WesWorld

The following is a formula for torpedo hits on targets acounting for range, target speed and target size. I'm planning to use this in a combat system using ships designed in Springsharp.

It is based on some percentage hit values for some naval rules I had kicking around and it seems to fit reality. I'll test it over Easter and post results.

I plan to use the procedure of:

1. Nominate target - torpedo is launched

2. All ships and torpedo move.

3. Torpedo heads towards target, if target is within red area (a circle on chart) then roll die (generate random number) as below. Red circle could be bigger depending on how many torpedoes in spread.

Formula:

=(100-((20000/({range}*({range}/(({range}/2500)+(SQRT({range})/80)))/10000))-2)+((100-(100-((20000/({range}*({range}/(({range}/2500)+(SQRT({range})/80)))/10000))-2)))*(((((LOG(1000,{size})))/0.944557)-0.69)*2.2)))+(({speed}-20)/3)


Size in tons
Range in yards
Speed in Knots

Destroyer Size
Size Range Speed
1500 3600 00 83 17% to hit
1500 3600 06 85 15% to hit
1500 3600 09 86 14% to hit
1500 3600 12 87 13% to hit
1500 3600 15 88 12% to hit
1500 3600 18 89 11% to hit
1500 3600 21 90 10% to hit
1500 3600 24 91 9% to hit
1500 3600 27 92 8% to hit
1500 3600 30 93 7% to hit

Size Range Speed
1500 4900 00 86 14% to hit
1500 4900 06 88 12% to hit
1500 4900 09 89 11% to hit
1500 4900 12 90 10% to hit
1500 4900 15 91 9% to hit
1500 4900 18 92 8% to hit
1500 4900 21 93 7% to hit
1500 4900 24 94 6% to hit
1500 4900 27 95 5% to hit
1500 4900 30 96 4% to hit

Size Range Speed
1500 7200 00 89 11% to hit
1500 7200 06 91 9% to hit
1500 7200 09 92 8% to hit
1500 7200 12 93 7% to hit
1500 7200 15 94 6% to hit
1500 7200 18 95 5% to hit
1500 7200 21 96 4% to hit
1500 7200 24 97 3% to hit
1500 7200 27 98 2% to hit
1500 7200 30 99 1% to hit


Cruiser Size
Size Range Speed
10000 3600 0 69 31% to hit
10000 3600 6 71 29% to hit
10000 3600 9 72 28% to hit
10000 3600 12 73 27% to hit
10000 3600 15 74 26% to hit
10000 3600 18 75 25% to hit
10000 3600 21 76 24% to hit
10000 3600 24 77 23% to hit
10000 3600 27 78 22% to hit
10000 3600 30 79 21% to hit

Size Range Speed
10000 4900 0 77 23% to hit
10000 4900 6 79 21% to hit
10000 4900 9 80 20% to hit
10000 4900 12 81 19% to hit
10000 4900 15 82 18% to hit
10000 4900 18 83 17% to hit
10000 4900 21 84 16% to hit
10000 4900 24 85 15% to hit
10000 4900 27 86 14% to hit
10000 4900 30 87 13% to hit

Size Range Speed
10000 7200 0 83 17% to hit
10000 7200 6 85 15% to hit
10000 7200 9 86 14% to hit
10000 7200 12 87 13% to hit
10000 7200 15 88 12% to hit
10000 7200 18 89 11% to hit
10000 7200 21 90 10% to hit
10000 7200 24 91 9% to hit
10000 7200 27 92 8% to hit
10000 7200 30 93 7% to hit

Battleship Size
Size Range Speed
35000 3600 0 62 38% to hit
35000 3600 6 64 36% to hit
35000 3600 9 65 35% to hit
35000 3600 12 66 34% to hit
35000 3600 15 67 33% to hit
35000 3600 18 68 32% to hit
35000 3600 21 69 31% to hit
35000 3600 24 70 30% to hit
35000 3600 27 71 29% to hit
35000 3600 30 72 28% to hit

Size Range Speed
35000 4900 0 72 28% to hit
35000 4900 6 74 26% to hit
35000 4900 9 75 25% to hit
35000 4900 12 76 24% to hit
35000 4900 15 77 23% to hit
35000 4900 18 78 22% to hit
35000 4900 21 79 21% to hit
35000 4900 24 80 20% to hit
35000 4900 27 81 19% to hit
35000 4900 30 82 18% to hit

Size Range Speed
35000 7200 0 80 20% to hit
35000 7200 6 82 18% to hit
35000 7200 9 83 17% to hit
35000 7200 12 84 16% to hit
35000 7200 15 85 15% to hit
35000 7200 18 86 14% to hit
35000 7200 21 87 13% to hit
35000 7200 24 88 12% to hit
35000 7200 27 89 11% to hit
35000 7200 30 90 10% to hit

Looks like a start, for a high-level system. Is there no affect from torpedo speed? And how would torpedo planes be handled (or wouldn't they, yet)? How about the effects of a target that was manuevering vs one that was in formation?

Looks pretty good to me.

Question: How long until you´ve a total set of rules? What is still missing?

IIRC, you introduced rules for gun fights, now for torpedos. There was also somethinig about damage, but I can´t really remember.

I think I'd argue that the length of the target is more important than the displacement...

I'd agree with that, an end on attack will have less space to shoot at.

Longer ship is also a easier target becose its turn circle is larger.
Historicly speed was not that much of a advantege as was manuver.As then manuver is already counted in the sistem so this point is mute.

You could decrease 'size' to account for aspect.

Speed will let you evade if you can.

With regards to length, you also need to think in terms of depth. A larger or bulkier target is less maneuverable and so has less options to predict for a fire control solution - or a hit is more likely.

The gun stuff was about 14 months ago and then I was bogged down with torpedoes so it went quiet. I hope to include this in a calculator in Flash.

Cheers,

Quoted

Longer ship is also a easier target becose its turn circle is larger.

That's generally true, Marek, but not always. IIRC, the Fletchers were notoriously un-handy, and those that served post-war had a much larger rudder installed.

The Alaska's with their single rudder had a larger tactical diameter than the Iowa's. And the Iowas were nearly twice as large at full load...

Regards,

Big Rich

http://www.navweaps.com/index_tech/tech-067.htm

Some statistics for Japanese torpedo effectiveness. IIRC, the RN scored better overall with a higher average. This is probablyy due to the shorter range at which torpedoes were launched.