The airplane that did the most to turn the tide of the war.

[Schweik]

These estimations were given for so called skip bombing and GP bombs hitting the ship sides near the waterline after bouncing off the water surface upon being released from the extreme low level flight. I doubt that 3 500 lbs GPs would sink a destroyer when dropped from dive bombing and hitting armored decks. Crippling yes, but sinking hardly.

Au contraire mon frere

SBD's carried 1,000 lb SAP and later fully AP bombs. They had no problem inflicting damage on well armored Japanese heavy cruisers and ships like the Battleship Hiei (which was also hit with torpedoes). The Battleship Haruna appears to have been sunk by bombs at Kure Naval Base in 1945 - it survived one bomb hit on 24 July, but on 28 July it was hit by 8 bombs from Task force 38 and sank at 16:15. There are no mention of any torpedo hits.

 

[Schweik]

The comment was made that that navy aircraft were noted as being more effective in a "Strategic Bombing Survey" which has darn little to do with sinking ships or blowing up tanks on the battlefield.

I've pointed this out before, in a naval context individual ships can indeed be Strategic targets. That is the whole point of Midway.

 

[michael rauls]

Imho the debate on whether dive bombers alone could sink a battleship is somewhat academic. For two reasons, first if they can sink aircraft carriers, cruisers, destroyers, merchant ships, etc, but only leave the battle ships as floating wreckage then seems like mission accomplished all the same. Secondly verry seldom would they be the lone asset being used. Once a battleship was floating listlessly in the water there would be plenty of time for subs, torpedo bombers, or perhaps surface ships to finish the job.

 

[Shortround6]

These estimations were given for so called skip bombing and GP bombs hitting the ship sides near the waterline after bouncing off the water surface upon being released from the extreme low level flight. I doubt that 3 500 lbs GPs would sink a destroyer when dropped from dive bombing and hitting armored decks. Crippling yes, but sinking hardly.

It would make no difference. Very few destroyers had much for armor, certainly not armored decks that keep out even small bombs. The mentioned Atlanta class cruisers had a 1.25 in deck and they went around 6,700 tons.

Destroyer armor, such as it was, was more confined to Bridges and gun positions as anti-splinter protection (or protection against machine gun fire).

There is quite a bit if debate as to whether the US Fletcher class was "armored". The US may have used slightly thicker steel of better quality than some other navies for hull construction
(the STS family of steels) but I am not certain that qualifies as "armor" as it is usually understood. Like 0.5 in STS steel on the hull sides over the engine rooms vs 3/8-7/16ths lower grade steel on a foreign ship?
The STS was stronger than normal construction steels but still ductile (flexible) enough to be used as construction steel in hull sides and decks, true armor is more brittle and might tend to crack after years at sea if used as construction steel. Most navies added the steel armor to the construction steel and didn't try to make the armor carry any of the load.

The gun "shields" on destroyers where there as much to protect the gun crews from the effects of weather as they were to protect the gun and crew from enemy gunfire.

 

[alsaad]

Au contraire mon frere

SBD's carried 1,000 lb SAP and later fully AP bombs. They had no problem inflicting damage on well armored Japanese heavy cruisers and ships like the Battleship Hiei (which was also hit with torpedoes). The Battleship Haruna appears to have been sunk by bombs at Kure Naval Base in 1945 - it survived one bomb hit on 24 July, but on 28 July it was hit by 8 bombs from Task force 38 and sank at 16:15. There are no mention of any torpedo hits.

yes 1000lbs SAP and AP, but I was referring to 500 lbs GP.

S Shortround6
With proper fuse setting like rear M112 or M115 series with longer delay US GP might penetrate destroyer's deck, but still more probably would sink it by exploding near the waterline on the side.

 

[Greyman]

The Admiralty conducted an appraisal (Report No.9/44 "Achievements of British and American Escort Carriers in the Anti Submarine Role 1943" reproduced in The Fleet Air A in World War II Vol 2) of the merits of the Avenger and the Swordfish and came down firmly on the side of the Avenger.

