Sunk my FIRST Destroyer!!!!!

[ddiplock]

Originally Posted by Puster Bill

:hmm:

The idea behind the 3:15 rule is that it allows you to equate hundreds of meters travelled during that time to speed in knots. If the destroyer travelled 1km in 3:15, that would be 1000 meters/100 = 10 knots.

Congrats on getting the destroyer, though. They are tough to hit because they are fast and shallow. The only times I've been consistently successful is when I let them get within 500 yards, then fire magnetics at them.

Still, conventional wisdom is to leave them alone unless you absolutely have to sink one. The nice thing is that you get to choose.

By the way, get a whiz wheel. They make AOB and speed calculations a breeze:
http://www.subsim.com/radioroom/showthread.php?t=114351

My preference is for the physical version, but there are Flash and in-game versions available.

Well, I used the ruler to measure the distance between the points and it measured the distance as 1. Now can that be interpreted as 1000 meters or 1km?? I'm wondering how close my speed calculation was, i can't have been THAT wrong if the torpedo hit But having said that they were not that far away, so being so close to the destroyer may have been the "saving" factor in allowing the torpedo to still hit the target.

[Puster Bill]

Originally Posted by ddiplock

Well, I used the ruler to measure the distance between the points and it measured the distance as 1. Now can that be interpreted as 1000 meters or 1km?? I'm wondering how close my speed calculation was, i can't have been THAT wrong if the torpedo hit But having said that they were not that far away, so being so close to the destroyer may have been the "saving" factor in allowing the torpedo to still hit the target.

Well, first off, 1km is by definition 1,000 meters.

Your speed calculation was fine. You measured the distance travelled in 3 minutes 15 seconds, and the speed was 10 knots. I don't know what extra step you used to get 6 knots, but whatever it was, apparently one of two scenarios came into play:

1. You were close enough that the speed error didn't matter. I doubt this, though for the following reason: At 300 yards a 30 knot torp would take 20 seconds to traverse that distance. A speed error of 4 knots would result in changing the point of impact by about 41 meters, almost half the length of the average destroyer. If you locked on to the center of the destroyer, you would hit it's stern, or completely miss it astern. Since that's the minimum torpedo attack distance, most likely you were farther away.

Using a faster torpedo speed would minimize this error, but even with a T1 at 44 knots, the 20 second/41 meter error at 4 knots distance is still at around 450 meters.



2. An error in your AOB calculation serendipitously counteracted your
error in speed. Hey, sometimes you hit the lottery.

In any case, it's never easy to hit the damned things, so just make your log entry vague enough that Onkel Karl will think it was due to skill, not luck Then soak up the glory that comes with hanging a red pennant off your periscope.

[Brag]

Well done. I could never resist a destroyer coming to the slaughter

[ddiplock]

Originally Posted by Puster Bill

Well, first off, 1km is by definition 1,000 meters.

Your speed calculation was fine. You measured the distance travelled in 3 minutes 15 seconds, and the speed was 10 knots. I don't know what extra step you used to get 6 knots, but whatever it was, apparently one of two scenarios came into play:

1. You were close enough that the speed error didn't matter. I doubt this, though for the following reason: At 300 yards a 30 knot torp would take 20 seconds to traverse that distance. A speed error of 4 knots would result in changing the point of impact by about 41 meters, almost half the length of the average destroyer. If you locked on to the center of the destroyer, you would hit it's stern, or completely miss it astern. Since that's the minimum torpedo attack distance, most likely you were farther away.

Using a faster torpedo speed would minimize this error, but even with a T1 at 44 knots, the 20 second/41 meter error at 4 knots distance is still at around 450 meters.



2. An error in your AOB calculation serendipitously counteracted your
error in speed. Hey, sometimes you hit the lottery.

In any case, it's never easy to hit the damned things, so just make your log entry vague enough that Onkel Karl will think it was due to skill, not luck Then soak up the glory that comes with hanging a red pennant off your periscope.

Well, i've been wondering now all this time if i've been using the nomograph correctly. I've now noticed i've not been using the far right column of the graph that lists time in minutes. I've only been using the distance covered and knots scales.....ooops. But ALL my torpedos have still been hitting the ships this way though

Can i ask, is there a quick document somewhere that explains how to use all parts of the nomograph then?? Cause now i've realised i've defo only been using half of it in all my attakcs......and somehow still hitting ships all the time

[Pisces]

Originally Posted by ddiplock

...
Can i ask, is there a quick document somewhere that explains how to use all parts of the nomograph then?? Cause now i've realised i've defo only been using half of it in all my attakcs......and somehow still hitting ships all the time

Just draw a slanted line through any 2 of the 3 numbers you know (time, speed or distance) and then the 3rd number is also crossed through, to match the formula "speed=distance/time". Nothing more to it.

[ddiplock]

Yeah cause i've only been using the distance to work out the speed on the nomograph. When I have the distance, I draw a slanted line to it on the nomograph to work out the speed. But I dont do any markings on the time scale of the graph

that's right isn't it? How else could I be hitting all my targets with the torpedos??

[Puster Bill]

Pisces is right. Nomographs are that simple.

Usually, though, I use either a whiz-wheel like this:



or a linear slide rule to do my calculations.

I do however have a maneuvering board that I printed out on cardstock, then laminated so that I could use dry erase markers on it, and it has a speed/time/distance nomograph on it. The only problem is that the scale is in yards, not meters! In any case, I very rarely use it anyway. It's very helpful for visualizing the situation, but it's a bit more work than just doing a quick procedure with a wheel or slide rule.

[ddiplock]

Well....I think i've been using it right....how else would I be hitting all my targets doing all the calculations myself?? I must be using it right

I'll take a screenie during my next target apprach and show you what i do.

[Platapus]

Originally Posted by Puster Bill

2. An error in your AOB calculation serendipitously counteracted your
error in speed. .

+300 Renown for using the word serendipitously