SBD Question

[renrich]

Actually, 500 pound bombs are quite destructive. I believe that the bombs the Vals carried were just over 500 pounds and they did plenty of damage and If memory serves on of the IJN CVs at Midway was sunk only with 500 pounders. I believe also that any Navy dive bomber pilot who sees an enemy flattop during WW2, once he has reported by radio, is going to be hard pressed not to attack.

 

[Markus]

"Best knew that his fellow squadron commander, Lieutenant W. Earl Galaher of VS-6, had to equip his unit with 500-pound bombs because, being the first dive bombers to take off, they did not have the deck space necessary for a run long enough to launch with 1,000 pound bombs."

Miracle at Midway Prange, Gordon W. P. 261

Right, Lundstrom mentions that too in "The First Team" but he adds some SBD were armed with a pair of 100 pounders under the wings. In Adm. Fletcher´s bio he informs the reader that US pre-war doctrine called for the use of these mini-bombs for triple-A suppression. Since the bombs were weak and would have required the dive-bomber to make another dive their use was resented. So the issue was technical and tactical.

 

[Markus]

Actually, 500 pound bombs are quite destructive. I believe that the bombs the Vals carried were just over 500 pounds and they did plenty of damage and If memory serves on of the IJN CVs at Midway was sunk only with 500 pounders. I believe also that any Navy dive bomber pilot who sees an enemy flattop during WW2, once he has reported by radio, is going to be hard pressed not to attack.

Sounds like Kaga. She took at least three 500lb bombs and one 1,000lb bomb too, but that´s not what sank her and the others as Japanese CV had survived such punishment in the past and would in the future. What sealed the fate of the IJN´s carriers at Midway was violating ammo handling safety procedures and admittedly inferior damage control.

 

[bobbysocks]

its akin, i guess, to recon with force. you are hundreds of miles away from your carrier, limited fuel, and spot something. by the time everything scrambles it might ellude that force. after you call it in...take a shot, you may just be able to hit it. what the heck...you miss you still have the status quo. but by chance you do manage to ....its easier to find a plume of smoke....or perhaps slow it down just a little.

 

[syscom3]

.......but that´s not what sank her and the others as Japanese CV had survived such punishment in the past and would in the future. What sealed the fate of the IJN´s carriers at Midway was violating ammo handling safety procedures and admittedly inferior damage control.

There was a multitude of factors that sank them. All four carriers at Midway sank from unique factors, but there was a common theme around them.

Bad damage control philosophy.
Poorly trained damage control teams.
Lucky hits
Akagi and Kaga were converted battle cruisers and suffered design issues that effected survivability
Soryu and Hiryu were lightly armoured and suffered accordingly.

And as future events showed, the remaining Japanese CV's were just as vulnerable to heavy bombs and torpedo's as they were off of Midway.

 

[Markus]

And as future events showed, the remaining Japanese CV's were just as vulnerable to heavy bombs and torpedo's as they were off of Midway.

You can not equate bombs and torpedos. At Coral Sea Shōkaku was hit by three 1,000 pounders and survived. At Santa Cruz she took at least three 1,000lb bombs and survived a second time. At Midway Akagi was sunk by a single 1,000 pounder igniting the armed and fueled planes and the excess ammo left lying in the hangar.

 

[timshatz]

There was a multitude of factors that sank them. All four carriers at Midway sank from unique factors, but there was a common theme around them.

Bad damage control philosophy.
Poorly trained damage control teams.
Lucky hits
Akagi and Kaga were converted battle cruisers and suffered design issues that effected survivability
Soryu and Hiryu were lightly armoured and suffered accordingly.

And as future events showed, the remaining Japanese CV's were just as vulnerable to heavy bombs and torpedo's as they were off of Midway.

Also had a goodly number of the trained DC teams wiped out by the bomb and susequent secondary explosions. The IJN did not, as a matter of fact, train all crews in DC as the USN started doing after the initial carrier battles. IJN was slow on the uptake in learning some of the lessons of those battles.

