WI U-boats with Long Lance torpedoes?

Its essentially irrelevant.
even then its got a hit rate of just over 6%.

The figure was 6.71%. The figure at Savo was 13.1%. The figures are indeed irrelevant because they refer to ship-launched torpedoes, sometimes at night, and sometimes a game changer, forcing Marines to eat maggot-infested rice.

The Japanese didn't employ Long Lance, Type 93, from subs. They used the also effective Type 95, a 21" fast torpedo with a big warhead. Anyone know the hit rate for the Type 95, and to be fair, all other sub-launched torpedoes?

The Germans could also derive some benefit from obtaining the air-launched Type 91 torpedo, and creating aircraft and tactical doctrine to employ them. They had the widest, easiest launch parameters in the business, they were fast, and made a big bang.
 
How much if that is down to the inherent flaws of the weapon, and how much down to the doctrine?

As I recall, German submarine doctrine changed two years before the war, from the initial idea of 3000+ metre shots from outside ASDIC range, which was expected to be quite wasteful of torpedoes, to 600-ish metre, almost point blank- at which in the first two years of the war they landed a hit rate of exactly 50%, 404 hits of 808 torpedoes fired.

American fleet submarines had enormous torpedo reliability problems to begin with, but also generations more sophisticated fire control, which still worked out at about 18-20% hits at longer range than most U-boats bothered to fire at.

The overwhelming majority of successful torpedo attacks are conducted at short range, and usually against unsuspecting targets, denying the target chance to manoeuvre and random chance much of a look in;

the miserable proportion of hits scored by the Japanese was almost entirely down to firing at too long a range- it's not the mechanical range of the torpedo that's the issue, the Long Lance could do almost to the horizon shots, it's the travel time, and anything over a couple of minutes is guided weapon or wild luck territory.

Extreme speed at medium- short range would have been a better bet than high speed at extreme range. That changes with homing torpedoes- and a 24.5" would have a larger seeker head, too.
 
From wikipedia for Type 92:

22000 m @ ~49 kts: ~870 s (~14 minutes)
33000 m @ ~38 kts: ~1670 s (~28 minutes)
40400 m @ ~34 kts: ~2300 s (~38 minutes)

the travel times are simply ridiculous without some kind of active homing.

On the other hand, the italian torpedo I mentionned would have a maximum travel time of about 116 -> 156 seconds i.e. 2 to 2 1/2 minutes. The travel time for the 600 m distance would be around 23 seconds, not enough for even the news of the incoming torpedo to reach the commander.

My recipe: short travel time (i.e. fast as hell with a non demented maximum range) and a as large as possible warhead for a one-hit-one-sink performance on anything below cruiser size.
 

CalBear

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The biggest advantage for the U-boat force early on by using the IJN Type 95, beside them being insanely fast (very helpful when using an unguided weapon) is that the warheads worked all the time.

The KM had a similar problem to the USN with magnetic detonators early in the war. once they got that sorted the KM torpedoes were fine for the mission.

The vessels that would really have benefited from IJN torpedoes were the S-boats and KM destroyers. Not enough to change the outcome, but S-boats with Type 93s would be scary as hell.
 

Driftless

Donor
I've asked this question elsewhere: at the start of WW2, weren't the Italian torpedos generally effective and reliable? More so than the German torpedos in the first couple of years?
 
With a more effective torpedo:

Merchant losses will go up, bulk imports will go down, the British may use their carriers to to fly top cover over the most critical convoys. Warship losses will go up but the British will become more cautious and not expose their warships to such losses.

Short term results:
1) Battle of Narvik April 40-June 40 more costly for British if Germans can sink transports/warships.
2) Bulk imports go down but this really doesn't affect production until after Battle of Britain
3) Harder to get stuff to mid east, but this doesn't really affect Operation Compass, but will hurt in 1941
4) British more cautious in Med, No Taranto raid
5) British may have to make some decisions about Crete, Malta and Tobruk in 1941 if they are worth the cost.

Long term results:
Likely the British are on their heels, don't try to defend Crete, Malta is less effective and may have to be surrendered in April 42, Operation Crusader doesn't happen, Tobruk is evacuated autumn 41 and North Africa is kind of quiet with both side content to have it that way for a while.

