Aerial Bombing Question

[swampyankee]

The issue is further complicated by the nature of "earthquake bombs" themselves. The RAF crippled the Tirpitz by hitting close but the ship itself, not knowing this they made another raid which hit and sank it. The raid on the V3 site hit it when actually it was supposed to narrowly miss, more devastation is caused by the bomb exploding deep under the foundations, in any case the V3 site was wrecked. On a viaduct they didnt want to hit it, if the bomb struck a column it may well just explode above ground, exloding alongside but deep underground destroyed the bridge and its foundations.

I think the USAAF had units of comparable skill, but that kind of accuracy could not be realized in anything other than small unit raids. As an aside, at least one of the bombs dropped on the Tirpitz went through the ship and detonated underneath.

 

[pbehn]

And the height at which a Lancaster could actually carry the bombs (especially the Grand Slam).

He He Wuzak it could be a topic all by itself, for example the Tirpitz was at sea level but a viaduct isnt. I saw a video with the bomber of the V3 site discussing the raid. He said he was instructed to aim at it and it was hoped that the inaccuracy in the system as a whole would produce a narrow miss. He hit the concrete but near the edge so the bomb did wreck all the underground workings and tunnels.

 

[stona]

In all cases the bombs were aimed at the targets, I have both heard and read several first hand accounts to confirm this.

Tirpitz had been attacked twice previously with 'Tallboys' the worst damage being done by a tallboy which hit the bow, passing through to explode in the water. She was certainly damaged by near misses. On the successful November raid, both British and US reports agree that the most damaging strike was the second (arguably) direct hit which passed through decks and armour before detonating in a filled wing tank near the torpedo bulkhead of the port engine room.

The dome at Wizernes was undermined by the bombs, but, again, the bomb aimers aimed at the dome. Some near misses were almost guaranteed given an average radial error (at that time) of close to 200 yards.

Several direct hits were scored on viaducts and similar, but most remember the near miss from a Grand Slam bomb which collapsed a substantial portion of the Schildesche Railway Viaduct, near Bielefeld, because the RAF had started to film these raids for propaganda purposes.

Tall Boys were dropped operationally from as high as 18,000ft, but Grand Slams from around 12,000 ft.

Cheers

Steve

Edit: the bomb illustrated above blew the port side and bottom of the ship out (and the torpedo bulkhead in) from frame 98 to frame 132 and across roughly 1/3 of her beam.
Bomber Command's ORS report (S.218) on the attack was published in May 1945.

 

[pbehn]

Our posts overlapped Steve, you cannot tell a bomb aimer to deliberately miss. With the Tirpitz a hit was the desired result though a near miss was almost as good. With the V3 and viaducts a narrow miss was preferred, the only way to get this is to aim to hit it.

 

[pbehn]

It just occurred to me that a hit on the bow is possibly further away from the aiming point than a near miss amidships.

 

[stona]

It was a good hit. When USN divers examined the wreck after its final sinking they estimated that this bomb (from the September 15th raid) had destroyed the front 100' of the bow and buckled or ruptured the 'shell' plating for 150'. The front 120' of the ship was flooded to some extent. None of this damage had been repaired by the time of the final raid. Had the Allies known this they probably wouldn't have bothered with the succeeding raids, Tirpitz was going nowhere.

It is generally accepted now that Tirpitz sustained three direct hits on the final November raid, the first near turret 'Bruno' the second as above, and the third near turret 'Caesar'. Nearly 16,000lbs of of high explosive will seriously ruin your ship. Several other bombs landed to the port side of the ship, three of them were close enough to inflict more serious damage.

Cheers

Steve

 

[pbehn]

Not questioning that it was a good hit or not, just that if you take the funnel as the aiming point then it is possible to be closer to the funnel and miss the ship than a hit in the bow is. I was just discussing accuracy, in this case a hit is not always more accurate in terms of the bombing than miss is. Happily most targets are not the shape of a battleship.

 

[Zipper730]

When using the Norden to aim then the automatic mode would have been used, it was an integral part of the system.

So basically it would be almost never unless it didn't release automatically, or for some sort of training purpose?

The SABS was statistically the most accurate bomb sight of the war, its why No. 617 (and 9) Squadrons used it to drop extremely large bombs onto extremely precise targets, like viaducts, V-1/V-2 sites and battle cruisers. No. 617 Squadron achieved an average radial error of 125 yards from 20,000 feet in the period February to March 1945. In the same period another 'precision' squadron, No. 9, using the Mk XIV achieved an average radial error error of 195 yards. This is the best comparison we have between the two British sights.
Comparisons are difficult, it is not just the sight that influences accuracy. In this period, visually, the USAAF was typically placing about 30% of bombs within 330 yards of the target, which is widely comparable to Bomber Command with its Mk XIV by day, but the skill of the bomb aimers/ bombardiers becomes an important factor.

Thought this might sound redundant, but average radial error = CEP, or 100% of the bombs falling in the radial error?

As for skill and precision that obviously goes a long-way.

The next questions I'm going to ask go quite a bit away from World War II but have to do with bombing carried out with various Cold War Equipment all the way up through Vietnam. I'm curious as to the CEP's achievable by bombers such as the B-47 and B-52 early on (1955 - 1965), and later (1965-1972).


BTW: I haven't been posting much because of a criminal justice course that requires a power-point created and creating a power-point with bibliographies frankly are exasperating.

