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Beobachtungsuhr - a brief explanation

23K views 3 replies 2 participants last post by  StufflerMike 
#1 · (Edited)
The German term „Beobachtungsuhr" goes back to pilot´s watches of WW II. Strictly translated it has to be an „Observer´s watch" or „Observation watch" but on most watch related fora you`ll read „navigator´s watch", „pilot´s watch", „B-watch" or even „Flieger", which is the expression I like most.

These B-watches have been made for the German Luftwaffe by only 5 manufacturers

A. Lange & Söhne
Laco (Lacher & Co)
Stowa (Walter Storz)
Wempe (Chronometerwerke Hamburg)
IWC

and contained high quality pocket watch movements:

Lange & Söhne: cal. 48/1
(due to limited capacities watches have been assembled by Huber/Munich, Felsing/Berlin, Schieron/Stuttgart, Schätzle & Tschudin/Pforzheim, Wempe/Hamburg).
Laco: Durowe cal. D 5
Stowa: Unitas cal. 2812
Wempe: Thommen cal. 31
IWC: cal. 52 SC (SC= „seconde central")

The specifications of these watches had been defined by the „Reichsluftfahrtministerium" (RLM) - Imperial Air Ministry (see attached file)



Due to those specifications all B-watches had the following features in common:

- A case diameter of 55 mm
- Marked on the back with FL 23883 (FL = flight, 23 = navigation)
- Equipped with large crowns in order to be used with gloves
- Hacking movement (the second hand stops when pulling out the crown / essential for a precise time setting)
- Breguet balance spring
- Regulated and tested as chronometers
- Long leather strap (to be worn on the sleeve of a flight jacket).

There have been two different types of dials (Pls. note: there are other figures available on the net. not sure whioch are correct)

Type A (Baumuster A) from 1940 to January 1941
a classic dial with numerals 1 to 11 and the triangle with two dots at 12

Type B (Baumuster B) starting in January 1941
Big minute numerals from 5 to 55 and a small inner circle with numerals for h, at the position of 60 min a triangle and a line on its top.

If your are interested in watches of WW II and their history I recommend to visit the hompage of Konrad Knirim (Militruhren: Collectors Site for Military Timepieces) .

The Stowa B-Uhr Baumuster B



A. Lange & Söhne, Baumusuer B:



Stowa, Baumuster A:



IWC, Baumuster A:



Laco Baumusuer B:



More to read: https://www.watchuseek.com/f7/b-uhr-beobachtung-uhren-438490.html
 
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#2 · (Edited)
Another interesting info re FL 23883 taken from a former post

FL 23883 is a specification of the Reichsluftfahrtministerium (RLM) for inventory purposes, FL 23 was used for navigation devices, see more here:

Document: RLM FL 23883 (B-Uhr) drawing of December 1942 - WW II -B-watch draft by Wempe

