Quote:
Originally Posted by TheDarkWraith
what if this number isn't the theoretical maximum speed of the engine in knots but rather the RPM of that engine's shaft (in the water)  The constants could be related to gearing reduction.
Anyone have any figures on what the RPM of the shafts were at different bells for the subs? |
Quote:
Originally Posted by keysersoze
Not sure if this is still relevant, but according to uboatarchive.net (for a VIIC), here is the max rpm for both the MAN and GW diesels.
Forward
Flank - 471 rpm
Full - 435 rpm
Standard - 340 rpm
One-Third - 275 rpm
Slow - 180 rpm
Reverse
Flank - 285 rpm
Full - 215 rpm
Standard - 160 rpm
One-Third - 110 rpm
Slow - 55 rpm
...
|
Yesterday I stumbled upon this other uboatarchive.net page:
http://www.uboatarchive.net/KTBNotesPropulsion.htm
What is good about it, is that it correlates telegraph speed orders with RPM's and speeds in knots empirically measured aboard a captured VIIC boat, for both diesel and electric propulsion. The information reported is compatible, though not identical, with the one pointed by keysersoze.
I have plotted on a graph RPM's and their resulting speeds. I was expecting some sort of logarithmic curve, similar to a torque curve (the higher the rpm, the more drag and cavitation, the lesser efficiency, etc.). To my surprise, diesel rpm/speed coordinates are fitted (with a R2 value of 0.9977) by a straight line. The same goes for the electric propulsion curve, though with a bit lesser R2 value (0.9818), and with five points out of six aligned with a straight line crossing the axis origin. Removing the one misaligned point gives an R2 value of 0.9991, which makes me to think of a measurement/reporting error
