[needed] British Fruit Machine

[keltos01]

could someone mod the TDC into a British fruit machine ?

operation of the BFM :

http://home.cogeco.ca/~gchalcraft/sm/attack.html

topic by Nisgeis over at kickingback :




http://forum.kickinbak.com/viewtopic.php?f=29&t=2033


keltos

[Hitman]

I have been wanting to do this since WDAD came out, the problem is that the only thing I can do for now is change the dials graphics, and not the sizes. I did recently an experiment using Karamazov's explanations about how the menu-ini works, as I wanted to have the slide out panels resize when you increase reslolution (Instead of becoming increasingly smaller as they do now) but it cause problems with the background of the panel!

Still, this is an area I'd like to work a bit on, though I can't promise any results soon.

I will start by doing the dial graphics as a direct-drop replacement, and we will see later if we can manage to resize the slide out TDC

[keltos01]

Originally Posted by Hitman

I have been wanting to do this since WDAD came out, the problem is that the only thing I can do for now is change the dials graphics, and not the sizes. I did recently an experiment using Karamazov's explanations about how the menu-ini works, as I wanted to have the slide out panels resize when you increase reslolution (Instead of becoming increasingly smaller as they do now) but it cause problems with the background of the panel!

Still, this is an area I'd like to work a bit on, though I can't promise any results soon.

I will start by doing the dial graphics as a direct-drop replacement, and we will see later if we can manage to resize the slide out TDC

This is Xmas !!!!!!!

thanks Hitman !!!

still trying to find out if the french had anything similar if any

keltos

[Hitman]

I'm progressing and have the main mask for the slide out TDC, but despite having done new dials, they don't show up???

[keltos01]

TORPEDO ANGLE SOLVER MARK VIII

Torpedo Angle Solver Mark VIII Operating Instructions, O.D. 3518, 1941 describes the hand operated torpedo fire control backup to the automated Torpedo Data Computer. It was commonly called the "banjo" and is used to calculate the angle a torpedo should be fired by an submarine.

INSTRUCTIONS FOR USE


1. The Torpedo Angle Solver Mark VIII is a simple portable instrument designed to compute the required data for firing submarine torpedoes of various marks and powers at gyro angles up to 90 degrees from all classes of submarines.

http://www.hnsa.org/doc/banjo/index.htm

[Hitman]

I'm afraid that I will have to give up on doing a full new and improved Fruit Machine to replace the current slide out TDC. I will continue and end the simple replacement graphics I have already showed, but sadly the menu.ini is too complicated for me to do something like Karamazov did for the UBoats with his KIUB. If he wants to do the new slide out TDC I will gladly provide the improved graphics I wanted to create, but without someone with better knowledge engaging the task of doing the new panel, I am powerless.

[keltos01]

some US skippers liked 0 degrees angle too !



Uploaded with ImageShack.us

Uploaded with ImageShack.us

nice reading ! from take her deep

[keltos01]

from Elanaiba :

Back to the problem at hand, which Keltos brought to my attention... I don't have more solutions than you guys. I should have thought about this one at some point and have the programmers ad some extra stuff to account for British practice, which was not completely unknown to me

I wonder if the firing button could be blocked when the gyro angle was different from a set of values?


from hitman :


http://www.subsim.com/radioroom/newr...eply&p=1556698

It's actually very easy with the US TDC, even if you set the torpedoes to the correct zero degree Gyro Angle. Here's how to do it:

1.- Determine target course, approximately, either by eyeballing AOB (To start) or plotting (Visual or radar). Get on a course that is perpendicular or, at least, something between 45º and 90º of the enemy track (So that the torpedo has enough angel of impact and does not make a dud)

2.- Feed the TDC with all the data, and start the position keeper. Make regular corrections as you see fit, by entering new data (New estimates of speed, distance, AOB, etc, as usual)

3.- Your reference for knowing when to shoot is the Gyro Angle needle on the "own ship" dial (The lower dial in the TDC). When that needle points exactly to the bow of the ship silhouette in the dial, you must shoot the torpedo. Why? Because at that moment the necessary Gyro Angle to hit the target is zero, which is exactly the only thing your torpedo is capable of

That's more or less how the british TDC worked, only that when the GA was zero you also got an audible warning in the form of a bellring or buzz

Originally Posted by Hitman

Here's a graphical example:



The red arrow represents the direction your bow is pointing at. A torpedo that follows the same course as you, straight from your bow, is obviously a zero Gyro Angle torpedo, and it will follow the red arrow in its course -same as your ship's course.

