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RE: ASW damage from AC

 
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RE: ASW damage from AC - 8/18/2013 8:13:40 PM   
Bullwinkle58


Posts: 8408
Joined: 2/24/2009
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quote:

ORIGINAL: sandman455

quote:

ORIGINAL: Bullwinkle58
I'd take my chances going to 700 feet on a Balao a lot quicker than a Type VII.


Hell no. A WW2 Balao at 700' - you sir are as close to dead as can be. Please don't reference the Chopper - it was a Guppy, far removed from it's WW2 configuration and it never sustained the depth. Wasn't even on an even keel which makes the depth readings unreliable. When she surfaced, she was so overstressed she had to be scrapped. For any type VII or IX uboat, 700' was a walk in the park - documented countless times. A depth of 900-1000' would have been approx crush depth for most of them if you had the guts to go there. A few did and IIRC they were still serviceable afterwards.


Chopper's bow went deeper than 1000 feet. Yes, a Guppy had been modified from WWII, but the pressure hull was the same. The damage done to her which resulted in her re-designation was as much from the rapid ascent from the depth excursion as the excursion itself.

My comments on U-boats were not predicated on the design parameters or that many did go not to 700 feet. It was on QA. U-boat COs commented in their private writings that boats from different yards were of very different quality. As the war progressed this became highly relevant. Speer ordered that U-boats be made in sections and assembled at a central yard. Many of the contractors assigned sections had no submarine, or even naval, experience. They employed tens of thousands of slave laborers. The sections were "persuaded" together at final assembly with sometimes terrible results. Further, many of the sub-assemblies were subject to sabotage by French and Polish yard workers, as were the final boats when in refit.

The pre-1943 boats were well-built. By the end over 100 Type 21s were so poorly sub-assembled that only seven made it to sea before VE Day. After the war both the RN and USN instituted trial programs to peel the Type21 design and learn from it. The programs were scrapped when numerous accidents, including battery explosions, occurred with such frequency that the boats were scuttled in deep water and the technology was adopted from blueprints.

I believe there is a documented depth excursion in USS Tang to about 670 feet. Part of the problem was USN depth gauges pegged before crush depth, so a lot of the reports in the USN came from TR pressure gauges and not control room conning depth dials.

I wouldn't want to go to 700 in any WII sub. But I'd rather trust US QA over German.

< Message edited by Bullwinkle58 -- 8/18/2013 8:15:10 PM >


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The Moose

(in reply to sandman455)
Post #: 31
RE: ASW damage from AC - 8/19/2013 4:53:17 PM   
Chickenboy


Posts: 17966
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From: Twin Cities, MN
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This from the Mk-24 FIDO Wiki: Interesting...

Upon water entry, FIDO performed a circular search at a predetermined depth controlled by a bellows and pendulum system. This continued until the potential target's 24 kHz acoustic signal detected by the hydrophones exceeded a predetermined threshold level, at which point control was then shifted to the passive acoustic proportional homing system. Initially the torpedoes were set to search for a target at a depth of 50 feet (15 m), this was later changed to 150 feet (45 m). To prevent the torpedo accidentally attacking surface ships, it resumed its circling search if it rose above a depth of 40 feet (12 m).

The torpedo's relatively low speed was kept secret because although U-boats could not outrun the torpedo when submerged, they could outrun it on the surface.

Combat history

On 14 May a Catalina of the US Navy attacked and destroyed a U-boat; this was either U-657[3] or U-640.[4] On 13 May Liberator B/86 had attacked a U-boat with a FIDO, but this vessel, U-456,[5] was only damaged, sinking the following day from damage received. One of these vessels was the first U-boat sinking achieved using FIDO. During its career, the torpedo sank a total of 37 submarines, achieving an effectiveness of about 22%, compared with about 9% for depth charges.

from US Navy OEG Study No. 289, 12 August 1946 provides the following data related to Mark 24 effectiveness:

Number of attacks in which Mark 24s were launched 264
Total number of Mark 24 torpedoes launched - all targets 340
Number of Mark 24s launched against submarines 204
Number of Mark 24 attacks on submarines by US aircraft 142
Number of Mark 24 attacks by Allied (primarily British) aircraft 62
Number of German U-boats sunk by FIDO 31
Number of German U-boats damaged by FIDO 15
Number of Japanese submarines sunk by FIDO 6
Number of Japanese submarines damaged by FIDO 3
Total number of submarines sunk by FIDO (German & Japanese) 37
Total number of submarines damaged 18


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RE: ASW damage from AC - 8/19/2013 5:25:51 PM   
btbw

 

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Fido was tuned for search noise under 40 feet. So it can be used against subs entereing in convoy's order. It why better use for Fido SUBMERGED sub.

(in reply to Chickenboy)
Post #: 33
RE: ASW damage from AC - 8/19/2013 10:16:21 PM   
sandman455


Posts: 201
Joined: 7/5/2011
From: 20 yrs ago - SDO -> med down, w/BC glasses on
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quote:

ORIGINAL: Chickenboy


quote:

ORIGINAL: sandman455
FIDO - it was kind of like a quick use mine. It homed in on noise - if I remember it was the band at which the diesel engines fuel injectors worked. Without that diesel running your weapon was worthless. It was the weapon of choice for a snorkled sub or any at night. Trying to hit a target with so little to aim at was pretty hard. Half the time you couldn't see the sub/snorkle in time to make a good drop. Any close aboard fly over could easily alert the sub ruining any chance of setting up again. This thing allowed the aircraft to pickle the weapon on the initial flyover or well ahead to remain unnoticed. Again, the weapon was going to be worthless if the enemy figured out how it worked.


This is contrary to the useage of the FIDO weapon system used against the U-boats, according to Blair.

The weapon was typically dropped by Avenger-type aircraft after the U-boat had submerged.
The attacks typically took place by daylight scout aircraft-often a pair of F4F and TBF/M. The F4F would strafe the submarine, forcing it to submerge. The Avenger would come in and drop on the swirl. Daylight attack, submerged U-boat.

The U-boats weren't using their diesels after submerging. Therefore, the guidance system of the FIDO was unlikely to be the diesel pressurization system.



Who is Blair? So are you and Mr. (Ms?) Blair suggesting that you could passively track and acquire a submarine running on batteries?? You guys are a heck of a lot better than the clowns I flew with.

My guess is that your Blair is an avid historian/author and has simply regurgitated what little there is out there on that particular weapon system. And you sir are a vet from the midwest who might not think too highly of the USN's officer corp, its naval flight officers and S-3 crew members in particular.

http://www.matrixgames.com/forums/fb.asp?m=3162068&key=last%2Cminute%2Cing%2Cflight%2Cofficer

I still wonder where you got that such a negative assessment of that small group of officers. Oh well, no ill will here. I'm not much for making judgments on stuff I know little about. What I do know a lot about is ASW. So if you would like to know more about the Mk24 FIDO Mr Chickenboy and Mr/Ms Blair please read on.

The Mk24 FIDO was a rather peculiar weapon. Look at its payload of 92lbs HE. What were they thinking? Here I am telling you all that 1000lbs of HE or even 30 million lbs of HE just isn't much when trying to kill a submarine designed to handle to the overpressure of copious amounts of water. Why would anyone ever want to carry such a weapon? There's your B-24 and they are loading it up with a FIDO. Would you not be tempted to tell those guys to skip with the FIDO and go with the 2000lb bruiser?

Well perhaps after a few more flight hours you might find that spotting snorkels and periscopes may be challenging, but targeting them is nothing short of a real bitch. There you are cruising along and someone blurps out "holy **** - periscope 3 o'clock" followed by the high banked turn, followed by the customary "where the hell did it go." Lots of shouting and confusion – ugh gives me headaches even today. And you will find the exact same issue happens at night with the whole damn boat on the surface. While it is relatively easy to locate and attack a surfaced or submerging sub in daylight, trying to reacquire something very small or in the dark can be most challenging. Simply put, your visibility on the target is approaching your turning radius. So if you can't see it from far enough out, how can you put together an effective attack run before it gets a clue and dives? This is the very reason why the FIDO was invented in the first place. Someone thought that if you just poke a hole in the bugger that forces him up on the surface and during daylight everybody can get back to the business of sinking them. It had the beginnings of being a pretty good weapon.

When the Mk24 FIDO first came out it was really hush hush stuff. It's probably why Blair and the rest of you enthusiasts can't find much about it. Even the USN's own historians appear to be struggling for data if their website is any indication. I'm not surprised. Very classified material gets destroyed when it is no longer useful. There is never any dissemination. This weapon was TS level stuff and its life cycle was really short. When it became useless, most of the data was destroyed or remained far too classified for PR types publish.

So why did the USN put all the secrecy around this rather small, short lived weapon? Seriously, they even went to the trouble of misclassifying it as a mine just to keep prying eyes off the scent of what it really was. Now that’s hardcore. Can you think about any other weapon systems where they did stuff like that!? I can, but I'll save that story for another beer tab.