I've come across a similar March 1944 report comparing the Swordfish performance on HMS Fencer and HMS Biter with that of the Avengers on HMS Tracker. The findings seem to be similar in regard to 'Time unservicable due to Deck Landing Damage' -- but it seems the flip side was the Avenger's radio:

Per 100 hours flying
Swordfish electrical & radio troubles cost -- 6.7 hours
Avenger electrical & radio troubles cost -- 90.4 hours

The cause of this would seem to be the design of the American radio and electrical equipment which is not easily repairable on board and the defective item must be replaced by a new one. A further relevant point is that servicing suffers from lack of proper equipment and data. Tracker only had theoretical circuit diagrams for some of her aircraft radio sets.

On the point of weather:

While there was no definite evidence to show that one type of aircraft may operate when another can not, indications are that low wind speeds will prevent an Avenger from taking off before they ground a Swordfish.

 

[Schweik]

The STS was stronger than normal construction steels but still ductile (flexible) enough to be used as construction steel in hull sides and decks, true armor is more brittle and might tend to crack after years at sea if used as construction steel. Most navies added the steel armor to the construction steel and didn't try to make the armor carry any of the load.

Now you just dipped into my wheelhouse.

Let me be clear (and fair) up front, I agree belt armor on warships was effectively brittle. I want to correct the idea about armor in general being brittle. So I'm not picking on you but I want to explain this a bit more, since even on ships armor was used in different ways and on a different scale.

The best quality steel armor actually was not brittle and in fact was flexible or springy. The metallurgy is complex but briefly the heat treatment process of medium carbon steel transformed harder more brittle steel into slightly less hard but far 'tougher' material, due mainly to flexibility. Toughness or fracture toughness (resistance to fracture) is the desired quality for steel armor, which is flexibility balanced with hardness. Toughness can be measured by something called a 'Charpy impact test' developed in the 19th Century but the processes to create highly flexible spring steel armor go back to the late middle ages.

To make tempered steel, after a steel object with the right carbon content has been forged and shaped to it's ultimate form (like a gun barrel, a helmet or an armor plate) and then quenched, it must be gradually reheated a second time and then quenched again after it has reached a certain temperature range for a specific length of time. This allows a specific type of iron carbon compound (for armor usually between 0.3 and 0.6% carbon) called martensite to diffuse gradually through the pearlite which forms a type of molecular structure now called Bainite. The correct amount of diffusion can be seen by the color of the metal.

For armor you want something over in the blue range.

Very hard steel by contrast becomes brittle and will crack when hit with ballistic objects. Iron carbide steel hard enough for industrial drill bits etc. is mostly made up of a carbon / iron compound cementite which is technically a ceramic.

Naval armor tended to be made in large and very thick pieces which is one of the reasons it could crack. To make properly tempered steel it can't be cast or rolled it has to be forged, and the giant plates used for belt armor on battleships etc. were far too big for that. So to make it more resistant it was typically rolled steel that was annealed to create a quasi-tempering effect and then face hardened.

However armor to protect other vital / internal parts of a ship from bomb fragments etc. could be properly tempered, and armored pieces, including the armor used in aircraft was often tempered and sometimes on tanks were tempered too.

The main reason was weight saving. Tempered medium carbon steel of 3mm has the same ballistic protection as non tempered medium carbon steel of 6mm or low carbon steel of 10mm. Which is a big deal for example for ballistic plates in body armor and armor on modern fighting vehicles.

In theory, if you had a big enough Haephestus style giants forge, you could have made 10 cm armor that was as effective as 20cm armor. That would have made battleships a bit more viable. But that is a science fiction type scale.

 

[Schweik]

I've come across a similar March 1944 report comparing the Swordfish performance on HMS Fencer and HMS Biter with that of the Avengers on HMS Tracker. The findings seem to be similar in regard to 'Time unservicable due to Deck Landing Damage' -- but it seems the flip side was the Avenger's radio:

On the point of weather:

While there was no definite evidence to show that one type of aircraft may operate when another can not, indications are that low wind speeds will prevent an Avenger from taking off before they ground a Swordfish.

