Sub Skipper's Bag of Tricks

[Rockin Robbins]

Yes, it's really easy to forget that all we're doing is drawing a scale model of the firing solution and start to confuse 4400 yards on the graphic solution with an actual 4600 yards distance required to make the shot.

Keep practicing and it all becomes automatic. But when you're first learning it's easy to become confused about all the details. Keep up the good work!

Hitman, the fact that the Germans did it could have lent a halo effect to the assumption in American sub movies that Americans did it too. The Germans had some important advantages. First the Atlantic was crawling with hundreds of pretty identical cookie-cutter Liberty boats. Once you learned the RPM/speed curve for one you had the keys to the city. Also the open nature of American and British societies, where information valuable to enemy combatants easily enters public knowledge, made information on our merchant shipping much more accessible than the relatively closed society of Japan.

[Hitman]

First the Atlantic was crawling with hundreds of pretty identical cookie-cutter Liberty boats. Once you learned the RPM/speed curve for one you had the keys to the city. Also the open nature of American and British societies, where information valuable to enemy combatants easily enters public knowledge, made information on our merchant shipping much more accessible than the relatively closed society of Japan.

Cheers, good observation

As far as I have seen, boy have you guys been able to capitalize on any new idea that someone has pointed out! The cold war american sonars were simply the best, despite germans having lead the way to that rpm count, and I always like to remember the memorable sentence from Jules Verne in his novel "A Journey to the Moon", where he said "What an american can imagine, another one can do it"

In any case, I wanted also to pay another tribute to the John P. Cromwell attack method (45º AOB shots) with something I recently readed:

The very same U-Boot Commander's Handbook says:

95.) When attacking ships with low and medium speeds, at close range, it ballistically advantageous to fire at an angle of the target of 90, as errors estimating the position will in this case have the least effect, besides which the speed of the enemy can be most accurately gauged in this position. If the range is longer (over 1,000 m), and the target is traveling at a high rate of speed, an attempt should be made to launch the torpedo at a smaller angle, say, 60.

Since the angle the book is referring to is the opposite to the track angle, it is in fact recommending a 40º attack , i.e. the John P. Cromwell one!

Amazing

[Rockin Robbins]

Amazing find! Yes, the John P Cromwell is a finicky beast too! If you're firing torpedoes in the daytime, you'd better be using electric eels. Especially if you're launching them with a longitudinal spread, all in the same line, all the target has to do is turn into the line of fire and watch them all miss.

But with electric torpedoes, the game changes entirely in your favor. The effective speed of the torpedo is greater because the closing speed with the target gets a healthy assist from 70% the target's own speed plus the speed of the torpedo. With a 31 knot Mark 18 and a 20 knot target, that's a healthy 45 knot closing speed! With no wake! This is calculated from the standard 45º attack.

Also those nasty warships have a habit of detecting you just before you unleash the Dick O'Kane shot. Then the whole plan goes to worms, you try to get a quick down the throat shot, which just puts you at death's door when you miss... It can be very bad for your disposition.

Yes you hit on a great point. The John P Cromwell is for warships! And we're not doing anything new. Those WWII sailors were pretty sharp!

[Hitman]

And we're not doing anything new. Those WWII sailors were pretty sharp!

Ah, you touched now a sensible point in me! I am a great enthusiast of the classics (I mean roman and greeks!), and did you know? The romans had a saiy that goes like this: "Nihil novum sub solem" which means in latin "Nothing new under the sun", i.e. we are continuously reinventing the wheel , but those before us knew that already!

Not a long time ago, I was developing a method of determining AOB based on "aspect ratio", and once I had finished, you know what happened? I discovered that by 1912 the periscope manufacturers Zeiss (German) and Barrs& Stround (Britain) had long ago developed such a method! And me, here, thinking I had found the keys to the holy grail

So, when I read books like those from O'Kane, Kretschmer and similar aces, I just can think: "Respect, man!" Those guys knew the same you just have found out, but decades, or even centuries before

[Distortion]

Yeeeaaah, on my 1st patrol, using the vector analysing, I`v got myself a nice Kongo class ship, and sink it with 3 torpedo`s. It was a convoy of about 2 Kongo`s in the middle, defend by some destroyers, and cruisers. My first plan was to use slow and fast torpedo`s, and put both kongo`s out of action. That didnt worked well. For the first kongo I used slow torpedos, with a speed of 31 knots. For the second I used fast torpedos with a speed of 46 knots. The speeds of the targets was 14.5 knots. I draw 2 line for the torpedo speed, one 3100 yards, the other 4600 yards, and calculated the lead angles. Strange thing it the slower ones didnt hit the target, the fast ones did. What gives? Do I need another tactic with this one?

thanks guys

Robert

[Rockin Robbins]

Error tolerance, man! When you're out there bobbing around in the big green ocean, there are errors in every measurement you make, especially in target speed. Warships love to speed up and slow down, zig back and forth and generally screw up our magnificent vector triangles. And they are moving fast. A small error can make us miss, not just hit an unplanned part of our target.

So everything we do in putting together an attack plan should have one goal in mind: mitigating the effects of inevitable error. The absolute BEST factor in that is torpedo speed. The faster the torpedo speed, the more error tolerant your solution.

Three rules for maximum error tolerance:

GET CLOSE a shot from 700 yards gives the enemy almost no time to avoid and is twice as error tolerant as a shot from 1400 yards.

WATCH YOUR TORPEDO TRACK ANGLE that's the angle at which the torpedo strikes the target. The closer to 90º the torpedo is, the more error tolerant your solution. As mentioned above in another post, there are reasons to toss this one out the window with warships.

USE THE SMALLEST POSSIBLE GYRO ANGLE preferrably zero, with the vector analysis attack. This eliminates range from the solution and is possibly the most important factor in mitigating error if you have no radar.

USE FAST TORPEDOES discussed above. The faster you can get the boom to the target the less time there is for something to go wrong. And the difference in impact point along the target length for a given error is larger or smaller in proportion to the torpedo speed, with the faster torpedo having the least variable impact point.

One, two three.........more than three. See? There is error in my targeting solution. And a final thought: you're going to have some misses. I have lots of them. If all you shoot is the sure things, your score isn't going to be very good. Take your misses with a smile and learn from them. No guts, no glory.

[Distortion]

I`l guess you are right, I trust to much on my calculations, and the fact that the enemy screw things up. Thanks for your tips, really appreciate it.

[Frederf]

Originally Posted by Rockin Robbins

WATCH YOUR TORPEDO TRACK ANGLE that's the angle at which the torpedo strikes the target. The closer to 90º the torpedo is, the more error tolerant your solution.

How do you explain this diagram?