Let’s take a quick look at the hydrogen bomb which was arguably the most classified project ever to be undertaken. You didn't see them call it an "incendiary device" after they had it all ironed out and ready to go boom. Why not? The thing was one heck of a game changer! I mean it ended wars. Yet nobody gave a care about keeping it all top secret. The beans were spilled that the good guys were splitting atoms and had become death, the destroyer of worlds, etc etc. You know why? Because it worked and there was nothing the bad guys could do to change that. When a weapon system works - there is little need to disguise it other than to keep them from finding a counter. Since you can't really counter a hydrogen bomb, there is very little need to keep a super high classification. What does that say about the Mk24 FIDO? Oh yeah, this thing was so sensitive that the bad guys already had the counter installed in their subs. Bummer! I guess maybe we should go to some crazy lengths to keep them from finding that out!

Is any of this making sense?

So what does this have to do with our Mk24 homing in on subs and junk. Well I sure as heck don't want to spend the next 5 hours explaining passive and active acoustics. All I'm going to give you is that you’ve got two ways of acoustically locating a sub. Listen for its sound signatures (passive) or generate your own sound and wait for it to return off the sub (active). Guess which one is super accurate and which one is just horrible for targeting data? Go watch "The Hunt for Red October" again. You know they did a lot of things right in that movie. Remember the ending were Sean Connery is trying to dodge the torpedo - that puppy isn’t using passive acoustics. In fact almost all of our torpedoes and our enemies too have used active homing. So that must mean the Mk24 was an active homing torpedo right? Nope, it was passively homed. The plot thickens . . .

First let’s explain a little about passive acoustics. There is both broadband and narrowband. Broadband is like “whoa that thing is loud.” Our ears and brain combined to form a good broadband sensor/processor. Broadband noise is usually what we are referring to when we complain about something being too loud or too hard to hear. But we can also process narrowband stuff as well. Otherwise we would not know to turn the burner off when the tea kettle is whistling. That’s a simple example of narrow band processing by your brain and ears. Certain things make certain sounds so when we hear the frequency we know something is afoot.

So what should we use to find subs? Well the ocean is louder than your neighbor’s last party. So broadband isn't looking good. What’s more is that surface ships are far louder than subs so trying to find one in and around your TF or convoy will be hard if you are looking for a broadband acoustic signature. Lucky for ASW, narrowband works real well. In fact when it comes to man-made machinery it is outstanding. All those moving parts make noise on very specific frequencies. Knowing your enemies frequency signatures is the first step in finding him using passive acoustics.

Today (or at least back in my day - 1990's) you would use a computer processor to create a nice waterfall display of the frequency spectrum over time picked up by your microphone(s). Back in FIDO's day computers weren't an option. They opted to use a simple 4 hydrophone array (one each axis – brilliant!) operating at 24 kHz, which in turn were connect to some vacuum tube steering mechanism. I’d say that’s pretty high tech stuff for 1942, wouldn’t you? So what does the 24 kHz mean? Well that's the only frequency those 4 hydrophones were going to hear. It's actually a pretty high freq – well above what our 20 Hz to 20 kHz capabilities. So why in the world did they choose 24 kHz?

http://www.bc.cityu.edu.hk/staff/bcaleung/homepage/publications/ZhengGT/asmeJEGTP124-645.pdf

Sorry it was all I could find on the internet with very limited time. Anyway, look at page 647-648. The chart on a pg 648 should be all you need to see. I'm no acoustic expert but I'd bet dollars to donuts that all diesel fuel injectors – since they are squirting the same liquid will pump out the same frequency noise.

Are you still with me?

If you are, I’m sure Mr. Blair is just itching to ask if the screw of a submarine also turned out 24 kHz. Or for that matter, is there any other part of a sub that makes noise in this 24 kHz range? In a word – no. There isn't much left for noise other than the skipper shouting orders and if he did it at 24 kHz, only his dachshund would be hearing it. A bottomed sub on batteries makes about as much noise as a flashlight at the bottom of your pool. They’ve got pumps, but the sub just dove and they would hardly be a reliable source to pick if you are attacking as he is initiating a dive. Honestly the only thing moving on that sub beside intermittent control surfaces is the shaft and the propeller. What kind of noise do they make? Easy question; since air and water are much the same when it comes to sound propagation, go turn on your ceiling fan. It has blades just like a propeller and it has a shaft powered by electricity. Sure doesn’t look good homing in the acoustic signature of a prop or shaft does it?

Yes, even using 1990 technology you are not going to reliably track, let alone attack a sub’s using the acoustic properties of its shaft or prop. And lest you have even the smallest amount of doubt of what I say - what do you think would put more noise into the narrowband frequencies associated with a turning shaft/prop – the big slow turning one a few hundred yards away or that small fast spinning one 3 feet from hydrophones on the tail of the torpedo? Ouch – guess that torpedoed the prop theory.

So yeah, the data you are seeing out there about the FIDO doing this or that is old and quite unreliable. The weapon was obsolete just as soon as knowledge submariners figured out it was homing on the diesel engine. Remember, they called this thing a mine. They certainly had no problem telling you Avengers would be strafing the sub to make it work - got to admit that made me laugh - because once that propeller got submerged . . . err . . . MORE submerged, it was going to be rocking out at 24 kHz. They would have told you anything to conceal the fatal weakness which was so big that just flipping an internal switch on the sub made the weapon useless.

Thanks for reading.




_____________________________

Gary S (USN 1320, 1985-1993)
AOCS 1985, VT10 1985-86, VT86 1986, VS41 1986-87
VS32 1987-90 (NSO/NWTO, deployed w/CV-66, CVN-71)
VS27 1990-91 (NATOPS/Safety)
SFWSLANT 1991-93 (AGM-84 All platforms, S-3 A/B systems)

(in reply to Chickenboy)
Post #: 34
RE: ASW damage from AC - 8/19/2013 10:45:58 PM   
Bullwinkle58


Posts: 8408
Joined: 2/24/2009
Status: online
Blair is Clay Blair.

24 kHz might be the weapon's sensor range. I don't know; I'll take your word for it. Above that was probably technically hard to deal with in the early 1940s in a pre-digital environment.

But a diving sub makes lots of narrowband noise other than the prop and control surfaces. What do you think turns the prop? If you have ASW experience in the 90s you know what I'm referring to. It's almost a certainty that the trim pump is going to be screaming too as the superstructure goes under. Also the hydraulic plant is going to be running full out to answer plane and rudder orders, especially if an evasion course is ordered as way comes on and the hull gets under.

A 24kHz sensor gets surfaced subs on diesel, and it gets snorkeling subs that don't know they've been popped. It doesn't get a fully-submerged sub on batteries (although in the Atlantic nobody was going down to sit on the bottom. In mid-ocean we were in circa 19,000 feet quite a bit.) I assume the FIDO was prototyped before snorkels were known. In that case it's great for catching a sub on the surface charging batteries, at night. It could be dropped on the run in, before the gyrations and come-around you describe.

It's also a good anti-diesel-powered ship weapon for a USN fleet boat to shoot as it went deep, pursued by a bear. But that's another story and as I recall another acronym.

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Post #: 35
RE: ASW damage from AC - 8/19/2013 10:49:10 PM   
AW1Steve


Posts: 12869
Joined: 3/10/2007
From: ME-FL-DC-GM-WA-NE-IL ?
Status: offline

quote:

ORIGINAL: sandman455


quote:

ORIGINAL: Chickenboy


quote:

ORIGINAL: sandman455
FIDO - it was kind of like a quick use mine. It homed in on noise - if I remember it was the band at which the diesel engines fuel injectors worked. Without that diesel running your weapon was worthless. It was the weapon of choice for a snorkled sub or any at night. Trying to hit a target with so little to aim at was pretty hard. Half the time you couldn't see the sub/snorkle in time to make a good drop. Any close aboard fly over could easily alert the sub ruining any chance of setting up again. This thing allowed the aircraft to pickle the weapon on the initial flyover or well ahead to remain unnoticed. Again, the weapon was going to be worthless if the enemy figured out how it worked.


This is contrary to the useage of the FIDO weapon system used against the U-boats, according to Blair.

The weapon was typically dropped by Avenger-type aircraft after the U-boat had submerged.
The attacks typically took place by daylight scout aircraft-often a pair of F4F and TBF/M. The F4F would strafe the submarine, forcing it to submerge. The Avenger would come in and drop on the swirl. Daylight attack, submerged U-boat.

The U-boats weren't using their diesels after submerging. Therefore, the guidance system of the FIDO was unlikely to be the diesel pressurization system.



Who is Blair? So are you and Mr. (Ms?) Blair suggesting that you could passively track and acquire a submarine running on batteries?? You guys are a heck of a lot better than the clowns I flew with.

My guess is that your Blair is an avid historian/author and has simply regurgitated what little there is out there on that particular weapon system. And you sir are a vet from the midwest who might not think too highly of the USN's officer corp, its naval flight officers and S-3 crew members in particular.

http://www.matrixgames.com/forums/fb.asp?m=3162068&key=last%2Cminute%2Cing%2Cflight%2Cofficer

I still wonder where you got that such a negative assessment of that small group of officers. Oh well, no ill will here. I'm not much for making judgments on stuff I know little about. What I do know a lot about is ASW. So if you would like to know more about the Mk24 FIDO Mr Chickenboy and Mr/Ms Blair please read on.

The Mk24 FIDO was a rather peculiar weapon. Look at its payload of 92lbs HE. What were they thinking? Here I am telling you all that 1000lbs of HE or even 30 million lbs of HE just isn't much when trying to kill a submarine designed to handle to the overpressure of copious amounts of water. Why would anyone ever want to carry such a weapon? There's your B-24 and they are loading it up with a FIDO. Would you not be tempted to tell those guys to skip with the FIDO and go with the 2000lb bruiser?

