The One Year Voyage of the LUIGI TORELLI

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Conslaw

Senior Airman
627
449
Jan 22, 2009
Indianapolis, Indiana USA
So, I was reading on the combinedfleet.com website, and I came across the interesting page relating to the Italian submarine Luigi Torelli. This submarine served under the flags of Italy, Germany and Japan, ending the war as I-504. What might be of most interest to members of this site is the cargo voyage undertaken by the sub starting June 15, 1943. Here is the list of cargo the sub was carrying for destination Japan on this trip:


14 June 1943:
Departs Bordeaux for the Far East under TV Enrico Groppello. She carries a cargo of mercury, steel, 800 Mauser MG 151/20 aircraft cannons,[4] a 500-kg SG 500 bomb and spare torpedoes. Her passengers include Colonel Satake Kinjo, a telecommunications officer returning to Japan after extensive training in Germany, radar engineer Heinrich Foders of Telefunken who has a set of Würzburg AA radar blueprints and two civilian mechanics. Two complete sets of Würzburg radars are also carried for delivery to the IJA and IJN. [5] AQUILA VI also carries three German engineers from the U-boat builder Deshimag AG Weser at Bremen on a technical mission to Japan.


The 800 MG 151/20 cannon could have shot down a lot of Allied aircraft, except - the sub didn't make it to Japan until June 25, 1944, over a year after it departed France. I note on the cargo list the "500-kg G 500 Bomb" I suspect that this was not a bomb. I think this is a transciption/translation error for what was likely the SG-500 recoiless rifle, an anti-bomber gun initially designed for the Me-163.

If anybody has any additional information on this submarine, it's cargo or other interesting tidbits, please post. It seems to me that if the 800 aircraft cannon really made it to Japan in mid-1944, they could have been put to good use in the year plus remaining in the war. Does anyone have any information on that?

It looks like Japan did make some prototype copies of the Wurzburg radar, but by the time this radar unit made it to Japan, Japan likely had indiginious designs that were just as capable and more in tune with Japanese manufacturing methods.
 
The wikipedia entry for MG 151/20 says that the 800 MG 151/20 exported via the Cappellini were used to equip 388 Kawasaki Ki-61-I Hei fighters.
 
From the Wikipedia Article on the SG 500 Jagdfaust:

The Jagdfaust design was based on the Schräge Musik, the manually triggered upward-firing air-to-air cannon extensively deployed with the Luftwaffe night fighter squadrons.[citation needed]

The Komet was so fast that pilots found it difficult to fire enough cannon rounds to destroy a bomber in a single pass. The Jagdfaust was developed to address this problem. A 5 cm shell was mounted in a launch tube held in place by a pair of thin pins. Four such tubes were mounted vertically (to fire upward) in each wing. To ensure it would be fired at the correct time, the weapon featured a simple form of automated trigger in which an optical photocell detected the dark silhouette of an Allied bomber replacing bright blue sky and triggered the firing of the armed Jagdfaust guns. When the weapon fired, the force of the launch would break the pins holding the tube in place and the heavy tube would be ejected downward to offset the momentum of the explosive force of the shell. As a result, the plane's flight was not affected.[1]

The Jagdfaust used a 5 cm "Minengranate" shell, whose thin walls traded fragmentation for additional explosives; when detonated within an aircraft with sheet metal skin, the skin would be blown off to devastating effect. The entire weapon was designed for economy. Because it was intended for short range use, the shell had an aerodynamically inefficient shape that could be easily forged or stamped. Its tolerances were loose, as its long-range accuracy was not an issue. Instead of a driving band, the shell flared at its base and was machined to engage the rifling. The launch tube was made of soft unalloyed steel since it would not need to keep its rifling over multiple firings. The shell used a simple type of fuse instead of the more complex and expensive AZ 39 Safety Fuse. It was probably shipped pre-assembled and ready to install.[2]

I couldn't find any sign that Germany had a bomb called the SG 500. They had a 500 KG general purpose bomb called the SC 500, but it just seems like an ordinary bomb with nothing that would seem to warrant high priority transport to Japan.
 
The SG500 wasn't a bomb, it was the Sonder Gerat SG500 "Jadgfaust" - a recoiless rifle designed for airfcraft.

It was to be mounted in the fuselage, pointing upward like Schragemusik and had a 50mm bore that fired mine shells. The system also featured an optic sensor that automatically discharged the weapon when the aircraft was below the target.

It was developed late in the war and intended to be used on the Me163, so it was never deployed outside of testing. However, one Lancaster was downed during trials towards war's end (not with the Me163, however).

It was similar to the Sonder Gerat SG116 30mm tested on some Fw190F-8s.
 
Japanese and German ammunition were not compatible--hell, IJN and JAAF weapons were not always compatible! So either a really hewge shipment of Luftwaffe 20mm was required, or Japan would've had to spool up to load enough MG151 to last the duration...
 
The Japanese munition industry was quite capable of manufacturing ammunition for use with German weapons, and did.
The Japanese used the MG151/20 on the KI-61 fighter, the 20mm cannons were shipped from Germany aboard the Italian sub Comidante Cappellini.

The Japanese also used the MG15, manufactured as the Army Type 98 and Navy Type 1 (both were 7.92mm.
They also used the MG131, manufactured for the Navy as the Type 2 (13mm).

Additionally, their Army and Navy aircraft used weapons based (or licensed) on Vickers, Browning, Lewis and even Oerlikon weapons.
 

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