Technology and Operations
This forum is for discussing technological & operational matters pertaining to U-boats.
Re: I might have an answer
Posted by:
ThomasHorton
()
Date: April 10, 2008 03:24PM
Robert,
Interesting idea but I think the size of the explosive and range is more determined by the length of the torpedo than its diameter.
Of the 21†torpedoes used on US submarines there does the diameter remains the same but the explosive weights change normally with an increased length (which also affected the range with larger flasks and such)
Bliss-Leavitt Mk 9 210 Lbs (TNT) range 7,000 yards @ 27 kts length 16.3’
USNTS Mk-X 497 lbs (TNT) range 3,500 yards @ 36 Kts length 15.25’
The Mk x had twice the explosives as the Mk 9 but with a shorter torpedo albeit with smaller flasks.
USNTS Mk XIV 643 Lbs (Torpex [42% RDX, 40% TNT and 18%powdered aluminum]) range 9,000 yards @ 31 kts length 20.5’
I am excluding the Mk XVIII as it had a totally different propulsion system.
Given this information, it does not appear that the 21†diameter is justified by either explosive weight or range as both seem to be more influenced by the length of the torpedo.
This can be illustrated by examining the Submarine launched 18†torpedoes.
Bliss-Leavitt Mk 7 326 lbs (TNT) Range 6,000 yards @ 35 kts length 17’
Bliss-Leavitt were able to put more TNT in to the Mk 7 than in the Mk 9 with almost the same range 3 inches less in diameter but only 0.7 feet longer.
Even the Bliss-Leavitt Mk 6 was able to have an explosive weight of 200 lbs (gun-cotton) in 18†diameter 17 foot long torpedo. This is only 10 Lbs less than the 21†Bliss-Leavitt Mk 9 (listed above)
So I don’t think the decision to move to 21†torpedoes by the USN was influenced by the need for more explosives as it appears that longer torpedoes were the answer to more explosive and more range (larger flasks and such).
Now the German Submarine torpedoes did change diameter that correlates to larger explosive charges.
450mm/17.7†C/06 and C/06D 270 Lbs (TNT) range 5,000 yards @ 27 kts length 18.5’
500mm/19.7 G6 362 Lbs (TNT/Hexanite) 9,000 yards @ 27 kts length 19.6
533mm/21†G7 series 660 lbs (Hexanite) 15,000 yards @ 30 kts length 23.7
So with the German torpedoes there is a correlation between diameter and explosive weight. This would support your hypothesis.
The Japanese always used 533mm/21†torpedoes in their submarines(Midget subs excluded). So we can’t use Japanese submarine torpedoes to either support or refute either of our hypotheses.
For the British there are only two data points
18†Mk VIII 320 lbs TNT range 4,000 yards @ 29 kts length unk
21†Mk VIII 750-805 lbs TNT or Torpex 7000 yards @ 41 kts length 21.7’
With these two data points it is inclusive that the move to 21†was justified by the added explosive weights.
In my thinking the justification to for Germany, Britain, and Japan to move to the 533mm/21†torpedo is not significantly justified by the higher explosive weight.
In the case of the United States, there seems to be indicators that the move to the 21†torpedo was also not significantly justified by the higher explosive weight.
Wadda ya think Robert?
Interesting idea but I think the size of the explosive and range is more determined by the length of the torpedo than its diameter.
Of the 21†torpedoes used on US submarines there does the diameter remains the same but the explosive weights change normally with an increased length (which also affected the range with larger flasks and such)
Bliss-Leavitt Mk 9 210 Lbs (TNT) range 7,000 yards @ 27 kts length 16.3’
USNTS Mk-X 497 lbs (TNT) range 3,500 yards @ 36 Kts length 15.25’
The Mk x had twice the explosives as the Mk 9 but with a shorter torpedo albeit with smaller flasks.
USNTS Mk XIV 643 Lbs (Torpex [42% RDX, 40% TNT and 18%powdered aluminum]) range 9,000 yards @ 31 kts length 20.5’
I am excluding the Mk XVIII as it had a totally different propulsion system.
Given this information, it does not appear that the 21†diameter is justified by either explosive weight or range as both seem to be more influenced by the length of the torpedo.
This can be illustrated by examining the Submarine launched 18†torpedoes.
Bliss-Leavitt Mk 7 326 lbs (TNT) Range 6,000 yards @ 35 kts length 17’
Bliss-Leavitt were able to put more TNT in to the Mk 7 than in the Mk 9 with almost the same range 3 inches less in diameter but only 0.7 feet longer.
Even the Bliss-Leavitt Mk 6 was able to have an explosive weight of 200 lbs (gun-cotton) in 18†diameter 17 foot long torpedo. This is only 10 Lbs less than the 21†Bliss-Leavitt Mk 9 (listed above)
So I don’t think the decision to move to 21†torpedoes by the USN was influenced by the need for more explosives as it appears that longer torpedoes were the answer to more explosive and more range (larger flasks and such).
Now the German Submarine torpedoes did change diameter that correlates to larger explosive charges.
450mm/17.7†C/06 and C/06D 270 Lbs (TNT) range 5,000 yards @ 27 kts length 18.5’
500mm/19.7 G6 362 Lbs (TNT/Hexanite) 9,000 yards @ 27 kts length 19.6
533mm/21†G7 series 660 lbs (Hexanite) 15,000 yards @ 30 kts length 23.7
So with the German torpedoes there is a correlation between diameter and explosive weight. This would support your hypothesis.
The Japanese always used 533mm/21†torpedoes in their submarines(Midget subs excluded). So we can’t use Japanese submarine torpedoes to either support or refute either of our hypotheses.
For the British there are only two data points
18†Mk VIII 320 lbs TNT range 4,000 yards @ 29 kts length unk
21†Mk VIII 750-805 lbs TNT or Torpex 7000 yards @ 41 kts length 21.7’
With these two data points it is inclusive that the move to 21†was justified by the added explosive weights.
In my thinking the justification to for Germany, Britain, and Japan to move to the 533mm/21†torpedo is not significantly justified by the higher explosive weight.
In the case of the United States, there seems to be indicators that the move to the 21†torpedo was also not significantly justified by the higher explosive weight.
Wadda ya think Robert?
