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

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

#196

Post by robdab » 26 Jan 2009, 17:30

Sid Guttridge,

Whether assailed by "shotgun" or "sniper", I would suggest your proposition is still showing rather too many holes to remain reliably airborne! - Had you been engaged in a Dec.5'41 discussion wrt a Japanese attack on Pearl Harbor then I think it likely that you would be providing similar suggestions.

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! - Sid, I am not crying "foul" or "fowl" either. I'm just expressing disappointment in your debating style and praise for Simon K's approach, as painful as that has been to my ATL scenario.

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? - I would make the exact same comment back to you. I have provided many sources for the points that I make, while you rarely do so, in any form. As I have stated here previously, I prefer to use internet sources (with their admitted inaccuracies) that my other readers can quickly check, both for their ease of effort, and my own. Yes, I can trudge down to my local refernce library to consult many of the tomes that I do not yet own but that takes much time and I have a life outside of this discussion to maintain. As do my other readers here.

As you point out, even hard copy such as the Latin American airlines book that you own, has it's own bias. By your own logic, should we not discount every book or data source published in the US between 1941 and 1945 because they were at war with Japan and such data might only be propaganda. Unless you want to use it in support of your own point, that is. Then any such data would be "as good as gold", I'm sure.

This discussion was never intended to be the defense of a thesis nor a book's pre-publication exercise. If you wish a scholarly debate with footnotes and annotation then I'd suggest that you first begin to live up to the standard that you request from me. So far you have not even matched my internet source standard that you now complain about.

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? - Whatever you say Sid. Whatever you say.

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

#197

Post by robdab » 26 Jan 2009, 18:53

phylo_roadking, your ability to function well on little sleep is hereby noted.

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. - You have included a couple of photos in your posts here that demonstrate an open gate would be clearly visible to an approaching "China Clipper" pilot even if he had not been "pre-warned" by a ground agent report already or in fact via a spillway "flyby" if the American defenders appeared to still be "asleep at the wheel". An open gate would not be attacked with a torpedo at all.

Certainly there existed a % chance that ALL 14 of the spillway gates might have been open on Dec.7'41. Just as the OTL Japanese knew that there was a good chance that the American aircraft carriers might NOT be at Pearl Harbor when the KB's warplanes arrived. In fact Yoshikawa, their agent in Honolulu had sent a Dec.6'41 report confirming that the carrieres were NOT there. Yet the Japanese attack on PH went in any way. To great tactical, if not strategic, success.

My ATL Panama attackers would take off at around dawn on Dec.7'41 (Panama time) from the Galapagos and head towards Gatun Lake. Should a Japanese ground agent near Gatun Dam report sometime over the next 5 hours of flight time, that they had no viable closed spillway gate targets, then they would have to make a decision. Whether to turn back to the Galapagos or to turn towards Galveston, Texas in search of Allied warship or oil tanker targets in the Caribbean or Golf of Mexico.

Certainly, if informed before Dec.6'41 that many of the spillway gates were already open and that heavy rain was forecast, an early choice of attacking the Galveston (or other target) area with bombs instead might have been made.

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.

I haven't looked. How would my 1941 ATL Japanese have known about modern day Panama Canal expansion plans ?

P.S. 2007 was actually a record WET year in Panama throughout the year - And yet your December 2007 photo shows only one spillway gate open. Does this not suggest that in the drier non-record wet years before 2007 no gates at all might have been open on a typical December day ? Once again though, my ATL Japanese would have no way to know was to happen wrt Panama's rainfall during the months of planning leading up to my ATL attack on the Canal. They would just have to go, under a good cover story, with alternate (US morale bending) targets in mind, in the hopes that their agents on the ground in Panama would confirm at nearly the last minute that there were viable targets.

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... - Was the USS Raleigh's hull, in the area of her torpedo hit, made from face-hardened steel armorplate ?

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. - I'd think not relavent as my ATL Japanese would most likey have to rely on direct visual reports from their agents on the ground in Panama rather than on the scientific analysis of rainfall data collected from all over the Gatun Lake watershed. Not enough time.

