Submarine Attack Course Finder (a.k.a. Is-Was / Banjo)

[Linton]

Perhaps this and any other device link could be made into a sticky??

[Hitman]

The aspect ratio approach outlined above takes the range into account indirectly - since the apparent mast height also changes with range like the apparent length, by using the ratios of the two you don't need to actually determine or know the range to solve for AOB - you only need the apparent height and apparent length (to compare against the known values from the recognition manual or pre-determined aspect ratios from a chart), and both of those can be obtained from the 'scope

Exactly that

As I had previously stated

because what you can see of the ship’s height remains constantly proportional (The mast) at any given distance, while the length you can see will change also proportionally depending on the AOB, you can read from your scope or TBT the new Aspect Ratio the ship shows you, and by comparing it with the standard aspect ratio at 90º, get the AOB directly

, so the range is irrelevant.

In the german method indicated by WernerSobe you must have at least one range readout, otherwise you have nothing because the same ship can f.e. extend 24 scope marks in horizontal at 90º AOB at 2000 yards or at 45º AOB at 1200 yards (Numbers not calculated precisely ). With my method that's not needed at all.

[Dustyboats]

Originally Posted by Captain Krunch

I agree that transparencies are not the best solution, but at least they're readily available to most people. My mock-up was made out of card stock and transparencies, and it seems to be holding up fairly well. But I like your idea of using clear lamination to give it strength; that's a lot simpler than what I was going to do (Which was make decals and put them on clear styrene sheets).

It's no problem to make a complete black and white one; it'll be a day or two at most.

I bought three different sized, circular plastic, school boys protractors. Cost UK £2.

[Miimike]

The back side is the run time calculator.

[Hitman]

Sorry sqk7744 but I think you got it wrong Though I might be wrong, of course, but see if this example seems more correct:



1.- Our own ship true course is 90, as highlighted in the red circle or our own ship BOW. The target's true course is 300º.

2.- We need to turn the scope left 60º, to our relative 300º, to see the target. The A ring scale is inverted exactly for that. When we turn the upper part of the scope left (Yellow arrow) we can correctly read in the opposite part of the scope ring that we have gone to the "300" mark of the A ring (yellow triangle marker in the handle), i.e. of our relative bearing. We also can see now in the middle ring (B ring of true course) that the relative course to our target would be 210º for us.

3.- Finally the AOB of the target can be read in the other scope ring marker (Highlighted with a green triangle). In this case it is 90º, not 120º as you had indicated. You got the wrong result because you reversed the own ship. This can be seen clearly in this edited picture of your setup:




Hope that helps

EDITED to add:

The tool is in fact, as the name says, a "course finder" so in real life the inputs of the tool would be: 1) Own true course, 2) Target bearing and 3) Target AOB. With that input the tool would give you as output the true course of the enemy.
But in SH4 as in SH3 people tend to do the opposite, i.e. determine first true course of target and use the tool to get the AOB. Probably as someone highlighted in another thread, this is due to the AOB being more difficult to determine in a flat screen as opposed to real (3Dimensional) world, but anyway the real use of this wiz-wheel comes to be very clear when you play at 100% realism, i.e. with no map contact update and view limited to your bridge/scope/TBT.

Also, another problem with this wheel is that in SH4 we are used to see in the upper part of the scope the graded reticle for the target bearing, so we tend intuitively to look for the bearing in the upper part of the scope. But when doing so in this wheel, the AOB would be reversed! This is the main reason why the scale is reversed in the A ring: That you can have in the same marker (Scope ring handle) both target bearing and AOB. If you put one of them in the opposite side, you get a wrong reading, and if you put both in the other extreme, you have a reversed result.

[don1reed]

My take on this neat addition to whiz-wheels is:

You have 3 templates:

A (the big outer wheel) = True compass

B (middle wheel) = Submarine (all bearings relative)

C (inner wheel) = Target

Scope (transparency) = cursor

Here is a copy of my old orig SH1 whiz-wheel,



as you can see, (forgive the blurriness), I've set it to the params of the problem. You need to do the same with the new wheel.

Cheers,

[WernerSobe]

Originally Posted by panthercules

Well, I assume that you would still need to know something else besides the known length and apparent length ("angle of projection") - i.e., the range, because the apparent length will obviously be different at different ranges. I was thinking about a method that used the range directly, along with actual and apparent length, but that of course requires you to first determine the range and then input it into some formula/chart/wheel mechanism for solving AOB. The aspect ratio approach outlined above takes the range into account indirectly - since the apparent mast height also changes with range like the apparent length, by using the ratios of the two you don't need to actually determine or know the range to solve for AOB - you only need the apparent height and apparent length (to compare against the known values from the recognition manual or pre-determined aspect ratios from a chart), and both of those can be obtained from the 'scope - a clever way to avoid the stadimeter CTD bug for those who still have that

I'm not sure if I'll take the time to use these methods during combat, but they sound like a pretty good way to confirm my AOB estimates and "train" my eye during sub school practice to make better guesses using the Mark 1 Eyeball.

youre right there was also the range involved.

