful that a 4000lb deep penetration bomb would create the earthquake effect that the larger bombs did, but surely it would be useful for damaging bunkers and underground facilities?

And of course being smaller and lighter it would be possible to carry the bomb in more aircraft. A Lancaster probably could carry two within its standard bomb bay.

Now here's the fun part.....

This is a 4,000lb HC "Cookie" nestled under the wing of a B35 Mosquito.

Posted Image

Having looked at both the Cookie and the test bomb (albeit a week and a half apart) I got the sense that the test bomb would fit where the cookie could - ie in a Mosquito!

If nothing else the bomb would be more accurate than the blast bomb "Cookie".


PS: Just read that the US military is developing 30,000lb+ deep penetration bomb.

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#2 PMN1

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Posted 14 July 2007 - 12:33 AM

US 'big bombs'...

http://home.aol.com/...42,000-lb, T-12

#3 PilotOfficerPrune

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Posted 15 July 2007 - 11:17 AM

Well, it's worth remembering that one of the primary targets for the deep penetration bombs was supposed to be German coal mines, most of which were conveniently located close to the UK in the Ruhr. Without any figures at all I can only guess whether the 4,000 pounders could have penetrated deep enough or been powerful enough to collapse some of the underground workings. It'd be interesting to know if anybody ever gave thought to trying to damage collieries with ordinary semi-armoured piercing bombs on long delay fuses. After ali, Hitler fought his war on coal and, as I say, most of it was dug up and used in the Ruhr or transported to other parts of Germany. It's also worth remebering that coal miners were and are extraordinarly skillful workers and very hard to replace if killed.

Incidebtally, there was a discussion a while ago on another thread about how the cookies were designed to explode before hitting the ground. THey used barometic fuses actuated by ground effect. As the blunt nosed cookies fell they pushed a shock wave of air in front of them. When it hit the ground the shock wave bounced back, encreased the air pressure in front of the bomb and triggered the fuse. Of course there was also a conventional impact fuse as well.

#4 Wuzak

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Posted 15 July 2007 - 02:36 PM

Interesting thoughs...

Were the German Coal mines deep underground or at a minimal depth?

Were any attempts made with Tallboys or Grand Slams against the mines?


As to a 4000lb deep penetration bomb, its weight may not have given it the penetrating power, but it would be carried higher than either the Tallboy or Grand Slam - probably 30,000ft+ when carried by a Mossie as compared to half that for a Lanc carrying a Grand Slam.

#5 PMN1

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Posted 15 July 2007 - 04:37 PM

quote:Originally posted by Wuzak

Interesting thoughs...

Were the German Coal mines deep underground or at a minimal depth?

Were any attempts made with Tallboys or Grand Slams against the mines?


As to a 4000lb deep penetration bomb, its weight may not have given it the penetrating power, but it would be carried higher than either the Tallboy or Grand Slam - probably 30,000ft+ when carried by a Mossie as compared to half that for a Lanc carrying a Grand Slam.


Tallboy and Grand Slam targets (From Stephen Wallis' 'Barnes Walis' Bombs')

Amongst others, in alphabetical order….

Arbergen Bridge

Arnsberg viaduct

Bad Oeynhausen bridge

Bergen U-boat pens

Bielefield viaduct

Boulogne E-boat pens

Bremen bridge

Brest U-boat pens

Dortmund-Ems canal (various sections)

Farge oil storage depot

Farge U-boat shelter

Hambourg/Finkenwerder U-boat shelters

Helgoland coastal batteries

Ijmuiden E-boat pens

Kembs barrage

Ladbergen canal banks and aqueduct

La Pallaice U-boat pens

Le Harve U-boat pens

Lorient U-boat pens

Lutzkendorf/Wintershall synthetic oil plant

Marqise/Mimoyecques V-3 supergun site

Nienburg bridge

Politz hydrogenation plant

Rilly-La-Montagne V-1 store

St Leu d’Esserent V-1 storage dump

Saumur tunnel

Siracourt V-1 launching bunker

Vlotho bridge

Waalhaven E-boat pens

Watten V-2 liquid oxygen plant

Wizernes V-2 launching bunker.




I dont recall any attacks made on coal mines.

#6 PilotOfficerPrune

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Posted 16 July 2007 - 08:38 PM

I never said any attacks were made on coal mines. I said that they were one of the targets Wallis had in mind when he first began thinking about his big bombs. He apparently started out with a theory of destroying different kinds of industrial energy sources -- oil, coal and water (i.e dams). Since the dams required smaller bombs, they became the priority. This site seems to have some interesting stuff, on the bombs and the Victory bomber

http://www.computing...ay/bigbounc.asp

You'll appreciate of course that I'm talking 1939/1940 here. Neither the aircraft nor the bomb aiming techology existed to hit the kind of pin point targets you've listed. Indeed, there was no way that Wallis could have known at that time that things like U-boat pens or V1 sites would ever be built, and certainly not as close as the French coastline. France hadn't been occupied then. But coal mines are big enough targets. Certainly the RAF spent a lot of its early efforts bombing rail junctions in the Ruhr trying to disrupt the movement of coal to the rest of Germany. Dropping eggs on Hamm became something of a standing joke because of the number of times the BBC mentioned British planes bombing Hamm (eggs was RAF slang for bombs).