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 Stoney Gates with a picture of what appeares to be a pivotting Folsom Gate? - That is an easy question to answer. Because I only saw the photo which I listed as a source. Had I proceeded on to also find http://www.osakac.ac.jp/labs/ishii/Fina ... apter1.pdf as I did today, it would have been possible to recognize the Folsom Dam as having radial Tainter type gates installed instead of the Stoney type. My bad.

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. - I don't think that my argument has yet collapsed. What is obvious is that only an expert in the field of torpedo caused damages, with full access to the design details and material strengths of those Gatun spillway gates, is going to be able to answer the question of whether or not a Japanese torpedo of the type used at Pearl Harbor is going to be reliably able to take down those gates with a single hit. I believe YES, based on the demonstrated damage to the USS Raleigh. You seem to believe NO, based on I don't know what ? And there sits the point, so far.


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

#198

Post by phylo_roadking » 26 Jan 2009, 19:37

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. - You have included a couple of photos in your posts here that demonstrate an open gate would be clearly visible to an approaching "China Clipper" pilot even if he had not been "pre-warned" by a ground agent report already or in fact via a spillway "flyby" if the American defenders appeared to still be "asleep at the wheel". An open gate would not be attacked with a torpedo at all.

Certainly there existed a % chance that ALL 14 of the spillway gates might have been open on Dec.7'41. Just as the OTL Japanese knew that there was a good chance that the American aircraft carriers might NOT be at Pearl Harbor when the KB's warplanes arrived. In fact Yoshikawa, their agent in Honolulu had sent a Dec.6'41 report confirming that the carrieres were NOT there. Yet the Japanese attack on PH went in any way. To great tactical, if not strategic, success.
WOULD it be visible??? :wink: I've shown ONE (1) pic of it silhouetted against a clear summer's sky looking UP at it from the spillway side, and one of it from wter level at a few hundred yards' out on Gatun Lake. NEITHER of these viewpoints will be visible to a pilot. The ONLY indicator a PILOT will have of the gates being opened is visual confirmation of the water outflow sparying out of the gates...which needs to be observed from either above or the spillway side - which means an attacking pilot would need to CIRCLE his objective before making a decision or getting into position for a bombing run!!! 8O Multiplying the time the garrison's AA has to react/muster, and for USAAF fighters to fnd him. Flying a circle like that and back into position for a torpedo run will take several minutes...

As for agents on the ground - I've let that go unchallenged until now. You haven't actually yet managed to find out ANYTHING about any Asiatic/Japanese community IN the Canal Zone, have you??? AND in the numbers they were present on Oahu to hide/shelter enemy agents....let alone a cuommunity with the free run of a military reservation, where there were ALREADY heavy security measures in place to stop "enemy agents" sneaking into the Canal Zone or Canal on board ships or in unidentified aircraft....
My ATL Panama attackers would take off at around dawn on Dec.7'41 (Panama time) from the Galapagos and head towards Gatun Lake. Should a Japanese ground agent near Gatun Dam report sometime over the next 5 hours of flight time, that they had no viable closed spillway gate targets, then they would have to make a decision. Whether to turn back to the Galapagos or to turn towards Galveston, Texas in search of Allied warship or oil tanker targets in the Caribbean or Golf of Mexico
So which is it to be??? NO SEDTA or Panagra in the Galapagos....OR commercial carriers using flying boats, who will be reporting unidentified traffic in the air and on the surface in the Galapagos, and unidentified shipping??? Once again, this is the sort of things commercial carriers were by the 1940's obliged to report - from the aspect of safety hazards for their scheduled traffic, let alone security issues.

