Japanese Type 91 Aerial Torpedo

[Dawes]

From the Wiki entry on the Type 91:

 

Germany approached Japan requesting the transfer of Japanese aerial torpedo technology. The Imperial Japanese Navy not only sent the plans, but also a number of Type 91 aerial torpedoes to Germany in response. They arrived in Nazi hands on August 2, 1942, courtesy of Japanese submarine I-30^] as part of a yanagi mission. It was designated the Lufttorpedo LT 850 in German service^.

Germany wished to acquire the knowledge behind the Imperial Japanese Navy Air Service's aerial torpedo technology in order to more effectively attack the Allied transport ships steaming in the Mediterranean Sea.^[6] It had previously imported Italian-made aerial torpedoes, which became unavailable following the Italian Armistice of Cassibile with the Allies in September 1943. The indigenous German aerial torpedo designs were badly restricted in launch speed and launch altitude.

So were the German aerial torpedo designs really that unsuccessful?

[lastdingo]

The Italian and Norwegian designs were the worst. The German LF5b was usable within tight limits. He 111 and Ju 88 torpedo bombers did use it with success in 42/43, but preferably at dusk or dawn (5-10 minute time windows) against transport ships.

Torpedoes almost keep the drop velocity until impact in the water. The longer the distance of flight prior to entry into the water, the farther away from the target can you drop the munition with the same probability of hit.

 

https://www.youtube.com/watch?v=w8XYZoR9ABE

 

http://www.combinedfleet.com/torps.htm

 

https://www.pacificaviationmuseum.org/pearl-harbor-blog/pearl-harbor-thunderfish-in-the-sky/

 

I've read multiple print publications on the German aerial torpedo topic, and useful figures for '42/'43 torpedo limits are hard to come by.

Edited April 27, 2018 by lastdingo

[Rick S]

Thanks very much for that Pacific Aviation Museum's detailed explanation of the design and working of the "fins" etc used on the Japanese torpedoes to make them run shallower.

I recall seeing a special on the Military Channel which "explained" how the wooden fins caused a decreased running depth and it even showed a recreation/simulation in a water tank that purported to show that the disposable fins had indeed caused the model torps to run shallower. That never made any sense to me whatsoever and now I know why.

Edited April 30, 2018 by Rick S

[Markus Becker]

What features made the Italian air dropped torpedoes that bad?

[lastdingo]

IIRC their maximum drop speed was too little above He 111 stall speed and the maximum drop altitude was ridiculously slow. They didn't run as intended once in the water either, at least not reliably.

The Italians had purchased few of those torpedoes for their own forces. It was a biplane era aerial torpedo design - OK for the 20's.

[Markus Becker]

What was the stall speed to the SM.79? It did very well as a heavy torpedo bomber, didn't it?

[lastdingo]

That's relative.

The Italian Air Force as a whole was quite an air farce in WW2.

I once read that the Italians had dropped more bombs in the Spanish Civil War than in WW2.

[Ken Estes]

That's news to me that there was anything wrong with Italian aerial torpedoes, used extensively by the German LW as the F5w, except that the manufacturing rate was unsatisfactory. The Italians had excellent air/kerosene torpedo engines, suffered none of the problems of USN and KM torpedos and managed to introduce a unique parachute delivered circling torpedo for use in harbors and confined waters.

 

I think Dingo's IIRC remains defective.

[lastdingo]

Sigh. He provoked me into diving into my library.

 

 

Waffen Arsenal Band 183

"Torpedo-Flugzeuge der Luftwaffe 1939-1945"

by Manfred Griehl, 2000

It's not exactly a historical science publication, but the most specialised source on the topic I ever found.

 

 

1934 delivery contract with Norwegian company Horten for several 650 kg torpedoes with 30 kts/4.000 m. Prototype-like manufacturing, 42 test drops with few duds

Company Schwartzkopff in Kiel began to produce 5 such torps per month, but till start of 1935 only 64 F5a were made. The German production torps were inferior to the Norwegian original.

By mid-1939 still 50% technical duds.

