Experiment 1 – range v gyro angle.

[Sea Hawk]

I have read on this forum that range does not matter when attacking a target using the fast 90’ method.

I decided to put this to test.

Method A
I imagined attacking a target using the fast 90’ method. My Sub was heading north, with the target travelling due East at 9N and due to pass directly in front of me at a range of 1000m. I pointed my periscope to 0’, set the AOB to 90’ from the starboard and set the speed to 9N. I then moved my periscope until the gyro angle was 000 – my intended firing position. This was assumed to be the perfect position and settings to hit the target.
I then altered the range on the TDC to simulate me inputting inaccurate range data into the TDC. I observed what effect altering the range had on the gyro angle, read off from the periscope.
I repeated the experiment assuming the target was approaching me heading SE (i.e. target heading at 45’ to my heading), this time moving the periscope to 45’ before setting the AOB to 90’ from starboard. I moved the periscope until the gyro angle was 000 and altered the range while observing the effect on gyro angle.
This was repeated with the target heading NE away from me.

Results A

The effect of inaccurate range estimation on gyro angle when fireing at 000 gyro angle

Target heading ...................SE ........................E .............................NE
..................................towards me ........accross my bow ...........away from me
Scope bearing ..................350 .......................344 ............................15

Entered range
into TDC............................Gyro......................Gyro...........................Gyro
300m................................000........................000...................... ......000
1000m..............................000........................000...................... ......000
10000m............................000........................000...................... .......000

Method B

My sub was again heading N with the target heading E at 9N due to cross my bow at a distance of 1000m. I inputted the target data into the TDC as above with the periscope pointing at 0’.
I then moved my periscope until the gyro angle was 45’ to the left (port) assuming that I fire before the target has reached the perfect gyro angle. I then altered the range and observed the effect on the gyro angle.
I repeated this with the periscope pointing so that the initial gyro angle was 45’ to the right (Starboard) assuming I fired after the target had passed in front of me.

Results B

The effect of inaccurate range estimation on gyro angle when firing at different gyro angle's

Target heading ....................E .........................E ..........................E
Scope bearing ...................309 .......................344 .......................27
initial gyro angle ................315 .......................000 .......................045

Entered range
into TDC........ ....................Gyro ....................Gyro .....................Gyro
300m .................................300 ......................000 .......................055
1000m ................................315 ......................000 ......................045
2000m ................................317 ......................000 ......................044
10000m ..............................319 ......................000 .......................043


Conclusions

• During the attack run accurate range estimation is not needed provided the torpedo is fired at a gyro angle of 000. This is applicable to any angle of bow, with the target heading in any direction relative to the U-boat (not only to when attacking from 90’).

• When making your attack run using the fast 90’ method then incorrect range estimation will effect the accuracy of your torpedo if it is fired at any gyro angle other than 000.

These conclusions apply to the game silent hunter 3 + GWE
I will leave it up to the members with a more extensive historical knowledge to say whether these conclusions are applicable to actual u-boats using a real TDC.

Experiments to come:-
The affect of inaccurate AOB data on gyro angle.
The affect of inaccurate speed data on the gyro angle.