Which way round do you want the Galapagos situation in THIS post??? 8O :lol:
Certainly, if informed before Dec.6'41 that many of the spillway gates were already open and that heavy rain was forecast,
So you're BACK now to NOT wanting heavy tropical storms and their associated cloud banks, as opposed to WANTING them for the purposes of concealment??? 8O :lol:
P.S. 2007 was actually a record WET year in Panama throughout the year - And yet your December 2007 photo shows only one spillway gate open. Does this not suggest that in the drier non-record wet years before 2007 no gates at all might have been open on a typical December day ?
No - it should that NOWADAYS as stated, the administration wants Gatun Lake kept at its MAXIMUM level concomitant with no local flooding or coastal erosion, to provide the water needed for increased traffic.
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 Stoney Gates with a picture of what appeares to be a pivotting Folsom Gate? - That is an easy question to answer. Because I only saw the photo which I listed as a source. Had I proceeded on to also find http://www.osakac.ac.jp/labs/ishii/Fina ... apter1.pdf as I did today, it would have been possible to recognize the Folsom Dam as having radial Tainter type gates installed instead of the Stoney type. My bad.
(I suggest you check out my edited answer; don't worry, I provided readers with a brief precis of the reasons for the collapse of the tainter gate on the Folsom Dam in 1995, coutresy of the Texas Dept. Of Reclamation)

Robert, I certainly wasn't accusing you of using a completely inappropriate example to make your point, don't worry...though I do of course have several reservations why a trained and experienced civil engineer didn't see that it was a Tainter Gate, and an amateur could; maybe it was the curved surface??? Maybe it was the lack of the cell-type support frame? Maybe it was the large actuating chain hanging spuriously in the picture? Maybe it was the trunnion of the UNdamaged gate to the left of it in frame that was the dead giveaway... 8O
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. - I don't think that my argument has yet collapsed. What is obvious is that only an expert in the field of torpedo caused damages, with full access to the design details and material strengths of those Gatun spillway gates, is going to be able to answer the question of whether or not a Japanese torpedo of the type used at Pearl Harbor is going to be reliably able to take down those gates with a single hit. I believe YES, based on the demonstrated damage to the USS Raleigh. You seem to believe NO, based on I don't know what ? And there sits the point, so far.
Given that a Stoney Gate relies on the heavy pressure applied to its water-facing side pressing in INTO its sills and then radiating out into the dam structure to seal it???
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... - Was the USS Raleigh's hull, in the area of her torpedo hit, made from face-hardened steel armorplate ?
I'm not sure if the Raleigh had any torpedo belt or not; but being an Omaha-class light cruiser I'd doubt it. However her hull was indeed constructed of 38lb HTS, as opposed to mild steel (used for her bulkheads, internal decking, framework etc.) or the Gatun Dam's hammer-wrought iron plating.

I presume you've actually read Capt. Simons' damage report for his vessel of January 14th, 1942?

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

#199

Post by robdab » 26 Jan 2009, 21:29

Ooops, wrong war ... for Panama 1941

It seems that I've been searching the wrong time period for an example of torpedoes destroying dam spillway gates.

May 1951 at the Hwachon Reservoir in Korea is what I was missing. By no means is it an exact match for my ATL Canal attack but it is close enough to still be interesting, I think anyway.

It seems that 8 American Skyraider aircraft, with Corsirs flying cover, dropped 8 Mk13 WW2 vintage torpedoes on the Hwachon Dam's 18 spillway gates. Five pilots out of the eight had NEVER DROPPED A TORPEDO BEFORE and the other three had dropped only one each, some two years previous.

The Korean War had been ongoing for some time and the Dam had been attacked with bombs, to no effect, on the day before so it's defenders were hardly in the "surprised" category that peacetime Panama would have been in on Dec.7'41.

It seems that out of 8 drops, one gate was totally destroyed and another had a 10' diameter hole blown through it. Two torpedoes were seen to veer wildly off target and a third hit an abutment but the remainder appeared to hit their target gates according to the pilots. Not bad at all for untrained pilots, attacking under AA fire, I'd say.

The photo at http://good-times.webshots.com/photo/10 ... dwipmGenDm is too distant to be sure but seems to show a spillway gate type similar to that installed at Gatun Dam, although in a straight bank rather than curved. I am only speculating but the photo shows 5 gates to be missing which might imply the real damage inflicted was greater than just 1 gate destroyed and 1 gate holed. The pilots did claim 5 torpedo gate hits. A coincidence ... ?

Additionally, and somewhat amazingly, there is video footage of the real attack available at cost from http://www.militaryvideo.com/store/stor ... &do=detail

Will wonders never cease ?

