So how big a bomb do you want?

[LurkerBelow]

It seems that 30,000 pounds of bomb isn't enough for the USAF:

Pentagon: 30,000 Pound Bomb Too Small - Slashdot (http://tech.slashdot.org/story/12/01/31/1818215/pentagon-30000-pound-bomb-too-small)

Looking at pictures of the thing, I would have thought the fins and paddle-thingies on the back end would cause serious drag issues.
After all, you only need to get close enough I would have thought and was the design principle behind Barnes Wallis's original idea.

[VinRouge]

the fins are chosen due to space available i would suggest in the B2 bomb bay. the bonus of them is they have a very low aspect ratio for lift generated and with the momentum of a 30,000lb device, you need a lot of lift to change the flight path. as for accuracy, you need to pu these things inside the bunker, or as close as is possible .

similar fins on russian AAMs. poor manoeverability through the transonic region apparently. all on Wikipedia.

[stilton]

Big Bomb,


How big were the 'Grand Slam' and 'Tallboy' of WW2 fame ?

[green granite]

The Grand Slam was a 22000 lb and The Tallboy 12000 lb

http://upload.wikimedia.org/wikipedia/commons/thumb/7/78/British_Grand_Slam_bomb.jpg/300px-British_Grand_Slam_bomb.jpg

http://www.bombercommandmuseum.ca/photos/p_tallboy1.jpg

[Harley Quinn]

Must use some dense material to aid penetration, I was surprised to find it is 6' shorter than the venerable Grand Slam (26' 6" long, 3' 10" dia) yet nearly half as heavy again

[Milo Minderbinder]

thicker case, less explosive
I think that was covered in the Big Blu thread

[Harley Quinn]

Yes I see, MOP fraction of bang to case ~ 1:4, MOAB & GS ~ 1:1
Also GS was equivalent to 6.5 tons of TNT penetrating c140' into earth, MOAB 11.6 tons of TNT is not a penetrator weapon, there doesn't seem to be much more info out there re MOP but it has claimed penetration of c200'.

[kbrockman]

Is this the mysterious G-13 weapon?
ziZHoCaZ1Fs

[Bushfiva]

Paddle thingies ensure the bomb is vertical at the point of impact. I assume they fold in when they detect the bomb is vertical. If I misremember incorrectly, Saddam's main bunker chamber survived because it was very strong, and also the ceiling construction was layered to fake floors. So floor-counting penetrators went off too soon. But the roof of the bunker would have been too strong anyway.

So no, the bomb probably isn't too large, especially if they haven't fixed the floor-counting issue yet.

[VinRouge]

One wouldnt be surprised if they arent dropped in multiples. penetrator style warheads can be used cumulatively I believe to "dig down" to get to where they need to.

I wonder if they are pure hardened steel or if the charge consists of some form of shaped effect? I believe the original penetrators from GW1 were machined from artillery piece barrels, although this could be an urban myth.

[Pontius Navigator]

Given the possible precision I like the idea of a bomb queue. Same as the Upkeep rather than Grand Slam that simply pulverised the whole area.

The Tall Boy was, I believe better on the submarine pens as its casing was stronger.

The Impact Velocity of the TB and GS was only 1020 fps assuming a release at 20,000ft.

From 40k a TV of 1600 fps would have been possible.

[Mike7777777]

U-boat pens at St Nazaire are impressive, scenic lift ride through the roof slab gives a good impression of the thickness of concrete. I thought that the RAF's Tallboys had penetrated the roof, but this website suggests otherwise U-Boat base in Saint Nazaire: Too big to knock | The Helpful Engineer (http://thehelpfulengineer.com/index.php/2011/08/u-boat-base-in-saint-nazaire-too-big-to-knock/)

[LowObservable]

The original 4,700 pound GBU-28s had bodies made from old 8-inch naval gun barrels, I believe, although eventually they ran out and went to custom cases.

//Nearly typed that as "gin barrels"

[Courtney Mil]

Interesting. Watch the video again and listen to the voice. It's synthetic. Why? What message is this trying to send and what is the origin?

No problem with the rear fins, they are that way for a reason - to give sufficent surface area to stabilize the munition whilst being able to be folded flat against the body for carriage.

20 is a very specific number to buy. Most munitins are bought in 1000s unless for a specific task - obviously, before you tell me that.

Pause for thought.

[whowhenwhy]

Message? This will be the Yanks suggesting to Mr I'llgetmadinnerjacket that they're ready for him if needs be. I'd suggest however that there's no way that they'd try and go through the "front door"

[Pontius Navigator]

CM, Grand Slam and tall Boy were built in small numbers too and were also serialled. The disposal of each was recorded.

[NutLoose]

This is more like it, the Israeli way... Fascinating reading..

How to Almost Make a Million Dollars - Robert X. Leeds - Google Books (http://books.google.co.uk/books?id=iInNeQP6AqQC&pg=PA99&lpg=PA99&dq=austers+stored+upright&source=bl&ots=86QnQv28PS&sig=4LBIzkCW4R3a4HF6eV01Vrxm16M&hl=en&sa=X&ei=044HT8GcG4P88QOyyPzIAQ&sqi=2&redir_esc=y#v=onepage&q=austers%20stored%20upright&f=false)

[NutLoose]

LowObservable
The original 4,700 pound GBU-28s had bodies made from old 8-inch naval gun barrels, I believe, although eventually they ran out and went to custom cases.

//Nearly typed that as "gin barrels"


There was a programme on them, they were actually developed as an in house project on the side by a team at some ordinance company, when the military were looking at taking out some of Baghdad's bunkers they rushed some into production, the barrel was a cheap quick fix to the casing problems, they dropped one in the desert to see if it worked but had no way to see if it achieved a 200ft penetration. After the first drop the other one or two built were rushed to the Gulf and dropped, no one knew if it worked until ENDEX when they were able to see they had, the charge was really small, but in the enclosed bunker complex it was devastating.

[reacher]

Is this the mysterious G-13 weapon?


I heard it destroys everything but the fillings in their teeth. Help pays for the war effort (God knows we need any cash we can find these days) :E

[stilton]

Thank you Green Granite.


The Bomb load a Lancaster could carry is still very impressive. Until the B29 came along the USAF had nothing to compare.

[LurkerBelow]

I would have thought the hardest part of an underground bunker would be through the roof. Wouldn't it be smarter (and what Barnes Wallis originally designed the Grand Slam to do) to actually miss slightly so that the bomb penetrates the softer ground next to the target and the explosion effectively is directed at the sides of the bunker. My recent experiences of earthquakes suggest that a sideways shake is very much harder to cope with (imagine desks, racks and cabinets being flung sideways across a room)

[Rosevidney1]

I agree with LurkerBelow. We have become fixated on hitting the target when a near miss is quite likely to accomplish the desired result.