Thursday, May 10, 2012

#63) Librascope Mk 13 Mod 0 Angle Solver - RFI

The following e-mail was recently received from a new subscriber to this Blog that I did not recognize:

The reason you do not have my email in your database is because I was never connected to Librascope. I subscribed so that I might be able to find out some information about a Librascope item I have in my collection . Perhaps you can help me find out the history and purpose of this creation.

What I have is an Angle Solver MK13 MOD 0, Serial Number 2. It also has a tag above this stating "Prototype". The unit weighs 984 pounds and I bought it from a person in Norfolk, Virginia who evidently bought it surplus from the government. The unit is set up for a motor torpedo boat. What I would like to find out is why it was made, and if any documents still exist that might show how to take the unit apart as the dials need some work because of some surface rust plus some of the wheels do not turn as freely as they should. I would be happy to send you pictures of the unit if that would help.
I thank you for any help you can render about this unit.
Richard Dembinski 

Note, I Googled "Angle Solver" for Richard, and found an interesting writeup on Wikipedia that may be of interest. Click here. I have asked  Richard to send me a photo of his unit to post on this Blog. In the meantime, if you have any information or questions for Richard, please e-mail me and I will forward them to him. Thanks, Carl 
June 1, 2012 update. 
Mr. Dembinski provided the above photograph of his Angle Solver.


  1. I recently received the following e-mail from Charles Buterbaugh:

    29 May 2012
    I hate to admit it, but I don't look at your blog site very often, but the computer was auto-archiving my Outlook files, your blog site flashed by, so I opened it. I am intrigued by your No.63, the e-mail from Mr. Dembriski. Several things don't seem right, but then, maybe not. First, my memory is absolutely blank as to an Angle Solver Mk.13. As an aside, I am really disappointed sometimes about my memory, but this is a penalty for getting old. I can't recall Librascope building such an angle solver, at least not between 1945 and 1974. Sperry had an angle solver as part of the torpedo fire control system it built for the first Polaris submarines. Even so, this device Mr. D. has weighs 984 pounds! The "banjo" mentioned in the Wikipedia page was called an angle solver, but none I worked on was a Mk.13, at least up to 1945. Besides, the "banjo" was hand held, or at least laid on chart table, and weighed at most about two pounds. For the young guys, the "banjo" was a nomograph with a set of curves depicting target speed and helped determine gyro angle. The note about motor torpedo boat intrigues me. During the war, we put slightly modified aircraft sights, Gunsight Mk. 8, just behind the windscreen of the PT boats, in front of the helmsman. The idea was to just head for the target as fast as you could, use the reticle of the sight to get some sort of lead angle, and hope for the best. I don't remember putting even a different reticle in the sight, although some boats did use a grease pencil on the reflector as an aide. Here is what I did want to relate. After the war, in the late 1940's, the Navy had four aluminum hulled PT boats built at a yacht yard, probably the John Trumpy yard, in Annapolis MD. These boats were larger, faster, and had longer endurance than the plywood hulled WWII boats. We put some kind of torpedo fire control "system" on them, but here is where my memory fails me. I cannot for the life of me remember what this equipment was. It was bigger than a bread box, as I remember numerous trips to Annapolis in connection with the installation, but there my memory stops.

    I hope Mr. D. sends you a photo, which I hope you will send me. I'm looking forward to more information.


  2. I received the following e-mail from Mr. Dembriski in response to Charlie's e-mail:

    Thanks for sending me his letter - when he mentioned the metal pt boats it made me wonder if my unit was designed for one of these as it has a plate with a pt shape and markings for four torpedo's - the mystery continues