The radio problems may in part have to do with operating a foreign aircraft, with different supply chains and training etc. However I do think the TBF / Avenger was too big for those small carriers. As I stated upthread I'm not a fan of the Avenger.

The SBD is the one I believe outmatched the Swordfish in every respect by an order of magnitude and also did better on smaller carriers in spite of not having folding wings.

 

[Schweik]

A little more on the Haruna:

• Interestingly, the entire (Kongo) class of battleship was designed by a British naval architect named George Thurston
• Though originally designed (as fast battlecruisers) around the time of WW1, they were upgraded and up-armored during the war.
• The Haruna at the time of it's sinking had 80-120mm deck armor, roughly the same as the Bismarck which had 100 - 120mm deck armor. They also had equivalent turret armor (13.5 vs. 14 inches) though the Bismarck had significantly thicker belt armor (8 for Haruna vs 12.6 for Bismarck).
• In it's final days it seems to have suffered a total of 13 bomb hits and 10 near misses before being sunk. As far as I've been able to determine, the damage appears to have been exclusively inflicted by US Navy SB2C Helldivers.
• At one point during the same 4 day period it was attacked by no less than 70 B-24s, and in spite of the fact that Haruna was tied up on a dock, they did not hit with a single bomb.
• The Haruna sunk in the harbor and remained half submerged for a long time after the war.
• Here is some video footage of it, which I found rather fascinating.

The fate of the Haruna, sunk by dive bombers, and done -in by 13 bomb hits- in my opinion proves that the SBD could have sunk battleships in general and could have specifically sunk the Bismarck. Like I said without additional AAA support or air cover, it would have been a sitting dunk for the Dauntless.

It also appears that the Japanese Battleship Hyūga was sunk by dive bombers, suffering 3 bomb hits on 19 March which damaged her, and then then suffering an additional 10 bomb hits on 24 July which "blew off part of her stern, destroyed her bridge and started major fires."

The Hyuga had 80mm armored decks and 254mm armored turrets initially, wikipedia claims 152mm armored decks after refit but that seems off.

Like the Haruna, the Hyuga survived an attack by B-24s, 24 of which bombed it but missed the now sunk but still visible ship on 29 July

 

[Schweik]

The wikipedia on the Dauntless states that "The Dauntless was one of the most important aircraft in the Pacific War, sinking more enemy shipping in the War in the Pacific than any other Allied bomber. "

Though I believe that is plausible, the source being Wikipedia and with no citation, take it with a grain of salt.



I will say this though, the ability of the Swordfish to carry a functional radar, and operate at night and in bad weather, would confer an interesting extra option for an early war navy. Even with a small carrier that only carried 30 planes, you might be tempted to carry 5 or 6 Swordfish just to have that night time / bad weather attack and search capability.

Round that out with 18 Dauntlesses and 12 Wildcats, and you have a fairly dangerous light carrier.

 

[Kevin J]

A little more on the Haruna:

• Interestingly, the entire (Kongo) class of battleship was designed by a British naval architect named George Thurston
• Though originally designed (as fast battlecruisers) around the time of WW1, they were upgraded and up-armored during the war.
• The Haruna at the time of it's sinking had 80-120mm deck armor, roughly the same as the Bismarck which had 100 - 120mm deck armor. They also had equivalent turret armor (13.5 vs. 14 inches) though the Bismarck had significantly thicker belt armor (8 for Haruna vs 12.6 for Bismarck).
• In it's final days it seems to have suffered a total of 13 bomb hits and 10 near misses before being sunk. As far as I've been able to determine, the damage appears to have been exclusively inflicted by US Navy SB2C Helldivers.
• At one point during the same 4 day period it was attacked by no less than 70 B-24s, and in spite of the fact that Haruna was tied up on a dock, they did not hit with a single bomb.
• The Haruna sunk in the harbor and remained half submerged for a long time after the war.
• Here is some video footage of it, which I found rather fascinating.

The fate of the Haruna, sunk by dive bombers, and done -in by 13 bomb hits- in my opinion proves that the SBD could have sunk battleships in general and could have specifically sunk the Bismarck. Like I said without additional AAA support or air cover, it would have been a sitting dunk for the Dauntless.

