Mk 13 Air Dropped Torpedo

I just finished the book "The Last Stand of the Tin Can Sailors" and it
raised some questions about the air dropped torpedoes (the Mk 13) in use by
the US Navy in WWII.

What drove the range/speed trade-offs for the Mk 13? According to the
spec's I've found, it had a range of ~6,000 yards and a speed of 33 knots.
With a likely launch range of 1,000 yards or less, wouldn't it have made
sense to sacrifice the 6,000 yard range to get an increase in speed?
Wouldn't a 45 or 50 knot torpedo with a 1,500 or 2,000 yard range have been
a better compromise? I'd certainly think the higher speed would have
increased the probability of a hit, because it would have reduced the
deflection at launch by 1/3 or so. Also, it would have given the target 1/3
less time to maneuver to avoid the torpedo.

A second question addresses launch speed. Early in the war, drop speed and
altitude were in the 110 knot, 150' range. Later, a couple of plywood
fairings were added to increase drag, lift, and stability, and these add-ons
improved the drop parameters for the torpedo. The sources I've found have
contradictions about the launch envelope after these fairings were added.
Can someone point me to a reputable source for this information?

Thanks,

KB

Ahh but the closer you get to the target the longer you are exposed to enemy
fire & the higher the chances of losing an expensively trained crew plus the
aircraft; Far better to waste multiple torpedoes saving the crews & AC for
further missions.

DD


"Kyle Boatright" wrote in message
...
I just finished the book "The Last Stand of the Tin Can Sailors" and it
raised some questions about the air dropped torpedoes (the Mk 13) in use by
the US Navy in WWII.

What drove the range/speed trade-offs for the Mk 13? According to the
spec's I've found, it had a range of ~6,000 yards and a speed of 33 knots.
With a likely launch range of 1,000 yards or less, wouldn't it have made
sense to sacrifice the 6,000 yard range to get an increase in speed?
Wouldn't a 45 or 50 knot torpedo with a 1,500 or 2,000 yard range have
been a better compromise? I'd certainly think the higher speed would have
increased the probability of a hit, because it would have reduced the
deflection at launch by 1/3 or so. Also, it would have given the target
1/3 less time to maneuver to avoid the torpedo.

A second question addresses launch speed. Early in the war, drop speed
and altitude were in the 110 knot, 150' range. Later, a couple of plywood
fairings were added to increase drag, lift, and stability, and these
add-ons improved the drop parameters for the torpedo. The sources I've
found have contradictions about the launch envelope after these fairings
were added. Can someone point me to a reputable source for this
information?

Thanks,

KB

You might drop it 1000 yds out, but it still has to run down the target.
This can be a long chase if the target is even semi quick.

Al


"Kyle Boatright" wrote in message
...
I just finished the book "The Last Stand of the Tin Can Sailors" and it
raised some questions about the air dropped torpedoes (the Mk 13) in use by
the US Navy in WWII.

What drove the range/speed trade-offs for the Mk 13? According to the
spec's I've found, it had a range of ~6,000 yards and a speed of 33 knots.
With a likely launch range of 1,000 yards or less, wouldn't it have made
sense to sacrifice the 6,000 yard range to get an increase in speed?
Wouldn't a 45 or 50 knot torpedo with a 1,500 or 2,000 yard range have
been a better compromise? I'd certainly think the higher speed would have
increased the probability of a hit, because it would have reduced the
deflection at launch by 1/3 or so. Also, it would have given the target
1/3 less time to maneuver to avoid the torpedo.

A second question addresses launch speed. Early in the war, drop speed
and altitude were in the 110 knot, 150' range. Later, a couple of plywood
fairings were added to increase drag, lift, and stability, and these
add-ons improved the drop parameters for the torpedo. The sources I've
found have contradictions about the launch envelope after these fairings
were added. Can someone point me to a reputable source for this
information?

Thanks,

KB

For a good WWII torpedo check out the Japanese Long Lance torpedo.

WDA

end

"Kyle Boatright" wrote in message
...
I just finished the book "The Last Stand of the Tin Can Sailors" and it
raised some questions about the air dropped torpedoes (the Mk 13) in use
by
the US Navy in WWII.

