Dec.7'41: A Day That Nobody Bombed Panama !

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#181

Post by phylo_roadking » 26 Jan 2009, 03:15

Robert - unfortunately I'm about to give you another one...

The "modified" Type 91 torpedo was NOT "shallow running" - it was shallow-LEVELLING. Dropped from an altitude of between 10 and 20 metres, but preferably towards the lower, it entered the water at quite a steep angle of incidence. The wooden attachment at the rear, and two smaller ones attached to the stubyy "anti-roll fins" immediately braked its speed even further, in addition to being dropped from a very low height...and then the wooden attachments(s) broke off. thus, with the torpedo entering the water MUCH slower than normal, instread of the usual 100 feet or so it took to level out and come back UP to its normal running depth, it only took sone 40 feet or so...

it took some time to find the figures, but the running depth of the Type 91 was adjustable between two very specific parameters; it could run as deep as twenty feet below the surface of the water...or as near the top as thirteen feet...

Remember that "thirteen feet" minimum - it's about to become VERY important...

P.S. the Japanese did NOT put a great deal of development into the wooden attachment, Robert. What they DID do was a lot of experimentation to find out the height it had to be dropped at, and the angle of incidence for entering the water at the right speed...for the Japanese copied the changes made to a standard torpedo by the BRITISH for the attack on the RM at Taranto...where the British torpedos had to "shallow level" in the waters of the harbour :wink: It's apparently proven years ago that the Japanese had access to details of the changes made to brake the Swordfish-dropped torps as they entered the water...

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#182

Post by phylo_roadking » 26 Jan 2009, 03:18

The NEXT thing to answer is Redcoat's question from page one of this thread about how strong the gates were; as far as I can see, while they were hardened plate, they certainly weren't face-hardened armourplate like a battleship's plates! and they were a single layer on an "I"-section steel frame, which as we know is hard to damage; it can bend, but hard to break. So we have relatively "soft" plate on a strong frame. See the framework supporting the plate clearly HERE -

Image


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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#183

Post by phylo_roadking » 26 Jan 2009, 03:33

Back to the thirteen feet minimum running depth for the Type 91 torpedo...

In the DRY season, the gates would of course normally have been CLOSED, to maintain the correct water level in Gatun Lake if possible. So...approx. 18 foot gates....and a running depth of 13 feet for the torpedos...

In the DRY season... X marks the spot! Five feet from the bottom of the gate - even FURTHER down the face of the gate if the water level is lower than the top of the CLOSED gates...

Image

Now what will probably happen is that the torpedo will blow a hole in the sheet plate, but it's going to be hard to mangle the "cell" structure behind it you can see in the picture above - I believe the technical terms for such a "deep" supporting framework is a "Stoney Gate", but I'd need to check on that - for it's DESIGNED to hold back millions of tons of water, and just like the dam itself the water is going to absorb a frightening amount of the blast...

But that's in the DRY season - what happens in the RAINY Season...in DECEMBER???
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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#184

Post by phylo_roadking » 26 Jan 2009, 03:47

In the month of December - in the Rainy Season - the gates are going to be OPEN to allow excess water - floodwater from rainfall runoff in the mountains - to be sluiced away into the Chagres river and marshes!

Robert...the agtes are going to be opening UPWARD...I.E. upwards OUT of the water and even further away from the possible point of impact 13 feet below the water line!

Your "best case" scenario is that a torpedo STILL manages to hit a gate if it's only raised a couple of feet, and it nibbles a bit out of the bottom of it -

Image

But if THIS happens - don't forget it IS the Rainy Season!!! - to reduce the impact of the excess water outflow from the damaged gate or gates - ALL THE ARMY HAS TO DO IS CLOSE THE UNDAMAGED GATES 8O 8O 8O

Your plan has the Japanese attacking the dam at the worst time POSSIBLE in the year, when there's TOO MUCH water around!!! A multi-sluice dam is adjustable for flow - and in THIS circumstance the OTHER gates...remember, even at a practical maximum you're only going to manage to damage three or four - and THAT is being VERY optimistic

But I said that is the "best case" scenario - what's the "WORST case" scenario???
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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#185

Post by phylo_roadking » 26 Jan 2009, 03:55

It's THIS....

