[greyrider]

i received your PM canovero, and thank you for inviting me to this thread.
the only subsims that i play was the silent hunter series, sh1 to sh4.
we all know that sh1 and sh2 had only one screw sound for propellers,
so it was impossible to do anything with sound with those versions.
so when frank, who was bdu at the time at wpl posted, and asked what should be
included in the next version of sh, i PM frank, and told him about how the u s navy was, or thought of using propeller turncounts
to determine speeds of enemy ships.
like neal, frank must have been in touch with the devs, and they could influence the devs into making the new version more realistic.
so i did write frank, and lo and behold, the new version, (sh3) had propeller sounds that we could use to determine different speeds.
tho the devs worked on it, and this was a start, they did not model propeller pitch realistically.
the way i made the rpm charts was the only way to do it. it was not real, but i was not going to let this opportunity slip away
and i demonstrated that sound can be used to sink ships.
heck when i was an forward observer, and i called for arty
on targets, i used the speed of sound itself to adjust rounds on target, along with my binos, nothing like getting steel on steel
and i could do that alot.
but in reality, how did they do it? how did they make speed curves for enemy ships, that i read in the torpedo fire control manual?
well, a lot of enemy ships had thier turbines built in england, from vickers shipyards, and Brown-Curtis, maybe others.
so these turbines driving propellers of enemy ships were made in an allied country, so in many cases, enemy ship engines sizes
and ratings were known already, and the allies knew what they had, and the propeller pitch could be figured out.
another way was to use the stadimeter, get a speed by observation, then listen in the sound room, for the rpm of that speed, record it
and pass out that info in speed curve charts to the rest of the fleetboats over the course of time.
until we get a sim, maybe sh5, that does model propeller pitch properly, we are limited in what we can do here.
i want to ask a favor from all you sh4 captains out there, i do not want to make speed charts the unreal way, and im not, so what i am doing
is when i play the game, i use the scope first to time the passing of a target, from bow to stern, passing the vertical line of the scope,
i use the formula:
3600 x length of ship / observed time / 2023 yards, at or near a 90 degree angle.
this gives the speed of the target from the scope, and then i go to the sound room, and record the rpm for 1 minute.
if we all do this, and contribute as a "fleet", we will have a good amount of speed curves or charts of enemy ships, and there can be no doubt
about the reality of getting the infomation in this fashion.
ill start with a couple of speeds of a couple of ships.

shiratsuyu destroyer: 12 sec scope time, 18 knots, 71 rpm.

akizuki destroyer: 14 sec scope time, 18 knots, 73 rpm.

medium old split freighter: 26 sec scope time, 9 knots, 40 rpm.
33 sec scope time, 6 knots, 34 rpm.

large old split freighter: 29 sec scope time, 9 knots, 26 rpm.

coastal composite freighter: 17 sec scope time, 9 knots, 47 rpm.

takao heavy cruiser: 31 sec scope time, 13 knots, 42 rpm.

medium modern split freighter: 31 sec scope time, 6 knots, 42 rpm.

large modern composite freighter: 45 sec scope time, 6 knots, 38 rpm.


the above is a pretty good display of military intelligence, for future encounters with these and other targets,
when you go out on your combat patrols,
bring back some intelligence!

oops, guess these observations belong in the sh4 forum
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