SUBSIM Radio Room Forums - View Single Post - Two Historical Firing Methods (Hit What You Are Aiming At Without AOB or Speed)

derstosstrupp · 03-09-16, 07:41 PM

Step 1:
Gain position forward of enemy’s beam. Submerge once a position sufficiently forward of the target’s beam has been achieved. Otherwise, at larger AOBs, a constant bearing may not be possible due to the low underwater speed of the sub. Not too far forward, however, that the target presents too sharp of an AOB – your eels will then have little surface area of the target to impact.

Step 2:
Achieve a collision course to target by either adjusting own speed or turning to or away so that the target bearing does not change.

Step 3:
Ideally, maintain this constant bearing for a period of 10-15 minutes, preferably the 10-15 minutes up to firing. 10-15 minutes allows you be sure you are truly on a collision course, however in practice you could get by with much less, perhaps 3-4 minutes. Use this time to set up your eels for firing (depth, pistol, outer doors etc).

Step 4:
Set up TDC for the shot.
1. With scope pointed at the target (collision bearing you’ve been hopefully maintaining), set AOB in TDC to 90 starboard or port based on the direction of the target’s bow.
2. Compute speed for the TDC as follows:
a. Own speed x sin(target bearing) = target speed to input into TDC. Remember, this is degrees from the bow, so if she’s constant at bearing of 330, the target bearing for this formula is 30!
3. Immediately prior to firing, obtain a range estimate and input into the TDC. Now toggle TDC to auto. This is a must to correct for parallax, or the error caused by the fact that you are not shooting torpedoes out of the lens of your periscope, unless of course the gyro angle is within 10 degrees or so of your bow, in which case parallax error is moot. Use whatever your GUI offers. I use Hitman’s top-notch GUI and thus only estimate using the scope reticles. This is more than sufficient. Just know that errors due to inaccurate range will be more pronounced the closer you are and the larger the gyro angle. Alternatively, you could start a turn toward the target once you obtain the gyro angle for the shot and pull the trigger once your bow crosses the zero gyro angle bearing, thus eliminating the need for the torpedo to turn and the need for a range estimate, but I have found this a bit unwieldy in practice.

Step 5:
Once at a good firing range, fire!

Nary was a mark or line or angle drawn on the map throughout this whole process. No information was needed from the rec manual either, although a rough knowledge of the target’s mast height is needed for a range estimate if at large gyro angles.

Below is a video demonstration of this method:

03-09-16, 07:41 PM	#2
derstosstrupp Grey Wolf Join Date: Aug 2008 Posts: 887 Downloads: 489 Uploads: 0	Ausdampfverfahren (Constant Bearing to Target) Step 1: Gain position forward of enemy’s beam. Submerge once a position sufficiently forward of the target’s beam has been achieved. Otherwise, at larger AOBs, a constant bearing may not be possible due to the low underwater speed of the sub. Not too far forward, however, that the target presents too sharp of an AOB – your eels will then have little surface area of the target to impact. Step 2: Achieve a collision course to target by either adjusting own speed or turning to or away so that the target bearing does not change. Step 3: Ideally, maintain this constant bearing for a period of 10-15 minutes, preferably the 10-15 minutes up to firing. 10-15 minutes allows you be sure you are truly on a collision course, however in practice you could get by with much less, perhaps 3-4 minutes. Use this time to set up your eels for firing (depth, pistol, outer doors etc). Step 4: Set up TDC for the shot. 1. With scope pointed at the target (collision bearing you’ve been hopefully maintaining), set AOB in TDC to 90 starboard or port based on the direction of the target’s bow. 2. Compute speed for the TDC as follows: a. Own speed x sin(target bearing) = target speed to input into TDC. Remember, this is degrees from the bow, so if she’s constant at bearing of 330, the target bearing for this formula is 30! 3. Immediately prior to firing, obtain a range estimate and input into the TDC. Now toggle TDC to auto. This is a must to correct for parallax, or the error caused by the fact that you are not shooting torpedoes out of the lens of your periscope, unless of course the gyro angle is within 10 degrees or so of your bow, in which case parallax error is moot. Use whatever your GUI offers. I use Hitman’s top-notch GUI and thus only estimate using the scope reticles. This is more than sufficient. Just know that errors due to inaccurate range will be more pronounced the closer you are and the larger the gyro angle. Alternatively, you could start a turn toward the target once you obtain the gyro angle for the shot and pull the trigger once your bow crosses the zero gyro angle bearing, thus eliminating the need for the torpedo to turn and the need for a range estimate, but I have found this a bit unwieldy in practice. Step 5: Once at a good firing range, fire! Nary was a mark or line or angle drawn on the map throughout this whole process. No information was needed from the rec manual either, although a rough knowledge of the target’s mast height is needed for a range estimate if at large gyro angles. Below is a video demonstration of this method: