wire-guided torpedo question
javier arzola
Recently, I finished reading Norman Friedman's U.S Submarines Since 1945
and I have a few questions
regarding wire-guided torpedoes that I would be most grateful if someone
would answer:
1. The author states that wire-guided torpedoes fired from 688 class
submarines have a tendency to
break their wires at the torpedo tube muzzle. The text implies that only
this particular class of
submarines suffers this problem and no mention is made of similar problems
in other types. Is this true
and, if so, why?
I would guess that, as the torpedo swims away on a different course to that
of the submarine, the flow of
water over the open door area will bend the wire back sharply over the
hull. Presumably, the faster
the submarine goes and the more violent its manoeuvers, the greater the
risk of breaking the wire. If this
is the case, wouldn't all submarines that use wire-guided torpedoes run the
same risk or is there some
peculiarity in the design of the 688?
2. If the wire does break and a reload is ordered, is it possible for the
bit that stayed behind to get caught
between the muzzle and the pressure cap thus preventing the cap from
shutting completely? If so, there
must be a risk of water coming in when emptying the tube or opening the
breech. Even if the cap could
close safely over the wire, wouldn't this wire have to be removed before
reloading?
3. I've also read somewhere that the crew has the option of cutting the
wire any time after having fired
one of these torpedoes. Could someone describe how this mechanism works?
Presumably, the wire will
be cut well before the muzzle so as to avoid the problems associated with
the questions in the previous
paragraph.
Thanks in advance,
Javier
Paul J. Adam
In article <01bc4a51$c3a66680$3c9e...@10.0.1.1.inf>, javier arzola
<bria...@bitmailer.net> writes
>Recently, I finished reading Norman Friedman's U.S Submarines Since 1945
>and I have a few questions
>regarding wire-guided torpedoes that I would be most grateful if someone
>would answer:
>
>1. The author states that wire-guided torpedoes fired from 688 class
>submarines have a tendency to
>break their wires at the torpedo tube muzzle. The text implies that only
>this particular class of
>submarines suffers this problem and no mention is made of similar problems
>in other types. Is this true
>and, if so, why?
It's not peculiar to the 688s, though the location of the torpedo tubes
in US submarines (midships and angled out, leaving the bow free for a
powerful spherical sonar array) accentuates the probkem somewhat.
The Mark 48 design is also more vulnerable to this than some others, but
it's a common problem: the British Mark 24 was originally _very_ poor in
regard to its guidance wires, but this was subsequently amended and it's
now among the best.
>I would guess that, as the torpedo swims away on a different course to that
>of the submarine, the flow of
>water over the open door area will bend the wire back sharply over the
>hull.
To a certain extent, though you typically have a dispenser at the
submarine's end of the wire too (so it's being paid out at both ends,
minimising the tension in the wire).
>Presumably, the faster
>the submarine goes and the more violent its manoeuvers, the greater the
>risk of breaking the wire. If this
>is the case, wouldn't all submarines that use wire-guided torpedoes run the
>same risk or is there some
>peculiarity in the design of the 688?
You're basically right: speed and manoevering increase the risk of
breaking the wires. To counter this, the wire is often led out through a
heavy, armoured "hosepipe" that gives it some protection. Don't know if
the Mark 48 does this.
This is the reason a standard counter to a torpedo attack is to fire a
weapon back in return: the enemy will have to manoevre to avoid it,
possibly breaking his guidance wires in the process.
And yes, it applies to all torpedoes, it only varies by degree.
>2. If the wire does break and a reload is ordered, is it possible for the
>bit that stayed behind to get caught
>between the muzzle and the pressure cap thus preventing the cap from
>shutting completely?
No, it's jettisoned, for the reason you propose. I'm pretty sure the
Tube Mounted Dispensers are recovered, but the wire is cut at the
inboard end and just falls out.
The wire is very fine anyway (I believe some weapons have used or at
least carefully considered fibre-optic line rather than copper) and
unlikely to significantly foul the tube.
--
There are four kinds of homicide: felonious, excusable, justifiable and
praiseworthy...
Paul J. Adam pa...@jrwlynch.demon.co.uk
lar...@bre.co.uk
In article <TiEdzWA8...@jrwlynch.demon.co.uk>, "Paul J. Adam" <pa...@jrwlynch.demon.co.uk> writes:
|>The Mark 48 design is also more vulnerable to this than some others, but
|>it's a common problem: the British Mark 24 was originally _very_ poor in
|>regard to its guidance wires, but this was subsequently amended and it's
|>now among the best.
