SUBSIM Radio Room Forums - View Single Post - Submarine Attack Course Finder (a.k.a. Is-Was / Banjo)

simple nuke · 04-23-07, 02:02 PM

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.

04-23-07, 02:02 PM	#53
simple nuke Nub Join Date: Apr 2007 Posts: 4 Downloads: 2 Uploads: 0	Attack Course Finder (a.k.a. Is-Was/Banjo) 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.