Well perhaps after a few more flight hours you might find that spotting snorkels and periscopes may be challenging, but targeting them is nothing short of a real bitch. There you are cruising along and someone blurps out "holy **** - periscope 3 o'clock" followed by the high banked turn, followed by the customary "where the hell did it go." Lots of shouting and confusion – ugh gives me headaches even today. And you will find the exact same issue happens at night with the whole damn boat on the surface. While it is relatively easy to locate and attack a surfaced or submerging sub in daylight, trying to reacquire something very small or in the dark can be most challenging. Simply put, your visibility on the target is approaching your turning radius. So if you can't see it from far enough out, how can you put together an effective attack run before it gets a clue and dives? This is the very reason why the FIDO was invented in the first place. Someone thought that if you just poke a hole in the bugger that forces him up on the surface and during daylight everybody can get back to the business of sinking them. It had the beginnings of being a pretty good weapon.

When the Mk24 FIDO first came out it was really hush hush stuff. It's probably why Blair and the rest of you enthusiasts can't find much about it. Even the USN's own historians appear to be struggling for data if their website is any indication. I'm not surprised. Very classified material gets destroyed when it is no longer useful. There is never any dissemination. This weapon was TS level stuff and its life cycle was really short. When it became useless, most of the data was destroyed or remained far too classified for PR types publish.

So why did the USN put all the secrecy around this rather small, short lived weapon? Seriously, they even went to the trouble of misclassifying it as a mine just to keep prying eyes off the scent of what it really was. Now that’s hardcore. Can you think about any other weapon systems where they did stuff like that!? I can, but I'll save that story for another beer tab.

Let’s take a quick look at the hydrogen bomb which was arguably the most classified project ever to be undertaken. You didn't see them call it an "incendiary device" after they had it all ironed out and ready to go boom. Why not? The thing was one heck of a game changer! I mean it ended wars. Yet nobody gave a care about keeping it all top secret. The beans were spilled that the good guys were splitting atoms and had become death, the destroyer of worlds, etc etc. You know why? Because it worked and there was nothing the bad guys could do to change that. When a weapon system works - there is little need to disguise it other than to keep them from finding a counter. Since you can't really counter a hydrogen bomb, there is very little need to keep a super high classification. What does that say about the Mk24 FIDO? Oh yeah, this thing was so sensitive that the bad guys already had the counter installed in their subs. Bummer! I guess maybe we should go to some crazy lengths to keep them from finding that out!

Is any of this making sense?

So what does this have to do with our Mk24 homing in on subs and junk. Well I sure as heck don't want to spend the next 5 hours explaining passive and active acoustics. All I'm going to give you is that you’ve got two ways of acoustically locating a sub. Listen for its sound signatures (passive) or generate your own sound and wait for it to return off the sub (active). Guess which one is super accurate and which one is just horrible for targeting data? Go watch "The Hunt for Red October" again. You know they did a lot of things right in that movie. Remember the ending were Sean Connery is trying to dodge the torpedo - that puppy isn’t using passive acoustics. In fact almost all of our torpedoes and our enemies too have used active homing. So that must mean the Mk24 was an active homing torpedo right? Nope, it was passively homed. The plot thickens . . .

First let’s explain a little about passive acoustics. There is both broadband and narrowband. Broadband is like “whoa that thing is loud.” Our ears and brain combined to form a good broadband sensor/processor. Broadband noise is usually what we are referring to when we complain about something being too loud or too hard to hear. But we can also process narrowband stuff as well. Otherwise we would not know to turn the burner off when the tea kettle is whistling. That’s a simple example of narrow band processing by your brain and ears. Certain things make certain sounds so when we hear the frequency we know something is afoot.

So what should we use to find subs? Well the ocean is louder than your neighbor’s last party. So broadband isn't looking good. What’s more is that surface ships are far louder than subs so trying to find one in and around your TF or convoy will be hard if you are looking for a broadband acoustic signature. Lucky for ASW, narrowband works real well. In fact when it comes to man-made machinery it is outstanding. All those moving parts make noise on very specific frequencies. Knowing your enemies frequency signatures is the first step in finding him using passive acoustics.

Today (or at least back in my day - 1990's) you would use a computer processor to create a nice waterfall display of the frequency spectrum over time picked up by your microphone(s). Back in FIDO's day computers weren't an option. They opted to use a simple 4 hydrophone array (one each axis – brilliant!) operating at 24 kHz, which in turn were connect to some vacuum tube steering mechanism. I’d say that’s pretty high tech stuff for 1942, wouldn’t you? So what does the 24 kHz mean? Well that's the only frequency those 4 hydrophones were going to hear. It's actually a pretty high freq – well above what our 20 Hz to 20 kHz capabilities. So why in the world did they choose 24 kHz?

http://www.bc.cityu.edu.hk/staff/bcaleung/homepage/publications/ZhengGT/asmeJEGTP124-645.pdf

Sorry it was all I could find on the internet with very limited time. Anyway, look at page 647-648. The chart on a pg 648 should be all you need to see. I'm no acoustic expert but I'd bet dollars to donuts that all diesel fuel injectors – since they are squirting the same liquid will pump out the same frequency noise.

Are you still with me?

If you are, I’m sure Mr. Blair is just itching to ask if the screw of a submarine also turned out 24 kHz. Or for that matter, is there any other part of a sub that makes noise in this 24 kHz range? In a word – no. There isn't much left for noise other than the skipper shouting orders and if he did it at 24 kHz, only his dachshund would be hearing it. A bottomed sub on batteries makes about as much noise as a flashlight at the bottom of your pool. They’ve got pumps, but the sub just dove and they would hardly be a reliable source to pick if you are attacking as he is initiating a dive. Honestly the only thing moving on that sub beside intermittent control surfaces is the shaft and the propeller. What kind of noise do they make? Easy question; since air and water are much the same when it comes to sound propagation, go turn on your ceiling fan. It has blades just like a propeller and it has a shaft powered by electricity. Sure doesn’t look good homing in the acoustic signature of a prop or shaft does it?

Yes, even using 1990 technology you are not going to reliably track, let alone attack a sub’s using the acoustic properties of its shaft or prop. And lest you have even the smallest amount of doubt of what I say - what do you think would put more noise into the narrowband frequencies associated with a turning shaft/prop – the big slow turning one a few hundred yards away or that small fast spinning one 3 feet from hydrophones on the tail of the torpedo? Ouch – guess that torpedoed the prop theory.

So yeah, the data you are seeing out there about the FIDO doing this or that is old and quite unreliable. The weapon was obsolete just as soon as knowledge submariners figured out it was homing on the diesel engine. Remember, they called this thing a mine. They certainly had no problem telling you Avengers would be strafing the sub to make it work - got to admit that made me laugh - because once that propeller got submerged . . . err . . . MORE submerged, it was going to be rocking out at 24 kHz. They would have told you anything to conceal the fatal weakness which was so big that just flipping an internal switch on the sub made the weapon useless.

Thanks for reading.



[/quote
Sorry , I totally disagree with most of the points you made. Blair is a ww2 Submariner who became a historian , in fact many ww2 submariners that I've interviewed refer to him as THE WW2 Submarine historian , largely to some very good connection with the post ww2 submarine brass. He did several official histories.

I didn't realize that the FIDO was in service at the same time you were , or that it had a S-3 NFO connection.

Maybe you can't track a submarine on batteries, but I know many people who can and have. Crews that I've served on have on many occasions.

Clowns? Nice. You treat your former shipmates as well as people on the forum.

I'd go into more detail , but don't want to 1) go into techniques that may or may not still be classified. 2) want to waste any time as it's only a matter of time before you called me liar again , no matter what I say 3) lose my temper and say something I'd regret and get banned from the forum.

So let me simply say that I totally disagree with you on most everything you've said here. Not surprise, I generally do.

_____________________________

"Geezerhood is a state of mind, attained by being largely out of yours". AW1Steve

"Quit whining and play the game. Or go home". My 7th grade baseball coach. It applies well to WITP AE players.

(in reply to sandman455)
Post #: 36
RE: ASW damage from AC - 8/19/2013 10:56:25 PM   
witpqs

 

Posts: 14619
Joined: 10/4/2004
From: Argleton
Status: online
I'm also questioning Sandman's dismissal of "92 lbs HE", which seems to ignore the existence of shaped charges.

_____________________________

Intel Monkey: https://sites.google.com/site/staffmonkeys/

(in reply to AW1Steve)
Post #: 37
RE: ASW damage from AC - 8/19/2013 11:13:16 PM   
Bullwinkle58


Posts: 8408
Joined: 2/24/2009
Status: online
quote:

ORIGINAL: AW1Steve

Sorry , I totally disagree with most of the points you made. Blair is a ww2 Submariner who became a historian , in fact many ww2 submariners that I've interviewed refer to him as THE WW2 Submarine historian , largely to some very good connection with the post ww2 submarine brass. He did several official histories.

I didn't realize that the FIDO was in service at the same time you were , or that it had a S-3 NFO connection.

Maybe you can't track a submarine on batteries, but I know many people who can and have. Crews that I've served on have on many occasions.

Clowns? Nice. You treat your former shipmates as well as people on the forum.

