Dive bomber accuracy in perspective.

[Shortround6]

Bomb down the funnel was popular description but rarely achieved in practice. On a destroyer it makes no difference. On A cruiser or battleship the funnel area is gap in the armor deck making it easier for a bomb to reach the boiler rooms. However even battleships had armored grates in the funnels to make getting a bomb (or shell) though the area much harder. On a destroyer with no deck armor any hit on the deck over the machinery spaces is going to penetrate into the machinery spaces.
Boiler rooms were sealed compartments and pressurized by fans with the funnel as an exit with the boiler fireboxes as the conduit, explosions that affected the funnel or uptakes could momentarily reverse the airflow and "blow out" the fires. Which then take a while to relight.
Arizona was famously reported to have been sunk by a bomb down the funnel, later research has concluded it was an AP bomb (modified naval shell) that penetrated the armor deck over a magazine.

 

[Greyman]

ORS 2nd TAF examined the accuracy of Typhoon bombers on operations between October 1944 and April 1945. Nine 'pin-point' bombing targets were analysed by plotting both bomb distribution from aerial photographs and examination of the targets on the ground. The average radial error for these attacks was 158 yards with only 50% of bombs falling within 130 yards of the target. The chances of actually destroying such a target are consequently rather slim.
Similar results were found in other surveys. For example a survey of seventeen railway line targets, 320 bombs dropped, found the average line error to be 69 yards with only 50% of bombs falling within 50 yards, either side of the target.

Was just reading a book and it referred to a British study of Stuka accuracy against their positions in the Western desert; CEP of about 30 yards when unmolested and 70 yards when being engaged by anti-aircraft fire.

Similar results were seen in Stuka attacks against British shipping; CEP of 70 yards (while being engaged).

 

[parsifal]

in my opinion, the most accurate divebombing attacks were those that sank the cruisers Cornwall and Dorsetshire. 5th April 1942. Attacks delivered 5th April 1942, in the space of less than 8 minutes by Vals of 1st mob flt. 53 attackers, at least 28 direct hits on the ships, and at least 15 near misses. That's a hit rate in excess of 80%. I don't think that level of accuracy against a high speed target has ever been matched since.

 

[Ascent]

Is there any information out there on the accuracy of dive bombing in the Burma theatre? On another forum I've read a veterans account of flying Vultee Vengeances out there.

He seemed to feel they were pretty accurate with their vertical dive. Also I believe Japanese AA was much lighter than would be encountered in the ETO.

 

[Greyman]

Sounds like the Vengeances were very, very accurate. Though as you say, the AA fire was a way different animal in Burmese jungle than it was in NWE. An anecdote from a Vengeance pilot mentions 800 foot bombing altitude!

Compare that with the 6,000 feet the Typhoons dive-bombed at ... heavily defended targets anyway.

 

[Zipper730]

AFDU testing Hurricane II - 250 lb bombs:

low level attacks - 50 feet altitude

• average error varied between 16.5 yards and 22.4 yards
• most accurate form of attack - but unsatisfactory against point targets in action due to 11-sec fuses and bomb ricochet

dive attacks - 3,000 feet down to 1,000 feet (1,500 feet release) & 4,000 feet down to 2,000 feet (2,500 feet release)

• average error was 27 yards and 24 yards respectively
• form of attack judged vulnerable to AA fire, 45 degrees found to be the best angle for attack

AFDU testing of Mustang III - 500 lb bombs:

60 degree adive attacks - 8,000 feet down to 2,600 feet (release at 4,700 feet)

• average MPI error of 27 yards
• distance between bomb impact points 5 to 112 yards, average 46 yards

Seems that the lower the bomb was released seemed to dictate accuracy the best

 

[Greyman]

Reading around about the Vengeance, it seems like 2,000 feet was a much more common drop height used by the RAF. Also came across this bit from Eric Brown:

True dive bombers like the Ju 87, the Dauntless and the Vengeance were of course always superior in that role to fighters adapted for dive-bombing as a secondary role. The Vultee Vengeance I was a poor aircraft, which, by modification to become the Vengeance IV, eradicated all the original faults, until it was probably the nearest in efficiency to the Ju 87.

 

[RCAFson]

Eight hits on a carrier size target by about 25 Stukas, that's what I would call deadly accurate.

Actually the 8 hits were delivered in 3 separate attacks, IIRC, with at least 50 attacking stukas. The initial attack delivered 6 hits from ~30 attackers, of whom 3 were shot down by AA.