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

#200

Post by Borys » 26 Jan 2009, 21:56

Ahoj!
I do not believe ANY armour can stop the effects of a torpedo explosion. An armoured torpedo bulkhead is INSIDE the hull, the futher away from the side, the better.
An armoured hull would make the effects of a torpedo hit even WORSE - there will be chunks of tough steel flying about, making holes in unarmoured bulkheads.
The Omaha class was lightly built, as it was a scout - a "see and scoot" type of ship. It was not a "real cruiser" which was suppose to slug it out with anything larger than a destroyer.

Some learned stuff on the subject:
http://www.navweaps.com/index_tech/tech-026.htm
and
http://www.navweaps.com/index_tech/tech-047.htm


Borys

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

#201

Post by phylo_roadking » 26 Jan 2009, 22:20

Yes, you're right, wonders will never cease...so, in no particular order...
The photo at http://good-times.webshots.com/photo/10 ... dwipmGenDm is too distant to be sure but seems to show a spillway gate type similar to that installed at Gatun Dam, although in a straight bank rather than curved. I am only speculating but the photo shows 5 gates to be missing which might imply the real damage inflicted was greater than just 1 gate destroyed and 1 gate holed. The pilots did claim 5 torpedo gate hits. A coincidence ... ?
Yes, a coincidence - because you seem VERY poor at doing the detail work your case REALLY needs, Robert. If you looked closer you'd see that pic shows FROZEN SPILL, confirmed HERE in a second pic from that album - http://good-times.webshots.com/photo/10 ... uLNynrddFf - See the icicles hanging from one of the support towers at the top of the pic???

So if that attack took place in MAY - your pic can only be from MONTHS later, 6 or 7 at least. Absolutely ANYTHING can have happened, ANY number of gates can have been raised or closed in ANY order and for ANY reason in the months in between!!! Or even gates removed fully for temporary repairs to be made while the dam was frozen!!! You see - without details you're making unsafe assumptions because you WANT the mising facts to agree with you.

Robert, speculation is the mistake you're consistently making. You'd do a LOT better looking at the details you yourself turn up....

One OBVIOUS thing here, for instance is that you've decided these ARE Stoney gates without verifying ANY facet of their construction or knowing anything else about them :lol: I for instance, the amateur here and not the civil engineer, can see ONE telltale indicator that they don't function in the same way as Stoney gates or the Gatun Dam gates....
It seems that 8 American Skyraider aircraft, with Corsirs flying cover, dropped 8 Mk13 WW2 vintage torpedoes on the Hwachon Dam's 18 spillway gates.
So because Skyraiders - dedicated precision groundattack aircraft - can do this, lumbering Mavis flying boats can drop torpedos with the SAME degree of accuracy??? 8O

And I'd suggest you look VERY closely at the history of the development of the Mk13 - they're in a completely different league for accuracy compared to the Type 91. I'll give you ONE hint, shall I?......

As we know, the "modified" Type 91 needs to be dropped from a heigh of 10 to 20 metres, with a minimum run of 650 feet to arm the warhead - thus necessitating Your attacking H6Ks manouvering through and UNDER the anti-aircraft cables we know about. On the OTHER hand...by the end of WWII, the Mk13 could be dropped accurately from heights of from 1,500 to 2,100 metres! 8O

Slight difference...in both mission profile and accuracy! :lol:
Two torpedoes were seen to veer wildly off target
Have you found out why?
The Korean War had been ongoing for some time and the Dam had been attacked with bombs, to no effect, on the day before so it's defenders were hardly in the "surprised" category that peacetime Panama would have been in on Dec.7'41.
Really? You actually haven't found out any more details on the raid, have you??? :wink:
The pilots did claim 5 torpedo gate hits. A coincidence ... ?
No, just inaccurate i.e. wrong. Your account differs entirely from the account provided for posterity by the squadron historian... :wink:

By the way - UNLIKE Gatun Dam in 1941 - the Hwachon Dam spillway gates were CLOSED :wink: Meaning there was no chance that the gates were raised far enough to ensure a miss...now, how do I know that?
Last edited by phylo_roadking on 26 Jan 2009, 22:27, edited 3 times in total.