View attachment 530095

It also appears that the Japanese Battleship Hyūga was sunk by dive bombers, suffering 3 bomb hits on 19 March which damaged her, and then then suffering an additional 10 bomb hits on 24 July which "blew off part of her stern, destroyed her bridge and started major fires."

The Hyuga had 80mm armored decks and 254mm armored turrets initially, wikipedia claims 152mm armored decks after refit but that seems off.

Like the Haruna, the Hyuga survived an attack by B-24s, 24 of which bombed it but missed the now sunk but still visible ship on 29 July

If you're going to use the Dauntless to attack the Bismarck then you need the carriers that can operate them. Only the Victorious and Ark Royal were available for the battle, IIRC. Neither could have operated the Dauntless as neither had lifts wide enough to strike them down below. If you want a dive bomber to do it then you need the Skua and that only carries 500 lb bombs, the same as the Dauntless at that time. Better still a crippling night attack by torpedo equipped Swordfish followed by a pounding by a Nelson class battleship firing 16-in inch shells weighing over 2000 lbs each. That's the way to do it and that's the way it was done.

Later in the war we used Barracudas with 3600 lb bombs in dive bombing attacks against the Bismarck's sister ship, the Tirpitz and they didn't sink her. It took Lancasters with 12000 lb tallboy bombs to do the job properly.

The suggestion that the Dauntless could sink the Bismarck is a fantasy.

 

[Shortround6]

Ok lets be real:

yes lets be real.

Semi-Armor Piercing bombs would have been sufficient. The superstructure on battleships is not armored sufficiently to protect against 1,000 lb bomb hits. Nor was all of the deck. Nor were the AA guns. Nor were, necessarily, the turrets.

The superstructure of a battleship (or cruisers) was not armoured well enough to protected against GP bomb hits, On most battleships. let alone cruisers, the horizontal armor didn't start until the weather deck (and many battleships it was a deck or two below that). Battleships in WWII varied tremendously as not only did you have the WW I leftovers (upgraded to a greater or lesser extent) but even the naval architects of the 1930s couldn't agree on protection plans given that most of them were trying to work within the 35,000 ton treaty limit. Armor placed high up in a ship (weather deck or superstructure) affects the stability and needs wider hulls (or ballast or.....)
Turret armor thicknesses are likewise all over the place, the really thick numbers are on the face of the turret facing the enemy (or most likely enemy) with thinner sides and rear (unless thick rear armor was needed to balance the turret). Roof armor varied with age and design. WW I battleships with elevation limits of 15 degrees or under on the guns didn't expect plunging fire coming in at steep angles and had thin armor on top. refitted battleships with elevations increase also had thicker armor added to the turret roofs. Modern Battleships (and few modernized old ones) had 40 degrees or more of elevation and plunging fire could be coming down at angles over 50 degrees.

The idea of using multiple armoured decks was that the upper decks (above the main armored deck, not superstructure decks) would act as "exploders" on shells or bombs causing their fuses to function before the bomb/shell made contact with the main armored deck. Or would cause the bomb/shell to tip and reduce it's penetration.

• The attack didn't have to be at night - it really shouldn't have been. As it was they would have sunk the Sheffield by accident if the magnetic detonators had worked. Swordfish took advantage of having radar. Attacking at night was safer in airplanes doing 100 mph 200 feet over the water. But SBD's could have attacked that ship in relative safety. Certainly SBD strikes were made against much more heavy AAA defenses without suffering heavy casualties. SBD also had much greater range, and was roughly twice as fast getting to the target, meaning it was more likely to spot the enemy ship more quickly.

a lot depends on the cloud cover, Visibility was hardly unlimited during most of the Bismark chase/engagement. truing to dive bomb when the clouds only open up below 1000ftor so doesn't work real well.

• They didn't need to blow up the magazine of the Bismarck, all they had to do was make it incapable of defending itself, then the ships could have finished it off. As it was in the real event, they only hit with one torpedo right? But jamming the rudder and causing a list was sufficient to cripple the mighty Battleship so that it's lesser rivals could finish it.