Operation Excess: HMS Illustrious off Malta, January 10, 1941

 

[RCAFson]

Of course we all know that these were the most feared strike aircraft in the Allied inventory and here is some of their practise dive bombing results:

The Swordfish was also capable of operating as a dive-bomber and in 1939 HMS Glorious used her Swordfish for a series of dive-bombing trials, during which 439 practise bombs were dropped at dive angles of 60, 67 and 70 degrees, against the target ship HMS Centurion. Tests against a stationary target showed an average error of 49 yd (45 m) from a release height of 1,300 ft (400 m) and a dive angle of 70 degrees. Tests against a manoeuvring target showed an average error of 44 yd (40 m) from a drop height of 1,800 ft (550 m) and a dive angle of 60 degrees.[36] The Fairey Albacore was also designed to act as a dive bomber and was used extensively in this role during World War Two.[37]
Dive bomber - Wikipedia​

 

[Ascent]

Sounds like the Vengeances were very, very accurate. Though as you say, the AA fire was a way different animal in Burmese jungle than it was in NWE. An anecdote from a Vengeance pilot mentions 800 foot bombing altitude!

Compare that with the 6,000 feet the Typhoons dive-bombed at ... heavily defended targets anyway.

800 feet seems unlikely as the bombing altitude unless that's the height they finished the pull up at. Remember the vengance dived at 90°, if you release and start to pull up there I can't see you avoiding the ground.

 

[Peter Gunn]

*SNIP*

it doesn't get better than 10 January 1941 for the divebombers

Possibly, I'd posit 4 June 1942 wasn't too bad either.

 

[Peter Gunn]

in my opinion, the most accurate divebombing attacks were those that sank the cruisers Cornwall and Dorsetshire. 5th April 1942. Attacks delivered 5th April 1942, in the space of less than 8 minutes by Vals of 1st mob flt. 53 attackers, at least 28 direct hits on the ships, and at least 15 near misses. That's a hit rate in excess of 80%. I don't think that level of accuracy against a high speed target has ever been matched since.

True, it is a good example of how well trained the IJN pilots were, so I rather agree. Although Cornwall and Dorsetshire were alone without CAP and not exactly throwing up a storm of AA fire whilst the attack came out of the sun, so the dive bombers were on them rather quickly.

Although at Midway, Yorktown was attacked by I think 7 bombers, three of which were shot down before they dropped too close to the carrier, so out of the remaining four, I think they scored three hits? And that was against a carrier moving at high speed and turning with two cruisers and five destroyers slinging lead and Yorktown's CAP active. Not too shabby a performance either.

 

[Glider]

In Burma one of the reasons the Hurricane was kept in service was due to its accuracy as a dive bomber. The thick wings of the Hurricane meant that it didn't tend to 'mush' when pulling out of a dive and as a result they would drop from a much lower height than other bombers.

Another interesting weapon was the use of modified depth charges in the Jungle. The much higher percentage of explosive to weight in depth charge was use to basically make an instant clearing taking the cover off the Japanese making them vulnerable to further attack

 

[Greyman]

Remember the vengance dived at 90° ...

Not necessarily. RAF fighter-bombers/dive-bombers had tactics for a variety of angles. Though in that anecdote he does indicate a very, very steep angle.

Perhaps there was a typo somewhere along the line and he meant the attack was started at 8000 feet.

 

[Zipper730]

Tests against a stationary target showed an average error of 49 yd (45 m) from a release height of 1,300 ft (400 m) and a dive angle of 70 degrees. Tests against a manoeuvring target showed an average error of 44 yd (40 m) from a drop height of 1,800 ft (550 m) and a dive angle of 60 degrees.

Ironic that they were more accurate against a moving target than a fixed one.

Admittedly, most people shoot basketballs better when just practicing than in a game and, while I was never a spectacular shooter, I was often better under pressure with somebody coming right at me, than just standing there -- I'm not sure why that's so, but I'm often a person that has trouble with anxiety, and yet in emergency situations I usually can respond just fine.

 

[Ascent]

Not necessarily. RAF fighter-bombers/dive-bombers had tactics for a variety of angles. Though in that anecdote he does indicate a very, very steep angle.

Perhaps there was a typo somewhere along the line and he meant the attack was started at 8000 feet.