Old joke:
On the Mk 24 project the only thing that was indispensable
was the guidance wire.
Ron L
Tim McFeely
>In article <01bc4a51$c3a66680$3c9e...@10.0.1.1.inf>, javier arzola
><bria...@bitmailer.net> writes
>>Recently, I finished reading Norman Friedman's U.S Submarines Since 1945
>>and I have a few questions
>>regarding wire-guided torpedoes that I would be most grateful if someone
>>would answer:
Within the restrictive bounds of classified info, I'll try.
>>1. The author states that wire-guided torpedoes fired from 688 class
>>submarines have a tendency to
>>break their wires at the torpedo tube muzzle. The text implies that only
>>this particular class of
>>submarines suffers this problem and no mention is made of similar problems
>>in other types. Is this true
>>and, if so, why?
Friedman is blowing smoke on this issue. 688 class subs are no worse
than any other USN submarine. There are some guidance wire issues
with 688s, but none that I want to publically discuss and none that
affect the weapon during it's run.
>It's not peculiar to the 688s, though the location of the torpedo tubes
>in US submarines (midships and angled out, leaving the bow free for a
>powerful spherical sonar array) accentuates the probkem somewhat.
Again the major issues lie in the end of run wire cutting evolution.
And you are correct that the midships tubes accentuates the problems.
>The Mark 48 design is also more vulnerable to this than some others, but
>it's a common problem: the British Mark 24 was originally _very_ poor in
>regard to its guidance wires, but this was subsequently amended and it's
>now among the best.
Major improvements in the damned flexhose have helped the 48. Not
perfect, but a major improvement. Let me add, though, that
improvements in the flexhose have led to other problems elsewhere.
>>I would guess that, as the torpedo swims away on a different course to that
>>of the submarine, the flow of
>>water over the open door area will bend the wire back sharply over the
>>hull.
Not just the flow of the water. Mk 48s perform a 'flyaway' manuever
at launch which clears the weapon and guidance wire away from the
muzzle area of the tubes. This is necessary because of the midship
mounted tubes.
>To a certain extent, though you typically have a dispenser at the
>submarine's end of the wire too (so it's being paid out at both ends,
>minimising the tension in the wire).
>
>>Presumably, the faster
>>the submarine goes and the more violent its manoeuvers, the greater the
>>risk of breaking the wire. If this
>>is the case, wouldn't all submarines that use wire-guided torpedoes run the
>>same risk or is there some
>>peculiarity in the design of the 688?
>
>You're basically right: speed and manoevering increase the risk of
>breaking the wires. To counter this, the wire is often led out through a
>heavy, armoured "hosepipe" that gives it some protection. Don't know if
>the Mark 48 does this.
See 'flexhose' above. To amplify the flexhose issue, the flexhose is
a stainless steel length of flexible tubing that is attached to the
TMD (torpedo mounted dispenser -- dispenser that feeds wire from the
shipboard end). The flexhose is pulled out by the torpedo until it is
fully extended and 2 plastic shear screws snap. The guidance wire is
housed inside, but is independent of the flexhose. After the flexhose
is deployed, the guidance wire continues to feed through it until
exhausted, cut, or a target is sunk. The hose is used to protect the
guidance wire from the edges of the muzzle door, fairing doors, ships
hull, torpedo tube, etc.
When the wire is cut, the flexhose is released and provides the
impetus needed to pull the wire out of the torpedo tube so the muzzle
door can shut and seal properly (supposedly/hopefully -- oops did I
say that?).
>This is the reason a standard counter to a torpedo attack is to fire a
>weapon back in return: the enemy will have to manoevre to avoid it,
>possibly breaking his guidance wires in the process.
>
>And yes, it applies to all torpedoes, it only varies by degree.
How about all "wire guided" torpedoes??
>>2. If the wire does break and a reload is ordered, is it possible for the
>>bit that stayed behind to get caught
>>between the muzzle and the pressure cap thus preventing the cap from
>>shutting completely?
>
>No, it's jettisoned, for the reason you propose. I'm pretty sure the
>Tube Mounted Dispensers are recovered, but the wire is cut at the
>inboard end and just falls out.