 

F5b developed from F5a, 36 kts/1,500 m, minimum depth 15 m, drop from 40 m at 200-250 kph

De facto all used in tests throughout 39/40.

 

order for 5,000 F5w at end of 1940, ordered from Italy (w for Whitehead)

fuze issues for two years kept its use insignificant

May 1943 only 87 of these F5w were ready for action

 

about 11 Nov 1942 335 F 5b and 211 F 5w available

11 Nov 1943 1,283 F5b and F 5w available

 

------------------------------------------------------------------

about those circling slow torps with parachutes:

 

lots of tests with LT350 and He111 till beginning of 1942

15,000 m with 65 minutes running and 13.5 kts dropping to 7 kts

minimum altitude for drop 150 m

23.7.1942 only 61 LT350 available

10 May 1943 interruption of their use because of lots of fuze and parachute defects

no successes off Sicily on 14 May 1944

KG 100 opined against further use of LT350

 

 

Quick googling reveals 40 m / 300 kph drop for F5w and Sparviero's torps by 1942.

I'm not going to dive deeper to my other sources on the German aerial torp thing, as most info is too scattered.

[Stuart Galbraith]

There is some good footage here of Torpedownia, the Luftwaffe's secret airdropped torpedo testing centre.

https://youtu.be/Xs_XQzzfdp4?t=2032

 

It does strongly suggest there was something wrong with their torpedos they felt the need to invest in something that belongs in a Bond film.

[lastdingo]

Germany already experimented with guided glide torpdoes in WWI (to be dropped from zeppelins then).

[Stuart Galbraith]

Wire guided?

[lastdingo]

Both. It's quite strange to see a biplane PGM. Though, those torpedoes turned out to be not all that precise due to the problem of 3D flight overwhelming the remote operator.

http://defense-and-freedom.blogspot.de/2009/02/precision-munitions-history.html

[Markus Becker]

... and managed to introduce a unique parachute delivered circling torpedo for use in harbors and confined waters.

Nice device technically but not a success tactically. Unlike the conventional torps. They worked.

[Ken Estes]

Still, we have little evidence at hand, it would seem. Italy was out of the war in mid-1943, we ought to remember.

 

The paucity of Axis success with aerial torpedos does not automatically fault the ordnance - only 6 RN warships in the Med:

 

http://www.naval-history.net/WW2BritishLossesbyArea08.htm

Edited May 3, 2018 by Ken Estes

[RETAC21]

Surely navweaps is known:

 

http://www.navweaps.com/Weapons/WTIT_List.php#World_War_II

 

http://www.regiamarina.net/detail_text_with_list.asp?nid=103&lid=1&cid=2

 

http://www.regiamarina.net/detail_text_with_list.asp?nid=104&lid=1&cid=3

 

Quote from the last: Torpedos

"The torpedo utilized by the torpedo bombers were the 450/170/4.5 built by the Whitehead of Fiume and by the Silurificio Italiano di Baia (Naples). Both models had a range of 3,000 meters at 40 knots. The torpedo was usually launched at a speed of 300 km/h and at an altitude of 30 to 40 meters. From this height, the torpedo would enter the water at an angle of about 30° and, after having sunk about 10 meters, would, within 160 meters from the launch area, stabilize on its course and depth.

During the war, several torpedos were modified to fit the need of an aerial launch and they incorporated interesting and innovative solutions.It should be mentioned that during the war Italy built several prototypes utilizing various aircraft, such as the smaller Ca.313 and Ca.314, although too underpowered for the task. Also the Re.2002 was equipped with a torpedo shortened to 2.38 meters, and so was the very new Fiat G.55. These solutions were later implemented after the war "

 

Sinkings don't tell all the story as 30 more ships were damaged in 1941 and those carried their own overhead in terms of repair and escort.

[Ken Estes]

Nice work, amigo RETAC. I had visited NavWeps' site but they lacked the details that you found on the RM site. I should have persevered. I really wished to have my copy of Campbell at hand, but I'm away from the office for now.

 

Really, there is no place for condemnation of Italian torpedos as biplane-era materiel [most all TBs were biplanes in the 1930s], nor is the Italian AF so easily dismissed as an 'air farce.' Such amateurism, I despair.

