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Subject: Surface fired Torpedoes
rayott34    3/26/2014 5:03:51 PM
World War II era destroyers often had torpedoes designed for an anti-surface attack; they were launched from above the water line and they dropped into the water. On US vessels they were fired from the side; forcing the destroyer to steam towards the enemy and then turn to the side to fire the torpedoes; making aiming tricky. Can anyone explain the technical issues that prevented them from having firing the torpedoes from the front point of the ship? Was it simply size and cost or was there anything more complex then that? I have seen photos of the launcher that they used, and it looks as if it would fit on the front tip of a destroyer, wouldn’t it be possible to mount it along the front end of a destroyer? Were there any surface vessels of that era that had forward facing torpedoes? Is there anyone who can give a good technical description of how modern surface ships use torpedoes? For example, are they only used against surface vessels or are they also used against subs?
 
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WarNerd       3/27/2014 12:51:02 AM
It is size and weight distribution. The torpedoes were 24’ long and weighed nearly 2 tons each.  There is not enough buoyancy forward due to the narrow shape of the bow.  Look at a typical warship, and the area forward of the foremost turret is usually used for crew quarters to minimize the weight.
 
The second problem with forward firing torpedoes is that you are going to run over any that fail to function.  Sure, submarines had the same problem, but submerged launchers are more gentle.
 
There were some capital ships that had a submerged bow tube, but most were removed before WWI.  Doubt there were any left by WWII.
 
Currently USN surface ships only have 12” ASW torpedoes. Russian vessels still mount 21” torpedoes.
 
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rayott34       3/27/2014 3:44:22 AM
Thank you; that makes sense.  I remember that the small PT boat's in the USN (like the PT 109 that JFK was on) had torpedoes attached to the sides of the boat, but pointed forward, but pointed and fired forward.  Theoretically couldn't a destroyer use a similar system?  Wouldn't this have made their torpedoes much more accurate, and wouldn't they have been able to fire a spread of 2 to four torpedoes, practically guaranteeing a hit?
 
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keffler25       3/28/2014 12:15:11 AM
\\Wrong... Warnerd. 
 
1. Side launch was the simplest  parallel speed problem and angle solution  Since torpedoes wander left or right off their base launch .bearing an average of 1 degree for very `10 percent of projected optimum run range little simple geometry will show you the simplest way to 'lead the target is parallel track speed launch with a very perpendicular torpedo launch vector to the launch platform's forward motion. In other words a torpedo broadside is easier to lead compute with an optical sight
 
2. The bow plows into a shot ladder first. The weight of a torpedo flat was no worse than an anchor and chain. So the weight was NOT the problem. The explosive warheads that would blow the bow off were. 
 
In fact, that was why the Americans removed their cruiser torpedo flats. They later noticed that when their bombs and shells hit Japanese cruisers in their torpedo flats and reload magazines, the Japanese ships tended to explode into halves. Smart decision prewar confirmed through enemy experience.
 
3. The Russians  use at least 12 types of torpedo of 53 cm, diameter none of which are worth an ASuW damn when compared to their European competitors such as the DM 3s and 4s.Which ones are not supposed to be ASuW, WN? AFAIK those Russian fish are ASW and not worth a damn in that role either. Which is why the Russians still make a 45 cm version of the Kolibri based on the American 32.4 cm Mark 44.   
 
 

It is size and weight distribution. The torpedoes were 24’ long and weighed nearly 2 tons each.  There is not enough buoyancy forward due to the narrow shape of the bow.  Look at a typical warship, and the area forward of the foremost turret is usually used for crew quarters to minimize the weight.

 

The second problem with forward firing torpedoes is that you are going to run over any that fail to function.  Sure, submarines had the same problem, but submerged launchers are more gentle.

 

There were some capital ships that had a submerged bow tube, but most were removed before WWI.  Doubt there were any left by WWII.

 

Currently USN surface ships only have 12” ASW torpedoes. Russian vessels still mount 21” torpedoes.