 

[fubar57]

The last question could be asked in the appropriate era...Other Eras WW2Aircraft.net Forums

 

[stona]

Average radial error and circular area probable are not the same.
Average radial error is precisely that, the average displacement of all the bombs dropped from the aiming point. It is a good measure of both accuracy and precision. It's why the British used it for specialist precision bombing units like No. 617 Squadron. They also used it for the fighter bombers of the tactical air forces.
Circular error probable is the radius of a circle, centred on the aiming point, within which 50% of the bombs will fall.
Cheers
Steve

Edit : CEP is a good measure of accuracy (what percentage of bombs fall close to the target) but not precision/concentration (the overall number of bombs that fall close to the target). 50% of bombs may fall within 300 yards of the aiming point, but 20% may fall literally miles away.

You can achieve a very precise/concentrated bomb fall, but which falls a long way from the aiming point, which is precise but inaccurate.

You can achieve a much less precise/concentrated bomb fall which is accurately centred on the aiming point, which is accurate but imprecise (see CEP above)

You can achieve a concentrated bomb fall accurately centred on the target, which is both accurate and precise. A small average radial error shows these criteria to have been met which is why the system was used to assess the accuracy and precision of the specialised precision bombing squadrons.

 

[Zipper730]

The last question could be asked in the appropriate era...Other Eras WW2Aircraft.net Forums

I can do that: I'm just unsure if it would be logical to create a thread that would basically be a duplicate on another forum.

Average radial error and circular area probable are not the same.
Average radial error is precisely that, the average displacement of all the bombs dropped from the aiming point. It is a good measure of both accuracy and precision. It's why the British used it for specialist precision bombing units like No. 617 Squadron. They also used it for the fighter bombers of the tactical air forces.

Did the USAAF or USN ever use Average Radial Error at all?

 

[stona]

I can do that: I'm just unsure if it would be logical to create a thread that would basically be a duplicate on another forum.


Did the USAAF or USN ever use Average Radial Error at all?

We've already discussed what method the USAAF used.
I don't know about the USN. Given that it tended to be bombing small targets which require both precision and accuracy to hit, it wouldn't surprise me if they did calculate average radial error.

CEP seems to have become a fairly standard method, dating back to its use for the fall of artillery. I would suppose the strikes from an artillery barrage and the bomb fall from a bomber formation have a lot in common, but the application of common sense rather than any expertise (which I don't have in such analyses) can lead to erroneous conclusions

Cheers

Steve

 

[fubar57]

I can do that: I'm just unsure if it would be logical to create a thread that would basically be a duplicate on another forum.

.....but it's OK to duplicate here???

 

[Zipper730]

.....but it's OK to duplicate here???

I don't mean responding to two people at once, I mean creating essentially a redundant thread. This thread is about bombing accuracy, so I figure it might be frowned upon to place a thread that's essentially the same in another forum.

Do we understand each other?

 

[pbehn]

Stona, was there any separation between bombing error in the North /South and East/West (fore aft/port starboard) It is referred to as a radial error but I would think it would be an ovoid shape depending on altitude and other factors.

 

[stona]

The actual pattern of bombs might well be non circular, but radial error is calculated as a function of a circle. In the most extreme example, if all the bombs fell in a straight line across the target, they would delineate (in this hypothetical case, literally) the diametre of an imaginary circle and a radial error can be calculated.

The average radial error can be greater than the CEP (obviously). For Typhoons attacking nine 'pin point targets' in late 1944/early 1945 the average radial error was 158 yards, but 50% of bombs fell within 130 yards of the target (the CEP).

Some targets required a different analysis. For attacks on a railway line only the error to each side of the target is relevant. This the British called a 'line error'. For British fighter bombers in the same period the average line error was 69 yards, but 50% of bombs fell within 50 yards of the target. Because these errors are line errors they do not represent an average radial error or CEP, for all we know the 320 bombs plotted might have extended for miles either side of the railway line!

Cheers

Steve

 

[Zipper730]

I'm curious if members would prefer it if I would create a thread on the Cold War era forum? The moderators, would I get in trouble?

It's about the technology and speed at the time...

 

[GregP]

No, we don't Zipper. This is a WWII forum, not a post-WWII forum. You'd be better off using the correct forum and staying on-topic, creating another thread for subjects that wander off-topic. Basically, one thread should have one central question. Other subjects are properly in another post. That way, you can find them later instead of remembering that it was discussed somewhere, but you can't ever FIND it again.

Cheers.

 

[Zipper730]

Okay

 

[Koopernic]

So basically it would be almost never unless it didn't release automatically, or for some sort of training purpose?
Thought this might sound redundant, but average radial error = CEP, or 100% of the bombs falling in the radial error?

As for skill and precision that obviously goes a long-way.

The next questions I'm going to ask go quite a bit away from World War II but have to do with bombing carried out with various Cold War Equipment all the way up through Vietnam. I'm curious as to the CEP's achievable by bombers such as the B-47 and B-52 early on (1955 - 1965), and later (1965-1972).


BTW: I haven't been posting much because of a criminal justice course that requires a power-point created and creating a power-point with bibliographies frankly are exasperating.

CEP "Circular Error Probable" refers to the radius of the circle within which 50% of bombs fall.

Typically, for a Gaussian distribution, 47% of the remaining bombs fall within one and two CEP radii and the remainder outside that.

I think everyone measured differently. I suspect the Germans may have used 60% CEP instead of 50% because its close to the 63% of the Gaussian distribution.

The CEP was easiest to evaluate from post strike analysis.