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

[bruschi sauro]

Very cool... thanks for well done job.

[sqk7744]

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

[tomoose]

I've made my own doohickey, whatchamacallit from your plans . Thanks for your efforts, much appreciated. I use it as initially described and not "upside down" as others have described. Personal preference. It works like a charm. I have found it has vastly improved my plotting and gives me a quicker and better method of determining a target's course and AOB. I have already used the IS-WAS to turn parallel to a prospective target's course, run ahead and then turn for an optimal 90-degree shot! Very gratifying. Unfortunately this has only been on SH III so far.

I've had better results with SH III as SH IV has become a pain in the arse. Current campaign has assigned me to patrol the Marshalls 5 times in a row!!. In all of those patrols I spotted and sank 1 single solitary japanese merchant. Frustrated I transferred to Australia and guess what, my next mission? Patrol the freakin' Marshall Islands!!!! Aaaaaaaaarrgh! I quit out and will wait for the next patch.

[Linton]

Originally Posted by Miimike

The back side is the run time calculator.

Would you be able to post a picture of that?

[bruschi sauro]

Originally Posted by tomoose

I've made my own doohickey, whatchamacallit from your plans . Thanks for your efforts, much appreciated. I use it as initially described and not "upside down" as others have described. Personal preference. It works like a charm. I have found it has vastly improved my plotting and gives me a quicker and better method of determining a target's course and AOB. I have already used the IS-WAS to turn parallel to a prospective target's course, run ahead and then turn for an optimal 90-degree shot! Very gratifying. Unfortunately this has only been on SH III so far.

I've had better results with SH III as SH IV has become a pain in the arse. Current campaign has assigned me to patrol the Marshalls 5 times in a row!!. In all of those patrols I spotted and sank 1 single solitary japanese merchant. Frustrated I transferred to Australia and guess what, my next mission? Patrol the freakin' Marshall Islands!!!! Aaaaaaaaarrgh! I quit out and will wait for the next patch.

yes we wait for the new patch but when we can get it?

[Front Runner]

The Is-Was goes together with the Publication 1310 very nicely.
I have found a site for a free official download of Pub 1310.

http://www.subsim.com/radioroom/showthread.php?t=110484

[sqk7744]

Originally Posted by Front Runner

The Is-Was goes together with the Publication 1310 very nicely.
I have found a site for a free official download of Pub 1310.

http://www.subsim.com/radioroom/showthread.php?t=110484

Bravo!

[simple nuke]

I spoke to a retired Submarine C.O. on Saturday, who originally qualified on an S Boat. He told me that the Is-Was was a circular slide rule that was used to calculate the rate of change of the target's bearing from the submarine, in order to determine the course of the torpedo. On the S Boats, the periscope was normally used in the Control Room, next to the Tracking Party. The target's AOB, Range and Speed (Is) was compared to what those values where (Was) after some measured time. The Bearing Rate Change was used by the Tracking Party, along with the boat's course and speed, to calculate the Target's course and speed, and then calculate the torpedo's course and when to fire, based on a known torpedo speed.

After the adoption of the TDC, the Is-Was was used as a means to check the TDC solution and for use incase of TDC failure.

[Hitman]

Yes that's right, this is how the rear part of the wheel works, I found it out recently and I'm already working in the graphics. It is more or less like this:

1.- You detect the target, identify it, take bearing and range and make a guess of the AOB, then plug the values into the part of the wheel we have already. Now you have an idea of the course and can plot an intercept

2.- You make a second observation some time later (Note bearing, range and time between observations) and then turn around the wheel and use the rear part: You start by fiddling around with the medium wheel until the difference in bearing matches and find the AOB with that. You guess of the AOB in the first observation helps you start already with an aproximate solution. Now you read across the wheel and know also the distance travelled. It's time then to use the inner wheel and adjust the "time" between observations to that distance travelled -read in the outer wheel- and bingo! you can directly read target's speed at the outside ring Wondeful tool, isn't it?

Stay tuned, I will post a downloadable template ASAP for the rear part of the wheel with a tutorial

[sqk7744]

Originally Posted by Hitman

Yes that's right, this is how the rear part of the wheel works, I found it out recently and I'm already working in the graphics. It is more or less like this:

1.- You detect the target, identify it, take bearing and range and make a guess of the AOB, then plug the values into the part of the wheel we have already. Now you have an idea of the course and can plot an intercept

2.- You make a second observation some time later (Note bearing, range and time between observations) and then turn around the wheel and use the rear part: You start by fiddling around with the medium wheel until the difference in bearing matches and find the AOB with that. You guess of the AOB in the first observation helps you start already with an aproximate solution. Now you read across the wheel and know also the distance travelled. It's time then to use the inner wheel and adjust the "time" between observations to that distance travelled -read in the outer wheel- and bingo! you can directly read target's speed at the outside ring Wondeful tool, isn't it?

Stay tuned, I will post a downloadable template ASAP for the rear part of the wheel with a tutorial

---
Thanks Hitman! Can't wait- I've been having great fun using Cap'n Cox's Is-Was (AOB side) hope my tutorial was helpful!

Cheers M8

[Captain Krunch]

Everyone, the good folks over at the Historic Naval Ships Association have posted "Submarine Attack Course Finder Mark 1 Model 3 Manual, O.D. 453", so we no longer have to guess how the heck to use the Is-Was! In addition, this manual has some fairly clear images of the back side of the Is-Was, so I might eventually be able to complete what I've already put together - but I probably won't be able to get to it for a while, so anyone else can feel free to step up and create the back side of this thing.

[jmr]

Damn I love this stuff! Thanks for that link and boy I can't wait for Hitman's work to be finished and uploaded

[CaptainHunter]

Finally I can get AOB right every time.
I use it this way....I set my heading on (B) to zero on (A) then set (P)reading to (A)then go to map and get enemy vessel heading and set it to the (B)scale now look at the periscope finder where the pointer touchies the (C)scale and that is the AOB.

Thanks

[Puster Bill]

Originally Posted by Captain Krunch

Everyone, the good folks over at the Historic Naval Ships Association have posted "Submarine Attack Course Finder Mark 1 Model 3 Manual, O.D. 453", so we no longer have to guess how the heck to use the Is-Was! In addition, this manual has some fairly clear images of the back side of the Is-Was, so I might eventually be able to complete what I've already put together - but I probably won't be able to get to it for a while, so anyone else can feel free to step up and create the back side of this thing.

Sounds like I've 'reinvented' the wheel, so to speak. The backside of the banjo is simply a circular slide rule with a few extras to make it easier to use for targeting (especially compensating for own speed).

What I did was take the banjo, and put it on the back of a circular slide rule that I got from the Sphere Research site (http://www.sphere.bc.ca/test/build.html). You want body image 1, print it out on cardstock, use a highlighter to highlight the S scale, then laminate it. Print the overlay/cursor image on inkjet transparency, then laminate it also (helps make it more rigid and durable). I pinned them back to back, and it looks like this...

Slide rule side:


'Banjo' side:



I would really be interested in getting that other side, though.

[Hitman]

Don't worry I have already finished it This weekend I'll do some test to print and see it has the correct size, and will upload as soon as I have it al ready