Although Italy was one of the first countries to consider the aerial use of the torpedo, as early as WWI, shortly before World War II the Regia Aeronautica still believed the best way to attack shipping was by bombing them! When Italy entered the War, on 10 June 1940, Italians realized their mistake, and hurriedly tried to find a torpedo-bomber. Lacking a dedicated aircraft, they adapted the SIAI S.79 Sparviero (‘Sparrowhawk’), and it was a happy choice. The aircraft proved to be agile enough and sturdy for this role. A subsequent attempt to try an updated version of it –the SIAI S.84- was unsuccessful, and the old ’79 ended the war continuing to threat Allied ships.

But the main problem at time was to have enough torpedoes for this use. The entire production, in fact, was dedicated to the Regia Marina and to the Luftwaffe, which understood the importance of torpedo-bombing before the Regia Aeronautica, and appreciated the quality of those Italian weapons. Notwithstanding new orders, torpedo shortage afflicted the RA throughout the War.

Apart from some experiments, only two types of torpedoes had been used by Regia Aeronautica, built respectively by Whitehead at Fiume (now Rijeka in Croatia) and by Silurificio Italiano at Baia (Naples). These torpedoes had some differences, which are interesting for modellers.

Fig. 1 – The factory drawings of Whitehead torpedo. The propeller area is not detailed. The “200 kg/cm²” refers to the charge power.

It was identified as Siluro 450/170/5.46, the numbers meaning respectively the diameter in millimetres, the warhead weight in kilograms and the length in meters. It weighted 860 kgs (1895.98 lbs), plus 16 kgs (35.3 lbs) of the detachable stabilizer. Its water run was of 3,000 meters (1.86 miles) at a speed of 40 knots-per-hour, and at a depth which could be set, before take-off, between 2 and 10 meters (7 to 33 feet).

Its body was of grey bronze. It was made of three parts: the warhead, the compressed air cylinder/tank and the motor, linked to one other by six rows of four oblique bolts each.

Fig. 2 – Mounting the warhead. The circular marks were to match the fit and were to be filled by streamlined rings. The tight fit leaves virtually no seam.

Fig. 3 – A detail of the fit between the middle and rear section.

THE WARHEAD. It was different from that of Regia Marina torpedoes, as the original ogival profile had been reshaped into a hemispherical one, for a better stability during water impact. Also the fuse had been modified, as the original device (the one shown in Ali d’Italia drawings, was actually a Type B nose fuse of a 160 kg (353 lbs) antisubmarine bomb) would had suffered the airstream during flight, and could crack in the dive. The new fuse was retracted in the warhead and covered by a cap. The latter popped off once the torpedo hit the water, leaving the fuse coming out and unfold its blades. The cap had a flat conical shape, with a square hole in the middle.

Fig. 4 - Ten Giorgio Sacchetti and his torpedo.

Fig. 5 – Another picture of the cap, this time with a mascot.

The fuse used by air-launched torpedoes had two foldable "handle-bar" blades.

Fig. 6 – The fuse in SIAI original blueprint no. 4374 of 22 Dec 1938.

Fig. 7 – On the top of the warhead there were two apertures for activating the fuses.

The warhead was filled with 170 kg (375 lbs) of Tritonal.

THE MIDDLE SECTION. essentially contained a 200 atm-compressed air cylinder/tank.

THE REAR SECTION. Contained all devices for propelling, the gyroscope, etc. At the rear, two contra-rotating propellers with four blades each. This detail has been missed by both factory blueprint of Fig. 1 and technical drawings in Ali d’Italia no. 11. The four fins were all symmetrical and of the long type.

Fig. 8 – Two shots of the Whitehead torpedo tail end at Vigna di Valle. Note that it has been overpainted. Actual torpedoes were left in natural metal, greased with oil to prevent corrosion.

Fig. 9 – On the top of the body there were a lot of holes, screws etc for activating cables depth adjustment and clockwork.

Fig. 10 – A detail of the top torpedo.

THE DETACHABLE FIN. In order to ensure a correct dive degree and flight stability, the torpedoes were fitted with a detachable fin, which was lost once in water. Several types were studied at Guidonia test centre, but the ultimate fin was the “Guidonia” type, shown in Figs. 11-13. It was made of plywood, and painted light grey, apparently paler than Grigio Azzurro Chiaro 1. It was fixed to the torpedo with a lock that was released, during water impact, by a system acted by two small plates. The torpedo had a gyro stabilizer which moved two ailerons; these could have been also of the short type (see circle in Fig. 1).

Fig. 11 – Sometimes the torpedo MM was applied over the fin.

Fig. 12 – Two small plates (arrow) are folded in the splash, and the fin is released.

