Zero Gyro Angle-No TDC Required Firing method video

gumbeauregard · 08-28-17, 11:52 PM

Here is a film of my Zero Gyro Angle attack method with a graphical explanation of the trigonometric relationship of target speed and torpedo speed.

Notes:

1 knot is 33.7 yards per minute so that is about 100 yards every 3 minutes for each knot.

If you take positions every three minutes the yards moved divided by 100 =knots of speed for the target.

I use two different torpedo speeds in the film.
29 knot Mark 18's and Mark 14's set to run at high speed at 46 knots.

The target speed was found to be 11 knots

Deflection angle for 11 knot target with 46 knot torpedo can be found on the Wiki chart
https://en.wikipedia.org/wiki/Torped...ctionAngle.png

Note this chart is only valid for 46 knot torpedoes.

Or you can use this calculator
http://www.couscouscrabcakes.com/okane.html

The above calculator works great.

Or you can make your own table of values in Excel using =DEGREES(ATAN Target Speed/Torpedo Speed)

Notice there is no need to put anything into the TDC with this method.

Once I know the target speed all I do is get to my shooting position, 1000 yards or less from target track and 100 degrees Torpedo track angle (The angle formed by the target track and the torpedo track)

The calculated firing bearing for 29 knot torpedo and 11 knot target is 21 degrees port which is a bearing of 339 degrees (360 - 21 =339). The 46 knot torpedoes for an 11 knot target is 13 degrees port or 347 degrees (360-13=347)

Range is unnecessary for this method as the ratio of the target speed to torpedo speed remains the same, thus the angle does not change with range to target.

The firing bearings generated by the chart are good for torpedo track angles of 70 to 110 degrees with the ideal angle being 100 as in the video

If you want to use this method at torpedo track angles outside this range there are simple rules of thumb to reduce the firing bearing.

For a 60 degree torpedo track angle, multiple the deflection angle by .75 which is 75% or three quarters of the calculated deflection for a 90 degree shot.
For example, a 29 knot torpedo fired at an 11 knot target is 21 degrees times .75 or a deflection angle of 15 degrees

At 40 degrees use half the table or calculated value. Half of 21 is 10 degree angle using the same example.

For a down the throat shot at 18 degrees, use 25% or one quarter of the calculated angle. 5 degrees in this case.

Be aware that shots deviating from the ideal of 100 degrees torpedo track will be proportionally less tolerant of errors in the target speed and more likely to get duds the further from the ideal you get.

The method demonstrated here was developed by me beginning in 2007 after reading everything available on the historical record, browsing this board and gleaning tidbits and employing my own personal interest in the math involved with shooting accurately.

It WILL NOT work for stern torpedoes in SH4 because you have to input a TDC solution for the stern tubes or the software prevents them from firing.

So no matter what you will have to learn to use the SH4 TDC if you want to shoot stern shots.

08-28-17, 11:52 PM	#1
gumbeauregard Seaman Join Date: Feb 2008 Location: Houston, Texas Posts: 41 Downloads: 16 Uploads: 0	Zero Gyro Angle-No TDC Required Firing method video Here is a film of my Zero Gyro Angle attack method with a graphical explanation of the trigonometric relationship of target speed and torpedo speed. Notes: 1 knot is 33.7 yards per minute so that is about 100 yards every 3 minutes for each knot. If you take positions every three minutes the yards moved divided by 100 =knots of speed for the target. I use two different torpedo speeds in the film. 29 knot Mark 18's and Mark 14's set to run at high speed at 46 knots. The target speed was found to be 11 knots Deflection angle for 11 knot target with 46 knot torpedo can be found on the Wiki chart https://en.wikipedia.org/wiki/Torped...ctionAngle.png Note this chart is only valid for 46 knot torpedoes. Or you can use this calculator http://www.couscouscrabcakes.com/okane.html The above calculator works great. Or you can make your own table of values in Excel using =DEGREES(ATAN Target Speed/Torpedo Speed) Notice there is no need to put anything into the TDC with this method. Once I know the target speed all I do is get to my shooting position, 1000 yards or less from target track and 100 degrees Torpedo track angle (The angle formed by the target track and the torpedo track) The calculated firing bearing for 29 knot torpedo and 11 knot target is 21 degrees port which is a bearing of 339 degrees (360 - 21 =339). The 46 knot torpedoes for an 11 knot target is 13 degrees port or 347 degrees (360-13=347) Range is unnecessary for this method as the ratio of the target speed to torpedo speed remains the same, thus the angle does not change with range to target. The firing bearings generated by the chart are good for torpedo track angles of 70 to 110 degrees with the ideal angle being 100 as in the video If you want to use this method at torpedo track angles outside this range there are simple rules of thumb to reduce the firing bearing. For a 60 degree torpedo track angle, multiple the deflection angle by .75 which is 75% or three quarters of the calculated deflection for a 90 degree shot. For example, a 29 knot torpedo fired at an 11 knot target is 21 degrees times .75 or a deflection angle of 15 degrees At 40 degrees use half the table or calculated value. Half of 21 is 10 degree angle using the same example. For a down the throat shot at 18 degrees, use 25% or one quarter of the calculated angle. 5 degrees in this case. Be aware that shots deviating from the ideal of 100 degrees torpedo track will be proportionally less tolerant of errors in the target speed and more likely to get duds the further from the ideal you get. The method demonstrated here was developed by me beginning in 2007 after reading everything available on the historical record, browsing this board and gleaning tidbits and employing my own personal interest in the math involved with shooting accurately. It WILL NOT work for stern torpedoes in SH4 because you have to input a TDC solution for the stern tubes or the software prevents them from firing. So no matter what you will have to learn to use the SH4 TDC if you want to shoot stern shots.