Then the moving needle in the dial, highlighted in green represents what Gyro Angle must your torpedo do in order to hit the target that is shown in the upper dial.

Hence, when the needle matches the red arrow, that means that the torpedo must not turn at all to hit the target, i.e. it will be a Zero GA shot, and the moment of shooting has arrived.

Is it all understandable?

Originally Posted by Hitman

Many thanks for taking some time to consider the problem Dan

Locking the fire button could be a solution, even if not a perfect one. If we can make it display the grayed-out graphic normally and highlight in red when the torpedo has a zero GA that would be somehow similar to the original buzzer and burning light in the Fruit Machine.

But I have no idea how to do that

Any suggestions on how to link the button graphic to the GA?

If the own ship dial was stationary, we could maybe solve it by converting the GA pointer into a circular dial with a hole that shows the button and makes it available only when the dial comes to zero. But since the own ship dial also rotates, the pointer shows the zero GA in any part of it, so we would need to have the fire button rotate all around with it, which would be confusing and probably also impossible to do.

Hmmmmm another alternative, since the own ship must somehow point close to the target line of sight (Top of own ship dial) could be to have the ownship dial be larger and hide the fire button until the own ship dial aims close to the line of sight ... say some 45º either side

But again we would stumble against the same problem, i.e. we would be free to shoot any moment with an instant-GA update on the fly insde those -/+ 45º

Not to mention that I absolutely lack the skills for modifying the menu.ini to do the trick with the dials

[keltos01]

I'll try tonight with the 0° torpedoes...

[Nisgeis]

What happens to the gyro angle indicator when you are using straight running torpedoes? Does the indicator still move, or does it stay at zero? I considered the problem of the British torpedo director when fiddling with the US one (which is why I went hunting and took those photos of a real one). I think it all comes down to what happens with the GA indicator as to whether something can be done.

Hitman - Where are you getting your details of the torpedo director from?

[Hitman]

Hitman - Where are you getting your details of the torpedo director from?

It's a long story, I was involved long ago in a mod about british subs that finally didn't see the light. I have still some stuff, including diagrams, etc.

Here's a part of a russian book that CCIP translated:

Despite certain successes achieved by British submariners during the First world war, in general the attitude towards this type of vessels remained negative at the Admiralty. Not the least role in this was played by the invention of ASDIC in 1918, which admirals decided was a panacea for subs in future wars. Coupled with the predominant policy of economy in naval spending during the early 1920s and 1930s, this led to the British submarine service entering the new world war with the most primitive TDC, compared to those in US and German fleets.

The electromechanical "Torpedodirector" was founded on the principle of calculating the submarine's course for the moment of attack. This was realized through an intricat system of logarithmic scales. The only element entered electrically into the device was the sub's own course from the main gyrocompass. The TDC was not connected to the torpedo tubes. Changes in the running depth of torpedoes were made manually by torpedo operators via special devices, installed on the tubes themeselves, but changing torpedo speed without removing them from the tubes was impossible. Gyro angles could be corrected without removing torpedoes from tubes, but the device only calculated solutions for straight or "angle" shots (90 degrees).

The device itself worked in the following fashion:
During the first periscope observation, the torpedo officer would enter the bearing and estimated heading of the target on the commander's orders.
Based on this the device calculated the target's angle on bow and the relative position of the sub to the ship (this was shown visually on the two rotating gauges in the centre of the device). Then the height of the target's masts and the angle of their rise calculated by marks on the periscope. Distance was determined in this way. Based on all earlier-entered data, the device calculated traverse distance - i.e. the distance at which the target will pass the sub if it maintains the current course. Seeing this, the commander could decide where and at what speed he should move for conducting the torpedo attack.