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

#202

Post by phylo_roadking » 26 Jan 2009, 22:21

An armoured hull would make the effects of a torpedo hit even WORSE - there will be chunks of tough steel flying about, making holes in unarmoured bulkheads.
Borys - you're quite right! :D This is EXACTLY what I meant about hardened steel plate being more friable than wrought iron. A torpedo will actually do MORE damage to hardened steel plate than to wrought iron... 8O And there's even something in the USS Raleigh story that confirms that!!!

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

#203

Post by robdab » 26 Jan 2009, 22:28

phylo_roadking

WOULD it be visible??? :wink: I've shown ONE (1) pic of it silhouetted against a clear summer's sky looking UP at it from the spillway side, and one of it from wter level at a few hundred yards' out on Gatun Lake. NEITHER of these viewpoints will be visible to a pilot. The ONLY indicator a PILOT will have of the gates being opened is visual confirmation of the water outflow sparying out of the gates...which needs to be observed from either above or the spillway side - which means an attacking pilot would need to CIRCLE his objective before making a decision or getting into position for a bombing run!!! Multiplying the time the garrison's AA has to react/muster, and for USAAF fighters to fnd him. Flying a circle like that and back into position for a torpedo run will take several minutes... - While you are certainly entitled to your own opinion, I do not agree with it. The Mavis IIRC had a crew of 9, some of whom could have been observing the spillway gates with binoculars or some other similar technology while the pilot flew the airplane and the co-pilot readied his torpedo sight.

As for agents on the ground - I've let that go unchallenged until now. You haven't actually yet managed to find out ANYTHING about any Asiatic/Japanese community IN the Canal Zone, have you??? AND in the numbers they were present on Oahu to hide/shelter enemy agents....let alone a cuommunity with the free run of a military reservation, where there were ALREADY heavy security measures in place to stop "enemy agents" sneaking into the Canal Zone or Canal on board ships or in unidentified aircraft.... - I have already posted here the source for the OTL MAGIC intercepts that came out of Panama in the pre-war period. They clearly show the degree of freedom that the OTL Japanese were able to demonstrate there. As previously stated here, I have no idea if there were more message sent back to Tokyo that weren't intercepted but I feel sure that the Japanese on the ground there could/would have been busier had my ATL attack been in the planning stages.

So which is it to be??? NO SEDTA or Panagra in the Galapagos....OR commercial carriers using flying boats, who will be reporting unidentified traffic in the air and on the surface in the Galapagos, and unidentified shipping??? Once again, this is the sort of things commercial carriers were by the 1940's obliged to report - from the aspect of safety hazards for their scheduled traffic, let alone security issues. Which way round do you want the Galapagos situation in THIS post??? - You keep making vigorous assertions that the Americans and Panamanians were enforcing a rigid control of Panama's airspace at this time but I have yet to see a single source presented in support of your assertions. Simply said, I don't believe you.
Certainly, if informed before Dec.6'41 that many of the spillway gates were already open and that heavy rain was forecast,
So you're BACK now to NOT wanting heavy tropical storms and their associated cloud banks, as opposed to WANTING them for the purposes of concealment??? - I've never typed anything about my ATL Japanese wanting heavy tropical storms. My rainy season experience in Panama was of a more gentle but persistant low cloud cover that dropped numerous regular rain showers than it was of violent thunderstorms belching lightning, which would be dangerous to any aircraft.

P.S. 2007 was actually a record WET year in Panama throughout the year - And yet your December 2007 photo shows only one spillway gate open. Does this not suggest that in the drier non-record wet years before 2007 no gates at all might have been open on a typical December day ?
No - it should that NOWADAYS as stated, the administration wants Gatun Lake kept at its MAXIMUM level concomitant with no local flooding or coastal erosion, to provide the water needed for increased traffic. - Which again implies that the spillway gates would be kept closed whenever possible so as to store the maximum amount of rainwater.
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 Stoney Gates with a picture of what appeares to be a pivotting Folsom Gate? - That is an easy question to answer. Because I only saw the photo which I listed as a source. Had I proceeded on to also find http://www.osakac.ac.jp/labs/ishii/Fina ... apter1.pdf as I did today, it would have been possible to recognize the Folsom Dam as having radial Tainter type gates installed instead of the Stoney type. My bad.
Robert, I certainly wasn't accusing you of using a completely inappropriate example to make your point, don't worry...though I do of course have several reservations why a trained and experienced civil engineer didn't see that it was a Tainter Gate, and an amateur could; maybe it was the curved surface??? Maybe it was the lack of the cell-type support frame? Maybe it was the large actuating chain hanging spuriously in the picture? Maybe it was the trunnion of the UNdamaged gate to the left of it in frame that was the dead giveaway... - There is a much simpler answer. It was late and I was tired.