[lastdingo]

Yeah, right, skip the part where you were wrong claiming that the Italian torpedoes had non of the problems that KM and USN torpedoes had (they had bad issues with fuzes just as KM and USN torps) and where you praised a torpedo that was found to be ineffective, amateur.

 

At least I was honest enough to write "IIRC", while you just spewed falsehoods with confidence/arrogance.

[RETAC21]

Yeah, right, skip the part where you were wrong claiming that the Italian torpedoes had non of the problems that KM and USN torpedoes had (they had bad issues with fuzes just as KM and USN torps) and where you praised a torpedo that was found to be ineffective, amateur.

 

At least I was honest enough to write "IIRC", while you just spewed falsehoods with confidence/arrogance.

 

For those challenged by links:

 

"The Italian torpedoes were equipped with fuses of the type "inertia pendulum", which would go off when the weapon hit against the hull of a ship (with a limit of 15 degrees and 5 knots). Such type remained the standard for almost all the duration of the conflict. Only in 1942 did Regia Marina start introducing fuses of the magnetic type «S.l.C.» produced by the Silurificio Italiano.

 

In the same period, Italy started employing on submarines German torpedoes type «G.7e» with magnetic fuses. This weapon did not generate a wake and was extremely efficient, but available in limited quantities.

 

In general, Italian torpedoes were very satisfactory and they did not have the well-known technical problems experienced by both the American and German models. As a matter of fact, the US Navy used some captured Italian torpedoes to study ways of improving their own models.

 

Adapted from "Le Armi delle Navi Italiane Nella Seconda Guerra Mondiale" by Erminio Bagnasco published in 1978 by Ermanno Albertelli - Parma

"Naval Weapons of WW II" by John Campbell, published by Conway Marittime Press "

[Ken Estes]

Indeed, amigo.

[lastdingo]

Ah, right. An Italian source praising Italian torpedoes. Totally more believable than the German source stating that fuse issues kept the Italian export torpedoes almost entirely from being used for two years.

Especially in light of the huge quantity of ships sunk by Italian aerial torpedoes in 1940-1942. Oh, wait.

 

 

https://weaponsandwarfare.com/2018/01/27/italian-torpedo-bomber-squadrons/

 

"[1941] ended with a total of nine Allied ships sunk and several damaged. The Italians had lost fourteen torpedo bombers and sustained several damaged in action. This was the best year for the Italian torpedo bombers(...)"

 

"Despite the increased activity in 1942, the results were considerably poorer than those of the previous year. The efforts made by the bombers were heavily criticized as being insufficient. Many debated the possibilities of torpedo manufacturing defects or even sabotage: the first 30 used in 1940 had excellent reliability, but a number of later torpedoes were found to be defective, especially those made at the Naples factory. During Operation Harpoon, over 100 torpedoes were launched with only three hitting their targets."

 

The description of Italian torpedo-bombing in 1943 is even darker.

 

--------------------------------

 

"Savoia-Marchetti S.79 Sparviero Torpedo-Bomber Units"

By Marco Mattioli

 

15 August 1940 to 8 September 1943

ALL Italian torpedo bombers flew in this long time a mere 2408 combat sorties and lost 110 aircraft in action.

21 ships sunk

17 ships damaged

That's ridiculous. One ship damaged or sunk per month, and this was the more effective part of Italy's bomber force in that war.

 

 

Regia Aeronautica - the Italian Air Farce.

[sunday]

https://weaponsandwarfare.com/author/critcalmass/

[Ken Estes]

At times, the LW was more successful attacking its own ships than the enemy's. Torpedo bombing is not for the faint of heart and carrier-qualified pilots have sui generis much better awareness of ship speeds and maneuvering and resulting relative motions/vectors than their landlubber cousins.

 

Perhaps Dingo can bring out the pic of Yamato's last battle and lecture us some more on the relative cowardice of US pilots engaging her.

Edited May 4, 2018 by Ken Estes

[sunday]

This space for rent.

Edited May 4, 2018 by sunday

[Ken Estes]

This one too.

Edited May 4, 2018 by Ken Estes