As lifting the 4,000 lb higher, yes, that would have been possible. But you'd need somebody to tell you at what height there was no point in going any higher because of the bomb's terminal velocity. I don't have the maths to make that call.

#7 PilotOfficerPrune

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Posted 16 July 2007 - 09:17 PM

Incidentally, a lot of people don't know that the USAF used a guided version of the 12,000 lb Tallboy in Korea. It was withdrawn from service because of some premature explosions which destroyed the carrying planes.

A quick check on Wikipedia tells me that Tallboy was actually intended to be dropped from forty thousand feet but the Lancs could only reach twenty five thousand feet, which resulted in a crater eighty foot (24 metres deep). I'd guess the smaller bomb digging in at a higher impact speed would probably have resulted in a similar kind of crater. Let's just say that I wouldn't have wanted to have been in an underground tunnel anywhere in the vicinity, no matter how deep down.

Incidentally, a very well known novelist called Neville Shute wrote a novel just before the war about what would happen if Britain was bombed. The title was "Whatever Happened to the Corbetts?" Neville Shute in real life was Nevil Shute Norway, a highly qualified aeronautical engineer who founded Airspeed Ltd. He therefore had a good idea of what he was talking about. He put foward an idea in the book that the Germans might be able to bomb pretty accurately at night by taking star sights with gyro stabilised sextants.

He wasn't quite right there but he also believed in using deep penetration bombs as the primary weapons to destroy a city -- or city life, at least. He expected the Germans to rain down fifty kilo delayed fuse bombs which would break open sewage and water pipes under the city streets. Pretty soon it would be impossible to keep up with the repairs and disease would do the rest, especially in summer. With no sewage, no fresh water and cholera on the loose, the population would have to move out into the country. I'm not sure that anybody yet has ever fully tried this out, although a lot of cities have certainly suffered plenty of infrastructure damage during bombing attacks. Perhaps it wouldn't work nowadays, with so much plastic piping around.

On the other hand it seems that London is still largely reliant on underground sewage and water pipes the Victorians built. So maybe Mr Shute knew a trick or two that The RAF should have picked up on.

#8 Wuzak

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Posted 16 July 2007 - 10:52 PM

Talking of Barnes Wallis, I watched Mosquito Squadron the other day. Interesting that he was mentioned as his Highball concept was used. The interesting thing was that it was used on land, and what appeared to be an official test of a Mossie dropping a Highball on land was shown.

Anybody know of the planned use of highball on land?

#9 Red Admiral

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Posted 17 July 2007 - 12:44 AM

quote:Anybody know of the planned use of highball on land?


Maybe not _planned_ usage exactly but I now there is a least one film with Mosquitoes using highball as the plot line. IIRC they were meant to bomb a tunnel in a hillside or something. There is good footage of Mosquitoes bouncing highball across an airfield.

#10 PMN1

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Posted 17 July 2007 - 04:44 AM

quote:Originally posted by PilotOfficerPrune

I never said any attacks were made on coal mines. I said that they were one of the targets Wallis had in mind when he first began thinking about his big bombs. He apparently started out with a theory of destroying different kinds of industrial energy sources -- oil, coal and water (i.e dams). Since the dams required smaller bombs, they became the priority. This site seems to have some interesting stuff, on the bombs and the Victory bomber


Oh I didn't mean to suggest you had, I was just pointing out that no attempts seem to have been made on what was planned to be an original target for Wallis bombs.

There is a very good description of the thinking behind his bombs in Paul Brickhill's 'The Dambusters'.

#11 Wuzak

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Posted 17 July 2007 - 05:21 AM

quote:Originally posted by Red Admiral

quote:Anybody know of the planned use of highball on land?


Maybe not _planned_ usage exactly but I now there is a least one film with Mosquitoes using highball as the plot line. IIRC they were meant to bomb a tunnel in a hillside or something. There is good footage of Mosquitoes bouncing highball across an airfield.


Yes, it is called Mosquito Squadron!

#12 pmjwright

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Posted 19 July 2007 - 03:33 AM

One of the biggest failings of the strategic bombing campaign was understanding that the German economy was so strongly coal-based, as the planning was done largely by people with an oil-economy experience (but even the coal-based Brits failed to recognize this). Only a few minds really got thinking about the coal side of things.

DP bombs on coal mines is an interesting theory, but would have been very difficult to have created significant damage in practice. Much easier to disrupt the transportation system and/or damage the synthetic oil and chemical plants on the surface.