Image

That the gates are raised SO high due to the water level IN THE MIDDLE OF THE RAINY SEASON that the sentry down below gets the shock of his feckin' life as a mid-air flying torpedo shoots past his pointy nose...having shot through the sluice!!! 8O 8O 8O

Robert - the gates don't even NEED to be that high out of the water for the torpedos to simply run underneath them - there's ONLY a five foot band at the bottom of the gate that's your potential target ANYWAY because of the minimum running depth of the Type 91!!!

The gates ONLY need to be moved up at least five of their eighteen feet for them to be perfectly on target - but miss completely!!!

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#186

Post by robdab » 26 Jan 2009, 03:57

phylo_roadking,

- the important thing is the GATES...as THEY are of course the ONE really vulnerable bit of the construction. - Yes, that is why my ATL scenario proposes attacking them only. Are you really only just now figuring this out ??

Because as Barnes Wallis found out in his extensive testing of his hypothesis on breaking the Ruhr Dams, ANY impact on the concrete would just be absorbed by the water. - I don't believe that to be the case at all. Water is virtually uncompressable so most of an explosive energy release goes up, as seen in a depth charge blast. However, if the energy release happens right beside a target that IS compressible, like a hollow submarine, a hollow surface ship's hull or a thin spillway gate then the blast wave goes in that weaker direct rather than trying to force it's way thru incompressible water. A massive underwater dam face is largely incompressible also due to the huge volume of material piled behind it to resist the water's pressure. However, a large enough bundle of explosive will still move material off the underwater face of that dam. Successive blasts at nearly the same underwater location will remove more and more of the dam's core material until the water pressure itself begins to work to crack the entire dam open.

He worked out conclusively that torpedos would be of NO use at all in attacking a dam of ANY construction, particulary a concrete, almost-vertical- inner face dam - but also an earth-bermed concrete topped dam like the Gatun Dam.... - Yes, most torpedoes don't contain enough explosive to do that job when one considers that their accuracy is not that precise. they cannot deliver enough small blast repeated hits on exactly the same location.

The Barnes Wallis bouncing bombs cracked the German dams because A. they carried a charge much larger than a typical torpedo and B. by using the "Y" shaped aiming devise, lined up with the dam towers, allowed those RAF crews to drop several of the bouncing bombs in almost the same location. A pressure detonator exploded each at the same depth as they sank down very close to the underwater face of the dam.

But this has nothing at all to do with my ATL attack proposal against the spillway gates.

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#187

Post by phylo_roadking » 26 Jan 2009, 04:00

I'm afraid that to stand any chance at all of managing to do any useful damage to the Gatun spillway gates - the Japanese have to start the war in the Pacific a few months earlier - in the DRY Season when the gates are most likely closed!!!

Robert - it's not even something that's predictable! The height of the spillway gates in the RAINY Season is likely to vary on a daily basis depending on tropical stroms and rainfall. There's no way they can know ahead of schedule IN DECEMBER how high the gates are going to be raised; they can't even match it to weather reports if they can get hold of them, for rainfall runoff can take a variable amount of time to hit any low point in the local catchment system.

