"raf cookie bombs accuracy (cep) ?" Topic

guys
the raf 2000lb 4000lb and 8000lb cookie bombs were simple long cylinders with no nosecones or tailfins ,
so they can't have been very accurate without them, so why were they not fitted with fins (does someone have figures for accuracy or cep)

How accurate does an 8000lb bomb need to be?

Accuracy simply wasn't in the design brief; they were intended for use against built up areas, not point targets. Their main function was to create enough blast to lift rooves, so that incendiaries could get in, so precision really wasn't demanded.

Yea, not much need for accuracy (I realize that sounds wrong, but in the larger scheme of things, it really is correct), when you are conducting area bombing, at night.

Yep – like it or not (and it's not a strategy I've ever really reconciled myself with) when your target is "this city" the optimal weapon mix is rather different from when you're going after specific assets.

even bombs with regular tails weren't very accurate when used from high altitude. In those days any bomb within 500m of the target was counted as a hit for bomb damage assessment purposes…

but even those apparently without a tail still had one. while it looks like a cylinder, the last part of the bomb was just an empty pipe. this also stabilises the bomb because the center of gravity is moved forwards

I thought tail fins were mainly to keep the nose pointing downwards – thereby reducing the drag and allowing it to fall faster – which would reduce scatter too.

Accuracy with iron bombs is still not great and was appalling in WW2. The USAAFs using the Norden bombsight could not hit precision targets either so went over to having all the bombardiers drop when they saw the lead a/c drop. Thus the target would be covered by a small carpet of bombs – a rug? – less wasteful and a less cavalier approach towards 'collateral damage' than the RAF's but by no means surgical.

I suspect 'Bomber' Harris' strategy of bombing cities and fomenting a revolt stems from how close Britain came to serious civil dissent in 1940. The propaganda of the time is full of 'taking it' and 'the spirit of the blitz' but I wonder how much this is the opposite of the truth.

"I thought tail fins were mainly to keep the nose pointing downwards – thereby reducing the drag and allowing it to fall faster"

Nope. Falling faster has no inherent virtue. Fins keep the bomb from tumbling. Tumbling produces unpredictable--and very large--aerodynamic forces. Same reason that bullets and shells are spin-stabilized.

'less wasteful and a less cavalier approach towards 'collateral damage' than the RAF's but by no means surgical.'

The RAF tended to bomb at night. They considered the US approach to be cavalier in the sense that day bombing produced more losses for your own side.

how close Britain came to serious civil dissent in 1940. The propaganda of the time is full of 'taking it' and 'the spirit of the blitz' but I wonder how much this is the opposite of the truth.

My understanding is that the government of the time designed a top secret "Keep calm and carry on" poster that would have been spread all over the country had the situation become sufficiently desperate.

More seriously, I presume that the British government put together some sort of secret reports about the morale of the general population. I presume that those might have also been available for researchers for a while by now.

Falling faster would reduce the time in the air before impact – thereby less time for drifting…in theory anyway.

Tumbling would obviously be a bad thing.

I read somewhere about large gangs of bombed out civilians roaming the countryside near London. Pretty sure this came from Clive Ponting's book 1940 Myth and Reality. He touches on the resentment and anger the Blitz caused Londoners as very little was done to protect them.

I don't think the UK was close to a revolution, but then the Blitz was small beer compared to the devastation heaped upon German cities – and Harris always planned more than he was ever able to inflict.

Adding fins to a twenty foot long dumpster may affect the accuracy of it hitting something from ten thousand feet by a few yards on the ground if at all.

Accuracy in comparing the USAAC vs RAF raids was pretty equal for '43-'44, with a slight edge to the RAF by '45! I'ld prefer that you start an independent post to discuss that. No slight to either group, a lot of good men were lost doing their best.

If target marking and bombing was within 300m then it was exceptionally good. That goes for both sides.

For raids of 700 or 800 bombers, the first one or two hundred bombers would actually concentrate on specific target areas, the next group would either shift the target along or even have other targets altogether. The bombload would vary widely depending upon the nature and build of the target. Brick tight packed residential, cinder block industrial, or even urban centre stone. Bombloads were geared towards the target as such. Will 250 or 500lb blast, armour piercing or a fragmentation be needed, 2,000lb cookies, a 4,000lb blockbuster or more. At what point do we mix in incindieres or just add them to the drop mix et cetera.

These are things that were practiced by both the USAAC and the RAF. The most effect was probably given by the use of larger blast damage of the RAF due to the larger capacity bombs used on a more regular basis. The Germans really admitted as much that an RAF raid would indeedcause more damage, it is stated in quite a number of books by ex-US aircrew as well.

I am trying to remember just how many tallboys hit the Tirpitz vs coming near enough?

"Falling faster would reduce the time in the air before impact – thereby less time for drifting…in theory anyway."

Very little effect. "Drift" in the sense of "wasn't aimed properly" is independent of velocity. If you're off by 0.01 degrees, you miss by exactly the same amount regardless of velocity.

Falling faster does (marginally) reduce the effects of cross-winds blowing the bomb off course. Compared to the effects of tumbling, cross-winds are trivial.

Hmm, why didn't the RAF use Biscuit Bombs?

But looking at the font of all knowledge, Wikipedia, these would certainly lift roofs off:
"We were flying at 6,000 feet which was the minimum height to drop the 4,000 pounder. We dropped it in the middle of town [Koblenz], which gave the aircraft a hell of a belt, lifted it up and blew an escape hatch from out of the top"

"Your biscuits are in your tin – sir."

I suppose biscuits were rationed and cookies a lend lease thing…

Sorry – I'll get my coat….

thanks guys
going to hijack my own tread now
you say fins weren't necessary because they were intended for area targets so why were nukes then and now b61 etc carry fins? very big area coverage

@wardog

Probably to keep them in a stable attitude while dropping. You don't want your very expensive bomb to fail because a component could not resist the additional forces from a 'tumble' or a 'spin'.

Dropping nukes was a very precise process. Randomness was a very undesirable attribute.

For one thing you needed predictable fall rate and forward displacement to give the aircraft an opportunity for an escape maneuver. As others have pointed out, if the bomb had randomness in it's wind resistance it might not travel as far forward from the drop point, and might drift more to one side. Might not matter to the target given the nature of area bombing, but might make a BIG difference if the dropping plane had a 270 degree banking turn escape maneuver.

Also most air-dropped nukes had radar altimeter based fuzes. They were set to detonate at a specific altitude. The radars were quite simple (both for size and because, well, you weren't going to use it for more than one purpose), and so uni-directional. If your bomb tumbles randomly you have very little predictability in where the radar is pointing, and when. Again, you don't want randomness in when that bomb goes off. Too high and you incinerate a lot of airspace (and your drop plane), too low and you greatly reduce the radius of blast effects on built-up areas, and kick up a lot of dust to become fallout far away. So pointing the nose down and keeping it there was kind of important.

Or so I understand.

-Mark
(aka: Mk 1)