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Images of the Dark class

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    Posted: 04 April 2011 at 2:03pm
The Veteran's web site has some very interesting and 'new' images of the Dark class. On the second page is a clever animation of the mechanical working of the Deltic engine.
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johnk View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote johnk Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2011 at 9:34am
Hi there,
 
Yes, very good animation indeed, just seen on the news they found a Donier bomber off the Kent coast, hopes to raise it for the Hendon museum, remember seeing something about one of the Darks sinking of the coast, be great to see her again, of course would cost a packet to do, and curious about what condition she would be in after all this time, the bomber apparently is quite good apart from some nose damage, also how the metal would be now, any reaction once back in the dry....they revovered orgional parts for the S-boat, very cold water though, and steel, not sure about the salt though. Another example would be the first RN sub Holland 1, raised and put on display but then started to rot very quickly, need to be completely encased in a tank and treated..
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mprints Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2011 at 4:27pm
An article on the welding of small craft in aluminium appreared in the 1955 Issue 4 edition of SARO Progress magazine. It refers to the ordering in 1945 of four experimental American PT boats PT 809 at 96ft all riveted, PT 810 at 89ft composite rivet and welded, PT 811 at 94 ft all welded and PT 812 at 105 ft all welded. All four were each fitted with four Packard V12 petrol engines of greater power that the ones uses in the UK. They were completed in 1951 and were made from aluminium 61S-T6. (Saunders-Roe claimed to have built the World's First aluminium MTB that was launched in 1948)
The Royal Navy commissioned the Dark Class built of aluminium frames and decks with timber hull sheeting. The article refers to the use of aluminium NS8 plate, NP5/6 sheet, NE6 extrusion and NW6 welding wire that resist seawater well.
It was from the early 1950's that seawater resistant aluminium alloys became more widely used for boat construction as in the five all riveted aluminium Dark Class FPB's for Burma T201 - T205 and the unique all welded Dark Scout for the Royal Navy. This would undoubtedly have also been made of NP5/6 and NS8.
I don't know what aluminium grades would have been used in aircraft construction during the war, but it would seem unlikely that corrosion resistance would have been of importance. The fact this Donier bomber has survived so weel in the sea is a promissing sign for further finds of aluminium boats such as for the possible recovery of MTB 539 (later P1602) that lies in 43m in the Irish Sea.
Dave
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Post Options Post Options   Thanks (0) Thanks(0)   Quote johnk Quote  Post ReplyReply Direct Link To This Post Posted: 20 April 2011 at 9:55am
Hi there,
 
Thank you very much for your most interesting reply, hm.... 43 metres is deep! but you never know, thanks again,
 
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