Bf 109 instrument dial identification

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Y

Yeomans

Airman
17
6
Mar 11, 2012
I am hoping the experts might be able to confirm the identity of the attached dial which is amongst a group of other parts in the artefacts store of our local museum. They are simply labelled as having been recovered from the crash site of a Bf 109 at Leigh. It is very difficult to make out any of the markings but to me it seems to most closely resemble a tachometer dial. Any help would be much appreciated. Thanks. Nick
 
I think your tach theory is correct, though the 1:2 and 2:1 between the 15 and 20 appear reversed in the example below.


The orientation of the 15 and 20 also differs slightly but the face on yours is crumpled.

German Luftwaffe Me109 Aircraft Tachometer Instrument | #198169104

This is a World War Two German Luftwaffe aircraft tachometer that was used in the Messerschmitt Bf 109, Junkers Ju 87 Stuka dive- bomber, and other German WW II aircraft to measure engine speed. It ha
www.worthpoint.com
 
I agree it is a dial of the tachometer. The indicator was made by a couple of the ww2 German manufacturers. These were made as the 1:2 and 2:1 ratio ones. IMHO your tachometr might have been the Drehzahlmesser/Drehzahlanzeiger of the Fl.20286 number. All of these of the FL number I have found via the net, had the central round hole and the support for the hand and dial seen. Additionally there were two small screws below the opening like for your dial. However the dials with the two additional screws above the hole were too. The layout of the digits was slightly different. Please notice the loctaion of the number "20" on the dials. But I found a similar layout to yours on the Fl.20219 of 1939 and Fl.20222-2 of 1941 tachometers. So there were variations for it depending on the manufacturers and the plane it was going to be used with.



the pic source:

Drehzahlmesser | Deutscheluftwaffe

www.deutscheluftwaffe.de

Drehzahlmesser | Deutscheluftwaffe

www.deutscheluftwaffe.de
 
Many thanks for this. I will make a closer examination when next in the museum archive to see if I can make out the Fl. number.
 
Last edited by a moderator:
Engineman said:
Hi,
Certainly a Luftwaffe Drehzahlmesser. The exact Fl number is not readable. Possibly Bf 109, but id from other parts would be wise.
Guess this is at Leigh, Kent?

Eng
Click to expand...

Many thanks.I will take a closer look to see if I can make out the Fl. number. I think this is likely to be Leigh in Kent rather than Surrey, as I am not aware of any Luftwaffe crashes in the immediate vicinity of the latter.
 
Yeomans said:
Many thanks for this. I will make a closer examination when next in the museum archive to see if I can make out the Fl. number.
Click to expand...

My pleasure. The Fl. number can be found on the data plate/ data sticker attached to the indicator case at its side or back. There may be found also the Gerät number and the manufacturer ( Hersteller ) name or three-letter code usually.
 
I realized years ago that tach dials are different, if the manufacturer knows what he is doing. The tach cable on my Ercoupe failed, and if you have ever had a speedometer cable fail, it was just like that. It suddenly went WHEEEEOOOOO! and the needle buried itself at the high side. The failure occurs when the center shaft in the cable, which is made like a long thin spring, snags on the outer shield and unwinds some.

In changing the tach cable I found writing on the case of the tach, "No Good." I had noted a little variation in the needle, which I took to be due to instability of the engine while idling on the ground and variations in the atmosphere while flying. but in fact it was the tach making that needle wobble. I bought a Chinese made tach on ebay and installed it. I soon realized that while it worked better than the old one in terms of being steady, it would not do.

The Chinese tach had the numbers around the outside edge of the scale, with the scale marks inside of the numbers. So the needle was much shorter. The reason this s problem is that when you are doing a mag check before takeoff you need to easily spot small variations in RPM. You normally do a run up at 1700 RPM and switching to one mag causes a slight drop in RPM, the allowable maximum drop typically being around 100 RPM. If the numbers are around the outer edge and the needle only comes up to just below them, that much of a drop is very hard to see. Putting the numbers inside the scale expands the scale and makes small changes in RPM much easier to spot. So I bought a new US made tach.
 
I'm not so sure the artifact is a tachometer dial. If you look at the lettering, I think it is more like O/min than U/min. Even with the dial crumpled I don't think you could get the curvature you see on the partially obscured letter. Maybe a careful brushing around the letter would clear the debris for a better assessment.

In addition, all the tachometers shown have a x100 underneath the U/min. The dial is pretty banged up, but you should still see some remnant of the x100, and you don't.
 


If "O/min" , for what would be the measurement unit ... ?
 

I think you need to propose something, other than saying "I don't see ..." . None of us can see all the details but, we can see what it is an example of.
From my view, the exact type is not identified yet. Yeomans has said he will try harder on some numbers.

Eng
 

I agree. What is more a close up inspection of the dial reveals more details we can expected although the dial is crumpled . First of all, the "U/min" is the German abbreviation stands for the "Umdrehungen pro Minute". In other words the RPM. Secondly, the marking of the scale with 5,10,15,20,25 and possible 30 ,35 fits the kind of the guage. I have to admit I haven't seen a such unit like the O/min unless it would be in Polish "Obroty na minute". But it is not the Polish indicator rather. The strange shape of the letter "U" looking like the "O" is because of the wavy deformation of the dial surface at the area. Especially at the left edge of the letter. Thirdly, the marking/ratio 1:2 also is quite characteristic for the known WW2 German tachometers. And finally, there seems to be a W number or better, the name of the manufacturer at the area that I marked with the blue colour. All the details indicate the tachometer. Additionally the lack of the "x100" below the " U/min" inscription could be for many reasons.


 
I have enlarged the image at the area below the 1:2 inscription. It is quite damaged and distorted. But IMHO the inscription there can be noticed although partially only. Judging by the shape of the letters I bet there is the "Deuta-Werke" name pressed/engraved. It was the German manufacturer from Berlin who produced the tachometers during the WW2. The Hersteller code was hnf. The full inscription should be then .... DEUTA WERKE BERLIN SWSS like in the enlarged image of the Fl.20286-3 Drehzahlmesser/Drehzahlanzeiger with the name printed.



 

Remarkable detective work! Very many thanks. I have now had a much closer look with a decent light source and magnification. I can indeed make out the following : DEUTA WERKE and the under the letters TA of DEUTA I can make out Fl but only a few other characters. It looks like a 5 under the W of WERKE and then 68 under the K. I have taken some more photos and will post these shortly.
 

The location of the Fl number looks correct. Initially I have thought there could be the second line for the full manufacturer's name or the W/serial number. But the location of the Fl one there was also possible and known from other German gauges and the dials. So with no doubt it is the German indicator measuring the U/min.
 
Some additional photos. There are some other numbers below the 25.
 

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Yep .. so I was correct thinking the inscription below the DEUTA WERKE is the second part of the manufacture's name, the BERLIN SWSS. The numbers below the "25" looks like just the FL number ... The top inscription is the Fl while the three digits seen below "028", "023" or "128","123" are the part of the FL number. Generally the Fl number was stamped on the data plate attached to the indicator casing usually. But it could be repeated (painted or stamped) on a dial and is also known from the other WW2 German gauges. See my post #3 above , the first top image from the left and the two bottom ones.

 
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