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This page is a stub
The Enigma D was developed in 1926 as the successor to the
Enigma C.
The official model number was A26 and it was given the internal
designator Ch. 8.
It was replaced a year later by the nearly identical
Enigma K (A27).
The Enigma D contained many improvements over the Enigma C. First of all,
the top lid of the machine was made more accessible,
so that it was easier to alter the basic settings (key).
The three coding wheels were now mounted on a removable spindle,
so that the order of the wheels could be changed as well.
Furthermore, the reflector (UKW) was made settable,
which means that it could be set to any of 26 positions.
All this increased the maximum number of permutations.
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As a result, 4 wheels protrude the top lid and hence there are 4 windows
through which the current settings can be viewed.
Because of this, it is sometimes assumed that this is a 4-wheel Enigma
machine. Although stricktly speaking there
are 4 wheels, the leftmost one is the UKW.
It should therefore be defined as a 3-wheel machine with a
settable UKW.
The machine was built on an improved die-cast chassis and the order of
the keys and the lamps was now similar to that of a standard German typewriter
(QWERTZ... rather than ABC...).
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Looking at the Enigma Family Tree it is obvious that around 1926
the Enigma D was the core product of the manufacturer, Heimsoeth und Rinke.
All further Enigma machines would be based (largely or in part) on the Enigma D design. The Enigma D itself was short lived and was replaced approximately
a year after its introduction by the Enigma K.
Apart from a few manufacturing changes, the Enigma K is identical to the
Enigma D.
The image above shows the first page of the instruction booklet of the Enigma D.
Click the image to take a closer look.
At present, no images of a real Enigma D machine are available to us.
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Descendants of the Enigma D
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In 1927, one year after the introduction of the Enigma D, several developments
of improved machines were started. This lead to a range of new - improved - commercial
machines and advanced high-end machines. The later military machines
were also initially based on the Enigma D.
The following machines are directly developed from, or inspired by, the Enigma D:
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- Reichswehr D (Ch. 11a)
Machine with a single-ended Steckerbrett. This ultimately lead to the
developement of the later Enigma I used by the Reichswehr
(later the Wehrmacht).
- Enigma K (A27, Ch. 11b)
From 1927 onward (right up to 1944), this was the main non-Stecker
machine. Many improvements were made and many different versions exist.
It was, for example, the basis for the Enigma T (Tirpitz),
the Swiss K variant
and the Enigma KD.
- Zählwerk Enigma (A28, Ch. 15)
This was a range of high-end Enigma machines with advanced mechanics
and enhanced cipher security. The later Enigma G range (G31) was
also based on this machine.
- Enigma Z (Z30, Ch. 16)
This was a numbers-only version of the Enigma machine. It had just 10 keys
(0-9), 10 lamps and the wheels each had 10 contact points.
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