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#188

Post by phylo_roadking » 26 Jan 2009, 04:12

Because as Barnes Wallis found out in his extensive testing of his hypothesis on breaking the Ruhr Dams, ANY impact on the concrete would just be absorbed by the water. - I don't believe that to be the case at all. Water is virtually uncompressable so most of an explosive energy release goes up, as seen in a depth charge blast. However, if the energy release happens right beside a target that IS compressible, like a hollow submarine, a hollow surface ship's hull or a thin spillway gate then the blast wave goes in that weaker direct rather than trying to force it's way thru incompressible water. A massive underwater dam face is largely incompressible also due to the huge volume of material piled behind it to resist the water's pressure. However, a large enough bundle of explosive will still move material off the underwater face of that dam. Successive blasts at nearly the same underwater location will remove more and more of the dam's core material until the water pressure itself begins to work to crack the entire dam open.
Robert, I really suggest you go and do some research on UPKEEP and CHASTISE - this is EXACTLY the case. Wallis found out through VERY rigorous testing using model dams of ALL sizes...right up to having a full sized section of one constructed in the Penines...that even if torpedos could be got to avoid torpedo nets somehow - they didn't even scratch the dams. This is a matter of recorded fact and scientific experimentation, and you can find COPIOUS material for it if you actually look rather than base an opinion on what you THINK.
Successive blasts at nearly the same underwater location will remove more and more of the dam's core material until the water pressure itself begins to work to crack the entire dam open
No. Wallis discovered that the ONLY way was to drop a device right down the face of the dam wall and use water pressure to HOLD it in place while the hydrostatic pistol detonated it at optimum depth. AND do it several times in EXACTLY the same place, an accuracy you do NOT get from torpedos. He discovered a torpedo simply doesn't behave like that...they're BUOYANT, they hit a target at their running depth, and when they exhaust their fuel they pop UP and float on the surface; historically there are MANY instances of submariners lingering and recovering exhausted torpedos that missed, especially on longer patrols. And they contain NOWHERE near enough explosive. What's the warhead on a 1941 Type 91 - 1,841 lbs of explosive? UPKEEP had to contain 6,600lbs of Torpex - over FIVE times as much...AND had to be ACCURATELY placed and detonated repeatedly within a couple of feet of each other.

Even if by some freak of chance ALL of your attack force's SIX Type 91 torpedos exploded at EXACTLY the same point on the dam, they wouldn't even total the explosive force of TWO UPKEEP devices. And you've still got ALL the problems of their force being dissipated in the water, and at the wrong depth.
- the important thing is the GATES...as THEY are of course the ONE really vulnerable bit of the construction. - Yes, that is why my ATL scenario proposes attacking them only. Are you really only just now figuring this out ??
No - my point is actually how indestructable by torpedos the DAM is...the gates are only vulnerable in the sense that they CAN be damaged to SOME extent IN IDEAL AND VERY LUCKY CIRCUMSTANCES that will NOT usually pertain in a rainy December. They are vulnerable compared to the dam....but still - not very at all.

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#189

Post by robdab » 26 Jan 2009, 05:07

phylo_roadking,

The gates ONLY need to be moved up at least five of their eighteen feet for them to be perfectly on target - but miss completely!!!

You took all that time, all those sketches, all those photographs and all those posts to just repeat what I typed in my 4:33 pm today posting ??

my point #24 there was:

" - an unusually heavy storm at the end of Panama's rainy season has so overfilled Gatun Lake that all 14 spillway gates are lifted wide open to prevent that dam from being overtopped and eroded away. My 3 ATL Mavis can't torpedo spillway gates that are lifted completely clear of the water."

Hey, it's not my fault (or choice) that the OTL Japanese picked Dec.7'41 as their best date to attack Pearl Harbor. The tail end of the rainy season is certainly NOT the absolute best time to hit the Panama Canal but I can only work with the situation that history gave me if i intend to plan my ATL scenario with the fewest possible changes from the OTL.

Your own posted December 2007 photo shows only one spillway gate open. That leaves 13 more as torpedo targets although I will certainly admit that only 7 are practical targets due to the spillway's curved constructed shape.

Yes, the number of gates opened depends on the day to day rainfall by the end of the rainy season but since the rainy season ends in the middle of December each year, roughly a week later than my ATL Canal attack, I'd not expect many gates, if any at all, to be open on a typical December 7th. Granted though that the Japanese could not predict with certainty ahead of time just how many or indeed which spillway gates would be open (if any) on any given day. They would be reliant on their on the ground agents to forward Panama weather forecats in the days before the attack as well as a dawn Dec.7'41 report on which (if any) gates were open. 'Tis the best that they could do in the circumstances.

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Wrt your gate damage analysis, the OTL Japanese at Pearl Harbor dropped 40 torpedoes and hit with 26, or 65%. Since I have 6 torpedoes to work with, I'd still expect 3.9 or rounded up just slightly, 4 spillway gates to be torpedoed.

