In World War II we did not have data on these Japanese vessels as there was no way to study the ships to determine the RPM/speed curve for each ship. The only thing they could tell by the turn count was the relative throttle setting and whether the target was speeding up or slowing down. There was no connection made between RPM and speed.
What little information we had was for warships and I haven't seen a single record of a submarine encounter where prop counts were used as a speed determination. To do so here, even if it were possible, would be making a simulation into a video game.
What? It IS a video game?