 
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WarNerd       3/28/2014 3:37:25 AM
Thank you; that makes sense.  I remember that the small PT boat's in the USN (like the PT 109 that JFK was on) had torpedoes attached to the sides of the boat, but pointed forward, but pointed and fired forward.  Theoretically couldn't a destroyer use a similar system?  Wouldn't this have made their torpedoes much more accurate, and wouldn't they have been able to fire a spread of 2 to four torpedoes, practically guaranteeing a hit?
Probably could be done with angled tubes.  Tactically it would have required the ship to drive straight at the enemy instead of on an intercepting course and deliberately cross you own ‘T’ to fire.  The mechanical problems that may have inhibited it would have been multiple the high pressure gas reservoirs required (PT boats used a black powder charge.  It had problems and were replaced by ‘roll-off racks’ that were also 60% lighter.) and obstruction of fore-aft access.  There might have also been a problem in rough seas impacting on the launchers.
 
There were also ‘roll-off racks’ used on PT boats, but these deposited the torpedo flat in the water (a belly flop)instead of in a nose first dive.  Not a problem with the PT boat’s less than 10’ freeboard when on the plane, but more of a problem with a 20ft+ drop form a destroyer’s deck
 
Broadside launchers weren’t as much of a problem as you assume because you usually wanted to open the range as fast as possible after launching, so why not launch while making the turn?  Torpedo range was less than 5000 yards, the effective range for 5” guns was 10 miles.  Torpedo attacks against warships were usually by surprise at night, to sink an abandoned ship (your side) to prevent capture, finish off a disabled enemy vessel, or as desperation tactic in daytime.
 
Torpedoes were almost always launching in spreads because of accuracy problems (especially the firer’s estimates of the target’s course and speed), most DD and DE torpedo launchers had between 3 to 5 tubes, and generally multiple launchers per ship.  They usually fired an entire launcher in rapid succession when up against a capital ship.  Reloading a launcher in combat was never done on a surface ship.
 
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keffler25       3/28/2014 10:06:25 AM
Torpedoes were almost always launching in spreads because of accuracy problems (especially the firer’s estimates of the target’s course and speed), most DD and DE torpedo launchers had between 3 to 5 tubes, and generally multiple launchers per ship.  They usually fired an entire launcher in rapid succession when up against a capital ship.  Reloading a launcher in combat was never done on a surface ship.
Wrong again, Warnerd.
 
Battle of the Java Sea. The Japanese, per their well practiced battle drill, withdrew, reloaded, and came at the ABDAFloat task force twice. The Japanese at the time fired over 100 confirmed torpedoes, scored 7-10 hits and only had seventy tubes present.
 

Thank you; that makes sense.  I remember that the small PT boat's in the USN (like the PT 109 that JFK was on) had torpedoes attached to the sides of the boat, but pointed forward, but pointed and fired forward.  Theoretically couldn't a destroyer use a similar system?  Wouldn't this have made their torpedoes much more accurate, and wouldn't they have been able to fire a spread of 2 to four torpedoes, practically guaranteeing a hit?

Probably could be done with angled tubes.  Tactically it would have required the ship to drive straight at the enemy instead of on an intercepting course and deliberately cross you own ‘T’ to fire.  The mechanical problems that may have inhibited it would have been multiple the high pressure gas reservoirs required (PT boats used a black powder charge.  It had problems and were replaced by ‘roll-off racks’ that were also 60% lighter.) and obstruction of fore-aft access.  There might have also been a problem in rough seas impacting on the launchers.

 

There were also ‘roll-off racks’ used on PT boats, but these deposited the torpedo flat in the water (a belly flop)instead of in a nose first dive.  Not a problem with the PT boat’s less than 10’ freeboard when on the plane, but more of a problem with a 20ft+ drop form a destroyer’s deck

 

Broadside launchers weren’t as much of a problem as you assume because you usually wanted to open the range as fast as possible after launching, so why not launch while making the turn?  Torpedo range was less than 5000 yards, the effective range for 5” guns was 10 miles.  Torpedo attacks against warships were usually by surprise at night, to sink an abandoned ship (your side) to prevent capture, finish off a disabled enemy vessel, or as desperation tactic in daytime.

 

Torpedoes were almost always launching in spreads because of accuracy problems (especially the firer’s estimates of the target’s course and speed), most DD and DE torpedo launchers had between 3 to 5 tubes, and generally multiple launchers per ship.  They usually fired an entire launcher in rapid succession when up against a capital ship.  Reloading a launcher in combat was never done on a surface ship.


 
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