This gets into a touchy area, but the originally poster brings up a
question that touches on a 688 class problem. Suffice it to say, Paul
is correct. Truth is things are often different on 688s.
>The wire is very fine anyway (I believe some weapons have used or at
>least carefully considered fibre-optic line rather than copper) and
>unlikely to significantly foul the tube.
Didn't I say something about the 'damned' flexhose...??
Tim McFeely
On 16 Apr 1997 10:33:07 GMT, "javier arzola" <bria...@bitmailer.net>
wrote:
<deleted, but see follow up in another post>
>2. If the wire does break and a reload is ordered, is it possible for the
>bit that stayed behind to get caught
>between the muzzle and the pressure cap thus preventing the cap from
>shutting completely? If so, there
>must be a risk of water coming in when emptying the tube or opening the
>breech. Even if the cap could
>close safely over the wire, wouldn't this wire have to be removed before
>reloading?
Yes to all of the above.
>
>3. I've also read somewhere that the crew has the option of cutting the
>wire any time after having fired
>one of these torpedoes. Could someone describe how this mechanism works?
>Presumably, the wire will
>be cut well before the muzzle so as to avoid the problems associated with
>the questions in the previous
>paragraph.
There are 2 systems in play here. First is the guidance wire. On 688
class boats, the wire is cut using a metal shear located on the inside
of the breech door that is powered by 700 psi air (same air that is
used for Tomahawk PVC cycles for those that have read any of my posts
on that).
The second system is the flexhose arrangement. The flexhose is a
stainless steel flexible tube which houses the guidance wire and
protects the GW from the submarine. The flexhose has an end that is
clamped into the TMD. The TMD (torpedo mounted dispenser) is a round
drum like thing that holds the flexhose in the outer reel and the GW
on the inner reel. The TMD comes mounted to the back of every Mk 48.
After the torpedo is tube loaded the TMD is released from the torpedo
and attached to the torpedo tube walls. When the tube is shot, the
weapon leaves, but the TMD remains in the tube. It is removed from
the tube prior to reloading. Damn things are heavy (~300 lbs full)
and can be a source of major sound transients when TM3 Shitforbrains
tries to remove one from the tube by himself and drops it on his foot.
When the button is pushed to cut the wire, 700 psi air activates the
shear for the guidance wire and releases the clamp for the flexhose.
The weight of the flexhose and water flow pull both the GW and the
flexhose out of the tube
>
>Thanks in advance,
>
>Javier
>
Mark Borgerson
Tim McFeely wrote:
>
<< major Snippage >>
> See 'flexhose' above. To amplify the flexhose issue, the flexhose is
> a stainless steel length of flexible tubing that is attached to the
> TMD (torpedo mounted dispenser -- dispenser that feeds wire from the
> shipboard end). The flexhose is pulled out by the torpedo until it is
> fully extended and 2 plastic shear screws snap. The guidance wire is
> housed inside, but is independent of the flexhose. After the flexhose
> is deployed, the guidance wire continues to feed through it until
> exhausted, cut, or a target is sunk. The hose is used to protect the
> guidance wire from the edges of the muzzle door, fairing doors, ships
> hull, torpedo tube, etc.
>
Is it possible to wind up the wire in the screw? That would seem to
be a major concern if enough wire wrapped around the shaft to ruin the
hydrodynamics so carefully generated by all those expensive milling
machines! Perhaps the launch sequence includes a gentle turn to
lead the wire a little off the beam and away from the screw. OTOH,
perhaps it's standard procedure to not be facing directly toward the
target so that the wire gets dragged off to the side a bit anyway.
If you've just launched on a target, you may want to be turning
away in case you have to evade return fire anyway.
Second question--if you launch more than one torpedo, do you
launch both from the same side so you can turn away from both
wires? Or is it usual to have more than one torpedo on the wire
at a time? Can a 688 even control more than one wire guided
torpedo at a time??
Well I guess that's enough questions meriting fuzzy answers for
one night!
Mark Borgerson
Karsten Paczkowski
On 18 Apr 97 Mark wrote to
"Re: wire-guided torpedo question" the following lines:
MB>Second question--if you launch more than one torpedo, do you
MB>launch both from the same side so you can turn away from both
MB>wires? Or is it usual to have more than one torpedo on the wire
MB>at a time? Can a 688 even control more than one wire guided
MB>torpedo at a time??
