I have the "box like" one, with a roller blind instead of a plastic slide, as shown in the last but one photograph, ( Lancaster navigator) right here, along with the type issued to me by the RAF in 1955, i.e the "thin" one with the slide, that I have always known as the E6B. That I used on BOAC Stratocruisers, Britannias and early 707's. although in later years the Nav. dept. produced G/S and Drift Component tables for climb, cruise and descent recommended speeds, that were quicker and easier to use than fiddling around drawing on the front of the computer, tho' the reverse side was still necessary for speed/distance/time calculations. ( no electronic computers or iPhones in those days - can you imagine ? !!! )
I also have a small, i.e 2", copy of the reverse side bought as a key ring gimmick some 50 years ago, from a shop on Nathan Rd. Hong Kong, now glued to the inside of my wallet. Was using that at the supermarket checkout one day, and the young assistant said " Wot's that " A circular slide rule, I replied. " Wot's a slide rule ? " One could weep.
Last edited by ExSp33db1rd; 20th Feb 2021 at 21:44.