In the last stage, the device calculated the attack course. For this the speed of the torpedoes and the length of the target were entered (the speed of the target was estimated by comparing bearings, later in the war - by counting screw turns on the hydrophone). If neccesary, by turning a handle the device could be set up for an "angle shot". After enering all neccesary numbers, the image of the submarine on the lower gauge "doubled" - the upper, lighter image matched the current position, and the lower - the one neccesary to achieve the attack course. All that remained was to read the angle from the scale on the side of the device and pass it to the helmsman. After the submarine was on the correct course (which could be judged by the two images coinciding) the commander read the lead angle from another scale on the side, turned periscope to that angle and waited for the target to enter the crosshairs of the periscope.

[footnote - due to the amount of gauges and scales the TDC was nicknamed "fruit machine". This is how submariners called a gambling device which today is commonly called the "one-armed bandit" (i.e. slot machine).]

Relatively simple and light (weight 52kg; size 487x645x368mm) and visual device, in practice it had many deficiencies. Only one parameter was entered into it automatically, with the rest having to be set by hand. The absence of a position keeper meant that after each periscope observation all numbers had to be reset. In combat conditions, there was often insufficient time for this, as a result of which many commanders had to calculate solutions in their head without consulting the "torpedodirector". A large number of data was calculated not by the device, but subjectively, which increased the risk of error. And finally, the need to take a strictly determined course (attack course) took up time, which could often not be afforded in combat.

All of the above deficiencies led to the fact that the degree of success with single-torpedo attacks was less-than-satisfactory. There was a hurried effort to develop methods for solving this situation. The answer turned out to be very obvious - switching to salvo fire, but because the torpedodirector could not set gyro angles, then the best method - firing "fan shots" - was unavailable. The solution was found in the stop-gap method of firing in intervals. This is how this method was characterized by A.V. Tomashevich in the "Collection of materials on combat experience of the USSR Navy" No.6 (1943):

"Launching torpedoes one after another, the British continued fire during the time required for the target ship to pass a distance equal to one, two or three times its own length. From this there were three firing options. The first was called concentrated fire, the second - scattered A, and the third - scattered B. With concentrated fire, if the target motion parameters were calculated correctly, all of the torpedoes launched would hit the target. If there were errors in the calculation, there will be hits only if the margin of these errors did not exceed half the length of the target ship. The aiming point was the bow of the ship. Therefore the middle torpedo (out of those fired) would hit the center of the ship. This firing method was prescribed for attacks from short distances and when the target's motion was calculated correctly enough in the commander's opinion.

In the case if the target's motion parameters were calculated correctly while using the scattered firing method A, the ship would be hit by 50% of the launched torpedoes. If there were errors, there would be hits only if the margin of these errors did not exceed the length of the target ship. The aimpoint was switched from the bow of the target to halfway between the bow and midships. This method was used when the target's motion parameters could not be calculated accurately enough.

With a correct firing solution using the scattered firing method B, the ship would be hit by 33% of the launched torpedoes. Errors in the solution could not exceed 1.5 lengths of the target ship. The aimpoint was switched to midships. This method of firing would be used in attacks from long distances, when the target calculations could contain serious errors.

In all scenarios, only the minimum number of torpedoes to be fired was determined: with concentrated fire - no less than two, with scattered A - no less than three, with scattered B - no less than four. This norm, in the British understanding, guaranteed a hit with at least one of the torpedoes. Otherwise the commander himself decided how many torpedoes to fire in each individual scenario.