I'd go into more detail , but don't want to 1) go into techniques that may or may not still be classified. 2) want to waste any time as it's only a matter of time before you called me liar again , no matter what I say 3) lose my temper and say something I'd regret and get banned from the forum.

So let me simply say that I totally disagree with you on most everything you've said here. Not surprise, I generally do.


I don't want to get between you two, but I don't discount everything he said. Thinking more about it.

I think he was saying that tracking a sub on batteries--from the air--in WWII wasn't happening. No sonobuoys or helos.

But the 24kHz thing does make sense to me on a technology level. Where I have trouble is in the tactics. When a D/E dives three things happen instantly in the ER when the diving alarm goes off. One of (usually) two watchstanders pulls the outboard induction valve shut. He then pulls the inboard induction valve shut. If the diesels are still running they're pulling on the people tank air. Very painful, very fast. The second guy therefore stops the diesels as fast as possible. How fast? From the diving alarm fifteen seconds would be pretty good. That gives maneuvering time to get the main motors up and going on the battery so the OOD has way to evade as soon as the hull is under. You don't turn in the initial dive if you can help it. Messes up the angle, and slows you waaaay down. Get under, then change course.

So say it's night. A FIDO equipped patrol plane finds a surfaced U-boat charging batteries. Maybe it's got radar, maybe it's using it sparingly for RDF reasons. Probably by that era the plane has radar too, but maybe it's off for the same detection reasons. The plane starts a run in. How far out does it drop the FIDO? The fish has to drop, activate, stabilize, and listen for diesel injectors that have, at best, about 15-20 seconds of noise, then they're gone. Does the FIDO get one good steer and then become a straight-runner? That might be enough if it's dropped close enough to the sub, but aspect and sub speed are going to drive the contact geometry. If too far out or not broad on the beam the sub can get out of the cone of contact pretty easily and then your expensive FIDO is just a mini-me straight-runner.

But if it does get a hit of injectors, and does a 30-degree steer to compensate for the bad drop aspect given by the plane's hurrying crew, it could increase hit percentage I'd say. Not to what an active homer could do, but better than a gravity bomb dropped in the dark.

< Message edited by Bullwinkle58 -- 8/19/2013 11:24:27 PM >


_____________________________

The Moose

(in reply to AW1Steve)
Post #: 38
RE: ASW damage from AC - 8/19/2013 11:21:19 PM   
witpqs

 

Posts: 14619
Joined: 10/4/2004
From: Argleton
Status: online

quote:

ORIGINAL: witpqs

I'm also questioning Sandman's dismissal of "92 lbs HE", which seems to ignore the existence of shaped charges.

Further on this, according to Wikipedia Hedgehog had 30 pounds of TNT or 35 pounds of Torpex. Did Hedgehog sink any subs?

http://en.wikipedia.org/wiki/Hedgehog_(weapon)

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(in reply to witpqs)
Post #: 39
RE: ASW damage from AC - 8/19/2013 11:23:05 PM   
witpqs

 

Posts: 14619
Joined: 10/4/2004
From: Argleton
Status: online
quote:

ORIGINAL: Bullwinkle58

quote:

ORIGINAL: AW1Steve

Sorry , I totally disagree with most of the points you made. Blair is a ww2 Submariner who became a historian , in fact many ww2 submariners that I've interviewed refer to him as THE WW2 Submarine historian , largely to some very good connection with the post ww2 submarine brass. He did several official histories.

I didn't realize that the FIDO was in service at the same time you were , or that it had a S-3 NFO connection.

Maybe you can't track a submarine on batteries, but I know many people who can and have. Crews that I've served on have on many occasions.

Clowns? Nice. You treat your former shipmates as well as people on the forum.

I'd go into more detail , but don't want to 1) go into techniques that may or may not still be classified. 2) want to waste any time as it's only a matter of time before you called me liar again , no matter what I say 3) lose my temper and say something I'd regret and get banned from the forum.

So let me simply say that I totally disagree with you on most everything you've said here. Not surprise, I generally do.


I don't want to get between you two, but I don't discount everything he said. Thinking more about it.

I think he was saying that tracking a sub on batteries--from the air--in WII wasn't happening. No sonobuoys or helos.

But the 24kHz thing does make sense to me on a technology level. Where I have trouble is in the tactics. When a D/E dives three things happen instantly in the ER when the diving alarm goes off. One of (usually) two watchstanders pulls the outboard induction valve shut. He then pulls the inboard induction valve shut. If the diesels are still running they're puling on the people tank air. Very painful, very fast. The second guy therefore stops the diesels as fast as possible. How fast? From the diving alarm fifteen seconds would be pretty good. that gives maneuvering time to get the main motors up and going on the battery so the OOD has way to evade as soon as the hull is under. You don't turn in the initial dive if you can help it. Messes up the angle, and slows you waaaay down. Get under, then change course.

So say it's night. A FIDO equipped patrol plane finds a surfaced U-boat charging batteries. Maybe it's got radar, maybe it's using it sparingly for RDF reasons. Probably by that era the plane has radar too, but maybe it's off for the same detection reasons. The plane starts a run in. How far out does it drop the FIDO? The fish has to drop, activate, stabilize, and listen for diesel injectors that have, at best, about 15-20 seconds of noise, then they're gone. Does the FIDO get one good steer and then become a straight-runner? That might be enough if it's dropped close enough to the sub, but aspect and sub speed are going to drive the contact geometry. If too far out or not broad on the beam the sub can get out of the cone of contact pretty easily and then your expensive FIDO is just a mini-me straight-runner.

But if it does get a hit of injectors, and does a 30-degree steer to compensate for the bad drop aspect given by the plane's hurrying crew, it could increase hit percentage I'd say. Not to what an active homer could do, but better than a gravity bomb dropped in the dark.

BTW, are you accounting for the fact that FIDO was dropped so close to the sub? The closeness might have forgiven a lot of shortcomings in the sensors.

_____________________________

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(in reply to Bullwinkle58)
Post #: 40
RE: ASW damage from AC - 8/19/2013 11:29:44 PM   
Bullwinkle58


Posts: 8408
Joined: 2/24/2009
Status: online

quote:

ORIGINAL: witpqs

quote:

ORIGINAL: Bullwinkle58

quote:

ORIGINAL: AW1Steve

Sorry , I totally disagree with most of the points you made. Blair is a ww2 Submariner who became a historian , in fact many ww2 submariners that I've interviewed refer to him as THE WW2 Submarine historian , largely to some very good connection with the post ww2 submarine brass. He did several official histories.

I didn't realize that the FIDO was in service at the same time you were , or that it had a S-3 NFO connection.

Maybe you can't track a submarine on batteries, but I know many people who can and have. Crews that I've served on have on many occasions.

Clowns? Nice. You treat your former shipmates as well as people on the forum.

I'd go into more detail , but don't want to 1) go into techniques that may or may not still be classified. 2) want to waste any time as it's only a matter of time before you called me liar again , no matter what I say 3) lose my temper and say something I'd regret and get banned from the forum.

So let me simply say that I totally disagree with you on most everything you've said here. Not surprise, I generally do.


I don't want to get between you two, but I don't discount everything he said. Thinking more about it.

I think he was saying that tracking a sub on batteries--from the air--in WII wasn't happening. No sonobuoys or helos.

But the 24kHz thing does make sense to me on a technology level. Where I have trouble is in the tactics. When a D/E dives three things happen instantly in the ER when the diving alarm goes off. One of (usually) two watchstanders pulls the outboard induction valve shut. He then pulls the inboard induction valve shut. If the diesels are still running they're puling on the people tank air. Very painful, very fast. The second guy therefore stops the diesels as fast as possible. How fast? From the diving alarm fifteen seconds would be pretty good. that gives maneuvering time to get the main motors up and going on the battery so the OOD has way to evade as soon as the hull is under. You don't turn in the initial dive if you can help it. Messes up the angle, and slows you waaaay down. Get under, then change course.

So say it's night. A FIDO equipped patrol plane finds a surfaced U-boat charging batteries. Maybe it's got radar, maybe it's using it sparingly for RDF reasons. Probably by that era the plane has radar too, but maybe it's off for the same detection reasons. The plane starts a run in. How far out does it drop the FIDO? The fish has to drop, activate, stabilize, and listen for diesel injectors that have, at best, about 15-20 seconds of noise, then they're gone. Does the FIDO get one good steer and then become a straight-runner? That might be enough if it's dropped close enough to the sub, but aspect and sub speed are going to drive the contact geometry. If too far out or not broad on the beam the sub can get out of the cone of contact pretty easily and then your expensive FIDO is just a mini-me straight-runner.

But if it does get a hit of injectors, and does a 30-degree steer to compensate for the bad drop aspect given by the plane's hurrying crew, it could increase hit percentage I'd say. Not to what an active homer could do, but better than a gravity bomb dropped in the dark.

BTW, are you accounting for the fact that FIDO was dropped so close to the sub? The closeness might have forgiven a lot of shortcomings in the sensors.


I'm saying it HAD to be dropped close if the only sensor input was diesel injectors. For surfaced subs here. If snorkeling the injectors would probably stay on as the sub had a bad chance of knowing it had been dropped on. Injectors then would be a steady data stream to the FIDO, which could do continuous corrections all the way to contact.

But a diving sub would need to be dropped on very closely. And getting that close without the sub starting the dive would be a nice trick if radar had to be secured else it would give the plane away. That might be some of the source of the 2-pane attack profile Blair speaks of. One plane with radar off angle from the "dark" plane carrying the FIDO.