 

[timshatz]

Actually, 500 pound bombs are quite destructive. I believe that the bombs the Vals carried were just over 500 pounds and they did plenty of damage and If memory serves on of the IJN CVs at Midway was sunk only with 500 pounders. I believe also that any Navy dive bomber pilot who sees an enemy flattop during WW2, once he has reported by radio, is going to be hard pressed not to attack.

You may be confusing the two different bombs, not in the weights but in the weight methodology. IJN used Kilograms while the USN used Lbs. So a Val might be carrying a 550Kg bomb while an SBD would be carrying a 500Lb bomb.

To confuse the details even more, the Val also carried and used a 250Kg bomb.

How's that for confusing a fairly straightforward post

 

[Nikademus]

There was a multitude of factors that sank them. All four carriers at Midway sank from unique factors, but there was a common theme around them.

Bad damage control philosophy.
Poorly trained damage control teams.
Lucky hits
Akagi and Kaga were converted battle cruisers and suffered design issues that effected survivability
Soryu and Hiryu were lightly armoured and suffered accordingly.

And as future events showed, the remaining Japanese CV's were just as vulnerable to heavy bombs and torpedo's as they were off of Midway.

The largest factor that led to eventual scuttling of all four carriers was that they were caught at a moment of max vulnerability for a carrier. It might be argued that any such caught under such circumstances short of 1944 USN (or the UK...which never lost a major CV to fire) would have been doomed. USN lost several carriers under similar circumstances of out of control fires after damage and lost the services of a fourth for the remainder of the war despite one of the best examples of damage control in WWII history.

Akagi and Kaga's large size would in theory have served them as well as it did Lexington, and Shokaku and Zuikaku for that matter. In terms of design issues, the enclosed hangers of the Japanese coupled with the larger explosive effect of 1000lb bombs is more relelvent and it can be noted in the case of Shokaku that her flight ops were totally disabled after multiple hits from such while the smaller bomb size of the D3A coupled with the open hanger arrangement of USN CV's, and the partial use of SAP fusing more often led to USN CV's able to not only survive bomb hits but resume flight operations after repairs, as long as any penetrating damage was not too severe.

However Shokaku's example also highlights that the more typical impact of bombs on the big carriers was disablement vs. sinking. Torpedoes remained the best bet and its signifigant that it was this weapon that primarily took out 4 USN CV's prior to 43.

A better case can be made with Hiryu and Soryu......very light fleet carrier designs which gave them "glass chins" Whether they would have been sunk remains questionable without armed planes on board and ordinance lying around but certainly they would have been disabled under most circumstances.

I agree that poor damage control would also be an important factor though it should be noted that Shokaku/Zuikaku proved that IJN DC was not poor in every case.

 

[renrich]

Tim, I was thinking that one size bomb carried by Vals, which was measured in kilograms, weighed slightly more than 500 pounds. However Eric Brown says the Val carried a bomb which weighed slightly more than 1000 pounds. Is that the 550 kilogram bomb?

 

[timshatz]

Tim, I was thinking that one size bomb carried by Vals, which was measured in kilograms, weighed slightly more than 500 pounds. However Eric Brown says the Val carried a bomb which weighed slightly more than 1000 pounds. Is that the 550 kilogram bomb?

Ren, yeah, that would be it. When you're doing a cross between Kilos and Lbs, it's generally 2lbs to the Kilo. Rough estimate.

Use in Europe. Half a Kilo of Cheese is roughly an Lb!

Hey, it works, ya' know....

 

[JoeB]

Tim, I was thinking that one size bomb carried by Vals, which was measured in kilograms, weighed slightly more than 500 pounds. However Eric Brown says the Val carried a bomb which weighed slightly more than 1000 pounds. Is that the 550 kilogram bomb?

The main bombs used were nominally 250kg, a few types within a few kg of that weight. 250kg*2.204lb/kg=551lb. They might carry a 60kg under each wing in addition or instead depending on target. There were IJN bombs in 500kg class but they don't seem to have been commonly used.

Joe

 

[syscom3]

.......

I agree that poor damage control would also be an important factor though it should be noted that Shokaku/Zuikaku proved that IJN DC was not poor in every case.

Midway proved that IJN doctrine for damage control was uniformly poor.