Firing calculations were made using three tables. The first table determined which method should be used in the given situation, the second - to calculate the length of the overall torpedo firing interval, depending on the number of torpedoes fired and the length of the target, and the third table allowed to calculate the intervals between individual torpedo launches based on the overall firing interval and target speed"

Thus, in addition to the device which required eight manual settings, there was also a set of three tables. Only in modified versions of the "torpedodirector" which started to appear from early 1943 there were automatic calculations for recommended time interval depending on earlier-entered target length, distance, speed and the number of torpedoes to be launched. That said, since all the torpedoes followed the same course, if the target evaded one torpedo it evaded the entire salvo. It seems that in 1944 the British gained the capability to enter gyro angles between 0 and 90 and switched to using fan shots, however no descriptions of the accompanying TDC devices could be found. It is most likely that the dispersion angles were entered manually by the torpedo operators themselves, although the latter seems to have been done by British submariners rather rarely.

The British TDC system turned out to be the most primitive compared to those used by Germany and the US. Many of the parameters had to be obtained visually and entered manually. The weakness of the firing apparatus could only be compensated by very professional and disciplined work of the crew - which judging by the overall success of British submarine attacks was exactly the case.

Diagram on that book (Including translation of terms by CCIP):

[Nisgeis]

I couldn't quite work out how the course change was relayed. I think it may have been the large white arrow on the own ship dial (see photo). Then there's the small downwards pointing arrow above it - any idea what that is? The dial text also refers to 'gyro angle' so I'm not sure what that's about either.

[TorpX]

Originally Posted by Nisgeis

I couldn't quite work out how the course change was relayed. I think it may have been the large white arrow on the own ship dial (see photo). Then there's the small downwards pointing arrow above it - any idea what that is? The dial text also refers to 'gyro angle' so I'm not sure what that's about either.

I was reading what has been posted about the BFM, and it is hard to see the details well enough to really figure it all out. The picture at the beginning of the thread and the diagram seem to have a significant difference. In the diagram, it seems to be set up for 0 or 90 GA shots, while the one pictured, seems to allow for GA up to 50.

I believe the ASDIC range item is related to the depth of the torpedo tube. In a description of the US "banjo", there is a reference to torpedo tube depth in the firing data. This would be to allow for the extra time needed for the torp to climb to its operational depth; effectively lengthening the track to the target.


The "distance from track" feature seems very worthwhile. Too bad SH4 doesn't have it. Would this be distance along the bow, or distance along the torpedo track?

I don't really understand what has been written about the buzzer and the computed course. If you know the target course, and have decided on a desirable track angle, the your own course follows from this and you don't need a fruit machine to figure it out. Is the machine supposed to calculate an optimum track angle? You would not need the buzzer to tell you when to fire, as you would see the target at the correct bearing. Maybe I'm missing something here.

The subs course is input automatically. Is the speed from the pit log also linked?

I had assumed the output values change in real time (in between observations), or do they only change when the cranks are used?

Much of what has been written about about the BFM was most likely written by people who were not too familiar with the device. As you are the only one around with any "hands on" experience, you may be the best authority available.

[joegrundman]

i wish i could remember the source for this, but it is my recollection that the 0/90 gyro torpedo was changed for a true variable gyro torpedo round about 1943

[Nisgeis]

Originally Posted by TorpX

I was reading what has been posted about the BFM, and it is hard to see the details well enough to really figure it all out.

There are better pictures over at http://forum.kickinbak.com/viewtopic.php?f=29&t=2033 with different problems that have been solved.

Originally Posted by TorpX

I believe the ASDIC range item is related to the depth of the torpedo tube.

ASDIC Length?

Originally Posted by TorpX

The "distance from track" feature seems very worthwhile. Too bad SH4 doesn't have it. Would this be distance along the bow, or distance along the torpedo track?

It's the distance you are from the target's track, e.g. the shortest distance between you and the target's predicted path along its own course.

Originally Posted by TorpX

The subs course is input automatically. Is the speed from the pit log also linked?

I had assumed the output values change in real time (in between observations), or do they only change when the cranks are used?

I assume speed is input automatical - I think so at least. The output only changes when the cranks are changed. As I understand it, it tells you what course to steer to in order to intercept for an attack.