_____________________________

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(in reply to witpqs)
Post #: 41
RE: ASW damage from AC - 8/19/2013 11:31:33 PM   
witpqs

 

Posts: 14619
Joined: 10/4/2004
From: Argleton
Status: online
Understood. Thanks.

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(in reply to Bullwinkle58)
Post #: 42
RE: ASW damage from AC - 8/19/2013 11:34:11 PM   
AW1Steve


Posts: 12869
Joined: 3/10/2007
From: ME-FL-DC-GM-WA-NE-IL ?
Status: offline

quote:

ORIGINAL: Bullwinkle58


quote:

ORIGINAL: witpqs

quote:

ORIGINAL: Bullwinkle58

quote:

ORIGINAL: AW1Steve

Sorry , I totally disagree with most of the points you made. Blair is a ww2 Submariner who became a historian , in fact many ww2 submariners that I've interviewed refer to him as THE WW2 Submarine historian , largely to some very good connection with the post ww2 submarine brass. He did several official histories.

I didn't realize that the FIDO was in service at the same time you were , or that it had a S-3 NFO connection.

Maybe you can't track a submarine on batteries, but I know many people who can and have. Crews that I've served on have on many occasions.

Clowns? Nice. You treat your former shipmates as well as people on the forum.

I'd go into more detail , but don't want to 1) go into techniques that may or may not still be classified. 2) want to waste any time as it's only a matter of time before you called me liar again , no matter what I say 3) lose my temper and say something I'd regret and get banned from the forum.

So let me simply say that I totally disagree with you on most everything you've said here. Not surprise, I generally do.


I don't want to get between you two, but I don't discount everything he said. Thinking more about it.

I think he was saying that tracking a sub on batteries--from the air--in WII wasn't happening. No sonobuoys or helos.

But the 24kHz thing does make sense to me on a technology level. Where I have trouble is in the tactics. When a D/E dives three things happen instantly in the ER when the diving alarm goes off. One of (usually) two watchstanders pulls the outboard induction valve shut. He then pulls the inboard induction valve shut. If the diesels are still running they're puling on the people tank air. Very painful, very fast. The second guy therefore stops the diesels as fast as possible. How fast? From the diving alarm fifteen seconds would be pretty good. that gives maneuvering time to get the main motors up and going on the battery so the OOD has way to evade as soon as the hull is under. You don't turn in the initial dive if you can help it. Messes up the angle, and slows you waaaay down. Get under, then change course.

So say it's night. A FIDO equipped patrol plane finds a surfaced U-boat charging batteries. Maybe it's got radar, maybe it's using it sparingly for RDF reasons. Probably by that era the plane has radar too, but maybe it's off for the same detection reasons. The plane starts a run in. How far out does it drop the FIDO? The fish has to drop, activate, stabilize, and listen for diesel injectors that have, at best, about 15-20 seconds of noise, then they're gone. Does the FIDO get one good steer and then become a straight-runner? That might be enough if it's dropped close enough to the sub, but aspect and sub speed are going to drive the contact geometry. If too far out or not broad on the beam the sub can get out of the cone of contact pretty easily and then your expensive FIDO is just a mini-me straight-runner.

But if it does get a hit of injectors, and does a 30-degree steer to compensate for the bad drop aspect given by the plane's hurrying crew, it could increase hit percentage I'd say. Not to what an active homer could do, but better than a gravity bomb dropped in the dark.

BTW, are you accounting for the fact that FIDO was dropped so close to the sub? The closeness might have forgiven a lot of shortcomings in the sensors.


I'm saying it HAD to be dropped close if the only sensor input was diesel injectors. For surfaced subs here. If snorkeling the injectors would probably stay on as the sub had a bad chance of knowing it had been dropped on. Injectors then would be a steady data stream to the FIDO, which could do continuous corrections all the way to contact.

But a diving sub would need to be dropped on very closely. And getting that close without the sub starting the dive would be a nice trick if radar had to be secured else it would give the plane away. That might be some of the source of the 2-pane attack profile Blair speaks of. One plane with radar off angle from the "dark" plane carrying the FIDO.


RADAR might do it. MAD certainly would give you a datum with attack criteria. And if the sub has just dived , a periscope swirl (as it dived) would certainly give you a "flaming datum" which would probably be good enough. Heck , it was good enough for depth charges.

_____________________________

"Geezerhood is a state of mind, attained by being largely out of yours". AW1Steve

"Quit whining and play the game. Or go home". My 7th grade baseball coach. It applies well to WITP AE players.

(in reply to Bullwinkle58)
Post #: 43
RE: ASW damage from AC - 8/19/2013 11:51:59 PM   
Bullwinkle58


Posts: 8408
Joined: 2/24/2009
Status: online

quote:

ORIGINAL: AW1Steve


quote:

ORIGINAL: Bullwinkle58


quote:

ORIGINAL: witpqs

quote:

ORIGINAL: Bullwinkle58

quote:

ORIGINAL: AW1Steve

Sorry , I totally disagree with most of the points you made. Blair is a ww2 Submariner who became a historian , in fact many ww2 submariners that I've interviewed refer to him as THE WW2 Submarine historian , largely to some very good connection with the post ww2 submarine brass. He did several official histories.

I didn't realize that the FIDO was in service at the same time you were , or that it had a S-3 NFO connection.

Maybe you can't track a submarine on batteries, but I know many people who can and have. Crews that I've served on have on many occasions.

Clowns? Nice. You treat your former shipmates as well as people on the forum.

I'd go into more detail , but don't want to 1) go into techniques that may or may not still be classified. 2) want to waste any time as it's only a matter of time before you called me liar again , no matter what I say 3) lose my temper and say something I'd regret and get banned from the forum.

So let me simply say that I totally disagree with you on most everything you've said here. Not surprise, I generally do.


I don't want to get between you two, but I don't discount everything he said. Thinking more about it.

I think he was saying that tracking a sub on batteries--from the air--in WII wasn't happening. No sonobuoys or helos.

But the 24kHz thing does make sense to me on a technology level. Where I have trouble is in the tactics. When a D/E dives three things happen instantly in the ER when the diving alarm goes off. One of (usually) two watchstanders pulls the outboard induction valve shut. He then pulls the inboard induction valve shut. If the diesels are still running they're puling on the people tank air. Very painful, very fast. The second guy therefore stops the diesels as fast as possible. How fast? From the diving alarm fifteen seconds would be pretty good. that gives maneuvering time to get the main motors up and going on the battery so the OOD has way to evade as soon as the hull is under. You don't turn in the initial dive if you can help it. Messes up the angle, and slows you waaaay down. Get under, then change course.

So say it's night. A FIDO equipped patrol plane finds a surfaced U-boat charging batteries. Maybe it's got radar, maybe it's using it sparingly for RDF reasons. Probably by that era the plane has radar too, but maybe it's off for the same detection reasons. The plane starts a run in. How far out does it drop the FIDO? The fish has to drop, activate, stabilize, and listen for diesel injectors that have, at best, about 15-20 seconds of noise, then they're gone. Does the FIDO get one good steer and then become a straight-runner? That might be enough if it's dropped close enough to the sub, but aspect and sub speed are going to drive the contact geometry. If too far out or not broad on the beam the sub can get out of the cone of contact pretty easily and then your expensive FIDO is just a mini-me straight-runner.

But if it does get a hit of injectors, and does a 30-degree steer to compensate for the bad drop aspect given by the plane's hurrying crew, it could increase hit percentage I'd say. Not to what an active homer could do, but better than a gravity bomb dropped in the dark.

BTW, are you accounting for the fact that FIDO was dropped so close to the sub? The closeness might have forgiven a lot of shortcomings in the sensors.


I'm saying it HAD to be dropped close if the only sensor input was diesel injectors. For surfaced subs here. If snorkeling the injectors would probably stay on as the sub had a bad chance of knowing it had been dropped on. Injectors then would be a steady data stream to the FIDO, which could do continuous corrections all the way to contact.

But a diving sub would need to be dropped on very closely. And getting that close without the sub starting the dive would be a nice trick if radar had to be secured else it would give the plane away. That might be some of the source of the 2-pane attack profile Blair speaks of. One plane with radar off angle from the "dark" plane carrying the FIDO.


RADAR might do it. MAD certainly would give you a datum with attack criteria. And if the sub has just dived , a periscope swirl (as it dived) would certainly give you a "flaming datum" which would probably be good enough. Heck , it was good enough for depth charges.


Yeah, but once you have a periscope swirl you haven't had injectors for about 30-40 seconds.

_____________________________

The Moose

(in reply to AW1Steve)
Post #: 44
RE: ASW damage from AC - 8/20/2013 12:29:07 AM   
AW1Steve


Posts: 12869
Joined: 3/10/2007
From: ME-FL-DC-GM-WA-NE-IL ?
Status: offline

quote:

ORIGINAL: Bullwinkle58


quote:

ORIGINAL: AW1Steve


quote:

ORIGINAL: Bullwinkle58


quote:

ORIGINAL: witpqs

quote:

ORIGINAL: Bullwinkle58

quote:

ORIGINAL: AW1Steve

Sorry , I totally disagree with most of the points you made. Blair is a ww2 Submariner who became a historian , in fact many ww2 submariners that I've interviewed refer to him as THE WW2 Submarine historian , largely to some very good connection with the post ww2 submarine brass. He did several official histories.

