Tarranto

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paul.mercer
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Tarranto

Post by paul.mercer » Mon May 25, 2020 8:48 am

Gentlemen,
It is widely assumed that the Japanese attack or Pearl Harbour was motivated by the RN attack on the Italian port of Tarranto. After watcing a documentary on the Pearl Harbour attack it showed the tail of the Japanese torpedoes being encased in some sort of wooden box which broke away on impact with the water and stopped the torpedo diving too deep.
Did the British torpedoes have the same modifications for their attack at Tarranto?

Mostlyharmless
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Re: Tarranto

Post by Mostlyharmless » Fri May 29, 2020 12:38 pm

The best answer to your question that I found on the internet was on the Armoured Carriers website https://www.armouredcarriers.com/operat ... llustrious which had:

"The Fleet Air Arm did not use timber attachments to their torpedoes in the same manner as the Japanese at Pearl Harbor, as many accounts report. (It was the Italians that developed this technique for dropping torpedoes from their SM79 trimotors. This was passed on to Japanese delegations in 1940/41).

Instead, each 18-inch Mk XII torpedo was linked to its Swordfish by a strand of wire. This would hold the nose of the torpedo up as it fell to the water, producing a belly-flop instead of a dive. This enabled them to be dropped in water as shallow as 22 feet.

At Taranto the torpedoes were set to run at 27 knots at a pre-set depth of 33 feet. This was calculated to enable the torpedoes to pass under anti-torpedo netting while still allowing the new Duplex magnetic warheads to ‘sense’ a warship above and explode while passing beneath, or detonate on contact. Taranto's battleship harbour had an average depth of 49 feet."

In fact the torpedoes were dropped from very low and possibly from inside the nets. The only aircraft lost from the first wave flown by Lt. NJ Scarlett who was taken prisoner may have put its wing tip into the sea after launching the torpedo that sank Cavour ("Taranto 1940: A Glorious Episode" by A J Smithers, pages 102-3).

Other sources are "The Attack at Taranto" by Angelo N. Caravaggio, Naval War College Review, Volume 59, Number 3 Summer, Article 8 and "Taranto 1940: The Fleet Air Arm’s precursor to Pearl Harbor" by Angus Konstam, which have maps of the harbour.

Before leaving, note that the USN torpedoes were later fitted with wooden boxes for the opposite reason of causing them to enter the water at about 26 degrees to enable them to survive dropping from relatively high and fast https://www.eugeneleeslover.com/VIDEOS/ ... ttack.html.

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wadinga
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Re: Tarranto

Post by wadinga » Fri Jul 03, 2020 8:02 pm

Fellow Contributors,

After some investigation I have some serious issues with the explanation on the Armoured Carriers site.

Any wire attached to the nose of the torpedo would be IMHO a very poor idea. It is supposedly strong enough to support the weight (c1600 lbs) long enough to gain this preferred attitude on water entry yet manages to part exactly when required. Where "whiskers" for contact detonation are fitted, they might become entangled, and if the wire, once detached is still secured to the torpedo, it would stream back and become entangled in the rudders/propellers. Every other source I have found suggests the last thing required is a belly flop or worse still, first water impact on the delicate rudders. It is always emphasised that a nose first water entry is required to minimise shock to the gyro, pendulum mechanism and other delicate parts. Too high an impact in belly flop might even snap the torpedo in half.

Commonly used descriptions of the FAA Swordfish of WWII include “antique” or “flimsy” but as it only entered service in 1936 and its resistance to battle damage was legendary IMHO these are ill-informed. As a combat aircraft it had many shortcomings and against modern fighters or heavy AA defence it might have little chance of survival. It was out-evolved in the fighting role by more modern torpedo aircraft. What it could do, in addition to operating from flight decks in weather conditions which other aircraft could not consider, was use its slow speed stability to give its torpedo the most gentle possible water entry. At Taranto they were as low as 30ft off the water and some even kissed the surface with their wheels as they turned away. Darkness might allow the attackers some chance of survival, despite these tactics. In daylight such slow moving targets would likely be annihilated even before dropping their weapons since volume and accuracy of defensive fire had developed rapidly in just a few years. Faster, high performance aircraft needed to drop at higher speeds and for shallow harbours, techniques to minimise the dangers of high speed water impact and deep diving were required. The box tails and structures developed for the Pearl Harbor attack were necessary because the weapons were dropped from greater altitudes and faster speeds in daylight.