[Hitman]

as you can see, (forgive the blurriness), I've set it to the params of the problem. You need to do the same with the new wheel.

Don, in my opinion you can't apply this to the wheel we are using because the outer ring has the ship silhouette -thus purpose made for own ship- and also inverted bearing scale. As I said before, the only way to make sense of that inversion is when turning scope left or right.

[Igorry]

I like give my 2 cents worth on how to use the Is-was/banjo using cpt krunch example.

The Is-was/banjo has 4 dial

A dial is the submarine
B dial is the true compass
C dial is the periscope ruler
D dial is the enemy ship

The banjo can used to find the AOB of the enemy ship or the course of the enemy ship. However in each case three piece of information is required.

1) TO FIND AOB OF ENEMY SHIP

Three piece of information is require - your sub course, the relative bearing, the enemy course

a) Our sub course is 90 degree east.

According to cpt Krunch, he align B dial 90 degree to A dial at 0 degree.
I disagree that is the right procedure.

I think you should align B dial 90 degree to A dial at 180 degree. The triangle protruding out of the A dial is always the submarine bow and the opposite semicircle in dial A is the submarine stern.

b) From the periscope we spotted a ship and the relative bearing is 300 degree.

This is the same as capt Krunch. Move the periscope tab or c dial so that the outer marker in the periscope tab is over the A dial at 300 degree mark. Note in the periscope tab, there are two markers. One is pointing to A dial and the other is pointing to D Dial.

c) We have a contact heading 330 degree.

Move the D dial 0 degree (which represents the bow of the enemy ship) to B dial at 330 degree. (B dial is the true compass)

When you have done this, you can find AOB easily by reading from the periscope tab, the inner marker which points to the D dial at 120 degree port.

2) TO FIND THE COURSE OF ENEMY SHIP

Three piece of information required: The sub course, the relative bearing and the estimated AOB

a) Our sub course is 55 degree.

B dial 55 degree to A dial at 180 degree. The triangle protruding out of the A dial is always the submarine bow and the opposite semicircle in dial A is the submarine stern.

b) From the periscope we spotted a ship and the relative bearing is 260 degree.

Move the periscope tab or c dial so that the outer marker in the periscope tab is over the A dial at 260 degree.

c) Estimated AOB is 45 degree starboard.

Move the D dial starboard 45 degree to the inner marker of the periscope tab. At this point the outer marker is pointing to 260 degree of A dial and inner marker is pointing to D dial at 45 degree starboard.

To find the course of ship, read the 0 degree of D dial (which is the bow of the enemy ship) to B dial. You will find the enemy course to be 90 degree.

I hope I have not confuse the picture further. My only difference is that I believe the 180 degree in A dial is the bow of the sub where as the 0 degree is the stern of the sub.

Igorry

[don1reed]

Rgr that, Hitman.

I'm in the process of building one of the new w-w's. I'll follow your instruction tomorrow when it's completed. (kinko's)

tnx,

[Igorry]

Originally Posted by don1reed

My take on this neat addition to whiz-wheels is:

You have 3 templates:

A (the big outer wheel) = True compass

B (middle wheel) = Submarine (all bearings relative)

C (inner wheel) = Target

Scope (transparency) = cursor

Here is a copy of my old orig SH1 whiz-wheel,



as you can see, (forgive the blurriness), I've set it to the params of the problem. You need to do the same with the new wheel.

Cheers,

Hi Don1Reed,

I have also constructed your whiz wheel and I believe the outer wheel is your submarine and the middle wheel is the true compass and the inner wheel is the target. Using your whiz wheel I can get the true course of the enemy ship or the enemy AOB with three piece of information

For true course

1) your sub course
2) relative bearing
3) Estimated AOB

For AOB

1) your sub course
2) relative bearing
3) True course of enemy ship


Basically the course finder or whiz wheel is the same as the banjo. I like the banjo better because it has the periscope tab and it is an exact copy of the ww2 banjo. However both can be used to find true course or AOB.

Igorry

[don1reed]

Basically the course finder or whiz wheel is the same as the banjo. I like the banjo better because it has the periscope tab and it is an exact copy of the ww2 banjo. However both can be used to find true course or AOB.

Igorry

Actually, Igorry, you & Hitman are both right...it's just a matter which of the templates the operator chooses to use as the True compass card.

...I like the new (more authentic for WWII) whiz-wheel too. The one I've been using is more from WWI.

-...-

sqk7744, your examples are very helpful, especially for the new guys using manual for the first time.

[sqk7744]

moved to: http://www.subsim.com/radioroom/show...=108931&page=2

[don1reed]

I think ya nailed it.

[sqk7744]

Originally Posted by don1reed

I think ya nailed it.

Cool!

A picture is worth a 1000 words.

Thanks again m'8