Dive Bombing improves accuracy how much?

[davebender]

The Ju-88 could dive bomb. The He-111 and Do-17 could not. Do we have historical data to compare bombing accuracy vs point targets like bunkers, bridges and artillery emplacements?

 

[Demetrious]

The Ju-88 could dive bomb. The He-111 and Do-17 could not. Do we have historical data to compare bombing accuracy vs point targets like bunkers, bridges and artillery emplacements?

Just because it COULD dive-bomb doesn't mean it DID. Ju-88 dive-bombing wasn't very common, as far as I can recall. I've never heard any stories or anecdotes about such attacks, at any rate. The retention of dive-bombing ability in every heavy bomber of the Luftwaffe was the result of starry-eyed generals crooning over the success of dive-bombing with the Stuka.

As for the accuracy of dive bombing vs. level bombing, that depends highly on the altitude. Level bombing with good bombsights (like the Norden,) could reasonably be expected to put a bomb within the "obliteration" range of a target from 10-12,000 feet, but against a target with any sort of significant AA coverage those altitudes were suicide for heavy, slow bombers. From higher altitudes, with multiple wind layers affecting the bombs free-fall, accuracy wasn't very good.

Dive-bombing, on the other hand, usually involved a smaller aircraft (was limited to them, in fact,) and allowed you to actually "point" the bomb roughly where you wanted to go, and impart most of your planes velocity to the bomb, keeping it on course better then a free-fall would. (Remember, "velocity" is "speed in a given direction.") Their release altitudes were much lower. I think it's a no-brainier that dive-bombing was far more accurate. For exact numbers, though, I can't help you.

 

[beaupower32]

In October 1937 Generalluftzeugmeister Ernst Udet had ordered the development of the Ju 88 as a heavy dive bomber. This decision was influenced by the success of the Ju 87 Stuka in this role. The Junkers development center at Dessau gave priority to the study of pull-out systems, and dive brakes. The first prototype to be tested as a dive bomber was the Ju 88V4 followed by the V5 and V6. These models became the planned prototype for the A-1 series. The V5 made its maiden flight on 13 April 1938, and the V6 on 28 June 1938. Both the V5 and V6 were fitted with four-blade propellers, an extra bomb bay and a central "control system". As a dive bomber, the Ju 88 was capable of pinpoint deliveries of heavy loads; however, despite all the modifications, dive bombing still proved too stressful for the airframe, and in 1943, tactics were changed so that bombs were delivered from a shallower, 45° diving angle. Aircraft and bomb sights were accordingly modified and dive brakes were removed. With an advanced Stuvi dive-bombsight, accuracy remained very good for its time. (from Wiki)

 

[davebender]

As a dive bomber, the Ju 88 was capable of pinpoint deliveries of heavy loads

If true I think this would be a popular delivery method. So what if the airframe is only good for a few dozen missions? The target is destroyed and only a few bomber aircraft were required. Much less expensive in aircraft and aircrew then level bombing using hundreds of aircraft.

 

[Butters]

The very steep angle dive-bombing technique used by purpose-built dive bombers was very accurate, but it left the bomber extremely vulnerable to both AA and fighter attack.

Which not only led to the demise of many dive-bombers, but also to the demise of the dive-bomber concept itself.

JL

 

[Waynos]

The Avro Manchester was also required to be capable of dive bombing. Imagine having to dive that thing! Just having to fly it was bad enough.

 

[davebender]

left the bomber extremely vulnerable to both AA and fighter attack.

But you are only risking a single dive bomber squadron to take out a factory size target. As opposed to risking 500 or so heavy bombers to accomplish the same mission.

 

[parsifal]

Divebombing as a technique also proved very vulnerable to flak. Whereas the average ammunition expenditure to bring down a High Level Heavy Bomber in 1944 was around 16000 shells per kill, to bring down a Divebomber, the ammunition expenditure for the allies was somthing less than 1500 rounds per kill. Fighter Bombers were somewhat less prone to flak damage, at around 6000 rounds per kill.

Why was divebombing so vulnerable? The path of attack was predictable, and the dive rate had to be relatively slow in order to achieve the high accuracy it boasted. I also think that the airframe was under such a heavy amount of stress that it only would take a few rounds hitting the aircraft to cause it to suffer catastrophic structural failures whilst in the manouvre

As far as the Ju88 was concerned, in naval terms it was not considered as great a threat as Ju87s, and was about the same threat level as an Me 110 though it was successfull in the role, and its longer range made it a dangerous opponent to the Royal Navy. The situation changed after October 1941, when Ju88s began to be fitted with reliable torpedoes (of Italian origin I believe)

 

[davebender]

Divebombing as a technique also proved very vulnerable to flak.

I realize that. But look at the flip side of the coin - a single squadron of heavy dive bombers (i.e. Ju-88s) can destroy an enemy factory or bridge. From a military point of view losing all 12 Ju-88s to destroy such a high value target is much less expensive then sending hundreds of heavy bombers which are likely to miss the target completely.