AFAIK on a 688 you can only use a single torpedo tube on each
side. If you want to fire another tube on either side, you'll
have to close the outer door of the other first.
A 688 can control two wire guided torpedos at a time, I think.
Probably it could theoretically handle even more, but as you
cannot have more than two torpedos running at the same time (see
above, closing the outer door would surely cut the wire), it's
just a question of theory...
Best regards,
Karsten
--
"Nothing is easier than being busy -
and nothing more difficult than being effective..."
(R. Alec Mackenzie)
>>> PGP-KEY available on request <<<
Tim McFeely
On 20 Apr 1997 12:47:00 +0100, pac...@private.westfalen.de (Karsten
Paczkowski) wrote:
>On 18 Apr 97 Mark wrote to
>"Re: wire-guided torpedo question" the following lines:
>
>
>MB>Second question--if you launch more than one torpedo, do you
>MB>launch both from the same side so you can turn away from both
>MB>wires? Or is it usual to have more than one torpedo on the wire
>MB>at a time? Can a 688 even control more than one wire guided
>MB>torpedo at a time??
>AFAIK on a 688 you can only use a single torpedo tube on each
>side. If you want to fire another tube on either side, you'll
>have to close the outer door of the other first.
>A 688 can control two wire guided torpedos at a time, I think.
>Probably it could theoretically handle even more, but as you
>cannot have more than two torpedos running at the same time (see
>above, closing the outer door would surely cut the wire), it's
>just a question of theory...
Not quite correct. The 688 class can only guide 4 torpedoes at a time
(tube limitations you know!!!!). Also, it is not necessary to close
the outer doors on the other tube before a 688 class can shoot from
the same side. The only restriction is a short delay allowing the ram
to return to battery.
For the most part tactic considerations would probably preclude
shooting more than 2 at a time.
>Best regards,
>
>Karsten
>--
>"Nothing is easier than being busy -
> and nothing more difficult than being effective..."
> (R. Alec Mackenzie)
>
> >>> PGP-KEY available on request <<<
Scopes under...
Tim McFeely
ex-TM2(SS)...a rating lost to downsizing.
fla...@wsii.com
Tim McFeely
On Fri, 18 Apr 1997 21:18:51 -0800, Mark Borgerson <bor...@peak.org>
wrote:
<snip>
>Is it possible to wind up the wire in the screw? That would seem to
>be a major concern if enough wire wrapped around the shaft to ruin the
>hydrodynamics so carefully generated by all those expensive milling
>machines! Perhaps the launch sequence includes a gentle turn to
>lead the wire a little off the beam and away from the screw. OTOH,
>perhaps it's standard procedure to not be facing directly toward the
>target so that the wire gets dragged off to the side a bit anyway.
>If you've just launched on a target, you may want to be turning
>away in case you have to evade return fire anyway.
Important question, classified tactics, answer is yes to wire in the
screw.
>
>Second question--if you launch more than one torpedo, do you
>launch both from the same side so you can turn away from both
>wires? Or is it usual to have more than one torpedo on the wire
>at a time? Can a 688 even control more than one wire guided
>torpedo at a time??
688s are limited to 4 wire guide torpedoes in the water at once, all
under control. However it is possible to have many more torpedoes
running at once. Why, though, is the first question I would ask?
Typical salvos are horizontal (ie. one form each side, due to recovery
time of the launch system).
>
>Well I guess that's enough questions meriting fuzzy answers for
>one night!
Fuzzier and fuzzier, someone said to Alice.
>
>Mark Borgerson
bria...@bitmailer.net
Many thanks for your very clear replies. The message regarding the
flexhose was understood. One last questions concerning this subject, if I
may:
According to the book "Submarine" by Tom Clancy , the tube mounted
dispensers seem to be a relatively new addition to the Mk 48 line of
torpedoes. The text implies that these appeared with the advent of the
ADCAP version and that previous models (e.g. model 4) did not have this
dispenser. The total length of wire was limited to that available on the
dispenser at the stern of the torpedo (about half the total length
available to the ADCAP). Is this correct? If so, It would appear that
earlier versions must have severe problems with breaking GWs due to the
greater tension in the wire as it is payed out.
Regards,
Javier
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