Given that a Stoney Gate relies on the heavy pressure applied to its water-facing side pressing in INTO its sills and then radiating out into the dam structure to seal it??? - Yes.

I presume you've actually read Capt. Simons' damage report for his vessel of January 14th, 1942? - Thank you for the confirmation but, thank the Good Lord, No I haven't. Why would i want to spoil your furious search for micro-details to find fault with ? You are very good at ferreting out "stuff" that most would never dream of. All are noted down for the next scenario.

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

#204

Post by phylo_roadking » 26 Jan 2009, 22:50

WOULD it be visible??? :wink: I've shown ONE (1) pic of it silhouetted against a clear summer's sky looking UP at it from the spillway side, and one of it from wter level at a few hundred yards' out on Gatun Lake. NEITHER of these viewpoints will be visible to a pilot. The ONLY indicator a PILOT will have of the gates being opened is visual confirmation of the water outflow sparying out of the gates...which needs to be observed from either above or the spillway side - which means an attacking pilot would need to CIRCLE his objective before making a decision or getting into position for a bombing run!!! Multiplying the time the garrison's AA has to react/muster, and for USAAF fighters to fnd him. Flying a circle like that and back into position for a torpedo run will take several minutes... - While you are certainly entitled to your own opinion, I do not agree with it. The Mavis IIRC had a crew of 9, some of whom could have been observing the spillway gates with binoculars or some other similar technology while the pilot flew the airplane and the co-pilot readied his torpedo sight.


Robert, this is not a rude question....but what planet are you on? Literally? Because on MY planet, looking DOWN from ABOVE you cannot see anything silhouetted against daylight! No matter what visual aids you use.

Likewise - to actually SEE the spill itself, if there is any - you have to be on the SPILLWAY side of the dam or physically OVER the dam, for the spill is below lake level from any other viewpoint as one of my pics shows. Which means being on the WRONG side of the dam at SOME point to check.

And no aerial observer is going to be able to tell HOW high the gates are actually raised unless they've got huge mumbers painted on them for the purpose...if the gap is STILL BELOW THE SURFACE OF THE WATER...

I have already posted here the source for the OTL MAGIC intercepts that came out of Panama in the pre-war period. They clearly show the degree of freedom that the OTL Japanese were able to demonstrate there. As previously stated here, I have no idea if there were more message sent back to Tokyo that weren't intercepted but I feel sure that the Japanese on the ground there could/would have been busier had my ATL attack been in the planning stages.


Panama, yes - not the CANAL ZONE. Find THOSE coming from within the military reservation of the canal ZONE and you may have a point...for ten miles is a LONG way to see how far the gates are raised...

So which is it to be??? NO SEDTA or Panagra in the Galapagos....OR commercial carriers using flying boats, who will be reporting unidentified traffic in the air and on the surface in the Galapagos, and unidentified shipping??? Once again, this is the sort of things commercial carriers were by the 1940's obliged to report - from the aspect of safety hazards for their scheduled traffic, let alone security issues. Which way round do you want the Galapagos situation in THIS post??? - You keep making vigorous assertions that the Americans and Panamanians were enforcing a rigid control of Panama's airspace at this time but I have yet to see a single source presented in support of your assertions. Simply said, I don't believe you.


