Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!att!cbnews!military From: kulkisar@mentor.cc.purdue.edu (Aaron Kulkis) Newsgroups: sci.military Subject: Re: WWII Submarine Navigation and Attack Terminology (LOOONNNG) Summary: target tracking equipment, reading suggestion Message-ID: <1990Sep27.031817.7980@cbnews.att.com> Date: 27 Sep 90 03:18:17 GMT References: <1990Sep24.002015.24721@cbnews.att.com> Sender: military-request@att.att.com Organization: Purdue University Lines: 200 Approved: military@att.att.com From: kulkisar@mentor.cc.purdue.edu (Aaron Kulkis) Reading suggestion at the end of this post you might regret having started me on this subject though...one of my favorites... In article <1990Sep24.002015.24721@cbnews.att.com> r_anderson@flyppr.enet.dec.com writes: > > >From: r_anderson@flyppr.enet.dec.com > >I have started reading some books concerning WWII submarine >operations and tactics. These books were written by submarine >Commanders and Execs, so they are fairly detailed and extremely >technical. Unfortunately, they are written for people versed >in navigation technics and terminology. > >Never having been in the Navy (or a ship for that matter), I >have some basic terminology questions that would help clarify >the tactics being described (why don't these books come with >manuals? :-)). This is the subject that first got me into reading military history, so, although I've never been on a sub of that or any other vintage, I have managed to decipher the lingo... If you do not understand trigonometry, learn a bit..navigation for a small area where you can assume a 'flat' planar navigation surface is almost trival...and since that's all we're worried about to sink our quarry once we've made contact, that's all you need to understand. In following, all male pronouns refer to enamy ship, all female pronouns refer to friendly ship (i.e. sub we're on), as was the usual standard of that era. > >1. When a target's bearing is "marked" through the periscope, >is the angle relative to submarine (0 degrees being the bow, 180 >degrees being the stern), or relative to the "true" geographic >course? His bearing marked is relative to submarine's course, as you stated above. > >2. Can someone clearly explain the term "angle on the bow" and >how this information is useful in determining a torpedo attack? > Angle on the bow is basically the bearing that the ship would mark if it were to "mark" bearing on the sub, or my bearing relative to him...still confused???? If a ship's Angle on the Bow is less than 90 degrees, it is comming more or less towards me, 90 - 270 more or less away, 270+ degrees, towards me. Angle on the Bow Description 0 he is headed right at me. 180 he is headed right away from me. 90 or 270 I am on his broadside range + Angle on the Bow ==> predicted path of travel relative to sub's current position. Most of the WW2 'dazzle' camoflauge patterns had nothing to do with hiding the ship but instead were to make it more difficult for the sub captain to figure out his speed, range and Angle on the bow. >3. Can someone clearly explain what an "Is-Was" is and how it >works? the Is-Was is a slide-rule device, commonly called the 'banjo' for it's distinctive shape. the technique was to arrange the device to reflect 2 sets of "Marks". I am not sure if this was used in conjunction with the running plot of the contact directly (as in used in physical contact with the charts of the current area) or used as a stand-alone calculator. Most subs relied very heavily on the banjo man, because due to the plodding speed of a submerged WW2 sub, you needed to know where the heck your contact was going as fast as possible, lest you wind up in left field with dead batteries. > >4. Can someone clearly explain what a "TDC" is and how it works? > It has been several years since I have read any 'I was there' accounts, but here is what my memory serves me. Do not take anything as ABSOLUTE because there were probably sever models of this thing all going under the same name, having different operational specs, but here is what there were like, basically: The TDC (Torpedo Data Computer) was an electro-mechanical computer which made American subs truly incredible machines after they were installed....as best I can determine, it was operated somewhat in this fashion: Whenever the captain or exec would 'mark' a set of target data, the TDC operator would dial in the data as told to him. As each set of marked data was dialed in, a more and more refined set of readings were available. The TDC would use/could tell you: 1) current Bearing of target. 2) Current Range 3) Current Angle on the Bow 4) Target speed 5) sub's bearing 6) sub's speed 7) Torpedo's speed 8) how many yards to "the track" (path of the target ship) 9) length of run of the torpedos if fired at this moment to hit target as defined above (in yards, or seconds, I forget) There may have been variances among different models, I do not know. Additionally, US torpedos had an option so that torpedos did not have to run along the same bearing that sub was sailing... It's been many years since I've read a submarine account, but I know that they could be steered several degrees off of the sub's current line of travel (45 - 90 degrees max, I believe). In pre-TDC days, these were set by hand. The TDC would constantly adjust for an optimal shot. Additionally at least some models could be manipulated relatively easily to fire several torpedos over a 5 - 10 degree spread (in case marked data was erroneous) in hopes that 2 out of 3 would hit or some such. At least some TDC's (all?) could handle multiple targets from what I gather. Later version may have been connected to the ship's navigation gear (don't bet $$$ on it though!!!) to make for even more efficient updating of data British subs had a device that could allow a torpedo to be shot 90 degrees off present course (to either broadside) called the Ninety Bender...idea was to sail parallel and ahead of your intended victim. since, as I have stated, it has been about 10 years since I've last read anything seriously on the subject, there may be minor mistakes, but you should get the idea from this post. Reading suggestions: 1 _Submarine!_ by Capt. Edward L. Beach, (US Navy, Ret.) several (like 20) US submarine war patrols in pacific are documented. Chapters alternate between Beach's experiences, and famous/notable patrols by other boats. So good that it is the only book in my entire life that I have ever checked out on 3 seperate occasions, each from a different library. Also has a wonderful poem, kind of a fighting verse for the USS Trigger, Beach's first command. Covers the whole US submarine war from opening days of faulty torpedos to the final days when nobody could find a target to save their life. Widely available at public libraries, and ...welll, I've looked it up so much, I've even got it's usual Dewey Decimal number memorized: 940.54B Capt Beach also wrote 3 fictional sub books: Run Silent, Run Deep Dust on the Sea All are excellant Cold is the Sea 2 There is also a very good book by a British sub captain whose name escapes me at the moment...as does the title of the book. it is one of the early titles in the highly successful Bantam War Book series of paperbacks. Very different craft which they sailed. External tubes f'rinstance. I will try to find book and post relevant info. 3 Explore beyond US submarines...German subs were a different life in many ways...they did not always have the technological upper hand, and yet they came up with some really neat innovations such as MAGNETIC-ACOUSTIC-HOMING-CIRCLING TORPEDOS and Piffenwhiffer (spelling) a chemical device which would generate false sonar reflections by making air bubbles. [mod.note: "Pillenwerfer", if memory serves. - Bill ] I ahve yet to find anything concerning Japanese submariners so far, though. And last but not least, I will suggest the game Submarine by the Avalon Hill Game Company, Baltimore Maryland. The advanced version of the game will give you an idea of what it's like to try to close in for the kill... Well, I think I've rambled enough now......... Good Luck, and Good Hunting! There used to be a psycho kitty here, Ackphffzzzt! It's Bill, Oh where, oh where did my psycho kitty go... Aaron R. Kulkis Ancient Engineer