As for my USS Raleigh damage example, her Japanese torpedo hit at 13.5' below her waterline.

I think that you still do not quite grasp what type of damage that I predict for the spillway gates hit by those torpedoes.

I used the USS Raleigh as an example of a ship hit and indeed, as happened to her, I'd expect a Japanese torpedo to blow a roughly 15" diameter hole at the point of torpedo impact, right thru the gate's steel skin. I'd also expect a majority of that gate skin to suffer shredding and multiple hole punctures similar to what happened to her supported hull plating.

However, the 50' x 30' dent of depth 8' that happened to the USS Raleigh's hull would not happen to the spillway gate because that ENTIRE gate would be blown out of it's mounting tracks and right off of the spillway by such a torpedo blast. Unlike the Raleigh's supported hull plating which was riveted in place, the spillway gates were mounted on axled wheels for easy lifting.

Niether those axled wheels nor the metal track (bolted to the conrete piers on either side of the gate) that they rode in were designed to resist any amount of blast pressure, let alone that delivered by a torpedo hit. The only real question would be whether the wheel axles tore off of the gate first or held until the metal track anchor bolts pulled out of the concrete piers

Stoney type gates, not Storey.
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Wrt your latest 9:12 pm comments about the Barnes-Wallis work, do you actually NOT realize that we are both saying exactly the same thing ? ?

It feels like I'd imagine it to feel when trying to discuss something with a mirror.

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#190

Post by phylo_roadking » 26 Jan 2009, 05:41

" - an unusually heavy storm at the end of Panama's rainy season has so overfilled Gatun Lake that all 14 spillway gates are lifted wide open to prevent that dam from being overtopped and eroded away. My 3 ATL Mavis can't torpedo spillway gates that are lifted completely clear of the water."
However - you DID miss that the gates only need to be lifted by a couple of feet in the rainy season - NOT just "Completely out of the water" for the torpedos to miss them.
Hey, it's not my fault (or choice) that the OTL Japanese picked Dec.7'41 as their best date to attack Pearl Harbor. The tail end of the rainy season is certainly NOT the absolute best time to hit the Panama Canal but I can only work with the situation that history gave me if i intend to plan my ATL scenario with the fewest possible changes from the OTL.
Exactly - ever think why they DIDN'T venture this as you describe it??? :lol: :lol: :lol:
Your own posted December 2007 photo shows only one spillway gate open. That leaves 13 more as torpedo targets although I will certainly admit that only 7 are practical targets due to the spillway's curved constructed shape.
Slight problem; NOWADAYS - i.e. since complete two-way traffic became possible - the call on water from Gatun Lake has gone UP some 45% per day. So nowadays even at the height of the rainy season - the lake is being kept at it's MAXIMUM level permanently....I.E. DOUBLE the rate of even the theoretical maximum in December 1941 after the Army mandated ONE WAY TRAFFIC ONLY to allow full security checking etc. :wink:
I'd not expect many gates, if any at all, to be open on a typical December 7th.
See my comments above about far more gates being kept open previously compared with today AND not even having to be fully open, just raised five feet or so for a torpedo to miss.
I used the USS Raleigh as an example of a ship hit and indeed, as happened to her, I'd expect a Japanese torpedo to blow a roughly 15" diameter hole at the point of torpedo impact, right thru the gate's steel skin. I'd also expect a majority of that gate skin to suffer shredding and multiple hole punctures similar to what happened to her supported hull plating.

However, the 50' x 30' dent of depth 8' that happened to the USS Raleigh's hull would not happen to the spillway gate because that ENTIRE gate would be blown out of it's mounting tracks and right off of the spillway by such a torpedo blast. Unlike the Raleigh's supported hull plating which was riveted in place, the spillway gates were mounted on axled wheels for easy lifting.
First of all - to cope with stress, Stoney Gates aren't STEEL faced, they're wrought iron. So at the point of explosion there will be a "burn-through" leeching away a certain perccentage of the force of the explosion, and far more easily than burning through the face-hardened steel armourplate of a battleship...so there won't be as much force to transmit through the gate to the concrete supports.

