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Old 10-07-2019, 10:55 AM   #1
jimbeau1571
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Default Torpedo Time to Impact

So in doing the Training Mission, i had an issue where the Time To Impact on firing a Torp didn't seem to match what i was seeing on the Map.
So I turned the Sub for a straight on shot and tried again.
Again it didn't match (out by about as 1/2 as long as it took).
I assume that my distance measuring to target is somewhat out. I've watched numerous videos looking for assistance in measuring the distance.

How to Fire and Hit a Torpedo being a good one.
Mast Height\ Number of reticules (x4 if zoomed)=Range

Any others recommended.

Or is the Time To Impact clock inaccurate?
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Old 10-07-2019, 11:59 AM   #2
Pisces
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Range does not come into play as much when determining where the torpedoes impact the target, or how much it leads. Especially not when firing straight. It only does when the torpedo needs to make a large turn and at close quarters. Speed and AOB does make a, more or less proportional impact on lead angle. It's most likely they were not exact in your case.

However the time to impact is directly related to the distance you put in. Your formula is correct.

There were bugs in the timekeeping of the game in earlier versions. This should have been correct in version .18 something.
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Old 10-08-2019, 04:34 AM   #3
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Back to the practice board i guess then lol
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Old 10-12-2019, 12:25 AM   #4
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Range matters a whole lot from any angle because it is the most significant factor that determines the time to target, and therefore it factors into the amount of lead given. That is unless you are using fast 90 to fire (which you shouldn't, it's ineffective in comparison with the traditional method as described in the game manual). Of course, at close range, you can be wildly off and still hit, but I presume we're discussing medium-to-long range shots.

Try to get all the quantities (AOB, speed, range) with as much precision as possible. For speed and range it means one decimal point of precision on knots and centiradians respectively. Do bear in mind that the speed dial is bugged: you always need to enter more or less target speed minus 0.2 knots because your character looks at the TDC slightly from below. Hit me up for details.

Last edited by gurudennis; 10-12-2019 at 01:26 AM.
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Old 10-12-2019, 07:14 AM   #5
Pisces
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Quote:
Originally Posted by gurudennis View Post
Range matters a whole lot from any angle because it is the most significant factor that determines the time to target, and therefore it factors into the amount of lead given. That is unless you are using fast 90 to fire (which you shouldn't, it's ineffective in comparison with the traditional method as described in the game manual). Of course, at close range, you can be wildly off and still hit, but I presume we're discussing medium-to-long range shots.
No, the range is no factor in the amount (angle) of lead. As the target is further away, it to needs to move further along from when you hit the button to when it meets the torpedo. And the torpedo equally needs more time before it makes contact. The triangle of these distances is always in the same shape despite a difference in target range. And it is determined by the target speed, AOB and torpedo speed. Range cancels out of the equation for which lead angle you need.

Range only maters for a correction if the torpedo is steered away from your own bow (or stern for tube 5), to correct for the curve as the torpedo makes a turn. (the correction becomes larger the closer the impact will be) Set the TDC locked to the periscope/UZO, set a non-zero speed and non-zero AOB. Then point the periscope/UZO such that the gyro angle is 0. No amount of range setting will change the amount of lead or gyro angle. The angle between the optical targeting line and the torpedo course is constant. Change the AOB, or speed, or both. Then adjust the periscope/UZO direction to get the gyro-angle back to 0. Try to budge it with the range again. It won't.

The Fast 90 is a combination of a 0-gyro angle attack and the choice for being positioned perpendicular to the target course. The 0-gyro angle can be equally be effective (for canceling out range) if you are at any different angle to the target course. 45, 60 90, 120, it makes no difference. The benefit a 90 degree angle between torpedo trajectory and that of the target course is the margin of error to prevent a miss (broadside impact versus narrow aspect miss), or if implemented in the game-mechanics, the impact/collision geometry and dud chances. If the situation demands you to fire a torpedo to the target impacting with a 45 degree angle, the 0-gyro angle still works to cancel out range. Your margin of error for a hit is just 70% of a full broadside.

The range setting does affect the time to target calculation (and salvo angle), but that is a secondary feature to help determine when it is due. The torpedo would hit early or later eventually if range was set incorrectly with this 0-gyro angle setup. It would just come as a surprise. That is all.

Quote:
Try to get all the quantities (AOB, speed, range) with as much precision as possible. For speed and range it means one decimal point of precision on knots and centiradians respectively. Do bear in mind that the speed dial is bugged: you always need to enter more or less target speed minus 0.2 knots because your character looks at the TDC slightly from below. Hit me up for details.
Good point. With 3d modeling of dials reading them introduces parallax-error. The perspective on the dial background behind the needle changes how you read it. Ideally you would read the dial when straight in front of it, but alas the WP viewpoint is fixed. Which also makes it easier to read as it is steady. Something to be aware of indeed.
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Old 10-12-2019, 07:32 AM   #6
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The GIF of all GIFs:



As Pisces said, the answer is very different and range does matter at larger gyros and close ranges due to parallax (since we are not shooting torpedoes out of our scope but some 40 m forward).

And yes does not have to be a 90° track angle, what the gif is showing is valid at any angle So long as Gyro angle is minimized.
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Last edited by derstosstrupp; 10-12-2019 at 07:44 AM.
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Old 10-12-2019, 11:23 AM   #7
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The additional benefit of the (standard) Fast-90 method is that impacts on the same row occur simultaneously when torpedoes are fired as the target passes the optical line one after the other. But that requires the rows of a convoy to be perpendicular to the convoy course as well. Which is not always the case in Wolfpack I noticed. The gyro angle being 0 allows to aim at all columns with the same settings.
In this skewed case you need to be turned to the target course at the same angle as the skewed rows. (so they all line up again at impact time) And then it would rather be properly called the Fast-Any method.
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