Robert - keeping rigid control or otherwise of PANAMANIAN airspace has nothing to do with reporting Japanese naval shipping in the NEUTRAL Galapagos, or Japanese flying boats in the area. It's not anything to do with "vigorous control", it's pilots being concerned for their OWN safety with unpredictable and unscheduled aircraft in an area where THEY are supposed to be the ONLY commercial carriers! NEXT you'll be trying to tell us the Pan-Am colours will fool PANAGRA :lol: :lol: :lol: Unfortunately for some of your counter-arguments, Robert, you simply can't hide in incredulity, not when your opinion relies on professional people NOT doing what they do on a daily basis...in this case if not an hour-by-hour or minute-by-minute basis....for their own wellbeing and that of their passengers 8O

Simply said, I don't believe you


Latin American in WWII by Thomas M Leonard, and John F. Bratzel -

"As early as October 1939 the United States regulated use of the Canal Zone's airspace, barring Panamanian planes and those of the European combatants from flying over the Zone. In the end a new Joint Aviation Board was was created to regulate flights across the isthmus, but Panamanian board members were expected to follow the lead of their U.S. counterparts."

In the end (that's the December 1940 agreement) A JOINT regulating board with American and Panamanian members working to AMERICAN policies? Looks cut and dried to me.

So you're BACK now to NOT wanting heavy tropical storms and their associated cloud banks, as opposed to WANTING them for the purposes of concealment??? - I've never typed anything about my ATL Japanese wanting heavy tropical storms. My rainy season experience in Panama was of a more gentle but persistant low cloud cover that dropped numerous regular rain showers than it was of violent thunderstorms belching lightning, which would be dangerous to any aircraft


Robert - the cloud thickness doesn't matter - you BOTH want cloud cover of SOME sort to hide the attackers, and yet want there to be no rainfall runoff. You still can't slice it both ways by hiding your argument in degrees.

I presume you've actually read Capt. Simons' damage report for his vessel of January 14th, 1942? - Thank you for the confirmation but, thank the Good Lord, No I haven't. Why would i want to spoil your furious search for micro-details to find fault with ? You are very good at ferreting out "stuff" that most would never dream of. All are noted down for the next scenario


It's a pity you didn't do something valuable, especially when the contents contradict your impression of the effects of a torpedo strike on the gates. if you're going to argue on details, it's best to HAVE them. And when you chose to "have them" I get rather worried when they turn out not to bear much resemblance to the facts. The attack on the Hwachon Dam is another perfect example of that.

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

#205

Post by glenn239 » 27 Jan 2009, 01:40

Rob -

Dumb question, but how much explosive could be packed into a H6K, under the assumption that the airplane would land on the lake and then run itself into the target?

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

#206

Post by phylo_roadking » 27 Jan 2009, 02:17

Glenn, in the abscence of Robert perhaps I can help with that. Possibly you know this already, of course...

An H6K's maximum take-off weight is 47,300 lb ;

It's loaded weight i.e. the weight it can take off and still make its notional top speed and service ceiling is 37,400 lb;

However, as you know with aircraft specs the "loaded weight" is arbitrary, but usually it's just a backwards calculation from the equation of wingloading/top speed...so while there APPEARS to be a payload gap of 9,900lbs, it's just a "mathematical" gap - and doesn't convert into extra payload.

To answer your question we would need to know -
weight of maximum fuel carried
weight of average personnel
weight of guns and ammunition (always a bigger amount that you'd believe!!!)

...and like most aircraft, i don't have these anywhere for the Mavis. If we COULD find these out, it would be a simple matter of adding these to its empty weight of 25,755 lb...

...but then we don't know anything about weight distribution around the airframe - vital for unsticking from a sea swell :wink: - or what parts of the airframe would actually support inboard weight....

We COULD however get a clue from the cargo weights specified for any of the transport versions....anyone??? For example the H6K2-L (Navy Transport Flying Boat Type 97) the unarmed transport H6K2 version powered by Mitsubishi Kinsei 43 engines...

But note that a "payload"-carrying Mavis would THEN be unarmed...adding to all its other issues of no armour and vulnerability to enemy fire

(This is a complication of combat aircraft converted to transports - they GET their loadcarrying capability by deleting their armaments etc.)

...thus throwing ALL the issues over early detection, evasion, aerial interception, AA fire etc. into SHARP relief again. Let alone the issues of manouverability and concealment if flying too far up towards its maximum take-off weight instead of down at its more operationally-capable...in terms of speed, altitude etc...."loaded weight"

In other words - if we find the cargo weight of a transport version...we could have a bomb - BUT we have to remember its unarmed, unarmoured and possibly even slower and more lumbering than a Mavis already was....

