Calculating Time to Impact of Torpedo

Able72 · 03-31-24, 09:47 AM

Okay. I'm working with excel.

I am trying to build an excel spreadsheet to help with the timing of my torpedo shots in U-boat (although this would work equally well with SH3-5).

Assuming you know the following:
Range to target at torpedo launch
Speed of target at torpedo launch
AOB at torpedo launch
Speed of torpedo

I am trying to calculate the run time of the torpedo to impact with the target.

I can't seem to find the formulas I need. Anyone have links or helpful information? Thanks.

Platapus · 03-31-24, 10:51 AM

Try https://maritime.org/doc/attack/index.php

If you are looking for precise timing, that gets complicated as you have to incorporate torpedo acceleration and speed during turns.

This is why a straight shot was easier to hit and when you use the "fast 90" or "Fast 45" techniques, it is all angles which makes it easier to hit.

Good luck with it

Able72 · 03-31-24, 11:37 AM

It doesn't have to be precise to the millisecond, just looking to get really close.

Thanks I'll check out the link.

Can you help me with figuring out the formulas I'll need? I've seen this doc and can't make heads or tails of it.

I would love to know how to figure out track angle, from that I could calculate the inverse of that angle and from there determine the range to impact. That relation to the speed of the torpedo would give me time to impact from torpedo launch. the problem is, I can't find out how to figure out track angle.

Able72 · 03-31-24, 06:23 PM

So...It took some digging and more frustration that I care to consider, but I finally figured out the answer to my problem. So I'm putting it here in case anyone else needs it or in case I delete the spreadsheet I made (again, don't ask).

If you know:
Range to Target
Target Speed
AOB
Torpedo Speed

The frustrating part about excel is that it calculates Sin, Cosin, Tan, etc, based on Radians, not Degrees. Therefore you have to employ the Radians and Degrees convertor in the right location to make the formulas work out. Using the values from the video below allowed me to check my formulas for accuracy.
Then you can calculate the following (formulas are for Excel):

Angle at Impact=180-(AOB + Lead Angle)

Lead Angle=DEGREES(ASIN(Target Speed*SIN(RADIANS(AOB))/Torpedo Speed))

Target Travel Distance to Impact=Range to Target*SIN(RADIANS(Lead Angle))/SIN(RADIANS(Angle at Impact))

Range to Impact=Range to Target*SIN(RADIANS(AOB))/SIN(RADIANS(Angle at Impact))

Time to Impact=Range to Impact/(Torpedo Speed*0.514444)

Mind you, these formulas are only useful for calculating the time to impact from torpedo launch (not gyro angles etc. and are closer to accurate the smaller your gyro angle).

These formulas also assume you are using the following units of measurement: Speed is in Knots and Distance is in Meters.

I found this video helpful in calculating this:

And this page helpful for solving the rest of the triangle: https://www.calculator.net/triangle-calculator.html

Platapus · 04-01-24, 03:06 PM

In the SH4 forum there are some excellent posts that explain this sort of stuff so that even I can understand it.

These may help

https://maritime.org/doc/index.php#sub

https://www.mathscinotes.com/2011/03...museum-docent/

03-31-24, 09:47 AM	#1
Able72 Captain Join Date: Mar 2008 Location: Somewhere in the North Atlantic Posts: 343 Downloads: 299 Uploads: 0	Calculating Time to Impact of Torpedo Okay. I'm working with excel. I am trying to build an excel spreadsheet to help with the timing of my torpedo shots in U-boat (although this would work equally well with SH3-5). Assuming you know the following: Range to target at torpedo launch Speed of target at torpedo launch AOB at torpedo launch Speed of torpedo I am trying to calculate the run time of the torpedo to impact with the target. I can't seem to find the formulas I need. Anyone have links or helpful information? Thanks. __________________ "Some ships are designed to sink, others require our assistance." Nathan Zelk

03-31-24, 10:51 AM	#2
Platapus Fleet Admiral Join Date: Oct 2006 Posts: 18,954 Downloads: 63 Uploads: 0	Try https://maritime.org/doc/attack/index.php If you are looking for precise timing, that gets complicated as you have to incorporate torpedo acceleration and speed during turns. This is why a straight shot was easier to hit and when you use the "fast 90" or "Fast 45" techniques, it is all angles which makes it easier to hit. Good luck with it __________________ abusus non tollit usum - A right should NOT be withheld from people on the basis that some tend to abuse that right.

03-31-24, 11:37 AM	#3
Able72 Captain Join Date: Mar 2008 Location: Somewhere in the North Atlantic Posts: 343 Downloads: 299 Uploads: 0	It doesn't have to be precise to the millisecond, just looking to get really close. Thanks I'll check out the link. Can you help me with figuring out the formulas I'll need? I've seen this doc and can't make heads or tails of it. I would love to know how to figure out track angle, from that I could calculate the inverse of that angle and from there determine the range to impact. That relation to the speed of the torpedo would give me time to impact from torpedo launch. the problem is, I can't find out how to figure out track angle. __________________ "Some ships are designed to sink, others require our assistance." Nathan Zelk Last edited by Able72; 03-31-24 at 12:09 PM.

03-31-24, 06:23 PM	#4
Able72 Captain Join Date: Mar 2008 Location: Somewhere in the North Atlantic Posts: 343 Downloads: 299 Uploads: 0	So...It took some digging and more frustration that I care to consider, but I finally figured out the answer to my problem. So I'm putting it here in case anyone else needs it or in case I delete the spreadsheet I made (again, don't ask). If you know: Range to Target Target Speed AOB Torpedo Speed The frustrating part about excel is that it calculates Sin, Cosin, Tan, etc, based on Radians, not Degrees. Therefore you have to employ the Radians and Degrees convertor in the right location to make the formulas work out. Using the values from the video below allowed me to check my formulas for accuracy. Then you can calculate the following (formulas are for Excel): Angle at Impact=180-(AOB + Lead Angle) Lead Angle=DEGREES(ASIN(Target SpeedSIN(RADIANS(AOB))/Torpedo Speed)) Target Travel Distance to Impact=Range to TargetSIN(RADIANS(Lead Angle))/SIN(RADIANS(Angle at Impact)) Range to Impact=Range to TargetSIN(RADIANS(AOB))/SIN(RADIANS(Angle at Impact)) Time to Impact=Range to Impact/(Torpedo Speed0.514444) Mind you, these formulas are only useful for calculating the time to impact from torpedo launch (not gyro angles etc. and are closer to accurate the smaller your gyro angle). These formulas also assume you are using the following units of measurement: Speed is in Knots and Distance is in Meters. I found this video helpful in calculating this: And this page helpful for solving the rest of the triangle: https://www.calculator.net/triangle-calculator.html __________________ "Some ships are designed to sink, others require our assistance." Nathan Zelk

04-01-24, 03:06 PM	#5
Platapus Fleet Admiral Join Date: Oct 2006 Posts: 18,954 Downloads: 63 Uploads: 0	In the SH4 forum there are some excellent posts that explain this sort of stuff so that even I can understand it. These may help https://maritime.org/doc/index.php#sub https://www.mathscinotes.com/2011/03...museum-docent/ __________________ abusus non tollit usum - A right should NOT be withheld from people on the basis that some tend to abuse that right.