Luftwaffe DR2 Knemeyer and its use

[Theodor]

A pity, this one has a part missing

[Theodor]

Or maybe you were asking about the one that is printed in the manual? Please excuse me if misunderstood you. Here is a better picture. It is German, too, DR2 dated April 1937.

[Huib Ottens]

Hi Theodor,

Thanks for the scans. I was referring your Dreieckrechner, but the other scan is also welcome. I was hoping for a Dreieckrechner of Bulgarian origin. Dreieckrechner of Hungarian, Swiss and British origin are known to exist.

I think these Dreieckrechner are highly collectable items. There are many versions of this instrument, and Siegfried Knemeyer himself is also a very interesting subject.

My personal collection holds 18 (14 versions) Dreieckrechner at the moment.

[Ronald van Riet]

In an earlier post, I mentioned the paper that I had written on the DR series.

I have now made this available through the following site:

sites.google.com/site/sliderulesite.

I intend to upload one or two more papers on aircraft navigation slide rules here in the weeks to come.

I will upload new versions as and when interesting new information becomes available, so do check back every once in a while.

And of course, if you have any additions to this or one of the other papers, by all means mail them to me and I will include this in such new version.

Ronald

[Theodor]

This was VERY interesting to read, thank you!!!!!

[Theodor]

BTW today I visited the Museum of Aviation. If you ever visit Bulgaria, my advise is, don't miss it! Lots of aircraft and choppers, some of those really interesting. And the location is good, in the middle of the country, just a couple of kilometers from the highway and right next to the Plovdiv Airport.

[Theodor]

But the purpose is not to advertise the museum - my point is to show you something related to this thread, the Bonanza of instruments, that I found in the museum building indoors exposition!

First, the Bulgarian copy of the DR. "Calculation Circle of the Pilot K-2", made by M. Kachulev. Over it an ordinary German DR2, to the right some old French flight calculator Mercator 100.

[Theodor]

And then.... another Bulgarian DR-like instrument! Navigation Calculation Instrument "Faki" /probably abbreviation/, made - again - by M. Kachulev. With the original manual, clearly pre-1945.



And another one from that type!



The little information visible on the manual is valuable for me! M. Kachulev built these two DR-like instruments /and maybe even more/ and his name is seen on the 1947 pilot slide rule, too. On the page is seen, that his name is Mircho Kachulev and he was Chief of the Air Photography Service of the Flight Schools of the Air Force. In other words, he was both photographer and Observer - this making him familiar with the subject of flight calculation instruments.

[Theodor]

And some more flight related instruments. A 1943 device, used for training calculations about fighters attacking:



Some rule:



A 1941 instrument - Russian?



And a postwar "Board table":