May as well paint a target on it instead of Pan-Am colours???

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

#207

Post by robdab » 27 Jan 2009, 02:22

glenn239,-

... but how much explosive could be packed into a H6K, under the assumption that the airplane would land on the lake and then run itself into the target?[/quote]

From http://www.combinedfleet.com/ijna/h6k.htm

The H6K2-L model had a maximum weight of 23,000 kg and an empty weight of 12,025 kg so a load of a little less (for one-way fuel from the Galapagos) than 10,975 kg = 24,145 lbs = 12 tons. Say 11 tons without crew/gear except for a pilot & navigator. Ballpark.

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

#208

Post by phylo_roadking » 27 Jan 2009, 02:31

There IS however one interesting indicator that provides a hint of weight problems...When the Mavis was re-engined from Nakajima Hikari 2 nine-cylinder air-cooled radial engines rated at 840hp to Mitsubishi Kinsei 43 radials rated at 1,000hp - the offensive payload of either two torpedos or 2,205lbs of bombs wasn't upgraded.

Like the problems leading to the up-rating the Fw200 Condor's engines during the war - this would indicate to me that it's performance had been marginal for the weight...and STILL was as its offensive capability wasn't improved! 8O

And when the H6K4 variant was introduced in 1941, with extra fuel tankage - THIS was only obtained by deleting the dorsal turret and replacing it with another hand-held 7.7 millimeter gun.

Does look as if performance vs weight was marginal...the offensive load wasn't upped until later in the Mavis' life, into 1942, when Kinsei 53 fourteen-cylinder radials, rated at 1,300 hp for take-off, were fitted in later variants, too late for this WI.

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

#209

Post by phylo_roadking » 27 Jan 2009, 03:17

Robert - you're making the disappointingly NORMAL mistake of looking JUST at the MTO weight and the empty weight. You're forgetting ENTIRELY how that weight-bearing capacity gets achieved. Will you PLEASE put some effort into your OWN WI...

Glenn, just been crunching some numbers; getting an "average weight" for a japanese male was hard with all the different numbers floating about, and of course this is a MODERN "instant noodle" total...around 145lbs. Probably a few more pounds' weight than in 1941, espeicially on a military ration. But I'll go with that figure out of generosity...of waistline :lol:

The H6K2-L could carry 18 passengers, I'll ALSO allow another 120Lbs each for personal kit and it's more primitive 1941 seating apparently, compared to later versions....

145 + 120 x 18 = 4770lbs. Round it up to 5000lbs

Robert - see the difference??? And how the weight for 18 men could be obtained JUST by removing guns and gunners? :wink:

Kindly remember you're positing the use of a FLYING BOAT; it has to come unstuck from the choppy wavy bit of blue stuff on the map. It's weight distribution has to ALLOW it to do that....and once airborne it has to NOT upset trim so much that the pilot can't actually FLY the plane! Your mission profile seems to involve a LOT...incalculable in advance of mission...of flying in and out of non-Canal Zone airspace for concealment, as well as being able to search for and keep in cloud cover.

You can indeed posit not flying with a full fuel load - for it won't be coming home...but then you'll be flying into a military reservation, liable to interception if you're unlucky...with partly-empty unarmoured WING tanks full of flammable petrol vapour. NOT the best situation to have an unfriendly fighterplane looking at you.

Ever wondered why the bombload of a Avro Lancaster 4-engined bomber was originally specified at only 8000lbs??? Because that was the weight it could carry at its specified range and performance. Early WWII payloads ARE that small.

Robert - do you happen to know - or have even thought of - what actual cubic size your ELEVEN TONS of explosive fills??? :lol: :lol: :lol: What's the CUBIC VOLUME of the Mavis' airframe??? Are they going to hang bits on the outside with duct tape???
Last edited by phylo_roadking on 27 Jan 2009, 05:54, edited 1 time in total.

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

#210

Post by robdab » 27 Jan 2009, 05:29

Glenn239,

Am I the only one that thinks that this phylo guy could suck the fun out of "a barrel full of monkeys" ?

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