History of the development of the NAV B-Uhr at Lange & Söhne 1935
As is well known, the later series models of the legendary observation watches of the Reichsluftwaffe were produced around 15,000 times during World War II; well-known watch manufacturers were involved, who merely carried out the final assembly of the movements of other manufacturers - e.g. Lange & Söhne Glashütte.
The B-Uhr, or observation watch, of the Reich Air Force was developed to series production readiness in the Glashütte manufactory Lange & Söhne.
Contents of the corresponding tender issued by the Reich Air Ministry in Berlin in 1935:
Subject: Clocks, Chronometers, Dials As reported on page 3 of the draft for a new Nautical Yearbook of Aviation, it is proposed that clocks and chronometers required for the purposes of astronomical navigation be provided with a corresponding degree scale instead of hour scales.
The reasons for this numbering are already outlined in the design. Manufacturing such clocks should pose no difficulties. Consultation with a leading German clock company has already been initiated. Regarding the design of the dial, several suggestions can be made, some of which are presented in the appendix.
In my opinion, the most viable proposal is the one put forward by Dr. Rapsold, a senior civil servant at the German Naval Observatory. The requirements for the dial of a clock, whether a B-Uhr (military watch) or a more conventional chronometer, are: clear numerals; and a clear and easy way to read the correct time.
To meet these requirements, any dual numerals, which might be considered, for example, when using the clock for both astronomical navigation and as a regular timepiece, must first be avoided. (Lindberg Longines clock) Furthermore, any type of adjustable dial must be omitted to correct for, for example, position, longitude, etc., also to avoid errors in setting the time due to the different signs.
The question to be examined is whether B-Uhr watches should be equipped with hand-stop devices to allow them to be regulated according to the MGZ (German Naval Observatory). The German Naval Observatory is of the opinion that the accuracy of good B-Uhr watches would not be affected. A further expert opinion on this matter will be obtained immediately from the company Lange & Söhne... Regarding the characteristics of the B-Uhr watches, the following general requirements must be imposed:
1.) High resistance to vibrations,
2.) Absolute reliability at low temperatures down to -20°C
3.) Uniform and controlled gait characteristics also in the cases mentioned under 1) and 2).
In terms of external form, all B-Uhr watches must be designed as wristwatches. Regarding the requirements listed under 1) and 2), no experience with German watches exists to date, so no general statements can yet be made, particularly concerning the performance of German watches at low temperatures. However, one B-Uhr watch from a well-known German manufacturer is currently undergoing testing at the chronometer laboratory of the German Naval Observatory.
Watches from other German manufacturers will also be requested for these tests, and the failure of the tests will be reported in due course. The same applies to sidereal time watches, of which one German-made (Junghans) and one Swiss (Zenith) are also currently being tested.
It has been observed in all clock tests at low temperatures that the clocks are lubricated with frozen oil. If the division were introduced, the sidereal time clocks would receive the same numbering system as other astronomical clocks. The same applies to the numbering of the time signal schemes.
Previous development stages of the newly developed navigation B-clock:
These prototypes – one of which was the piece of military watch history included in this offer – already possessed the essential components of the later Standard B-Uhr watches, even though the Lange & Söhne standard pocket watch caliber 43 was used as the basis for development.
- Dial type A
- Seconds stop (however, via the olive and not, as later, via the crown)
- Onion crown
- black dial with luminous numerals and hands
- Central second
- Underlink long strap bracelet
- an above-average size for a wristwatch at 55mm, which later became the standard size for the B-Uhr watches of the German Luftwaffe.
One of these deliveries from Lange & Söhne to the Reich Air Ministry is documented in Konrad Knirim's "Bible of Military Watches," page 335, for prototype serial number 92665 on March 31, 1936. Since this particular watch was already scheduled for delivery in March 1935, it was clearly a very early example of this limited production run.
During these tests, the later tasks and characteristics of an RLM B-Uhr were defined: the stop-seconds function, case and snap-on case back, size and dial diameter, serial number, dial design with easily legible numerals, later exchange of dials from type A to type B for better legibility, large central seconds hand, etc.
The 189 prototypes with pocket watch calibers from Lange & Söhne were partly produced on a trial basis in planned dial variations with grade divisions, which were never mass-produced or only in very small series.