 

[Demetrious]

I realize that. But look at the flip side of the coin - a single squadron of heavy dive bombers (i.e. Ju-88s) can destroy an enemy factory or bridge. From a military point of view losing all 12 Ju-88s to destroy such a high value target is much less expensive then sending hundreds of heavy bombers which are likely to miss the target completely.

You just explained why some bombers were used in the roles they were.

As parsifal explained, heavy bombers required more flack to kill- because they were attacking from much higher altitudes. The inaccuracy of high-altitude bombing, however, becomes a moot point when you attack large, valuable targets like factory complexes. The Ford Motor Company transmission plant in Livonia, Michigan, where my father used to work is easily five hundred acres square, and I might be underestimating it badly. A single dive bomber squadron might be able to hit one or two buildings, but wouldn't be able to concentrate a devastating amount of ordinance on every part of the facility- the testing buildings, the office buildings, the factory buildings, the vehicle test track, etc. A heavy bomber formation from altitude could easily hit such a large target, and their heavy payload would be needed to properly saturate the target.

However, if you're going after small, hard-to-hit, high value targets like bridges, the equation is reversed because the bombers will probably miss the target, exposing themselves for no gain. This is where the higher risk of dive bombers pays off- the accuracy allows you to strike small, high value targets.

This is why they call it strategic bombing, as opposed to tactical.

 

[fastmongrel]

However, if you're going after small, hard-to-hit, high value targets like bridges, the equation is reversed because the bombers will probably miss the target, exposing themselves for no gain. This is where the higher risk of dive bombers pays off- the accuracy allows you to strike small, high value targets.

]

Or you load up a few Lancasters with Grand Slam or Tallboy bombs and you wipe that bridge off the face of the earth


View: https://www.youtube.com/watch?v=R-Mm-zFW_nA

 

[davebender]

load up a few Lancasters with Grand Slam or Tallboy bombs and you wipe that bridge off the face of the earth

Only if you hit it. Otherwise you just make a big splash in the water and kill a lot of fish.

 

[fastmongrel]

Only if you hit it. Otherwise you just make a big splash in the water and kill a lot of fish.

The idea behind the big earthquake bombs was that you didnt hit the target you aimed to miss. The bomb penetrated the ground or water then exploded. The explosion created a large cavity in the ground which collapsed bringing the structre down. The bomb didnt directly destroy the target the cavity formed by the expanding gas caused a crater this plus the blast effect was very impressive in destroying targets like U-Boat pens and the V3 launch sites.

A similar theory was behind the magnetic torpedo exploder you set the depth of the torpedo so it ran underneath the ship (exploding amidships if the aim was right) causing a large gas bubble under the ship. A ship cant float on a gas bubble so the ends of the ship were supported but amidships wasnt so breaking its back.

 

[beaupower32]

These massive bombs designed by Dr. Barnes Wallis reached the speed of sound during descent being streamlined and equipped with angled fins that produced a rapid spin. Penetrating the ground before exploding they worked by setting off shock waves that would bring down nearby structures. The 5.443 kg (12.000 lb) "Tall Boy" dropped from 6.096m (20.000 feet) made a 24 meter (80 feet) deep crater 30 meter (100 feet) across and could go through 4,88 meter 16 feet of concrete. On 8-9 June, 1944 eight Lancaster bombers of No. 617 Squadron used the deep penetration "Tall Boy" bomb in an attack against the Saumur Rail Tunnel. The new weapon proved its worth, but at the cost of losing 5 of the 8 bombers on this mission. Eventually 854 Tallboy bombs were used, the most note-worthy mission resulting in the destruction of the battleship Tirpitz

The "Grand Slam" (Earthquake) bomb was of the same design as the Tallboy but larger and heavier weighing 9.979 kg (22.000 lb). The Grand Slam was first used on 14 March, 1945 when a force of Lancaster bombers led by Royal Air Force Squadron Leader C.C. Calder attacked the Bielefeld railway viaduct destroying two spans. In another attack against submarine pens, (Bunker Valentin) near Bremen, two Grand Slams pentrated 4,5 meters of reinforced concrete. 41 Grand Slam Bombs were dropped by the end of the war mainly against bridges and viaducts.

In mid-1944 the British had to realize that with traditional weapons (torpedoes, mines and bombs) there was no way to put the Tirpitz out of commission permanently. At this time a new bomb was put into service, the "Tall Boy", a weapon developed under the direction of Professor Dr. Barnes Wallis, under whose leadership the 3.900 kg (8.600 lb) rotary water bombs, used with great success in the spring of 1943 on reservoir dams in Germany, also originated. The RAF Bomb Command thus received orders to attack the Tirpitz with the new "Tall Boy" bombs. With their weight of 5.443 kg (12.000 lb) they were the heaviest bombs ever built up to that time. In fact, the "Tall Boy" was a "Superbomb". It belonged to the category of thick-walled, teardrop-shaped GP bombs (GP "General Purpose", thus a multipleuse bomb) and were 6,35 meters (21 feet) long with a diameter of 0,95 meter (38 inches). Their warhead consisted of 2.358 kg (5.200 lb) of "Torpex", a highly explosive substance with a detonation speed of 7.600 meters (8.350 yards) per second (in comparison: the detonation speed of traditional TNT is "only" 6.900 meters (7.580 yards) per second). The ignition delay could be set to a maximum of eleven seconds. Such bombs could be carried only by the four engined bombers of the "Lancaster Mark I S" type, and then only one per plane, which also had to be rebuilt for this purpose. At the end of the war a total of 854 "Tall Boy" bombs had been dropped, of which 77 were dropped in the three attacks on the Tirpitz in September, October and November of 1944 alone. In the first attack, two direct hits on the bow was achieved, in the second only a near miss. In the decisive third attack there were three direct hits and one near miss. At the third attack, 12. November 1944, Tirpitz capsized and had to be written off as a total loss.