A battleship like the Bismarck, with no air cover and no flak screen from friendly warships, would have been dead meat from a squadron or two of SBD's. The Swordfish was a versatile old biplane, but it wasn't in the same league as a ship killer. Not even close.

Accounts differ, some say there was more than one hit. It was the hit in the rudder area that spelled the end of the Bismark. The other (if it did hit) was into the torpedo protection area and caused minor flooding and the loss of some fuel oil, some accounts credit this damage to a shell hit or perhaps there were both?

However the idea that 12-24 dive bombers could sink the Bismark in a single raid seems a bit optimistic, I would note that the two ships that pummeled the Bismark where hardly light weights. The Rodney may have been slow but she packed a pretty good punch. Rodney alone fired around 340 16 in shells (Wiki) or up to 382 shells ( Campbell's) sometimes from as close as 3,000yds. these were 2375lb projectiles with 54-55lb bursters of TNT. Rodney also tried to torpedo the Bismarck accounts differ at if there was hit.

One account gives these totals for shell fired not hits.

• 380 of 40.6 cm from Rodney
  339 of 35.6 cm from King George V
  527 of 20.3 cm from Norfolk
  254 of 20.3 cm from Dorsetshire
  716 of 15.2 cm from Rodney
  660 of 13.3 cm from King George V

even with several underwater examinations of the wreckage the total number of torpedo hits doesn't seem to be known.

While bombs from the Dauntless would hardly bounce off they would need to be extremely lucky to inflict fatal or near fatal damage to the ship below the armoured deck.

 

[swampyankee]

Ok lets be real:

• Semi-Armor Piercing bombs would have been sufficient. The superstructure on battleships is not armored sufficiently to protect against 1,000 lb bomb hits. Nor was all of the deck. Nor were the AA guns. Nor were, necessarily, the turrets.
• The attack didn't have to be at night - it really shouldn't have been. As it was they would have sunk the Sheffield by accident if the magnetic detonators had worked. Swordfish took advantage of having radar. Attacking at night was safer in airplanes doing 100 mph 200 feet over the water. But SBD's could have attacked that ship in relative safety. Certainly SBD strikes were made against much more heavy AAA defenses without suffering heavy casualties. SBD also had much greater range, and was roughly twice as fast getting to the target, meaning it was more likely to spot the enemy ship more quickly.
• Yamato was wrecked and became unable to defend itself due to bomb hits. In the first attack, quoting from the wiki: "the Yamato was hit by two armor piercing bombs and one torpedo. One of the bombs started a fire aft of the superstructure that was not extinguished." Fires that "are not extinguisehd" aren't good for warships. It was then hit by 8 torpedoes and 15 more bombs. Again quoting the wiki: "The bombs did extensive damage to the topside of the ship, including knocking out power to the gun directors and forcing the anti-aircraft guns to be individually and manually aimed and fired, greatly reducing their effectiveness " Clearly the bombs had an impact, pun intended. No mention of any of them 'bouncing off'.
• They didn't need to blow up the magazine of the Bismarck, all they had to do was make it incapable of defending itself, then the ships could have finished it off. As it was in the real event, they only hit with one torpedo right? But jamming the rudder and causing a list was sufficient to cripple the mighty Battleship so that it's lesser rivals could finish it.

A battleship like the Bismarck, with no air cover and no flak screen from friendly warships, would have been dead meat from a squadron or two of SBD's. The Swordfish was a versatile old biplane, but it wasn't in the same league as a ship killer. Not even close.

Of course, the SBD couldn't have attacked the Bismarck without the US seriously violating neutrality; the RN didn't operate them at this time.


A related question is, though, whether the SBD could have operated onto and off of carriers in the weather conditions prevailing during the chase and destruction of the Bismarck. The weather was, by all accounts, hellish, and it's not impossible that the SBD or an equivalent aircraft could not have operated from the RN's carriers in those weather conditions at that time.

Reportedly (iirc, in an article by Friedman on the genesis of the Forrestals), Essex-class carriers were damaged by weather after transfers to the Atlantic.