Although they – insofar as the dial of the later Type A was used – at first glance – like the artifact of this offer – closely resembled the later "RLM Standard B-Uhr", there were still significant differences to the later standard:
- The pocket watch calibers 43 and 45 used were slightly smaller than the later standard movements of the B-Uhr watches.
- the prototypes had soldered bridges, unlike the bridges of the series production which are connected to the housing as a single unit.
- The prototypes had hinges and an inner protective cover; the later standard only had a pressed-in bottom.
- The hands on the prototype were set like on pocket watches and not yet via the crown.
- The prototypes mostly had the typical onion crown of earlier pocket watches, which were later sharply grooved for easier operation with gloves.
- The prototypes were still signed at the factory like Lange & Söhne pocket watches: "Deutsche Uhrenfabrikation Glashütte", the later series models were signed in clear lettering only "A. Lange & Söhne"
- All Lange & Söhne prototypes had a serial number around 92,650, while later standard B-Uhr watches from Lange had serial numbers around 210,000 - 215,000.
- Factory architecture: The restless structure is located opposite the elevator wheel.
The more than museum-worthy, almost unique artifact offered here is without a doubt a specimen of these 189 prototypes from Lange & Söhne dating from the mid-1930s: every single one of the aforementioned characteristics applies.
It is documented in the literature - Konrad Knirim "Military Timepieces", page 335 - that the prototype of this offer must have been built and delivered at the beginning of 1935, since the delivery of a prototype 11 serial numbers "older" to the Reich Air Ministry is documented as having taken place on March 31, 1935.
Furthermore, as clear proof: The museum artifact offered here is only 11 serial numbers away from a B-Uhr prototype from 1936 described in specialist literature: 92665 and 92654
Considering that most of the 189 prototypes from Lange & Söhne were actually tested and flown in combat, with many being shot down and destroyed, as well as the natural attrition due to age, loss, and uninformed heirs over the past 90 years, it can be assumed that there are definitely fewer than 100 of these military milestones and pieces of aviation watch history left worldwide today, and these are located in private collections and museums.
In my 30 years of collecting military watches, I've seen hundreds of thousands of them online, in auction catalogs, and at auctions – never once have I seen one of the 189 Lange & Söhne prototypes.
The artifact offered here could be the last of its kind ever to be offered on the open collectors' market.
Description:
Earliest RLM B-Uhr with central seconds from 1936, A. Lange & Söhne Glashütte i.Sa., one of only 189 prototypes of the later standard observation watch of the Reichsluftwaffe, case number no. 92654
Nickel case, case with inner protective cover, both covers hinged
Movement caliber ALS 43, 43mm movement diameter, stop-seconds function via the olive
Movement number 92654, no case number is given (because it's a prototype), dial type A, soldered lugs, hand setting not via crown but via side lever
Black dial, type A, with luminous Arabic numerals, large luminous hour scale with Arabic numerals, luminous hands, luminous central seconds hand.
DUF pocket watch caliber 43 as used for all 189 prototypes of the Reichsluftwaffe
Manufactured in 1935, this magnificent piece of (military) watch history starts and runs (accuracy not tested)
According to an excerpt from the archives of the Glashütte Watch Museum, a planned sale (for testing purposes) to the German Naval Observatory in Hamburg was scheduled for March 28, 1935. The excerpt states that the watch in question was, for whatever reason, exchanged for an identical model from the same small production run; presumably, a minor defect occurred or it was not yet fully calibrated.
This documented exchange, however, does not change the fact that the unique artifact in this offer is one of the 189 prototypes of this small series and was already completed in March 1935 (!!).
The archive extract also proves that this piece of military watch history already met the aforementioned requirements of the Reich Air Ministry regarding dial and degree markings in March 1935.
A unique, museum-quality artifact and piece of military watch history: the German B-Uhr of the Luftwaffe has been copied tens of millions of times worldwide in the last 80 years, some tens of thousands of originals were built and used in combat during World War II, this is definitely the first B-Uhr ever built!
Condition: 2 - normal, barely noticeable signs of age and use, no damage or deep scratches, tarnishes slightly, the glass has scratches and could be replaced, but that was probably not original either.