As for the supports themselves - exactly WHY do you propose a gate will be ripped out of its runners? Do you know what a Stoney gate DOES? As designed by F.G.M. Stoney, their strength is IN the supports, and the depth the gates are recessed into them. A bit like chainmail, Stoney gates are designed to radiate the pressure of millions of tons of water out to every inch of the edges of the gates in their slide tracks and side guides...and to radiate in turn out to the reinforced slot lining. They are in other words DESIGNED to take EXACTLY the pressure you expect a torpedo to apply to them, that's how they're MEANT to work! Don't forget a gate even PARTLY raised will have LESS pressure on it anyway, and be able to shrug off a torpedo hit BECAUSE it's possibly been raised out of the water and a part of what SHOULD be bearing on it is passing underneath!!!
Unlike the Raleigh's supported hull plating which was riveted in place, the spillway gates were mounted on axled wheels for easy lifting.

Niether those axled wheels nor the metal track (bolted to the conrete piers on either side of the gate) that they rode in were designed to resist any amount of blast pressure, let alone that delivered by a torpedo hit.
THAT may be how they were moved - but as you can see from above, and I'm sure any local library will let you check out the civil engineering side of Stoney Gates - they dealt with the pressure on them in the way descirbed. ALL you're doing is momentarily applying EITHER an extra pressure - a couple of thousand pounds per inch at most in ONE location - or possibly the SAME pressure if the pressure as ALREADY been relieved by raising the gate at all!
do you actually NOT realize that we are both saying exactly the same thing ? ?
No we're not - The UPKEEP device was FIVE times the size of any of your torpedos, and were designed and delivered in such a way as to deliver their efect in exactly the same place WITHIN A COUPLE OF FEET - which your bombers cannot do; EVEN THEORETICALLY...the maybe twenty feet between torpedo runs from the PORT side of a Mavis and the STARBOARD side of a Mavis is enough for their explosive force to render upon the structure ahead of them separately - if not actually on completely different gates!!! :wink:

Also - torpedos at Pearl didn't run exactly true; the effect of the water-brake on hitting the water was recognised to throw them off-track; The USS Raleigh was 555 feet long....and STILL one of the TWO torpedos fired at her missed! And the Gatun spillway gates are what...45 feet wide? :wink: :wink: :wink: Your attack force is NOT going to be able to hit exactly the SAME point on the SAME target twice 8O Not with all the variables affecting the torpedos' tracking.

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#191

Post by phylo_roadking » 26 Jan 2009, 05:43

By the way - Robert, there's ONE more really major factor you've forgotten regarding the torpedos and aiming them... :wink: I'll let you work it out while I have a night's sleep...

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#192

Post by robdab » 26 Jan 2009, 08:01

phylo_roadking,

However - you DID miss that the gates only need to be lifted by a couple of feet in the rainy season - NOT just "Completely out of the water" for the torpedos to miss them. - So ? Neither did I mention the shoe size of the lead Mavis pilot. Such micro-detail is not required for the purposes of this ATL discussion.

Exactly - ever think why they DIDN'T venture this as you describe it ??? - This thread is posted in the "What IF" section, not in the "Why Didn't They" folder.

Slight problem; NOWADAYS - i.e. since complete two-way traffic became possible - the call on water from Gatun Lake has gone UP some 45% per day. So nowadays even at the height of the rainy season - the lake is being kept at it's MAXIMUM level permanently....I.E. DOUBLE the rate of even the theoretical maximum in December 1941 after the Army mandated ONE WAY TRAFFIC ONLY to allow full security checking etc. :wink: - Have I not read of transit reductions in recent years due to rainfall shortages in Panama resulting from El Ninio (or was it La Ninia ?) effects ?

See my comments above about far more gates being kept open previously compared with today AND not even having to be fully open, just raised five feet or so for a torpedo to miss. - AFAIK all of the open spillway photos that I have seen show that one spillway is always opened fully before the next is opened.