Here are some other inventory FL

20274 Elt. Doppeldrehzahlanzeiger 2 x 500 – 3600 U/min

20286 Elt. Ferndrehzahlanzeige 500 – 3600 U/min

20342 Elt. Schmierstofftemperaturanzeige 0 – 130 ° C

20343 Temperaturanzeige 0 – 160 ° C

20349 Außenlufttemperaturanzeige -20 bis + 60° C (Siemens)

20555 Ladedruckanzeige 0,6 – 1,8 ata

20556 Dosenladedruckanzeiger 0,6 – 1,8 ata

20569 Doppel-Drehzahl-Ladedruckmesser 0,6 – 1,8 ata

/0 – 3600 u/min

20572 Elt. Kraft-/Schmierstoffdruckanzeiger 0-3/0-10 kg/cm³

20682 Vierfachanzeige 2 x 0-130° u. 0-1/0-10 kg/cm²

20723 Elt. Kraftstoffvorratanzeige

20743 Tankanzeige

20841 Borduhr (cyx)

21118 Zündschalter

21119 Zündmagnetschalter 45/8Z (ssh)

21214 Anlaßschalter

22___ Flugüberwachungsgerät

22230 Fahrtmesser 60-550 km/h (Bruhn-Werke)

22234 Fahrtmesser 100 – 900 km/h

22316-1 Feinhöhenmesser 0-1000 m

22316-10 Grobhöhenmesser 0-10000 m

22320 Fein- u. Grobhöhenmesser 0 – 10000 m

22382 Variometer –15 bis + 15m/s

22384 Variometer –15 bis + 15m/s

22410-1 Wendehorizont

22411 Wendehorizont

22413 Notwendezeiger

22414 Notwendezeiger

22557 Notauslöseknopf LAK

22559-1 Hauptschalter für Kurssteuerung Lschü 4

22561 Kurskreisel Lku 4

22562 Kurszeiger LKz 3

22600 Borduhr Junghans

22602 Borduhr Kienzle

22810 Dreifachtrimmanzeige

23___ Navigationsgeräte (navigation tools)

23233 Nahkompaß FK 38 (nfe) (Askania)

23234 Bordkompaß OK 38 (bxx)

23235 Armkompaß AK 39

23322 Höhenmesser

23331 Mutterkompaß PFK/m (Eckhardt AG)

23334 Führertochterkompaß PFk/f2

23338 Führertochterkompaß PFk/f3 (Patin)

23379 Peilumschalter PSH 15

23474 Peiltochterkompaß KT/p2

23501 Deviatstafelschieber mit Ablenkungstafel für Führer-

tochterkompaß

23825 Dreieckrechner DR 2 (C. Plath)

23883 Armbanduhr B-Uhr

23885 Borduhr Bo-UK 1

23886 Borduhr Kienzle u. Junghans Bo-UK 2-1

23888 Borduhr – Blindflug Schlenker–Grusen Bo-UK2-1

23888 Borduhr – Blindflug Schlenker –Grusen Bo-UK 3

23894 Astronomisches Rechengerät – Carl Zeiss (blc)

23905 Ablenkungstafel 5 für Peiltochterkompaß

23906 Ablenkungstafel K 6 für Nahkompaß

25___ Nachrichtengeräte

25591 Stationsuhr - Luftwaffe

26749 Schwingungsanzeige Sch A 2

26751-1 Schwingungsnazeige SAM

30486 Sauerstoffanzeige

30489 Sauerstoffwächter (Rüstsatz)

30496 Sauerstoffdruckmesser (Rüstsatz)

32112-4 Kommandoschalter

32112-6 Kommandoschalter

32116-1 Leitungsstecker 1-polig

32331 2 Meßstellenumschalter

32315-2 Netzausschalter

32349-2 Kippwechselschalter

32350 Kippschalter

32401 Verdunkler

32401-2 Verdunkler

32402 Verdunkler

32502-4 Stromspannungsmesser -30/+30 A/V

32502-7 Amperemeter – (Siemens)

32509-3 Amperemeter – (AEG)

32510 Voltmeter (jjb)

32525-3 Schauzeichen für Staurohrheizung

32529-1 Merkleuchte rot

32532 12 Lampengerät

32601 Preßstoffsteckdose - Vierkantsteckgehäuse

32616 Steckerplatte

32636 Leitungsverschraubung

32950 Durchführungsflansch

32951-2 Leitungsstecker

32953 Dichtring

47915 Steuerknüppel KG 13 A (ngk)

47919 Steuerknüppel KG 13 B

50001 Selbstschalter 6A (Luftgerätewerk Hakenfelde)

681801 Dreiachsentrimmschalter
 
#3 ·
An old post. Thank you StufflerMike! It would seem your attached pictures are no longer available? I am looking for original documents specifying the requirements. I believe I have seen they were supposed to be "Chronometerwerke" too, chronometer standards from some German institute? Would be interesting to see how these standards were specified, e.g. if they were x +-seconds per day.
 
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