Byron Angel wrote:Forstmeier and Breyer (Deutsche Grosskampfschiffe 1915-1918) give the following cruising radius values for MACKENSEN and ERSATZ YORCK designs in their appendix of comparative ship/design statistics -
For 35431mt displacement (4000mt coal + 2000mt oil) = 6800 sea miles @ 13 knots <<<radius of action>>>
Paul L wrote: Radius of action means there and back again, suggesting the endurance at 13kts is 6800 x 2 = 13600 @ 13kts. Is that what they are suggesting ?
Die Fahrstrecke gemass Probefahrt bezieht sich auf den Brennstoffvorrat bei der Probefahrt (sog. Probefahrtverdrangung, in der Regel niedriger als die Konstructionsverdrangung).
Regarding range, it´s perhaps of interest that Mackesen & co should recieve sets with geared cruise turbines on the two inner shafts with the outer shafts driven by direct drive turbines. Ers. Yorck should receive Föttinger hydraulic drives for all four shafts, which can be expected to increase the range significantly ove rthat of the previous DERFFLINGER´s / HINDENBURG´s.
delcyros wrote:Considering that the MOLTKE´s -with their less efficient hullform could go 4,120nm @ 14kts with 3,100t of fuels with direct drive turbines, I wouldn´t call 8000nm @ 14kts with reduction geared turbines on 6,000ts fuels an improvement...
Specific fuel consumption in forced power, 6 hour trial runs in VON DER TANN to SEYDLITZ ranged from a low of 0.654 kg/SHP to a high of 0.785kg/SHP. Note that these ships typically had direct drive setups. On the other hand, these trials were conducted under peacetime rules with the lighter trial displacement and Whelsh, high grade steaming coal.
SMS MOLTKE achieved an average of 27.85 kts at 76,795 SHP in her 6 hours trials and burned 45,2t coal and oil in the period. The buncerage was enough for 68 hours forced trial (in case the machinery could cope, which I don´t believe) and a corresponding theoretical range of close to 2000nm at 27 to 28kts.
Cruise range wasn´t much better, mosly due to the rapid increase in specific fuel consumption.
MOLTKE has a spec. fc of 0.667 kg/SHP at 76,795 SHP raising to 0.712 kg/SHP at 71,275 SHP and further to 0.828kg/SHP at close to rated power, 53,187 SHP.
Reduction gears greatly helped in limiting the raise in specific fuel consumption.
I have a more hypothetical question. How difficult would it have been to retro fit such diesel engines to the BattleCruiser line [Motkle , Sedlitz , Derfflinger etc etc? Perhaps the two mid shafts are run on Diesel for long cruise and the outer two shafts on Turbines driven by oil?
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