Beautiful Stowa, interesting write up.....Once upon a time, someone in the Luftwaffe decided that their aircrew needed a standardised flying watch. The Germans tend to like to standardise things, as I (who for a couple of years served as a co-opted member on a DIN committee) can attest -- the idea being to know what you're getting.
Whoever it was gave the job to the technical department at the Air Ministry, and it must have landed with some functionary (whom we shall refer to as "Hedwig") to sort out.
Hedwig presumably consulted with people who actually had to fly planes at the time as to what features were important, and, in1940, came up with Air Ministry specification number Fl.23883 -- the aircrew Observer Watch (Beobachtungsuhr, or B-Uhr).
The specification required a black sterile dial with large and easily legible roman numerals and indices, sword hands, a central (hackable) second hand, the number 12 replaced by a triangle with two dots (to aid orientation), and excellent lume. It also had a largish "mushroom crown" designed to be operated in flying gloves.
Thousands were manufactured by five companies: IWC (neutral Switzerland!), Stowa and Laco in Pforzheim, and Wempe and ALS (now GO) in Glashütte. And Hedwig accidentally set the design standard for a large number of the pilots' watches or "Flieger" of today.
This is an original B-Uhr manufactured by Lange in 1941 . . . . . (pics from Chrono24) . . . .
Most modern homages to the B-Uhr ignore one important element of the specification (the 55mm diameter) and are manufactured in a more wearable 40-44mm.
So, we come to my watch for the day. I am not normally into "homages", but in the case of the five companies mentioned above I find it perfectly acceptable that they make an (albeit smaller) version of a watch they were producing eighty years ago.
Mine is from Stowa -- a robust and nicely made "tool" . . . .