First of all - to cope with stress, Stoney Gates aren't STEEL faced, they're wrought iron. So at the point of explosion there will be a "burn-through" leeching away a certain perccentage of the force of the explosion, and far more easily than burning through the face-hardened steel armourplate of a battleship...so there won't be as much force to transmit through the gate to the concrete supports. - Just as happened with the USS Raleigh's torpedo damage, as I have listed several times now. A 15" diameter hole at the point of impact, with shredded hull plating over 35' x 25 ' with still enough blast energy left over to dent in her hull by 8' over 50' x 30'. it is the energy devoted to that 8' deep denting process that will be going towards ripping any torpedoed gate right off of the spillway.

As for the supports themselves - exactly WHY do you propose a gate will be ripped out of its runners? Do you know what a Stoney gate DOES? As designed by F.G.M. Stoney, their strength is IN the supports, and the depth the gates are recessed into them. A bit like chainmail, Stoney gates are designed to radiate the pressure of millions of tons of water out to every inch of the edges of the gates in their slide tracks and side guides...and to radiate in turn out to the reinforced slot lining. They are in other words DESIGNED to take EXACTLY the pressure you expect a torpedo to apply to them, that's how they're MEANT to work! Don't forget a gate even PARTLY raised will have LESS pressure on it anyway, and be able to shrug off a torpedo hit BECAUSE it's possibly been raised out of the water and a part of what SHOULD be bearing on it is passing underneath!!!

Please then explain the partial gate failure pictured at http://www.pbs.org/wgbh/buildingbig/won ... 2_dam.html that occured without the benefit of any torpedo hit ?

THAT may be how they were moved - but as you can see from above, and I'm sure any local library will let you check out the civil engineering side of Stoney Gates - they dealt with the pressure on them in the way descirbed. ALL you're doing is momentarily applying EITHER an extra pressure - a couple of thousand pounds per inch at most in ONE location - or possibly the SAME pressure if the pressure as ALREADY been relieved by raising the gate at all! - I am a civil engineer by training, with nearly 30 years of heavy construction field work experience. I have both installed and repaired/replaced Stoney type gates in Thailand and the Southwestern United States. I can assure you that your viewpoints are not correct on the subject.
do you actually NOT realize that we are both saying exactly the same thing ? ?
No we're not - The UPKEEP device was FIVE times the size of any of your torpedos, and were designed and delivered in such a way as to deliver their efect in exactly the same place WITHIN A COUPLE OF FEET - which your bombers cannot do; EVEN THEORETICALLY...the maybe twenty feet between torpedo runs from the PORT side of a Mavis and the STARBOARD side of a Mavis is enough for their explosive force to render upon the structure ahead of them separately - if not actually on completely different gates!!! - I have never even suggested that my ATL attack would be directed against any part of the Gatun Dam, save it's spillway gates, with torpedoes.

Where did you get the idea that I would even consider a torpedo attack against the body of that dam itself ??? Such would be an utter waste of 6 good torpedoes.

Your attack force is NOT going to be able to hit exactly the SAME point on the SAME target twice Not with all the variables affecting the torpedos' tracking. - And never have I suggested that my ATL Canal attackers would even try to do so. In fact they would be aiming their 6 torpedoes at 6 different spillway gates in an effort to breach as many of them as possible.

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#193

Post by Sid Guttridge » 26 Jan 2009, 12:06

Hi Alaric,

Anyone wanting to follow up the tale about supposed post-war U-boat landings in Argentina is welcome to go to that thread. There is clearly no substantive evidence for this proposition but I would encourage anyone interested to draw their own conclusions from the evidence presented by all parties there. This is not the place.

On a point of information - I never thought that there were any airbases on the Galapagos. Please check. It was one of Robdab's Japanese intelligence links that suggested this. You should be taking this up with him, not me.

Cheers,

Sid.

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#194

Post by Sid Guttridge » 26 Jan 2009, 12:31

Hi Robdab,

Whether assailed by "shotgun" or "sniper", I would suggest your proposition is still showing rather too many holes to remain reliably airborne!

Is there something wrong with asking questions? I thought you wanted your proposition tested. You can't put it up in a public forum such as this asking for "Your thoughts and constructive criticisms", and then cry "foul" when that is precisely what you get!