Read "Shattered Sword" for all the ins and outs of the IJN philosophy.

 

[Nikademus]

Midway proved that IJN doctrine for damage control was uniformly poor.

Read "Shattered Sword" for all the ins and outs of the IJN philosophy.

Midway proved that bombs and loaded hangers don't mix. I own Shattered Sword and it is a good book on the battle. If your interested in IJN practices on a broader scale i'd recommend "Kaigun" by Evans and Peattie.

Japanese damage control was not great but it was not always uniformly poor. Citing the Midway disasters as a crucible example is not very fair. Lexington surcombed to a far less level of damage and Wasp died in similar fiery fashion after several torpedo hits while she was also at a most vulnerable state...prepping and refueling aircraft.

 

[Nikademus]

The main bombs used were nominally 250kg, a few types within a few kg of that weight. 250kg*2.204lb/kg=551lb. They might carry a 60kg under each wing in addition or instead depending on target. There were IJN bombs in 500kg class but they don't seem to have been commonly used.

Joe

The 60kg bomblet armament recalls a fierce argument i participated in long ago regarding the "standard" anti ship armament for D3A. I was unable to find any instance of them being used in anti-ship strikes against the USN carriers though there were some claims that they were dropped on Hermes. A land based D3A unit used them during a one way mission early in the Guad campaign (in lieu of proper 250kg bombs) but that appeared to be a last min improvisation.

 

[timshatz]

Japanese damage control was not great but it was not always uniformly poor. Citing the Midway disasters as a crucible example is not very fair. Lexington surcombed to a far less level of damage and Wasp died in similar fiery fashion after several torpedo hits while she was also at a most vulnerable state...prepping and refueling aircraft.

True, it was not terrible. But it did not go through the advances that the USN went through in giving DC a much higher level of importance than the IJN.

Your examples are instructive in that they are both early war (circa 1942) examples of damage control not to it's highest level (agree completely on the Lexington while the Wasp was a light frame carrier that went down to as many torpedoes as most other carriers would, in some cases even less).

By 1944-45, DC was very advanced in the USN. Two examples suffice to illistrate the point. The USS Franklin and the USS Laffey. Both were critically damaged yet did not sink due to the work of the DC.

 

[renrich]

Thanks, Joe, I seemed to remember in "Shattered Sword" that the Vals were armed with bombs slightly heavier than 500 pounds but could not check because the book was a library book and long since checked in. Anyway the 500 or so pound bombs were pretty effective. The 18 Vals from Hiryu, according to Lundstrom carried either 242 KG or 250 KG bombs and they damaged Yorktown severly with them.

 

[JoeB]

see next

 

[JoeB]

The 60kg bomblet armament recalls a fierce argument i participated in long ago regarding the "standard" anti ship armament for D3A. I was unable to find any instance of them being used in anti-ship strikes against the USN carriers though there were some claims that they were dropped on Hermes. A land based D3A unit used them during a one way mission early in the Guad campaign (in lieu of proper 250kg bombs) but that appeared to be a last min improvisation.

They carried only 250kg in the attack on Hermes according to the 'kodochosho' of the 5 carriers, and I also don't know of any case of them being used v US carriers, by divebombers, at least in 1942. But they were used against other targets fairly regularly. For example, the 2nd (later 582nd) Air Group's Type 99's in missions in New Guinea in 1942, usually v Allied airfields, usually dropped either250 plus pair of 60's, or just the pair of 60's, according to their mission reports.

The 60kg was used against Allied ships, but usually by Land Attack Planes or Carrier Attack Planes bombing horizontally, when lacking torpedoes, and/or loaded out for possible land targets, then diverted to ship targets; or by floatplanes. For example in the Dutch East Indies USS Langley and Marblehead suffered apparent 60kg hits in different attacks by Land Attack Planes: the attackers were dropping a mix of 60 and 250kg. Type 97 Carrier Attack Planes (Kates) also went after ships with 60kg bombs at times, for example Ryujo's attack on seaplane tender William B. Preston at Davao Gulf PI first day of the war.

Joe

 

[syscom3]

Renrich;

250 KG = 550 Lbs.