Technology and Operations
This forum is for discussing technological & operational matters pertaining to U-boats.
Re: U480 A stealth Uboat
Posted by:
Seeker
()
Date: October 20, 2009 06:18AM
Reading Rosslers book "The Uboat", its apparent that some problems did exist on the XXI design, but these were being worked out through tests in late 1944. It was realised that the flooding slits slowed the boat too much as did the flak turrets . Fast diving and flak was intitally demanded by Donitz for XXI , but when removed, the boats top underwater speed got back upto 17knots. The modified boats showed dive time of 25 seconds compared to 20 seconds for the original and the top underwater speed reached 17.94 knots.
The structural problems with some boats only effected about 1 in 5 boats causing those production times to double. But the main delay factor had to do with constant allied bombing of the yards and the training areas. This caused a number of boats to delay deployment.
With regard to diesels the reduction in power due to no supercharger was more like 1760 horse power corresponding to 15.4 knots surface speed. However,
" As pure surface performance was no longer of paramount importance for this type of boat in 1944-45, there was no particular gain in using the supercharger during schnorkel travel , and it was omitted from later boats....The maximum schnorkel performance was now 2 x 1200 hp (= 2 x 1060hp on the shaft, corresponded to 10.9knots. However in practice , due to oscillations in the periscope and schnorkel 6 knots was hardly ever exceeded in schnorkel travel".
In dive tests 170m was reached in several dives but tests were halted due to unrelated problmes [dingy exploding , amongst other things]. Problems with the 10.4 frame were identified and strengthing on all subsequent boats ordered. Resumed tests later that month regularly reached depths of 220m with out any problems.
pp 273-275.
Its interesting to note the XXIII had no problems with schnorkel speeds of up to 10.8knots.
The structural problems with some boats only effected about 1 in 5 boats causing those production times to double. But the main delay factor had to do with constant allied bombing of the yards and the training areas. This caused a number of boats to delay deployment.
With regard to diesels the reduction in power due to no supercharger was more like 1760 horse power corresponding to 15.4 knots surface speed. However,
" As pure surface performance was no longer of paramount importance for this type of boat in 1944-45, there was no particular gain in using the supercharger during schnorkel travel , and it was omitted from later boats....The maximum schnorkel performance was now 2 x 1200 hp (= 2 x 1060hp on the shaft, corresponded to 10.9knots. However in practice , due to oscillations in the periscope and schnorkel 6 knots was hardly ever exceeded in schnorkel travel".
In dive tests 170m was reached in several dives but tests were halted due to unrelated problmes [dingy exploding , amongst other things]. Problems with the 10.4 frame were identified and strengthing on all subsequent boats ordered. Resumed tests later that month regularly reached depths of 220m with out any problems.
pp 273-275.
Its interesting to note the XXIII had no problems with schnorkel speeds of up to 10.8knots.