If you have any specific questions about my sources, please ask. In return, I would ask you to go a little further than internet links and generalised references to NARA. Thus far you haven't actually offered any microfilm numbers or publication details that can be tracked down to hard copy purely from the information you give. If you want to demand a certain standard of evidence, would you not be best advised to practice it yourself?

Burden's book was published under US foreign affairs auspices during the war. On matters of commercial trivia, such as which US airline, or which US aircraft carrying what livery was on which route, there is no reason to question his work as such information was publicly available, but with regard to Axis airlines in Latin America one must be more cautious, as the US had an active contemporary campaign to eradicate them. Would you rather I kept this information from you?

Cheers,

Sid.

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Re: Dec.7'41: A Day That Nobody Bombed Panama !

#195

Post by phylo_roadking » 26 Jan 2009, 16:10

However - you DID miss that the gates only need to be lifted by a couple of feet in the rainy season - NOT just "Completely out of the water" for the torpedos to miss them. - So ? Neither did I mention the shoe size of the lead Mavis pilot. Such micro-detail is not required for the purposes of this ATL discussion
The fact that a torpedo would most likely MISS the target its aimed at for a raft of reasons, or do a diminishing amount of damage the more the gate is open even if hit - is hardly "micro-detail" - it's an incredible LACK of detail in the initial planning and scoping.
Slight problem; NOWADAYS - i.e. since complete two-way traffic became possible - the call on water from Gatun Lake has gone UP some 45% per day. So nowadays even at the height of the rainy season - the lake is being kept at it's MAXIMUM level permanently....I.E. DOUBLE the rate of even the theoretical maximum in December 1941 after the Army mandated ONE WAY TRAFFIC ONLY to allow full security checking etc. :wink: - Have I not read of transit reductions in recent years due to rainfall shortages in Panama resulting from El Ninio (or was it La Ninia ?) effects ?
I'm sure you have - *I* however would prefer to go with the future plans for expansion of the water supply made necessary by increased traffic...at least as said by the present administration of the Canal on their various business plans that can be found on the Net; being a civil engineer I'm suprised you've not found these.

P.S. 2007 was actually a record WET year in Panama throughout the year :wink:
First of all - to cope with stress, Stoney Gates aren't STEEL faced, they're wrought iron. So at the point of explosion there will be a "burn-through" leeching away a certain perccentage of the force of the explosion, and far more easily than burning through the face-hardened steel armourplate of a battleship...so there won't be as much force to transmit through the gate to the concrete supports. - Just as happened with the USS Raleigh's torpedo damage, as I have listed several times now. A 15" diameter hole at the point of impact, with shredded hull plating over 35' x 25 ' with still enough blast energy left over to dent in her hull by 8' over 50' x 30'. it is the energy devoted to that 8' deep denting process that will be going towards ripping any torpedoed gate right off of the spillway
While I've never seen the word "shredded" used in conjunction with face-hardened steel armourplate, it's notable that armourplate is more...is "friable" the correct word, perhaps...than hammer-forged wrought iron. The Raleigh suffered this damage with the plates in question being attached on all four sides i.e held rigid against itself - a Stoney Gate as YOU know depends on radiating energy away INTO the supporting structure.
See my comments above about far more gates being kept open previously compared with today AND not even having to be fully open, just raised five feet or so for a torpedo to miss. - AFAIK all of the open spillway photos that I have seen show that one spillway is always opened fully before the next is opened
Which will of course be an argument ONCE you have found out what the procedure was in 1941 with a lower water requirement than present, and you've found out details about the rainfall figures and water height in December 1941.
As for the supports themselves - exactly WHY do you propose a gate will be ripped out of its runners? Do you know what a Stoney gate DOES? As designed by F.G.M. Stoney, their strength is IN the supports, and the depth the gates are recessed into them. A bit like chainmail, Stoney gates are designed to radiate the pressure of millions of tons of water out to every inch of the edges of the gates in their slide tracks and side guides...and to radiate in turn out to the reinforced slot lining. They are in other words DESIGNED to take EXACTLY the pressure you expect a torpedo to apply to them, that's how they're MEANT to work! Don't forget a gate even PARTLY raised will have LESS pressure on it anyway, and be able to shrug off a torpedo hit BECAUSE it's possibly been raised out of the water and a part of what SHOULD be bearing on it is passing underneath!!!