Looking at it from a mining engineer's perspective: DP bombs would have 2 likely results--collapse of tunnels and workings, and/or triggering massive explosions of methane gases and coal dust. Damage would be dependent on depth of the workings, which I think would have to be less than 30m below surface to be susceptable. Most mines are already engineered to deal with the physics and stresses of the weight of rock above--techniques such as pillars, shoring, bolting the hanging wall etc. Rockfalls and collapses happened regularly enough that miners are familiar and "ready", and so could be cleared within a short time. So the disruption of mining from tunnel collapse by an "earthquake bomb" is likely to be minor--possibly a few workers killed, a few days lost production.

(to put the above in perspective, look at the history of Frank, Alberta. A massive landslide of nearly 100 million tonnes of rock destroyed the town and buried the coal mines, yet all the miners survived and were able to dig themselves out within a matter of hours. The underground workings were hardly damaged. So, what effect would a "little" bomb have by comparison?)

OTOH, many underground coal mines are explosions waiting to happen. Methane explosions are usually very destructive to the workings, not to mention the massive loss of life. But with proper ventilation to control gas and dust, coal miners used explosives all the time to break up the coal seams without causing the big bumps (as a gas explosion is called). Conditions would have to be "just right" for a bomb to trigger a bump.

But only certain types of coal are methane problems--some bituminous coals (called high-volatile). The majority of German coal was brown-coal or lignite which gives off relatively little gas. Therefore bombing is not very likely to trigger the massive explosion needed to really have the strategic impact on the resource. Only some mines would have therefore been good candidates.

There were 3 main areas of German coal production--the Ruhr, Silesia and the Merseburg area (which fed the massive Leuna synthetic oil plants and associated chemical plants). Only the Ruhr was "easy" given the factors of bomb load and range. And only the Ruhr had the quantities of the high-methane hard coals. However, many of the Ruhr mines were at depths of several hundred metres by this time, as a result of hundreds of years of mining. That's way too deep for bombs to have effect! The brown coal mines were much shallower, but as mentioned, this coal doesn't have the volatility.

Overall, then, there would have seemed to be minimal opportunity to disrupt German coal mining industry by bombing. As I said above, it was far easier to disrupt the transportation or the processing of coal into war materials. And as it turned out the SBC had virtually halted the movement of coal by late 1944. And that collapsed the German war economy as effectively as any other Allied action.

(As an aside, the last German coal mines are expected to close by 2018. What a change from the coal economy of WW2 and the post-war era!)

#13 PilotOfficerPrune

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Posted 19 July 2007 - 07:21 PM

That's an extremely interesting analysis and as far as I'm concerned it settles the question, unless anybody else has got any insights to offer.

#14 Wuzak

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Posted 29 January 2009 - 02:35 AM

Was there any thought to using Tallboys against targets such as Luena, or factory complexes?

What would the effect of 15 to 20 Tallboys used against a facility like Luena, particularly if the bombs could be targetted at key buildings (not all would hit, of course, but there may have been some near misses)?

#15 merlin

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Posted 29 January 2009 - 09:23 AM

The other thought - goning off in a different direction - what if they were still available? Wouldn't they have been useful in Iraq - bunker busting, or in Afganistan!? As long as they didn't trigger a real earthquake!

#16 Astrodragon

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Posted 29 January 2009 - 05:24 PM

Was there any thought to using Tallboys against targets such as Luena, or factory complexes?

What would the effect of 15 to 20 Tallboys used against a facility like Luena, particularly if the bombs could be targetted at key buildings (not all would hit, of course, but there may have been some near misses)?


I would have suggested a mix of Tallboys (destroy plant, and damage a lot more with the shockwaves), plus a mix of A/P bomblets (stop the firefighting effort) and incendiaries.
Don't think that would leave much plant afterwards

#17 Red Admiral

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Posted 29 January 2009 - 05:45 PM

The other thought - goning off in a different direction - what if they were still available? Wouldn't they have been useful in Iraq - bunker busting, or in Afganistan!? As long as they didn't trigger a real earthquake!


Similar types but a lot smaller are used in the Ghan. A large increase in explosive power and greater accuracy means the weapons can be smaller. There's probably not much that can carry a 22000lb weapon anyway. If more penetration is needed then terminal rocket boost is the way to go.

#18 Wuzak

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Posted 29 January 2009 - 09:46 PM

I would have suggested a mix of Tallboys (destroy plant, and damage a lot more with the shockwaves), plus a mix of A/P bomblets (stop the firefighting effort) and incendiaries.
Don't think that would leave much plant afterwards


Have just read that tallboys were used on a synthetic oil plant with little success.

The theory was that blast bombs (HC bombs) did more damage to pipes, etc. But I would have thought that tallboys into storage tanks and buildings (or near misses) would do a lot of damage.

So a few well aimed Tallboys as well as blast bombs and incendiaries.

#19 Red Admiral

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Posted 29 January 2009 - 10:28 PM

Just try and hit the fire fighting part of the oil refinery first. After that you're pretty well sorted. Tallboy penetrations might help disrupt below ground water pipes.




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