Certainly for the pilot who's anecdotes I've seen that was there only attack profile. Their sighting mechanism was in fact a yellow line painted on the cowl.

They pass the target until it appeared behind the right wing, then wing over and point the nose at the target in a vertical dive. If they were perfectly vertical and lined the yellow line up with the target then they could be very accurate. I can't remember what altitude they started or pulled out though. I'll look but it's hidden in the middle of a thread over 500 pages long.

 

[Greyman]

... during the Battle of Ngakyedauk Pass ...two Vengeance squadrons flew no less that 269 sorties in just over a week in tactical support of ground forces holding this position. Up to 50 sorties were mounted a day, with a maximum of two dozen aircraft on some targets. But most attacks were made by boxes of six diving from 8000 ft at 320 mph and pulling out around 2000 ft.

... 19 March 1944 ... enemy artillery batteries on Hill 1301, which were holding up the advance of Allied troops who were within 200 yards of the target, 'hence precision bombing was required to destroy this strong gun position'. The mission was led by Squadron Leader Prasad with six aircraft. They attacked at 1130 in a steep dive from 9000 ft down to 2000 ft with 6000 lb of GPTI bombs. Direct hits on the guns were scored by Prasad himself and Warrant Officer Lamb. The remaining bombs burst in a close concentration within 30 yards all round.

... the third mission this day saw all 12 aircraft, led by Squadron Leader Prasad and Curtis in two boxes, attacking PT162 once more. Prasad again made a perfect approach and dived from 8000 ft ...

'We went on operations immediately,' said Hugh Seton with 8 Squadron ... 'Dives were usually commenced at 10,000 ft to 12,000 ft above the target, with release of the bombs and immediate pull-out usually made at about 3500 ft. ...'

... the mission was to cut Japanese lines of communications at Apakuwa ... at 1535 they tipped over into the steep attack dive from 9000 ft down to 2000 ft at 300 mph.

... next day another six-plane attack was mounted against buildings thought to be a Japanese HQ on the northern side at the foot of a hill at Point PN3030. Twelve 500 lb bombs were dropped in steep dives from 11,000 ft down to 2000 ft ...

The target was a Japanese forward position at Point 124. The weather was good, slightly hazy, and the leader and his vic attacked at 1710, as specified by the Army, in a north to south run and was then followed by the second vic on south to north-west steep dives from 10,000 ft down to 2500 ft at 310 mph ...

... on the last day of the year a similar attack was mounted against buildings at Kanwa and Linfu with dives from 11,000 ft down to 3000 ft.

'... we usually went into our dive at about 10,000 to 12,000 ft at an angle of 75 degrees plus, reaching a speed of about 350 mph with our dive brakes out and then retracting our brakes after dropping bombs and pulling out at about 3000 ft. ...'

' ... I can remember greying out. You went from 10,000 ft to 2,000 ft; it seemed like a long time. Four or five seconds hanging on the brakes, but it seemed like a long time and you wondered if you were going to come out of it.'

'The high dive-bombing phase from 12,000 ft was, however, not without incidents. The only hands usually approached the target, rolled over and down on the target and selected dive brakes out in a well coordinated operation. The difficult part was to judge the release of the bomb and the pull-out from the dive. Here the old hands counted to themselves on the way down at 300 knots, released the bomb, broke the dive at about 2000 ft, and, at an angle of about 60 degrees to the ground, selected dive brakes in, and escaped at high speed at ground level.'

'I commenced each dive from about 12,000 ft, releasing my bombs between 2000 and 3000 ft.'

 

[davebender]

Skip bombing was highly accurate too but like torpedo bombers was vulnerable to AA fire.

 

[wuzak]

Skip bombing was highly accurate too but like torpedo bombers was vulnerable to AA fire.

Weren't dive bombers also vulnerable to AA fire?

 

[parsifal]

once in the dive they were. up until that point they were about the same as any other aircraft.

Typically the D/B would approach at about 10000ft, then push into dives in twos and threes, descending to about 5000 ft . Whilst in that steep attack, they were vulnerable as the pilot struggled to stay conscious and the aircraft virtually froze up. Diving straight, they were ideal targets.

the problem was the release height. At 5000 ft, they were beyond the effective ceiling of the two pounder pom poms and 20mm guns. They were beyond the effective ceiling of the IJN 25mm guns, and the DKM C-38 37mm guns were too slow to be considered effective. the bofors was the only really effective medium calibre AA weapon in mass scale service that could be considered effective