Please then explain the partial gate failure pictured at http://www.pbs.org/wgbh/buildingbig/won ... 2_dam.html that occured without the benefit of any torpedo hit ?
Please explain why YOU have chosen to attempt to illustrate your point about vertical Stoney Gates with a picture of what appears to be a pivotting radial Tainter gate? :lol: :lol: :lol:
On the morning of July 17, 1995, spillway tainter (radial) gate No.3 failed at Folsom Dam, California. It was one of five service gates which had been operated by the Bureau of Reclamation since 1956. There was no warning of structural distress prior to the failure. No one was injured, even though there was a sustained release of 1,132 m3/s into the Lower American River. A multi-disciplinary, multi-agency forensic team was formed to investigate the failure. All of the remaining gates were thoroughly inspected for signs of structural degradation, apart from some corrosion, nothing detrimental was found. The failed gate was removed and then thoroughly examined to determine the mode of failure. This examination determined that a diagonal brace joint, adjacent to the trunnion was the initial point of failure. Theoretical finite element models substantiated this study when a trunnion friction coefficient of 0.25 was considered. This value had been confirmed also from friction tests performed on the actual trunnion from the failed gate. Trunnion friction moment was the key factor, and it had been omitted in the original design calculations
Bureau of Reclamation, Denver Technical Service Center.

In other words - the PIVOTTING gate broke near the PIVOT due to the stresses of PIVOTTING...

I hardly think that bad example applies here...
THAT may be how they were moved - but as you can see from above, and I'm sure any local library will let you check out the civil engineering side of Stoney Gates - they dealt with the pressure on them in the way descirbed. ALL you're doing is momentarily applying EITHER an extra pressure - a couple of thousand pounds per inch at most in ONE location - or possibly the SAME pressure if the pressure as ALREADY been relieved by raising the gate at all! - I am a civil engineer by training, with nearly 30 years of heavy construction field work experience. I have both installed and repaired/replaced Stoney type gates in Thailand and the Southwestern United States. I can assure you that your viewpoints are not correct on the subject.
I'll have to give you you years of experience - whereas MY information merely comes from Design of Hydraulic Gates by Paulo C. F. Erbisti...based on the author's 35 years of experience as an engineer on hydromechanical projects - seeing as we're NOW reduced to playing Top Trumps as your argument collapses.
The UPKEEP device was FIVE times the size of any of your torpedos, and were designed and delivered in such a way as to deliver their efect in exactly the same place WITHIN A COUPLE OF FEET - which your bombers cannot do; EVEN THEORETICALLY...the maybe twenty feet between torpedo runs from the PORT side of a Mavis and the STARBOARD side of a Mavis is enough for their explosive force to render upon the structure ahead of them separately - if not actually on completely different gates!!! - I have never even suggested that my ATL attack would be directed against any part of the Gatun Dam, save it's spillway gates, with torpedoes.
Did I SAY that the attackers would INTENTIONALLY target the Dam??? I was merely reacting to your

"However, a large enough bundle of explosive will still move material off the underwater face of that dam. Successive blasts at nearly the same underwater location will remove more and more of the dam's core material until the water pressure itself begins to work to crack the entire dam open"

...to illustrate the exactitude and application of force actually required to "remove more and more of the dam's core material"... :wink:
Your attack force is NOT going to be able to hit exactly the SAME point on the SAME target twice Not with all the variables affecting the torpedos' tracking. - And never have I suggested that my ATL Canal attackers would even try to do so. In fact they would be aiming their 6 torpedoes at 6 different spillway gates in an effort to breach as many of them as possible
After X number of hours then, you STILL haven't worked out the remaining major factor impinging on accurate targeting of anything on the spillway gates during the Rainy Season??? 8O 8O 8O
Last edited by phylo_roadking on 26 Jan 2009, 18:07, edited 3 times in total.

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