Mark 13 torpedo 'box tail' stabilizers

[fcorsair]

Hi all, I'm trying to do some research into the Mark 13 and one thing I'm struggling to pin down is exactly when the plywood 'box tail' stabilizers on the torpedo were first used, and indeed any detail as to why they were introduced. So far I have the fragmentary facts laid out:

1. A photo of Newport Torpedo Station's TBD-1A dropping a Mark 13 with a box tail, dated 1939
2. Photos of VT-6 TBDs dropping Mark 13 Mod 1s in October 1941, tests that were notable for the problems with the torpedo - no box tails evident at all
3. A secondary source that states VT-6 used box tails on the 1st Feb 1942 raid on Kwajalein, specifically because of the shallow depth of the anchorage
4. Screenshots from John Ford's VT-8 tribute film that appear to show some sort of box tail, but it's very grainy.
5. Photos of USAAF B-26s loaded with Mark 13s, box tails very much in evidence, circa October 1942.

Thereafter the trail goes a bit cold but I'm certain the box tails were used routinely from August 1943 onwards, labelled as the "Mark 2 Stabilizer". Later, the NDRC and CalTech researches found that the stabilizer was particularly useful for ensuring clean water entry but it seems that BuOrd had some other reason in mind when using the earlier type of tail. Frustratingly I haven't been able to find any documentary evidence about this device, so I'm a bit stuck. Can anyone shed any light?

For reference on the other improvements to the Mark 13 I'm 99% sure that the 'pickle barrel' plywood drag ring on the nose was first used by VT-9 at Truk on 16th Feb 1944, and the welded steel ringtail was introduced and tested during early 1944 before being used in combat for the first time by VT-13 on 4th Aug 1944.

 

[Greg Boeser]

USAAF used Navy torpedoes, and the B-26s carried torpedoes with box tails throughout 1942.

 

[Barrett]

Sidebar: VT-13/CV-13 introduced the ringtail torpedo to combat 1944. CO was Larry French who was sidelined to F4Fs for Midway.

 

[MIflyer]

Recommend you get the book "Hellions of the Deep" by Robert Gannon. It is a great history of US torpedoes in WWII and before.including development of the Mk 24 Fido homing torpedo.

Hellions of the Deep- Robert Gannon, 1996, 1st Edition | eBay

Aside from the wooden tails later adopted, early in WWII it was thought that it was necessary to drop the torpedo from low altitude and low speed. But they then discovered that was the worst way to do it, producing a bellyflop and unstable entry. Higher altitudes and speeds were preferable, since they gave the torp more time to stabilize in the air before it entered the water.

Later in the war the success of the air dropped torps was such that launching tubes were dispensed with on PT boats and they just activated them and rolled them off the deck into the water.

Note that the wooden tail fins used on IJN air dropped torpedoes at Pearl Harbor were designed to keep them from diving too deep and getting stuck in the mud.

 

[Gunsights]

A Training film showing the wood assemblies
being installed on the MK13

 

[MIflyer]

Take a look at this, The MK13 Air launched torpedo, A WWII Success Story:

DTIC ADA301197: The Mk 13 Aircraft-Launched Torpedo: A World War II Success Story. : Defense Technical Information Center : Free Download, Borrow, and Streaming : Internet Archive

But in reality the RI Torpedo Factory were a bunch of screwups. The USN brought in an academic/industry team to develop the Mk24 and then let them fix the other torpedoes when they succeeded with the Fido.

There is also this: A Brief History of U.S. Navy Torpedo Development : E. W. Jolie : Free Download, Borrow, and Streaming : Internet Archive

 

[fcorsair]

Thanks all, I've seen all of those sources and videos, plus I have a copy of Hellions of the Deep - but none of them explains the origin of the box tails at all. I guess the answer lies in some archive somewhere.

 

[Micdrow]

Thanks all, I've seen all of those sources and videos, plus I have a copy of Hellions of the Deep - but none of them explains the origin of the box tails at all. I guess the answer lies in some archive somewhere.

Not sure if this helps much

 

[Reluctant Poster]

Thanks all, I've seen all of those sources and videos, plus I have a copy of Hellions of the Deep - but none of them explains the origin of the box tails at all. I guess the answer lies in some archive somewhere.

HyperWar: US Navy Bureau of Ordnance in World War II [Chapter 6]
A more honest history of US torpedos.