I didn't realize that the FIDO was in service at the same time you were , or that it had a S-3 NFO connection.

Maybe you can't track a submarine on batteries, but I know many people who can and have. Crews that I've served on have on many occasions.

Clowns? Nice. You treat your former shipmates as well as people on the forum.

I'd go into more detail , but don't want to 1) go into techniques that may or may not still be classified. 2) want to waste any time as it's only a matter of time before you called me liar again , no matter what I say 3) lose my temper and say something I'd regret and get banned from the forum.

So let me simply say that I totally disagree with you on most everything you've said here. Not surprise, I generally do.


I don't want to get between you two, but I don't discount everything he said. Thinking more about it.

I think he was saying that tracking a sub on batteries--from the air--in WII wasn't happening. No sonobuoys or helos.

But the 24kHz thing does make sense to me on a technology level. Where I have trouble is in the tactics. When a D/E dives three things happen instantly in the ER when the diving alarm goes off. One of (usually) two watchstanders pulls the outboard induction valve shut. He then pulls the inboard induction valve shut. If the diesels are still running they're puling on the people tank air. Very painful, very fast. The second guy therefore stops the diesels as fast as possible. How fast? From the diving alarm fifteen seconds would be pretty good. that gives maneuvering time to get the main motors up and going on the battery so the OOD has way to evade as soon as the hull is under. You don't turn in the initial dive if you can help it. Messes up the angle, and slows you waaaay down. Get under, then change course.

So say it's night. A FIDO equipped patrol plane finds a surfaced U-boat charging batteries. Maybe it's got radar, maybe it's using it sparingly for RDF reasons. Probably by that era the plane has radar too, but maybe it's off for the same detection reasons. The plane starts a run in. How far out does it drop the FIDO? The fish has to drop, activate, stabilize, and listen for diesel injectors that have, at best, about 15-20 seconds of noise, then they're gone. Does the FIDO get one good steer and then become a straight-runner? That might be enough if it's dropped close enough to the sub, but aspect and sub speed are going to drive the contact geometry. If too far out or not broad on the beam the sub can get out of the cone of contact pretty easily and then your expensive FIDO is just a mini-me straight-runner.

But if it does get a hit of injectors, and does a 30-degree steer to compensate for the bad drop aspect given by the plane's hurrying crew, it could increase hit percentage I'd say. Not to what an active homer could do, but better than a gravity bomb dropped in the dark.

BTW, are you accounting for the fact that FIDO was dropped so close to the sub? The closeness might have forgiven a lot of shortcomings in the sensors.


I'm saying it HAD to be dropped close if the only sensor input was diesel injectors. For surfaced subs here. If snorkeling the injectors would probably stay on as the sub had a bad chance of knowing it had been dropped on. Injectors then would be a steady data stream to the FIDO, which could do continuous corrections all the way to contact.

But a diving sub would need to be dropped on very closely. And getting that close without the sub starting the dive would be a nice trick if radar had to be secured else it would give the plane away. That might be some of the source of the 2-pane attack profile Blair speaks of. One plane with radar off angle from the "dark" plane carrying the FIDO.


RADAR might do it. MAD certainly would give you a datum with attack criteria. And if the sub has just dived , a periscope swirl (as it dived) would certainly give you a "flaming datum" which would probably be good enough. Heck , it was good enough for depth charges.


Yeah, but once you have a periscope swirl you haven't had injectors for about 30-40 seconds.


The torpedo 1st began a circular hunting pattern at 15 kts. I don't think too many ww2 subs ran that fast for long on batteries. If it didn't run into the sub, I'd imagine it would pick up some kind of noise. The FIDO is quoting as having a 33% success rate. A sub trying to clear datum would be going fast and turning tight. That should make a fair noise, considering the sub in question has no idea that he's being acoustically hunted. Combine that with MAD , and Sonobouys , both of which entered wide spread service about the same times as FIDO, and maybe 33% is not all that unreasonable.

_____________________________

"Geezerhood is a state of mind, attained by being largely out of yours". AW1Steve

"Quit whining and play the game. Or go home". My 7th grade baseball coach. It applies well to WITP AE players.

(in reply to Bullwinkle58)
Post #: 45
RE: ASW damage from AC - 8/20/2013 2:01:24 AM   
Bullwinkle58


Posts: 8408
Joined: 2/24/2009
Status: online

quote:

ORIGINAL: AW1Steve

The torpedo 1st began a circular hunting pattern at 15 kts. I don't think too many ww2 subs ran that fast for long on batteries. If it didn't run into the sub, I'd imagine it would pick up some kind of noise. The FIDO is quoting as having a 33% success rate. A sub trying to clear datum would be going fast and turning tight. That should make a fair noise, considering the sub in question has no idea that he's being acoustically hunted. Combine that with MAD , and Sonobouys , both of which entered wide spread service about the same times as FIDO, and maybe 33% is not all that unreasonable.


If that was the attack profile it didn't home on 24 kHz diesel injectors, for the reasons I've outlined. They're very temporary unless snorkeling.

In the USN it was normal to dive on surfaced course to at least 150 feet before setting an evasion course. Deeper was better. If there was a layer doctrine was to get below it before changing course. From your first days in subs you are taught "depth is life." (Like speed for airedales.) If you're in trouble you go deep, then try to get away. There's no benefit in letting the attacker watch you turn 70 degrees off the last course he had eyeballs on you.

Against DCs generally they didn't turn tight. The tighter the turn the more speed bleed, plus you make more rudder and plane noise. You go deep, below the layer if possible, rig for DC, rig for silent running, and slowly come to a first evasion course, using the skimmers' convoy pattern last seen if advantageous, plus any geographic or weather factors which help. A squall would be great.

Against a FIDO this would be a bad set of moves, IF the FIDO had sensors which could pick up something a sub does on batteries, every time. I don't know what that frequency would be, which is why injectors makes some sense. But they don't work for the battery evasion phase.

_____________________________

The Moose

(in reply to AW1Steve)
Post #: 46
RE: ASW damage from AC - 8/20/2013 3:04:11 AM   
vettim89


Posts: 3321
Joined: 7/14/2007
From: Toledo, Ohio
Status: offline

quote:

ORIGINAL: witpqs


quote:

ORIGINAL: witpqs

I'm also questioning Sandman's dismissal of "92 lbs HE", which seems to ignore the existence of shaped charges.

Further on this, according to Wikipedia Hedgehog had 30 pounds of TNT or 35 pounds of Torpex. Did Hedgehog sink any subs?

http://en.wikipedia.org/wiki/Hedgehog_(weapon)


Ah yeah, USS England

Hedgehog and its little brother Mousetrap where different animals altogether. The were forward fired as the attacked crept up on the submerged sub firing a large pattern right over the top of it. The projectiles sank rapidly and had a shaped charge warhead. They were basically a bazooka shell that sank. The shaped charge created a super heated jet that punched a hole right through the pressure hull

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(in reply to witpqs)
Post #: 47
RE: ASW damage from AC - 8/20/2013 3:10:16 AM   
witpqs

 

Posts: 14619
Joined: 10/4/2004
From: Argleton
Status: online

quote:

ORIGINAL: vettim89


quote:

ORIGINAL: witpqs


quote:

ORIGINAL: witpqs

I'm also questioning Sandman's dismissal of "92 lbs HE", which seems to ignore the existence of shaped charges.

Further on this, according to Wikipedia Hedgehog had 30 pounds of TNT or 35 pounds of Torpex. Did Hedgehog sink any subs?

http://en.wikipedia.org/wiki/Hedgehog_(weapon)


Ah yeah, USS England

Hedgehog and its little brother Mousetrap where different animals altogether. The were forward fired as the attacked crept up on the submerged sub firing a large pattern right over the top of it. The projectiles sank rapidly and had a shaped charge warhead. They were basically a bazooka shell that sank. The shaped charge created a super heated jet that punched a hole right through the pressure hull

I confess it was a loaded question!

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RE: ASW damage from AC - 8/20/2013 4:17:41 AM   
btbw

 

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Again - Fido designed for atack subs, not ships. It why Fido was targetting submerged subs. For exclude ability for attack surface ships which can be current target of subs (inside order of dozen of merchants ships) or which pursuited sub (KV, DE, DD etc).
Fido homing system have limitation on receiving noise signal from upper area if depth lesser then 40ft. First torpedoes had initial search pattern started on 50ft, but that removed with 150ft! What diesel can run on 150ft, sorry?
With care of own ships (Nazi dont have in Atlantic Surface Taskforces right?) deeper noise homing system solve problem of background noises coming from surface (wakes, wind, bio and own ships).
Diesel-runned subs dont need Fido for kill them. Just bomb or DC. Sub can be easy detected and attacked from plane. But if sub dive deeper - then you need series of attack by DC (or very fast bombing run). Fido solve this problem.

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Post #: 49
RE: ASW damage from AC - 8/20/2013 6:07:52 PM   
Bullwinkle58


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Found this description of the targeting system on the Cutie, which was a modified FIDO made to launch from subs. The description doesn't say so, but everything in it seems to indicate it worked on broadband, not narrowband, data, most probably in the aural range.

