10 Feb
2015
10 Feb
'15
9:37 a.m.
On 02/10/2015 09:29 AM, Pete Turnbull wrote:
Yes, this is as I suspected, due to the difficulty of
sending anything across the Atlantic, and the
EXTREME sensitivity of the project. They actually did a LOT
better at keeping this one
secret than they did with the Manhattan project.
Jon
I'm not an expert, but I think you're a bit wide of the
mark in places. You're evidently referring to the US Navy
bombes. Although the original contract was apparently for
350, only 121 were ever built, including prototypes, and
they were used at the US Navy Communications Annex in
Washington, not Ft Meade. The US Army also had a small
number of bombes built closer to a British design. And
the reproduction at Bletchley doesn't run at the full
speed of the later British ones, although it's true the US
Navy Bombe was a good deal faster (850rpm or 1725rpm vs
120rpm; various sources suggest between 5 and 10 times
faster in practice).
There is a 7-part article about the building of the NCR
Bombes that I read. It was written largely
by Joe Desch's daughter. He was the main designer and
project leader of the NCR Bombe.
It is an interesting story, but I have failed to find the
link again in a quick look. Possibly the 350 number
was the number originally ordered, and she found this number
in documents, but didn't
know that the production was cut short as the machines were
so successful.
Bletchley itself had only a small number of bombes. Most
of the 224 built in Britain were housed at outstations.
Because I've not seen the film, I don't know what the
"clunk-clunk-clunk" you refer to is, but I've seen and
heard the bombe running and I would bet it's the sound of
the middle wheels advancing, roughly once a second on the
replica, but faster on most of the British bombes.
Yes, exactly.
It only makes sense for there to be a big array
of NCR
Bombes, not
the slow British-built ones, but
with all the ships being sunk, how could they be sure
such a shipment
could make it across the Atlantic?
They didn't. No bombes were ever shipped across the
Atlantic. Only design drawings and information were, in
the care of officers from the US Army and Navy in 1941,
and later two USN and some senior Bletchley staff in
1942. The US Navy bombe was an adaptation of the British
design from the latter exchange, and went into service in
1943. Britain had been using their bombes for several
years by then, of course.
Bletchley apparently did use USN bombes, but not
directly. They did it by sending cribs and getting the
stops and settings back over encrypted cable, to be used
for decryption of 4-rotor Naval Enigma messages at
Bletchley Park.