Since the 80th anniversary of Taranto raid a Youtube channel has been demonstrating the method used in which a tension wire connects Swordfish and its torpedo in order to ensure a belly flop and thus a shallow initial dive, the tension wire running from torpedo nose to a reel in Swordfish. There was also a wooden aerodynamic tail as both splinters of wood and tension wires are said to have been later floating around. I wonder what is the background of this because the concept involves a wire holding a long and heavy object (CofG close to 50 %) under the aircraft with the other end unsupported. Maybe this matter has already been discussed elsewhere but here are my thoughts.

A wire should not be necessary at extremely low altitude. The torpedo possibly stays near horizontal and in calm conditions skims shortly on the surface. Aircraft's speed is still high compared to any surface craft so bouncing could also happen. Then tail planes and control rods could get damaged. On the other hand unwinding wire should produce no pull upwards at all. The reel should also be above torpedo's nose where Swordfish has its engine. What would detach the wire from both ends and would it not whirl around ?

The wooden tail was to prevent rolling and give the right angle of entry, hardly needed at a very low level. In general, usual means to control depth (in short) was done by adjusting hydroplanes, depth gear and engine. Torpedoes could also be made to run light without fuel and water ("cold") as CMBs did in Kronstadt in 1919. Depth control was critical on coastal waters and improvements were tested in the 1930's. Perhaps RN had developed its own system.

Both initial dive and depth keeping varied greatly. For comparison one 45 cm 800 kg torpedo dived down to 5-6 m before reaching 3 m depth setting (static tube, 1,5 m height). A margin was accepted. I do not know Taranto waters but battleships (9-10 m) could move there and Conte di Cavour was immersed by the barrels of C turret. The height from the ship's bottom (17 m) suggests a fair depth even if embedded in mud. With magnetic exploder a depth setting of 9-10 m plus something plus margin was obviously needed. These torpedoes must have run this deep all the way. To my knowledge in 1940 no device could gradually guide a torpedo deeper.

In developing its Avio torpedo, Whitehead of Fiume conducted shallow water (20 m) trials with an aerodynamic tail. An initial dive of 11,2 m was achieved (angle 32 deg, weight 880 kg, speed 312 km/h, altitude 85 m, 4 m depth setting). What actually was the desired initial dive for Taranto and how low the aircraft flew ?

Olli