Germans have hundreds of more transport aircraft available for Barbarossa to help supply with no Crete, since Leningrad was close to falling OTL lets say this means Leningrad falls.

Perhaps we can delay Torch for a month or two with some follow up effects that the Germans have enough extra strength with that and the fall of Leningrad to lessen the Stalingrad catastrophe.
 

Delta Force

Banned
I've asked this question elsewhere: at the start of WW2, weren't the Italian torpedos generally effective and reliable? More so than the German torpedos in the first couple of years?

I've heard this as well and it wouldn't be surprising. Italy never lost its naval infrastructure, while Germany did. Navies take decades to establish and can lose experience rapidly if disbanded, so the German Navy wasn't going to be as effective as others for a few years.
 
The biggest advantage for the U-boat force early on by using the IJN Type 95, beside them being insanely fast (very helpful when using an unguided weapon) is that the warheads worked all the time.

The warhead did work all the time.

But the seals on the oxygen filling gear, and on the storage bottles, did not.

Which was real bad on a boat filled with chlorine and diesel fuel vapors.

If it was so awesome(which it was, when everything worked) why did the IJN bother with improving the Electric Type 92 in 1942?
 
The warhead did work all the time.

But the seals on the oxygen filling gear, and on the storage bottles, did not.

Which was real bad on a boat filled with chlorine and diesel fuel vapors.

If it was so awesome(which it was, when everything worked) why did the IJN bother with improving the Electric Type 92 in 1942?

Two Type 95s of 6 launched struck the Indianapolis end of July 1945, and she sank in 12 minutes. If any other torpedo was better for the job at hand, the Japanese hadn't found it by war's end. The type 97 midgetsub long lance was noted for seal leakage, and didn't see prolonged use. Electric torpedoes underwent continued development, as did aerial torpedoes, until war's end, because that was what they did.
 
Thanks for the replies, all. To clarify, the one I am thinking of is the Type 95, which was the Long Lance modified for submarine use, although the Italian torpedoes which have been referenced also seem interesting.

Regarding the British torpedo, it sounds interesting as well. Why wasn't it developed further?
 
Where would the boat get the LOX to fuel them? LOX is not a storable propellant in the sense that you can load the torpedo and keep it filled for any great length of time. All Japanese surface ships that used the Long Lance had a LOX plant on board to fuel the torpedoes.

In a WW 1 U-boat of a few hundred tons at most, given the technology of the period, it would have been impossible to do. Measurable quantities of LOX were first made in 1883, roughly just 20 years prior to WW 1. Most of its properties as a propellant and oxidizer were poorly understood at the time.

Then you come to a second problem: A WW 1 U-boat sits pretty low in the water and is using hydrophones for sound equipment. The viewing range and sound range of these is at best a few thousand yards. On the surface, a U-boat's visual horizon is maybe 15,000 yards and reliable targeting on something given the crude instruments available at the time (predictors like the Dyer Table were invented in 1914ish timeframe) means reliable targeting is maybe 5,000 yards, if that.
 
This is in WW2.

Even in WW 2 the same problems occur. You still need a LOX plant. That in turn increases the size and complexity of boats. That in turn means fewer of them. Then there's the dangers involved in using LOX on the sub at all.
Outside the engineering hazards involved, the boat needs to be surfaced to operate the plant. That in itself is problematic.
U-boats were kept small in size by the KM to make them more maneuverable and less of a target when surfaced. Compare their size to US or Japanese boats.

Targeting really doesn't change. The U-boat still has a maximum firing range of 10,000 to 15,000 yards realistically as there is no way to fire on an over the horizon target.

In fact, it would be better to want to equip U-boats early with decent radar and RDF equipment so they can better find targets and avoid enemy warships than giving them a "better" torpedo.
Another big improvement would have been equipping them with air conditioning so the crew's living conditions, particularly when submerged, were better.
 
As it says, how would the Battle of the Atlantic have gone differently if Germany had had long Lance torpedoes? Let's say the Germans get them before the war as part of a tech trade with Japan.

Very little impact - its just a torpedo and was not nearly the awesome uber weapon that some people think it was

It proved to be no better a military weapon than anyone else's Torpedoes - barring early war German and US weapons which were tragic.