" Target detection was accomplished by four hydrophones symmetrically arranged around the circumference of the torpedo mid-section in the left, right, up and down positions. Such an array is useful for target acquisition because the four hydrophones together cover essentially all directions from the torpedo and for homing because "body shadow", meaning that the hydrophone on the right side, for example, being in the acoustic shadow of the torpedo body could not hear a target on the left side, provides directionality. The basic idea is to compare the signals from the left and right hydrophones and move the rudder in such a way as to steer towards the stronger signal. In the BTL implementation of this scheme, the hydrophone signals were amplified, rectified and subtracted. This net signal was combined with the voltage from a potentiometer which was coupled to the rudder. The combined signal drove a DC amplifier which, in turn, controlled a differential relay that caused the rudder motor to move in the appropriate direction to reduce the input voltage (hydrophone derived voltage plus rudder potentiometer voltage) to zero. The vertical control circuit was identical except for including inputs from a hydrostat that measured depth and a pitch pendulum, which were also voltages derived from potentiometers. These signals caused the torpedo to operate at a fixed depth until a sufficiently strong acoustic signal was received. When such a signal was detected, the hydrostat/pendulum control was disabled and acoustic depth control prevailed. As a safety feature, acoustic depth control was disabled and hydrostat/pendulum control re-established if the torpedo dove below a limit set to about 150 feet. These control systems produced rudder angles that were proportional to the difference in strength between the signals from the right and left (or up and down) hydrophones.

It was recounted by J.J. Ott, that it was fun (during operational checks) to make noises from several directions and watch the 'cutie' rudder and elevator wiggle around, trying to acquire the source. As they were an acoustic device, all effort must be made to insure that the submarine is quiet immediately after the launch or (being closer to the sub than the target) the torpedo would acquire the submarine. Since the Bergall failed to remove engine power before firing the first 'Cutie', it was the "loudest" target found when the 'Cutie' was released. The first 'Cutie' used fired by the Bergall against an enemy vessel, almost acquired the Bergall!

The enemy ship had to be "drawn" into close proximity to the submarine in order for the 'Cutie' to acquire the target. On the Bergall this was accomplished by rising to periscope depth, raising the periscope and "wiggling" the scope around, giving the enemy a better chance of seeing the periscope head. At this point the patrol craft would begin a run on the submarine. The Bergall would then drop to about 150 feet depth and wait as the enemy before firing.

The Mk.27 torpedo was based on the Mk.24. The original Mk.27 Mod 0 was a minimally modified Mk.24 with wooden rails to fit 21" torpedo tubes, and various arming, warm-up and starting controls to suit a torpedo tube, swim-out launch mode. Eleven hundred Mk.27 Mod.0 torpedoes, known as CUTIE, were built by Western Electric and delivered between June 1944 and April 1945."

http://www.bergall.org/cutie.html

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RE: ASW damage from AC - 8/24/2013 5:41:25 PM   
sandman455


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Sorry about the long time in replying. Don't get much time. Scanning the forums from my phone is about it and that is hardly conducive to formulating replies. Last Sunday at 4am I was just about to succinctly respond to all of your responses and retorts using the information that I still had in my head from 25 years ago about things worked. And then by chance I went to Uboat.net and started to read some ASW after action reports about the Mk24 FIDO.

With each one read, I had no choice but to conclude that I didn't know what I was talking about. Nothing made any sense.

When active duty, I briefly read something about it and always consider it to be a novelty weapon. Little was available and who cared, there was little point. Long gone from the inventory and any one familiar with modern ASW could figure out how it would work and why it was useless. Consequently, what I was reading in detail accounts of its useage during 1943 and 1944 knocked me completely out of my chair. So much so that Monday morning I start shooting off emails to long lost friends or starting up conversations with those I see daily about the Mk24 Mine and its brother the Mk27 torpedo. How could this thing work? Why the incredibly conflicting data about how it worked and how it was used?

For clarification, here is the breakdown of the contradictions regarding the Mk24/M27 weapons:

The after action reports of the FIDO's found on Uboat.net have the weapon being dropped on a recently submerged boat. The boat was frequently attacked prior to the drop with more conventional DC's and bombs. The boat was also strafed for self preservation of the attacking aircraft. As soon as the sub was no longer visible, aircraft immediately went to the FIDO. My theory about how this thing was homing on the diesel was junk. The diesel on the boat needs air and it can't run while the boat is submerged. My understanding about diesel-electric boats is that the diesel is killed just prior or after to the hatches all secured. That means we have a the Mk24 homing on something else. All sources report that it was the prop or even more specifically the cavitation on the prop. Now that's great and completely retarded.

The prop that was spinning FASTER and making more source strength while the Uboat was running on the surface. The prop was creating more cavitation while it was on the surface. It makes no sense. But wait it's even better. They gave the FIDO to the submarine community, call it the Mk27 CUTIE and told them it is wonderful on surface ships because it will home in on the prop. Ok, the Mk24 can't work on surfaced uboats but change it's name, and all of the sudden the Mk27 works fine on surface boats?!

And no we are not done. the contradictions are still coming. . .


The Mk24 FIDO was R&D during late 1941 through 1942. The weapon was ready for limited fleet introduction in the middle of 1943 and we see that they gave it to the CVE's that were working the mid Atlantic in defense of the convoys. In fact all drops that I stumbled across were from the CVE aircraft. Hmmm . . . that's a pretty limited introduction. Wonder why? Not a biggie just another odd shaped piece to the Mk24 puzzle.

Come 1944-45 the Navy had order a bunch of these things. They opted to dramatically scall back their order because. . . the weapon worked so well. I guess with all the bad guys sunk, they were projecting a surplus. And because all the bad guys were gone from the world the weapon was retired in 1947 about 3 years before the introduction of the Mk32 torpedo which was using the far more viable method of homing called active acoustics. Let's review this; we have an effective weapon retired at the start of the cold war. The Soviets were given a couple of type XXI german subs to play with. All of their initial submarine efforts (just like everyone elses) after WWII were heavily influenced by these captured boats. The Mk24 FIDO should/would have been highly effective against type XXI subs because they had a prop, they liked to dive. So why retire the weapon??

I never expected to find such a mystery. And while everything I had believed fit the puzzle I was forced to conclude that the after action reports clearly had me in the wrong. Hmmm. . .

I started asking around, by Friday, anyone I knew with ASW experience (all ex-navy or active duty, AW2 - O6) was sick of hearing about the FIDO. And all I got back from them was Wikipedia stuff back and yes it doesn't make sense. Thanks guys. When I asked for their best guess on the contradictions, their responses could be lumped into 3 possibilities.

1. They didn't know what they were doing or how their own weapon was working. Very big, all but two supported this with a retired warrant officer acoustic operator (P3/S3 type) being the lead evangelist behind the theory. "You know how effe'd up we were sandman - just imagine what it was during a raging war."

2. The second explanation is mine and I had only one other supporter, a retired O-5 who had S-3 flight time as well as ASWOC command experience. The AAR reports were forged. The contradictions are too great. Evidence supporting this theory would be the very limited delivery aircraft, possibly all restricted to CV ops. Perfect situation to control the data. If you read the reports - they all sound much the same as if written or re-written by the same person(s). Why would they forge the reports - well we both agreed that my initial premise about this being a useless weapon if anyone figured out how it worked is a major factor. Indeed, this is universally accepted by all I asked. The weapon should not work if the diesel is off, if it homes on the diesel. If the weapon homes off the prop, then it will work surfaced or submerged. The Mk27 confirms this. Espionage was as real back in WW2 as it is today. The US and especially the British had their share of enemy or neutral agent infiltrating their networks. To safe guard how this weapon worked, they controlled the utilization and any after action reports. That way the weapon would not be compromised by a infiltrated chain of command. Oh yeah, I admit, I'm on Pluto with this one. It was so bad the O-5 says it is good source material for a book on the weapon.

3. Finally the winning answer was provided by a former P-3 aircrew. I respected this person's opinion since he definitely had a far better understanding of the physical sciences than anyone I know. He's personal library is full of books I would be scared to pick up less I get ideas in my head that I could not reconcile with my own existance. He's also not the kind to speculate, rooting all of his answers with rock solid facts or scientific analysis. Point blank, after being challenged repeatedly to give me some answer to why all the contridictions related to the Mk24/Mk27. . . you know what he said:






"Bigfoot"



"That or the thing was just too slow (12kts) to work against a post war boat or even a XXI. It does work against escorts because they always loved to drop to a crawl when prosecuting a sub to improve their active acoustics. The Mk27 bagged them as they started their ASW prosecution. Besides, prop cavitation makes a broadband noise, it hits everywhere, including at 24 kHz. Given that the sub might be on full ahead to max its dive rate and increase its datum expansion, you should at least have something even minor off the prop. Looks like it worked 20-25% of the time so yeah maybe. It's all you got to make it work. On a surface ship the prop cavitation would only help the normal noise off the diesel which apparently also hits at 24 kHz. Also noteworthy is that the Mk27 torpedo was kept in service for another decade after the M24 because little had changed in their methods. All that said - I'm still going to say with 90% certainty that it is related to the bigfoot conspiracy."

Sounds good to me and thanks for reading.

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AOCS 1985, VT10 1985-86, VT86 1986, VS41 1986-87
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VS27 1990-91 (NATOPS/Safety)
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Post #: 51
RE: ASW damage from AC - 8/24/2013 6:17:13 PM   
Bullwinkle58


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I think you dug up some good info here. Thanks for the effort.

