quote:

Originally posted by sigfreund:
What was always a mystery to me, though, was the obsessive secrecy about it during the war, and yet there must have been countless examples that fell into German hands due to the number of aircraft that were shot down over the continent.

quote:

...
Until late 1943, the Norden bombsight was always protected by exceptionally heavy security. Sights were normally stored in air-conditioned, dustproof vaults that were patrolled by armed guards. During training, USAAF bombardiers had to swear a solemn oath to guard the secret weapon with their lives (see sidebar below), and they were responsible for destroying it in the event of an emergency landing behind enemy lines. Whenever a bombardier or ordnance technician carried a sight out to an aircraft, two armed guards accompanied him.

After hundreds of Norden-equipped bombers were shot down over enemy territory during 1943, Allied officials knew that the Germans had surely studied the bombsight and learned its secrets. As a result, security was finally relaxed. When the war ended, details of the ingenious device were finally made public. But U.S. intelligence experts received a shock when they interrogated Luftwaffe personnel: The Germans had known the bombsight’s secrets even before the war, thanks to a spy at Norden.

Herman W. Lang, a naturalized U.S. citizen, had been employed as a draftsman and inspector at the Norden factory during the 1930s. American authorities didn’t know that he had served as Nazi stormtrooper in Germany between 1923 and 1927. Recruited as a member of the Duquesne Spy Ring, in 1938 Lang gained access to the plans for the bombsight and hand-copied the blueprints, which were then smuggled to Germany via ocean liner. He traveled to Germany for a “vacation” to assist Luftwaffe technical experts, receiving 10,000 Reichsmarks for his efforts. Lang returned to his job in America, but was later betrayed by a double agent, convicted of espionage and sentenced to 18 years in prison.

The Germans built a mock-up of the Norden sight and compared it to the new Lotfernrohr 7, or Lotfe 7, bombsight then being used by the Luftwaffe. The Lotfe 7 was similar in operation to the Norden, but much simpler and easier to operate. It consisted of a single metal casing holding the majority of the mechanism, with a tube extending out the bottom containing a mirror that reflected the image of the target into a small telescope in the box. The mechanisms within combined the functions of the Norden’s stabilizer and optics, moving the mirror to stabilize the image, as well as tracking the target. The Lotfe 7’s controls were also simpler than the Norden’s, consisting mainly of three large knobs to adjust aim.

The Luftwaffe decided their Lotfe 7 was better than the Norden and gave the American device no further consideration. So despite years of extraordinary efforts by U.S. military and civilian authorities to keep the Norden bombsight secret, America’s secret weapon was never secret—except to the American public.

quote:

Originally posted by BamaJeepster:

quote:

Originally posted by sigfreund:
What was always a mystery to me, though, was the obsessive secrecy about it during the war, and yet there must have been countless examples that fell into German hands due to the number of aircraft that were shot down over the continent.

Your post prompted me to look for an answer, because I was curious as well and didn't really know the answer. Found an article online written by an Air Force veteran who is a former curator at the National Air and Space Museum and an expert on the Norden sight:

quote:

...
Until late 1943, the Norden bombsight was always protected by exceptionally heavy security. Sights were normally stored in air-conditioned, dustproof vaults that were patrolled by armed guards. During training, USAAF bombardiers had to swear a solemn oath to guard the secret weapon with their lives (see sidebar below), and they were responsible for destroying it in the event of an emergency landing behind enemy lines. Whenever a bombardier or ordnance technician carried a sight out to an aircraft, two armed guards accompanied him.

After hundreds of Norden-equipped bombers were shot down over enemy territory during 1943, Allied officials knew that the Germans had surely studied the bombsight and learned its secrets. As a result, security was finally relaxed. When the war ended, details of the ingenious device were finally made public. But U.S. intelligence experts received a shock when they interrogated Luftwaffe personnel: The Germans had known the bombsight’s secrets even before the war, thanks to a spy at Norden.

Herman W. Lang, a naturalized U.S. citizen, had been employed as a draftsman and inspector at the Norden factory during the 1930s. American authorities didn’t know that he had served as Nazi stormtrooper in Germany between 1923 and 1927. Recruited as a member of the Duquesne Spy Ring, in 1938 Lang gained access to the plans for the bombsight and hand-copied the blueprints, which were then smuggled to Germany via ocean liner. He traveled to Germany for a “vacation” to assist Luftwaffe technical experts, receiving 10,000 Reichsmarks for his efforts. Lang returned to his job in America, but was later betrayed by a double agent, convicted of espionage and sentenced to 18 years in prison.

The Germans built a mock-up of the Norden sight and compared it to the new Lotfernrohr 7, or Lotfe 7, bombsight then being used by the Luftwaffe. The Lotfe 7 was similar in operation to the Norden, but much simpler and easier to operate. It consisted of a single metal casing holding the majority of the mechanism, with a tube extending out the bottom containing a mirror that reflected the image of the target into a small telescope in the box. The mechanisms within combined the functions of the Norden’s stabilizer and optics, moving the mirror to stabilize the image, as well as tracking the target. The Lotfe 7’s controls were also simpler than the Norden’s, consisting mainly of three large knobs to adjust aim.

The Luftwaffe decided their Lotfe 7 was better than the Norden and gave the American device no further consideration. So despite years of extraordinary efforts by U.S. military and civilian authorities to keep the Norden bombsight secret, America’s secret weapon was never secret—except to the American public.

https://www.historynet.com/not...norden-bombsight.htm

I ran across this old Periscope film about the Principles of the Norden bombsight that I though was pretty cool:
[FLASH_VIDEO]<iframe frameborder="0" height="408" src="https://www.youtube.com/embed/143vi97a4tY" width="725"></iframe>[/FLASH_VIDEO]

quote:

Originally posted by sigfreund:
<snip>
It’s also interesting that the Germans had a sight they considered superior to the Norden. Another of those inconvenient facts that often don’t appear in histories written by the winners.

quote:

Originally posted by V-Tail:

quote:

Originally posted by PHPaul:

Other than a neat mechanical/technical exercise...why?

An excellent device to calculate the cost of restoring a bulldozer.

quote:

Originally posted by flashguy:
^^^^^ Slide rules couldn't add or subtract, and they had limited precision--even the way oversized ones were limited to 4 or 5 significant figures. The big Friden electro-mechanical calculators had 10-digit data entry and 20-digit product/dividend registers. My first hand-held calculator (a Sanyo) cost $175 and could display 16 digit answers (limited to 4 decimal places, though); it had BIG buttons--very easy to use, and the display was LED.

There have been calculation races between skilled abacus users and those with calculators--the abacus usually wins.

flashguy