It did have some very successful moments but had the IJN been using say a copy of the British 21" MK IX Torps the results would have been similar.

Also the Long lance is considerably larger than a 21" Torp so fewer could be carried and given that torpedoes are already Maintenance intensive I think the Oxygen Engine type weapon would prove to be even more so not to mention more dangerous to the crew and submarine carrying it.

Far better to have been able to conduct better testing pre war but torpedoes are probably the most expensive 'munition' being built in the late 30s and generally testing was conducted with dedicated testing weapons that had dummy warheads and were designed to be reused or weapons being used for a live test would be very well serviced and therefore less likely to fail as opposed to one that has been on board a submarine or destroyer for several weeks, so in the case of the US mk 14s and the early German G7as problems soon discovered in wartime sops were not likely to be discovered in peacetime.
 
Again, the one I am thinking of is the Type 93, which was a 21" Long Lance modified for submarine use and was used on Japanese submarines throughout the war. I am going to edit the OP to clarify this point.
 
Again, the one I am thinking of is the Type 93, which was a 21" Long Lance modified for submarine use and was used on Japanese submarines throughout the war. I am going to edit the OP to clarify this point.

You'd be more clarifying if you called the 21" torpedo a Type 95.
 
This article pretty much drives a stake through the heart of this what if...

http://www.navweaps.com/index_tech/tech-067.htm



In these battles the IJN hit 30 enemy ships with 44 Type 93, 1 Type 8 and 2 Type 6 torpedoes in these battles, sinking 18. The average hit rate was 6.71%, far below the required 15%. Of 130 torpedoes in an opening salvo for the Night Battle, only 9 would find a mark, at an average of 1.6 per ship, resulting in hits on about six ships which would probably be two CAs, two CLs and two DDs. Of these, one of each would probably sink based off historical results. The 280 torpedo salvo at the start of the daylight Decisive Battle would net only 18 hits at a rate of 6.71%.
In terms of efficiency (rounds expended per hit obtained) the Japanese needed to achieve a rate of 6.67:1. In actuality, they achieved a rate of 16.76:1. Instead of achieving a hit rate equivalent to slightly more than one per average destroyer (8-tube Kagero Class) firing a full load, the IJN achieved a rate slightly worse than one per two full loads fired from an average destroyer. To answer the question posed by this article; the IJN did not achieve the necessary hit rate or efficiency in action to make the Decisive Battle strategy a success, had that course been pursued. Even the world’s best surface torpedomen were not good enough to bring the Decisive Battle to fruition for the IJN. All they could do was make it costly, and die fighting.
So, the problem isn't a better torpedo, it's lack of a better fire control system and means of guiding the torpedo to its target.

http://www.fischer-tropsch.org/prim...Reports/USNTMJ-200F-0086-0124 Report O-32.pdf

https://en.wikipedia.org/wiki/Torpedo_Data_Computer

The problem with these WW 2 systems is that many of the inputs are estimates, almost guesses at best. Radar would give a better range input than any optical system by ten times or more. It would also better estimate the target's heading and speed.
With modern electronics these can be input automatically into a fire control system rather than manually.

Adding guidance to the torpedo would help too. The acoustic homing torpedo like the German Zaunkönig would help for example.

Bottom line here: Improved fire controls and torpedo guidance might have doubled hits regardless of what type of torpedo was being fired. Adopting the Long Lance doesn't improve the chances of hitting and does produce a number of technical and haz mat issues for submarine crews.
 
@Just Leo Facepalm! Thanks. I have corrected the error.

@Enoki I'm not saying the Type 95 would improve accuracy, but it would detonate when it hit, unlike OTL German torpedoes.
 
@Just Leo Facepalm! Thanks. I have corrected the error.

@Enoki I'm not saying the Type 95 would improve accuracy, but it would detonate when it hit, unlike OTL German torpedoes.

That's a fuzing issue, not a torpedo issue. If the Germans had a better fuze for their own torpedoes it would have helped, just as the same goes for many models of US one.
 
That's a fuzing issue, not a torpedo issue. If the Germans had a better fuze for their own torpedoes it would have helped, just as the same goes for many models of US one.

All the same, the Type 95 would include its fuze and in so doing solve the problem.
 
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