(According to the Haze Gray site (World Aircraft Carriers List: US Fleet Carriers, Pre-WWII), the only pre-war USN carrier to serve more than a few months in the Atlantic after Pearl Harbor was USS Ranger, which could not operate its aircraft in heavy weather. Yorktown and Hornet were in the Atlantic, but transferred to Pacific after Pearl Harbor. Wasp went to Pacific in mid-1942. No Essex class ships served in the Atlantic during WW2)

 

[Milosh]

The Swordfish did a pretty good job on the Italian fleet at Taranto.

 

[Schweik]

The suggestion that the Dauntless could sink the Bismarck is a fantasy.

Please see :

• The Haruna at the time of it's sinking had 80-120mm deck armor, roughly the same as the Bismarck which had 100 - 120mm deck armor. They also had equivalent turret armor (13.5 vs. 14 inches) though the Bismarck had significantly thicker belt armor (8 for Haruna vs 12.6 for Bismarck).
• In it's final days it seems to have suffered a total of 13 bomb hits and 10 near misses before being sunk. As far as I've been able to determine, the damage appears to have been exclusively inflicted by US Navy SB2C Helldivers.
• At one point during the same 4 day period it was attacked by no less than 70 B-24s, and in spite of the fact that Haruna was tied up on a dock, they did not hit with a single bomb.
• The Haruna sunk in the harbor and remained half submerged for a long time after the war.
• Here is some video footage of it, which I found rather fascinating.

At least two Japanese battleships were sunk with bombs, the exact same kind of bombs carried by the SBD. Your claim to the contrary is the fantasy.

 

[Airframes]

Bur first, you'd have to get the Bismark to a convenient location for a SBD to sink it - rather difficult, as it was already gone by the time the USA entered the war and, to the best of my knowledge, the SBD didn't serve with the RN Fleet Air Arm.

 

[Schweik]

No, as usual here we are getting in trouble by toying with imaginary scenarios. If the carrier elevator was too small for an SBD then they could not have operated an SBD to sink it. My only point is that the canard that dive bombers couldn't sink battleships is just that - a myth. Thank god for the US dive bombers, in particular the SBD, turned out to be so good at sinking enemy warships in general that they were able to make up for the fact that they lacked reliable torpedoes until well past the tipping point of the war.

Pre-war doctrine suggested that torpedo bombers were the only real way to sink ships, with dive bombers as kind of a backup. But the reality thank god was that our better quality dive bombers were more than up to the task. Wartime experience also showed that torpedo bombers were very vulnerable to defensive efforts and tended to suffer high loss rates especially against well protected military targets, whereas dive bombers could attack very difficult targets and survive sorties much better.

As for the Swordifsh, I'm sorry I know some people like them, and sometimes you just do the best you can with what you got, I certainly respect that. And I'll even concede with the early radar functionality, they provided some interesting all-weather capability. But I still think they were kind of an embarrassment and not a very good warplane by WW2 standards.

 

[swampyankee]

The Swordfish did a pretty good job on the Italian fleet at Taranto.

The fact that the RN had working aircraft torpedoes doubtless helped.

 

[KiwiBiggles]

SBDs, and dive bombers in general, were great at sinking warships in the clear skies of the Central Pacific, and probably would have been in the Mediterranean. But in the continual low overcast and generally filthy weather of the North Atlantic, you are going to find it very difficult to drop from the optimum altitude of 8000 - 10000 ft. I don't doubt that if Dauntlesses were able to sink heavy battleships; I just doubt that they would have been able to see, let alone bomb, the Bismarck in the North Atlantic or Denmark Strait.

 

[Schweik]

Deck armor on the Bismarck was about 120mm - US dive bombers sunk at least two battleships with bombs alone that had the same thickness of deck armor. So I call bullshit on that claim. Even the mighty Yamato, which far outclassed any ship that sailed in the North Atlantic, did not prove to be immune to bombs per the Trope.

Weather may have been typically bad in the North Atlantic but it wasn't always great in the Tropical Pacific either, ever heard of a Typhoon? (I don't mean the plane) Or read about the weather around New Guinea? Or for that matter Alaska? Or Japan?