Angle on bow and impact angle?

[Silence Suzuka]

Hi, I heard some saying that AOB is the angle of you on the perspective of target. Which make sense to me as it can use to define the triangle of you, target and expected hit point.

But when looking at impact angle, it makes me confused.

If AOB is about 85 degrees on both side, we get a 90 degree impact angle, which make sense to me again, as when enemy drives forward it gets a larger angle.

But then when i try a larger AOB like 130, it gives a very small impact angle. So the torpedo is hitting the front of target? I think i must misunderstood something.

[Valen]

When the AOB is 130 at the time of firing then it is well past the closest point in front of you. The enemy still moves forward, and the torpedo needs to be aimed further in front. So the impact angle becomes more closer to the rear of the enemy. A small angle if you will, but then it is to the enemy rear. A large angle to the enemy bow.

[ShepherdOfCats]

If your impact angle doesn't make sense when you look through the scope, then your angle on bow setting is *probably* wrong. Impact angle will usually be roughly similar to what you see when you look through the scope (unless you are doing some REALLY long range shooting and/or you wait a long time to fire). If you are looking at the enemy's butt, then the torpedo should hit them approximately in the butt. Looking at the side, the impact angle should show a predicted hit in the side. etc.—Again, it depends also on how far away your target is, because at long range, the computer will have to send the torpedo farther out in front of the target to get a hit, which will affect the angle of the torpedo to the target. In your example, you say the difference was 85 degrees and 90 degrees, which sounds like it was a pretty accurate shot worth taking *at that particular moment*, assuming your TDC data was correct. I don't think I really have enough information from your example to help you, but forget about angle of impact for a moment, I'm more concerned with why you are fiddling with the AOB setting as time goes by:

If you already determined the angle on bow to be roughly 85 degrees, why would you change it to 130? (unless you or the target changed course). Forget everything you know about angle-of-bow and remember it in this simple way:

**The AOB is just a measure of the degree difference between your own ship's course and the enemy's course.** Don't over-complicate it. Once you have calculated this input, AOB should NOT change unless (1) your enemy is taking evasive maneuvers, or (2) if you change course yourself, or (3) if you have good reason to believe your initial estimate of the enemy's course was very incorrect, and you must adjust it. Otherwise, the angle of bow should NOT be changed once calculated. If anyone touches it, you should reach over and slap his hand.

I'm guessing neither you nor your target changed course when you adjusted the AOB from 85 degrees to 130 degrees. That's why the computer was now giving you an impact angle that didn't "feel" right. Your angle of bow was more accurate when it was set at 85. You had it right (or at least close), but I'm guessing you let what you were seeing though the periscope confuse you and trick you into changing it. As you followed the target in the cross hairs, you were turning your periscope, but you weren't turning your whole ship, and unless you scared the enemy, his course probably never changed either, so the angle between both of your bows (your relative courses) never changed.

If you know the target's course and it is not changing, and you know your own course and it is not changing, then it is easier to calculate angle on bow from the map, since tracking the target through the scope is just going to confuse you. Just draw two intersecting lines, one representing your ship's course and one representing your target's course, and measure the difference in degrees between the two. (this is a good job for the navigator, assuming you have been stalking the convoy long enough to get a good estimate of their course). Try it yourself and I guarantee you will have a "EUREKA!" moment when it comes to understanding angle of bow. THEN you can worry about impact angle, because that information is just feedback from the computer based on what you tell it, and is more useful as a way for you to determine whether or not your calculations and conditions are decent enough to fire a shot. It won't match up exactly, due to the speed and distance of your target, but it should at least seem reasonable.

[edited several times for clarity purposes]

[Silence Suzuka]

Originally posted by Valen:

When the AOB is 130 at the time of firing then it is well past the closest point in front of you. The enemy still moves forward, and the torpedo needs to be aimed further in front. So the impact angle becomes more closer to the rear of the enemy. A small angle if you will, but then it is to the enemy rear. A large angle to the enemy bow.

