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 Author  Topic: 20mm Fixed Mount Training Aid for Mark 50 Launchers
Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Dec 3, 2023 - 7:27am
In the Bureau Ordnance, DoN Publication “U.S.Navy Bureau of Ordnance in World War II”, they address that the BuOrd contractors sent to the Philippines area (in December 1944) to install the new Mark 50 launcher 5” spin stabilized rockets noted that this system required extensive training to realize the potential of this armament. The supply of rockets was “marginal”, at best and remained critical well into 1945, so “their use as a training aid was out of the question, so some special training device was necessary for the success of the program.” The solution was to mount a fixed 20mm on the bow of each PT that was then wired for electrical firing on the signal that ordinarily activated the rocket firing. When mounted correctly, the fire control problem was the same for both weapons, so this became a great training aid. This device soon turned into an actual weapon where both launchers and the fixed 20mm were fired simultaneously.

So, has anybody heard about this or have any supporting photographs? It seems this was only done in the Philippine theater, so not something directly coming out of Elco or Higgins.



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Travis B

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Travis B   Send Email To Travis B Posted on: Dec 3, 2023 - 10:13am
Here is PT 596 from RON 40 the boat arrived at Samar, Philippine Islands, in the summer of 1945.

pcF1Z.jpg

Here is a close up of the MK 50

pcMPa.jpg

pcamf.jpg
pclej.jpg


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Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Dec 3, 2023 - 10:44am
Thanks! Looking for this fixed bow mounted 20mm they mentioned or any additional info on this in the field setup. I have a good amount of photos of the standard Mk-50 launchers.


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Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Dec 4, 2023 - 3:09am
This is a portion of what the publication says...

pcsU6.jpg


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Joe Reese

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: Dec 6, 2023 - 7:58pm
Hi Andy,

This is the only thing I've been able to find so far. Not much of a pic, I know, but it appears* to be another 20mm Oerlikon directly behind the 37 mm, with the forward port 20mm visible as well. The former has what appears to be an AA handle on it, though, so I don't know if it's one of the fixed training ones or if they just threw an extra one on, and/or maybe found a way to fix that in place for rocket practice. I don't know, only guessing.

https://www.ibiblio.org/hyperwar/USN/CloseQuarters/img/PT-p433.jpg


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Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Dec 7, 2023 - 10:32am
Thanks Joe, I believe you found it! I must have skipped right by that photo millions of times and never noticed it!

pcIo5.jpg


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Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Dec 7, 2023 - 10:42am
Closer view from the Naval History and Heritage Command site.

pcRnS.jpg


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Joe Reese

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: Dec 7, 2023 - 10:50am
Hi Andy,

I'm kind of surprised. I was searching for something on the center line, never thought about it being mounted right next to the launchers.

This makes me wonder about the forward center 20mm. Could this boat maybe have had the 4.5 rockets first, and moved their 20mm to the center line to be out of the way, then got a refit with the 5 inch?


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TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: Dec 7, 2023 - 12:21pm
Andy and Joe;

Funny, I have looked at this photo a million times over the past 30+ years, saw both 20MM ‘s but never thought twice about it. I believe this is PT 525. RON

Take Care,
TED


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Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Dec 7, 2023 - 1:04pm
It was a common place for the extra 20mm mounts, so maybe it's all just a WAG at this point. I'm going to keep looking since I too was looking for something right on the bow.


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