Fig. 13 – The fin was fixed to the torpedo once the latter was hung to the aircraft. An idea for a diorama!

Some images show that some ‘79s, particularly from 278ª and 279ª Squadriglia, had torpedoes without the fins. It’s not known whether this was due to a device shortage or to a temporary change of the release technique (i.e., lower level release).

THE SILURIFICIO ITALIANO (SI) TORPEDO (LT F5i for Luftwaffe)

To obviate to the chronic lacking, from 1941 the Regia Aeronautica started to buy its torpedoes even from the other main factory, the Silurificio Italiano. The SI torpedo was codified as 450/170/5.25, with the same meanings as above. This weapon was essentially similar to the Whitehead, but with some differences which are interesting for modellers:

1. It was shorter by 21 centimetres, and weighted 860 kilograms (1895.98 lbs)
2. The bolt holes were covered by two thin steel belts
3. The warhead profile was left ogival, but a light alloy hemispherical shape was fixed with a bolt to it, with the double purpose of the better water dive and to avoid the cracking of the warhead against the target before the fuse exploded (one millisecond – 15 to 20 cm of run). The shape was light blue, perhaps the same blue protective paint of propellers and spinners ...

Fig. 14 – A Silurificio Italiano (SI) torpedo.

Fig. 15 - A SI torpedo is going to be hung under 281-2 at Gadurrà (Rhodes), in 1941. Note the blue head.

... but sometimes it was a darker colour, as shown by 204-5, at Rhodes in 1942. Again, it could have been the same dark blue of Italian bombs.

Fig. 16

4. In the tail section, the fin on top was very short. The other fins had a slightly different profile than Whitehead’s. Also, it seems they were a little wider (some 2-2.5 cm –one inch or less- each fin).

Fig. 17

5. The detachable fins were of different types. The first was the Guidonia-type, but without the ailerons and related bar, as the SI torpedo lacked the gyro stabilization system.

Fig. 18

A similar device with three vertical fins was tested ...

Fig. 19

... but its operative use seems to be rare. It has been verified only in 130° Gruppo until now.

The third type was more common for SI torpedo. It was essentially a Guidonia-type fin in which the vertical fins were enlarged and moved to horizontal plane tips. The latter was also wider than Whitehead’s.

This type was tested by Cap. Carlo Emanuele Buscaglia’s 281ª Squadriglia at Rhodes, in Summer 1941. It was found that the fin suffered by vibrations during flight, and sometimes was lost in air before releasing. As a solution to the problem, Buscaglia suggested to link it to the fuselage by two elastic cords, which were unlocked before or during release.

Fig. 20 – The commonest fin for SI torpedoes.

This problem was later solved, as there is no sign of such cables in other Units.

RELATED DEVICES OF MODELLING INTEREST:

Until 1941, torpedoes were released through a Bowden wire, controlled by a lever placed between the pilots’ seats. A control box was just ahead of them.

Fig. 21 – The early release system in S.79. (by the manual).

Lever in forward position was the safe, in the middle position the torpedo was activated and in the rear position it was released. A further safe box was ahead of the levers. In operational use, the starboard lever was sometimes removed together with the correspondent underbelly release gear. Above is a curious, but accurate description of this lever.

The system above was prone to malfunctions, so, after request from the pilots, the lever was moved to starboard spoke of pilot’s wheel.

Fig. 22 – The words on the right lever read: PER SGANCIO SILURO PREMERE FINO IN FONDO (Push to the end to release torpedo). As a sidenote, the left lever was the standard wheels’ brake, on which a warning reads: I FRENI COSTITUISCONO UNA RISERVA CHE VA ABITUALMENTE RISPARMIATA E USATA SOLTANTO IN CASO DI NECESSITÀ (The brakes are a reserve which must be usually saved and used just in case of necessity).

The S.79 was a civilian transport aircraft transformed into a bomber, then into a torpedo-bomber. The torpedo rack was a modifcation of the underbelly 800 kgs (1,763.7 lbs) bomb racks (however never operationally used). It was a complex rods structure which remained virtually unchanged throughout the war. Here are some pictures to detail it.

Fig. 23 – The propellers blocker seen in early Whitehead installations.

Again, there were some small differences between the racks for W and SI torpedoes: for instance, in the first case a carved plate prevented the propellers to be moved by airstream (see above), in the second, propellers were locked by safety pins (Figs 19 and 20). The torpedoes were suspended by a metal rope or by a metal band.

The SIAI aircraft factory then projected a new aircraft, the S.84, mainly for torpedo-bomber duties. Here are images from the S.84 manual, showing details of the torpedo arrangement.

Fig. 24 – Torpedo release commands in S.84: 1) safe buttons – 2) release levers – 3) manual release handle.

Fig. 25

Fig. 26