I'm not changing the AOB during my aiming, that is what i did when i try to figure out how does the AOB works.

I thought AOB is like the angle between the you and the enemy route. So like if the enemy is heading North, and i set at north west, the AOB will be somewhere like 45 to the left of enemy, and if i'm at south east, the AOB will be like 135 to the right. Like this image shows
http://upload.wikimedia.org/wikipedia/commons/1/1d/FiringGeometry.png

Then if the enemy is at full stop and i'm facing the enemy, the torpedo should hit at same angle as my AOB. And if it is still moving forward, the angle will be larger as you said "closer to the rear of enemy", but my TDC gives an impact angle like 40 degrees when i use an AOB of 130.

So either i misunderstand the AOB, so when i'm behind the enemy i should use an AOB smaller than 90 degrees. Or the Impact angle is counted from the rear of the ship, so when i hit someone at 130 AOB, the impact angle is roughly 40 degrees.

[Lexor76]

In your picture the top left angle of the triangle is AOB(I'd estimate about 50° bow right)

[Silence Suzuka]

Originally posted by Lexor76:

In your picture the top left angle of the triangle is AOB(I'd estimate about 50° bow right)

yes i do think so. But the problem is in this case, if the target is stationary, we should have an impact angle close to the AOB, which is 50 degrees right, but in TDC it gives an impact angle larger than 90 degrees.

[Valen]

I've had another look in the TDC and the Impact angle needle does seem to be indicating a confusing angle. That is, the color indicates which side the impact is on, but the number indicates the angle from Target course to Torpedo course (so the angle when it is outbound having passed without detonation). Which seems technically correct as impact angle is Target course to Torpedo course measured from target bow. I used these descriptions as reference: http://tvre.org/en/torpedo-directors

I used the following TDC state. I did not record the Uboat course so let's consider it to be dead North. No other dials on the TDC are north referenced, nor is the Uboat turning so it doesn't matter.

http://ricojansen.nl/image/Wolfpack/FunnyImpactAngle.jpg

TDC: feed director off (i.e. bearing from TDC heading)
Bearing/Heading=348
AOB = 134 (135-ish large scale and 4 green mark at the bottom faster dial if you look carefully)
Speed =7 kts
Range 1.5 km
Gyro Angle 358

The above would mean that the Target course is 034. (=348-180-134)
With the gyro angle being 2 degrees port, the impact angle as shown in the referenced documentation (alpha) would be 36 degrees. That is angle 36 on the stern for the torpedo, which is by rule of X-angles the same as target course to torpedo outbound course as counted from target bow.

I'm not sure if this dial is wrong, or just non-intuitive.

[Snipsild]

The dial of the AOB setting on the TDC is wrong. It should be 0 downwards and 180 upwards.
0 deg means that the target is coming straight to you and 180 is if the target is going away from you.

[Lexor76]

Originally posted by Snipsild:

The dial of the AOB setting on the TDC is wrong. It should be 0 downwards and 180 upwards.
0 deg means that the target is coming straight to you and 180 is if the target is going away from you.

No it's not wrong - the way it is depicted in the game is exactly how it was installed in real life.

[Jakob]

https://i.imgur.com/wjtlnOa.jpg

[Snipsild]

Then the arrow is not pointing in the course heading of the target?

[Lexor76]

Originally posted by Jakob:

https://i.imgur.com/wjtlnOa.jpg

Nice picture, looks like U-995

Originally posted by Snipsild:

Then the arrow is not pointing in the course heading of the target?

No, the needle points towards your submarine.
https://steamcommunity.com/sharedfiles/filedetails/?id=1708455928

[Snipsild]

But if the target is heading straight to you, is the AOB not 0 deg?

[Lexor76]

Originally posted by Snipsild:

But if the target is heading straight to you, is the AOB not 0 deg?

Yes, it is 0°

[Snipsild]

That is not what is stated in the manual!

[Snipsild]

https://steamcommunity.com/app/490920/images/