As a sub guy I might think about this stuff a little differently, but not much.

The 12kts is very important, but very aspect dependent. On a closing target it would be fine--see my USS Bergal post. If the attacker is coming down the line-of-sight 12 kts is enough to still hit on a react if the attacker goes broad beam at the last minute. It's also, as your correspondent said, enough if the ASW platform is loitering to re-establish dived datum and maybe see an initial evasion course by the sub. In a stern chase range at drop becomes pretty key. A U-boat might do 7-8 kts on battery for an hour or so at most. But the FIDO couldn't do 12 kts. very long, and if the U-boat turned and gained time that way the 12kts would be a miss.

Cavitation, as you know, is a VERY complex acoustic topic. Cavitation by a surfaced vessel is very different in the physics than cavitation off a prop under sea pressure. The frequency spectrum is just different, and as depth increases most of the sound goes out of aural ranges. But the prop of a diving sub leaving the surface is really no different than the cavitation of a surface ship. Yes, a sub pounced upon by airborne ASW is going to at least a full bell as the angle comes on and MBTs fill. It's class-dependent, but sometimes a flank bell helps and sometimes it could work against developing max speed the fastest possible. Near the surface the prop blades, on their up-stroke, are often less efficient due to wave action and the sound emanating from it is largely a function of the interaction with the water-air interface. As the boat goes deeper that ends and the frequency spectrum stabilizes in a range and alters in absolute level. The one thing which argues for the weapon being designed to home on cavitation is that every sub has a prop and it's always spinning in a dive. Every time. Any other sound profile, from pumps to planes, might be a variable present or missing. The prop is the one fixed element to plan around.

On the issue of the CVEs getting the weapon I could imagine that was a political pull thing, or maybe a training and maintenance support issue. If you put it in one channel in one service it's a lot easier to manage the back end of the program, at least in start-up. Security is easier to manage too for sure; CVE pilots in mid-Atlantic were less likely to run their mouths than LBA ASW crews in the pubs in Britain, Iceland, or Bermuda.

Interesting topic though.

< Message edited by Bullwinkle58 -- 8/24/2013 6:21:57 PM >


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Post #: 52
RE: ASW damage from AC - 8/24/2013 6:50:39 PM   
witpqs

 

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quote:

I think you dug up some good info here. Thanks for the effort.


+1, Sandman.

On the aircraft deployment versus the name-change when deployed to subs: my first thought is that the air-dropped (convoy protection) version might have had a depth cut-out that prevented it going after surfaced vessels??

BTW, out of curiosity I'm still interested in that kill radius for a 15kt nuke. Also forgot to ask in that post, against what hull are those lethal-distance figures for? I'm sure not all submarine hulls are equally tough.

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Post #: 53
RE: ASW damage from AC - 8/24/2013 8:51:16 PM   
Disco Duck

 

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Since Clay Blair was mentioned I looked up his Obit in the N.Y. Times.
http://www.nytimes.com/1998/12/20/us/clay-blair-73-navy-veteran-and-an-expert-on-submarines.html

It does make me question his creditability. When he was editor of the Post the magazine lost a $450,000 libel suit. There are other questionable things in the Obit.

On the few times I have read about the Fido being used it was always against a Submarine that had just dived. It does sound like the design tried to take advantage of the broadband noise created during diving. During an airplane attack I can't see the Submarine going to silent running mode.

If, as other posters have mentioned, Submarines dive first and then turn, then maybe Fido had just enough course correction to increase the odds of a hit.




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Post #: 54
RE: ASW damage from AC - 8/25/2013 3:19:26 PM   
sandman455


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quote:

ORIGINAL: witpqs
BTW, out of curiosity I'm still interested in that kill radius for a 15kt nuke. Also forgot to ask in that post, against what hull are those lethal-distance figures for? I'm sure not all submarine hulls are equally tough.



Hehe - not much and that's all I feel comfortable saying. To get some perspective - a Balao class sub was positioned 2000 yards away at PD when they set off a NDB in 1962. It was shaken but little else. The pressure hull of Balao had a test depth of 400'. For every 33' you go down you increase 1 bar or 14.7PSI. So if a titanium alloy Alpha could easily good handle 2000', maybe even 3000' you are talking about a minimum 48x increase in the capacity of a submarine to handle the stresses associated with underwater exploding ordnance.

As for the little chart - I don't remember. I think it was from a post-WW2 training aid/manual. I remember seeing it in an intro class to modern ASW back in 1986. So if it is post-WW2 stuff than I'd say it was probably for the typical 750t U-boat - a Type VII. For each sub you would have a different chart based on the quality of outer hull and inner pressure hull. I think it is far to say a Japanese or American sub would of had significantly bigger numbers. The significant thing to me when I saw the chart was not the rapidly decreasing effectiveness of more and more HE - but rather the EFFECTIVENESS of very little HE when it detonates directly next to the hull. Hence the reason for the hedgehog working so well when it got a hit. They didn't have shaped charges in them. They merely had contact fuses so if they hit the sub they detonated.

_____________________________

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AOCS 1985, VT10 1985-86, VT86 1986, VS41 1986-87
VS32 1987-90 (NSO/NWTO, deployed w/CV-66, CVN-71)
VS27 1990-91 (NATOPS/Safety)
SFWSLANT 1991-93 (AGM-84 All platforms, S-3 A/B systems)

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Post #: 55
RE: ASW damage from AC - 8/25/2013 8:19:32 PM   
msieving1


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From what I've read, the order to only use the Mk 24 against submerged U-boats was for security purposes, so that the target would not realize the attack was from a homing device. Similarly, proximity fuses were not issued to Army artillery units until late in the war to prevent the enemy from learning about the fuse from duds. The Mk 24 was clearly capable of homing in on surfaced vessels.

The first successful attack with the Mk 24 was by a British Liberator bomber, and the first successful USN attack was from a PBY. So no, they weren't issued only to CVEs.

The Mk 24 was retired in 1948 and replaced by the Mk 34, another passive homer that was in service from 1948 to 1958.


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Post #: 56
RE: ASW damage from AC - 8/26/2013 12:36:08 PM   
Barb


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Interesting debate ... and I would like to add some oppinions:

1) Homing - I would go to find out what sound a propeller of a typical VII or IX class sub would sound on hydrophones. As they were not turning very rapidly (it is not a fan), its noise would be pretty low - in fact type VII-A had about 470 to 485 rpm on diesels and 322 rpm on electrics - that makes 8Hz frequency (8 revolutions per second) for diesel and 5Hz for electric. Even if counting each list of a propeller as contributing to the frequency that makes 15-24Hz frequency noise.

2) 24kHz piezo-eletric hydrophones does not mean, they are listening for 24kHz frequency... But that they are operating on 24.000 cycles per second. Otherwise 24kHz is pretty high frequency noise (human ear on average can hear sound coming at 20Hz to 20kHz) - I doubt anything mechanical on sub could produce 24.000 cycles per second.

3) Mk.24 (FIDO) minimal depth limit - allied ASW surface forces were often dispatched to the vicinity of spotted sub - so to use the torpedo near own forces would be risking a friendly fire - thus they were to remain under the safe depth. And to get the submarine to be successfully attacked by Mk.24 with depth restriction you will have to get the sub under the depth limit - thus the conventional DC attack to get the sub under the water.

4) Mk.27 (CUTIE) had no need for depth limit, as it was not usual to have submarine operating near its own surface forces and its guiding system was able to home on enemy ASW vessels

5) Mk.24 and Mk.27 speed limit was of little concern until revolutionary sub designs (like XXI and XXIII) went into service. Subs usually do not run on flank speed on their limited battery capacity, nor ASW vessels are sailing around fast, because their own noise would preclude the effective use of hydrophones ...

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Post #: 57
RE: ASW damage from AC - 8/26/2013 6:38:01 PM   
Disco Duck

 

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While looking for information on FIDO i ran into this.
http://www.i-52.com

If you click on the tab for the avenger pilots you will see that they were listening to the subs propellers with a sonobouy.

So obviously the hydrophones could pick up sub running on electric.

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Post #: 58
RE: ASW damage from AC - 8/26/2013 11:21:39 PM   
spence

 

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Comparing mid-40's ASW tech to 1980's-1990's or 21st century ASW is like comparing swords to machine guns.

Regardless of all the technical gobbolly-gook the statistics indicate that the Mk24 Fido hurt or killed submarines at about 3 times the rate that depth charges/bombs did. That is a statistically significant difference. Which is also irrelevant since the MK24 is not included in the Allied inventory.

The game system appears to allow only the Japanese to improve ASW technology and/or doctrine over their miserable performance in real life.


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Post #: 59
RE: ASW damage from AC - 8/26/2013 11:41:49 PM   
AW1Steve


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quote:

ORIGINAL: spence

Comparing mid-40's ASW tech to 1980's-1990's or 21st century ASW is like comparing swords to machine guns.

Regardless of all the technical gobbolly-gook the statistics indicate that the Mk24 Fido hurt or killed submarines at about 3 times the rate that depth charges/bombs did. That is a statistically significant difference. Which is also irrelevant since the MK24 is not included in the Allied inventory.

The game system appears to allow only the Japanese to improve ASW technology and/or doctrine over their miserable performance in real life.




How much ASW experience do you have Spence?

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