Tirpitz - The "Tall Boy" and "Grand Slam" Bombs


Its amazing what the Allie's went through to sink the Tirpitz. This ship tied up numerous resources just from its mear presance. It cost many lives from both sides in the end.

 

[davebender]

uboat.net - Boats - Flotillas - Bases - St. Nazaire, France
It appears to me the St. Nazaire U-Boat pen was still intact during 1991 when this picture was taken..

 

[beaupower32]

Some of the U-Boat Pens today are still around. A few are accessable, but some are not.

 

[davebender]

Let's attack this dive bomber accuracy discussion from another angle. Erprobungsgruppe 210 was formed during the summer of 1940, operating the Me-110C4/B.

Me-110C4/B. Fighter-Bomber variant of Me-110C.
WW2 Warbirds: the Messerschmitt Bf 110 Zerstrer - Frans Bonn
.....Additional armor protection for the crew.
.....2 x ETC-250 racks. Each rack can carry a 250kg bomb.
.....1,270hp DB601N engines. A bit more power to counter the additional weight.

How accurate were these Me-110s vs point targets compared to the dive bombing Ju-88s?

 

[davebender]

HyperWar: The Battle of Britain--A German Perspective

Summary.
An average Ju-87 dive bomber pilot had a 25% chance to hit within 30 yards of the aim point.

Summary.
A Ju-88 dive bomber had a 50% chance to hit within 50 meters of the aim point.

Summary.
German level bombers attacking from low altitude could place 20 to 25% of their bombs within 330 feet of the aim point.

Summary.
An average B-17 aircrew had a 20% chance to hit within 1,000 feet of the aim point.

If this data is correct then the Ju-88A was an exceptionally accurate bomber. When used as a dive bomber accuracy approached that of the Ju-87. Which leads me to think the late 1930s German emphasis on dive bombing was a good thing.

the Ju87B-1 (the model in service in 1939-1940), "was to prove effective in the hands of expert pilots, who, in dives of eighty degrees to within 2,300 feet from the ground, could deliver a bomb with an accuracy of less than thirty yards. Even average pilots could achieve a twenty-five percent success rate in hitting their targets

By comparison, US Army air forces typically designated a radius of 1,000 feet as the "target area" aim point for the "pickle-barrel" bombing conducted in Europe. "While accuracy improved during the war, [US Strategic Bombing] Survey studies show that, in the over-all, only about 20% of the bombs aimed at precision targets fell within this target area.

In 1938, "even well-qualified bomber crews could achieve only a two percent bombing accuracy in high-level, horizontal attacks (up to 13,500 feet), and twelve to twenty-five percent accuracy in low level attacks against targets of between 165 to 330 feet in radius

Eventually the twin-engine Ju88 "wonder bomber" (as the propaganda of the day called it), and even the He177 "heavy bomber" were to fall victim to the momentum of the dive-bomber craze. The original specifications and indeed the early prototypes of the Ju88 were quite good when compared to the fighters actually available during the Battle of Britain. "In March 1939, one of the first prototypes established a new 621 miles closed-circuit record by carrying a 4,409 lb. payload at an average speed of 321.25 m.p.h.."30 (The maximum speed for the Spitfire Mk 1: 355 mph, and that of the Hurricane Mk 1: 328 mph.) But, following extensive (about 25,000) modifications to meet the "dive-bomber" specifications and to provide for additional armament as well as a fourth crew member, the performance of the final production models of the Ju88 were disappointing. As an example, when the production version, Ju88A-1, arrived in September 1939 it had a maximum speed of only 258 mph, and a range of 550 miles with a 2,000-pound bomb load. With a maximum bomb load of 3,800 pounds performance was further reduced to 190 mph with a radius of just 250 miles! However, and this is significant in light of the reasons for the modifications to the original design: a production model, when properly flown under test conditions, could deliver 50 percent of its bomb load within a 50-meter circle

 

[stona]

Surely one of the best illustrations of just how accurate dive bombing could be was provided by the Americans at Midway. It took only minutes to destroy three carriers (Kaga,Akagi and Soryu) followed later by Hiryu.
Anyone who was on Yorktown will tell you the Japanese could do it too,though of course she was finished by torpedoes.
Steve

 

[riacrato]

Nice info dave.