Reading Campbell’s Naval Weapons of WWII And Captain Sutton’s account on the FAA Museum website gives what I believe is the real picture on the “attached wire” story. Torpedoes need to be “vertical” in the cross sectional sense in the water, so as to apply gyro corrections to the vertical rudders and depth control to the horizontal. If the torpedo is not vertical, movement applied to the rudders may cause undesirable changes in depth and/or direction. Captain Sutton, a navigator/observer in one of the attacking aircraft described
Now the trouble with the torpedoes in those days was that they were converted ships’ torpedoes and had to be dropped extremely carefully into water. You had to fly - for a period after you had released it - easing it into the water - where there were two spools of wire attached to the aircraft which put it (the torpedo) nose down so it entered the water at the right angle and so we waited those few seconds - which seemed an immense period when you were doing it but a only few seconds after we released the torpedo.” The torpedo must be fired from at least 275m away.
Campbell says there was an air-tail which had limited aerodynamic capability, and fitted onto the horizontal rudders. This helped the torpedo enter the water nose first. Its main function however was to have two 18ft long wires attached to the outboard ends, which were wound on drums in the aircraft’s after fuselage, which payed out evenly as the torpedo dropped away, keeping it vertically orientated as it emerged from aircraft propwash and turbulence. The aircraft end of the wire was not secured and just ran off its drum. When the weapon entered the water, the air tail was torn off, complete with the wires, their job done. The torpedo was already correctly orientated for a relatively short run to the target.
The FAA had plenty of experience of harbour torpedo attacks, having used them against both Dunkerque at Mers-el-Kebir and Richelieu at Dakar. However, the bravery of the Taranto attackers in doing the same thing at night, through heavy AA fire and amongst barrage balloons is outstanding.

Faster aircraft, like the Beaufort and the Torbeau invariably used the Air Tail and later developments as they dropped their weapons from ever-greater heights and speeds. Since a torpedo is not aerodynamic, the enlarged unit Monotail was required to stabilise the weapon through a longer fall.

All the best

wadinga
"There seems to be something wrong with our bloody ships today!"

Steve Crandell
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Re: Tarranto

Post by Steve Crandell » Fri Jul 03, 2020 11:57 pm

Wow. Thank you for that very informative post. It's kind of amazing to me that none of the swordfish crashed into the water.

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wadinga
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Re: Tarranto

Post by wadinga » Wed Jul 15, 2020 10:06 am

Fellow Contributors,

I recently found an illustration of a Swordfish in a wartime book which may explain the confusion over the "nose wire". This showed a short wire from the aircraft fuselage attached to an arming pin on the weapon's nose, by which the pin was pulled out as the torpedo dropped away. The short wire and pin remaining with the aircraft. The weapon had a small propeller-like fitting which was rotated and screwed in by water flow finally arming the explosive charge once the torpedo was safely in the water.

The pin obviated the possibility of the arming propeller being rotated by airflow and arming the weapon whilst still aboard the aircraft.

One Swordfish was shot down and ended up in the water. Lt N J Scarlett, mentioned above, was the observer, the pilot and attack leader being Lt-Cdr K Williamson. They hit Conte di Cavour with their torpedo, and survived the shoot down to become POWs. The Italians craned the wreck of their aircraft, L4A up from the harbour floor and a photo reproduced in The Swordfish Story by Ray Sturtivant shows it still to be largely in one piece, showing how tough the airframe actually was.

All the best

wadinga
"There seems to be something wrong with our bloody ships today!"

OpanaPointer
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Re: Tarranto

Post by OpanaPointer » Sat Jul 18, 2020 12:17 pm

Saved me from posting the same material. BZ

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wadinga
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Re: Tarranto

Post by wadinga » Sat Jul 18, 2020 4:25 pm

GMTA
"There seems to be something wrong with our bloody ships today!"

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