Destroyer sunk by Tuskagee Airmen - More information needed

Great story! thanks for sharing!

Too bad this story was not available a few months ago during the debate about the low power of the 50 BMG compared to the various cannon.

renrich said:

Too bad this story was not available a few months ago during the debate about the low power of the 50 BMG compared to the various cannon.

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I believe there is also a story about Wildcats sinking a Japanese destroyer. Which if I remember the story correctly was also a WW I left-over of around 1000tons or less.

Causing a magazine explosion by bullets getting though an open hatch doesn't really prove much about the power of the gun, one way or another.

Destroyers were also made of rahter thin metal for lightness. It was usually of better quality steel than larger ships (higher tensile strength) to help get the speed that was wanted. This does not in any way mean that it was armour plate.

A good burst of .50 cal Mg fire might be able to penetrate sides of ship a bit below the water line. Can the multipule small leaks let in more water than the pumps can handle?

Might depend on if the pumps or auxilary machinery were damaged by the MG fire. it might also depend on if the MG fire managed to cause a leak in a boiler or steam pipe which rendered the machinery space/s uninhabitable.

Shortround6 said:

Destroyers were also made of rahter thin metal for lightness. It was usually of better quality steel than larger ships (higher tensile strength) to help get the speed that was wanted. This does not in any way mean that it was armour plate.

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On The Sullivans, DD537, a Fletcher class destroyer, the deck and hull plate used varied between 12#HTS and 25#HTS. A square foot of steel 1" thick weighs 41.82 pounds (Manufactures' Standard Gage for Steel Sheets).

It may be repeating an earlier post (probably on another thread) but the plating on late WWII big US DD's (Fletcher/Sumner/Gearing) was much thicker and stronger than that not only on a WWI era Italian TBD like TA-22, but also even compared to most other 1930's-WWII DD's in most navies.

Two different sources ("Anatomy of the Ship" and Friedman's "US Destroyers") both describe it slightly differently, as 30# STS (ie ~3/4" ~18.5mm) on the hull sides above waterline in midships area and 20# (~1/2" ~ 12.5mm) on most of the upper deck. STS, Special Treatment Steel was a specific USN grade under the general heading of high strength steels. It was essentially equal to homogeneous armor plate. This plating was specifically intended to provide protection v strafing and bomb or shell fragments. Such protection had been considered on 1930's DD designs in USN, but always rejected on account of weight, given treaty restrictions on displacement of DD's. With those requirements expired, a larger DD design was possible, and could include such protection, inspired especially by serious damage to British DD's from bomb fragments early in WWII.

The shell plating on an Italian WWI era TBD like TA-22 would have been much thinner. Even Italian cruisers of the 1920's had thicknesses around 4-5mm mild steel in unarmored portions of their side shells. Italian warships were famously lightly built. TA-22's thin hull, further thinned by almost 20 years of corrosion, would have been easily penetrable by .50 cal fire, with plenty of energy left to do damage inside.

F4F-3's of VMF-211 did sink a Japanese DD in the defense of Wake, Kisaragi, of 1920's Mutsuki class. However a 100# bomb may have been the critical hit, though there was lots of strafing as well. Either way it appears depth charges were set off, which was the immediate cause of the ship's destruction.

F4F-4's strafing of French DD's seriously affected their fighting ability at the naval battle of Casablanca in November 1942, mainly from loss of key personnel, though one ship had her steering gear temporary ko'ed by .50 fire. There were other similar cases in Pacific but in the French case the opponent's account was easily available soon after the fact. Several of those ships were L'Adroit class built in 1920's, whose shell plating varied from 5-10mm mild steel in various parts of the hull (per "Les Torpeilleurs de 1500 tonnes du Type L'Adroit").

Joe

From the Anatomy of the Ship book Joe.



25# = 0.717"
20# = 0.478"
12# = 0.287"

DD537 laid down Oct 10 1942 built to a 1940 design study.

A good burst of .50 cal Mg fire might be able to penetrate sides of ship a bit below the water line.

One thing to keep in mind is that as the angle gets closer to perpendicular to the hull, rounds that strike the water in front of the hull on a path toward the hull below the water line have a greater tendency to be deflected by the water. (literally ricochet) Also, rounds that actually strike the hull below the water line are no longer traveling along their axis (they begin to tumble and arc upon impact with the water) and lose velocity extremely fast all of which which greatly diminishes penetration.

I would be skeptical of .50 AP rounds penetrating 1/4" of hull even 6" under water and in sufficient number in any event to cause the ship to take on a threatening amount of water.

For further reading on just how effective a barrier water presents to bullets, see:

Haag, L.C., "Bullet Ricochet from Water," AFTE Journal, Vol. 11, No. 3, July 1979, pp. 27-34.
Nennstiel, R., "Study of Bullet Ricochet on a Water Surface," AFTE Journal, Vol. 16, No. 3, July 1984, pp. 88-93.

[Edited to reflect 6" under water"]

Milosh said:

From the Anatomy of the Ship book Joe.

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I'm going from Friedman's description of the design process which specifically says the heaviest 30# protection was settled on, plus same Anatomy of Ship book, p. 9 describing thickness of plating strakes: "Starting at the main deck there were two [strakes] of 30# STS...". A weakness of those drawings pages is none of the elevations (that I noticed) show the frame numbers. Frame 152 might be aft of the portion protected by 30#.

Back on the general issue, for a typical thin skinned WWI or WWII era DD, not a thick skinned one like a Fletcher class, .50 rounds might penetrate right at the water line (I agree, any significant distance below and the water protects the ship), or penetrate above with enough energy to damage stuff inside, cause fuel tanks to leak etc, but most of all kill and wound personnel. And the personnel issue would be equally or more true with hits to the superstructure, where a typical WWII DD had little to hide behind that would stop a .50 cal bullet, until after some navies adopted splinter protection in specific locations, bridge area especially. The French and Japanese both did so in direct response to experience of effective .50 cal strafing by USN a/c in 1942. A sinking by simply filling up with water was unlikely, but .50 cal strafing could be devastating to DD's lacking any splinter protection, which most lacked early in WWII.

Joe