What drove the range/speed trade-offs for the Mk 13? According to the
spec's I've found, it had a range of ~6,000 yards and a speed of 33
knots.
With a likely launch range of 1,000 yards or less, wouldn't it have made
sense to sacrifice the 6,000 yard range to get an increase in speed?
Wouldn't a 45 or 50 knot torpedo with a 1,500 or 2,000 yard range have
been a better compromise? I'd certainly think the higher speed would
have
increased the probability of a hit, because it would have reduced the
deflection at launch by 1/3 or so. Also, it would have given the target
1/3 less time to maneuver to avoid the torpedo.

A second question addresses launch speed. Early in the war, drop speed
and altitude were in the 110 knot, 150' range. Later, a couple of
plywood
fairings were added to increase drag, lift, and stability, and these
add-ons improved the drop parameters for the torpedo. The sources I've
found have contradictions about the launch envelope after these fairings
were added. Can someone point me to a reputable source for this
information?

Thanks,

KB





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"Al" wrote in message
. ..
You might drop it 1000 yds out, but it still has to run down the target.
This can be a long chase if the target is even semi quick.

Al

You're right and in a sideways way you bring up another problem with a 33
knot torpedo. If it gets in a chase situation, the torpedo can't catch the
enemy, regardless of the torpedo's range. Destroyers, some cruisers, some
carriers, and some battleships are as fast or faster than 33 knots. A
faster torpedo gives the enemy less time to avoid the attack in the first
place.

"Dave Deep" wrote in message
...
Ahh but the closer you get to the target the longer you are exposed to
enemy fire & the higher the chances of losing an expensively trained crew
plus the aircraft; Far better to waste multiple torpedoes saving the crews
& AC for further missions.

DD

Agreed, but as I stated earlier, air dropped torpedoes were launched at
1,000 yards or less. I'm not advocating launching closer, I'm simply asking
why the torpedo's speed and range wasn't better matched to how the actual
launch range...

KB

"W. D. Allen Sr." wrote in message
...
For a good WWII torpedo check out the Japanese Long Lance torpedo.

WDA

end


Which wasnt an air dropped weapon

Keith

Keith Willshaw wrote:
"W. D. Allen Sr." wrote in message
...

For a good WWII torpedo check out the Japanese Long Lance torpedo.

WDA

end



Which wasnt an air dropped weapon

Keith



I seem to recall the long lance was too an air dropped weapon. Kates
used it in Pearl Harbor...I think.

Eric

The Japanese long lance type 93 was a 24-inch monster weighing almost 6000 lbs. The air-dropped weapon was the type 91, 450mm (17.7in) in diameter with a weight in the 1700-2300 lb range depending upon mod. There were Japanese torpedoes developed using the long lance's oxygen propulsion system, but I'm not aware of any air-dropped models in service.

www.combinedfleet.com

Originally Posted by Eric Joiner

I seem to recall the long lance was too an air dropped weapon. Kates
used it in Pearl Harbor...I think.

Eric

"Eric Joiner" wrote in message
...
Keith Willshaw wrote:
"W. D. Allen Sr." wrote in message
...

For a good WWII torpedo check out the Japanese Long Lance torpedo.

WDA

end



Which wasnt an air dropped weapon

Keith

I seem to recall the long lance was too an air dropped weapon. Kates used
it in Pearl Harbor...I think.

Eric

Nope. The Long Lance was a shipboard weapon only. It weighed something like
6,000 lbs, and was almost 30' long - a real monster. It had a range of
20,000 meters at 48 knots. On the slow setting, it had a range of 40,000
meters at 36 knots. A downsized version was used aboard submarines. It
weighed 4,000 lbs and had a 9,000 meter range at 49 knots.

The air dropped torpedoes used by the Japanese during WWII were 17.7"
torpedoes and weighed approximately 2,000 lbs depending on variant. Very
comparable to US airborne torpedos. EXCEPT for their dynamic performance,
which gave a drop speed of 260-350 knots (variant dependant), a speed of 41
knots, and a 2000 meter range.