"One of the most secret weapons used during World War II by the United States."

So begins a typical description of Carl Norden's invention. The object of myth, propaganda and Hollywood movie makers, the Norden Bombsight achieved legendary status during WW2. The reason for this can be attributed to a number of factors; it was available at a time when the United States needed heroes - including technological heroes - and it was probably the best bombsight of the war.

The subject of spy movies and propaganda during WW2, the Norden Bombsight achieved legendary status almost overnight. The Norden's "secret plans" were always a plausible reason for Hollywood writers to embark on a confrontation between the forces of good and evil. In the movies the plans never made it to Berlin, however in reality they arrived there in 1938, and were shrugged off as inconsequential by Reichsmarschall Goerring.

The Norden bombsight was a mechanical analog computer, designed to determine the exact moment bombs needed to be released in order to hit their target. The bombardier's job was to "program" the computer with the information it needed to make the calculations. On the bombing run, the sight would fly the aircraft and determine the proper point at which to drop the bombs. Sounds simple today, but in 1930 this was a very big ask. However for its inventor this was only another problem to be solved.

Carl Norden, born in 1880 in Java to Dutch parents, studied mechanical engineering at the Federal Polytechnic Institute in Zurich. In 1904 a wealthy uncle helped Norden immigrate to America. There, in 1911, the inventor Elmer Sperry hired him to work on ship gyro-stabilizers. Their relationship soon turned to animosity - Sperry despised Norden's appetite for "vile, black cigars," while Norden resented his employer's suggestion that any of his future patents relating to gyro-stabilizers be assigned to the Sperry Gyroscope Company. In 1913 Norden left Sperry and formed his own company.

Norden was described by his contemporaries as a man of immense nervous energy, excitable and volatile, with a fierce temper. One senior naval officer referred to him as 'Old Man Dynamite.' Unsociable and reclusive, a major reason for Norden's obsession for privacy were his exacting standards. He prefered to start with a new design rather than first determining what others had done, believing that if he took too much notice of the way things had been done before it would stiffle his creativity. Only after he'd worked out his way of doing things would he then make comparisons.

Norden began his bombsight design in 1920 for the Navy's Bureau of Ordnance. In their search for an effective means of sinking enemy ships, the Navy had studied level bombing, dive bombing, glide bombing and aerial torpedo attack. Norden's initial assignment was to improve on the state of the art, a World War I bombsight designed by Harry Wimperis of the British Royal Navy. It was a crude device - a board fitted with a bubble level and two adjustable rifle sights. Tests showed that bombs aimed by it seldom struck within a hundred yards of their target. The reason for this was the pitch and roll of the aircraft during the bomb run, something the bombsight was incapable of compensating for.

Norden added gyro-stabilization, a telescope for better target sighting and a means of signalling flight directions to the pilot. When the first tests were unsatisfactory, he went back and designed an all-new sight at his own expense. To assist him the Navy assigned him an assistant, Theodore Barth, an engineer and ex-Army colonel who had a reputation for being able to get the job done.

Progress was still slow, in many ways Norden had underestimated the complexity of the problems he was trying to solve. Tests in 1925 of a new sight at the Navy's Virginia proving ground were disappointing, and bombardiers complained that operating the device demanded both hands, feet, and teeth to make it work so complicated were the control mechanisms. Norden made improvements but problems persisted. Strangely, the Navy pushed for a production contract for this early device christened the Mark XI. Norden and Barth resisted, but in 1928 they established Carl L. Norden, Incorporated, to fulfill Navy orders

Enter the Army Air Corps

The story of the Norden bombsight is also one of interservice rivalries and subterfuge. During the 1920s the Army had issued a requirement for a bombsight and although in the intervening years several models were developed including designs by Elmer Sperry, who stabilized the bombing platform with an autopilot he'd designed, none were accepted. Sperry and the Army Air Corps had created a close relationship and Sperry, still bearing his antagonism towards his old colleague Norden, refused to endorse any of Norden's work. After agreeing to work for the Navy, Norden returned to Zurich where he remained at his mother's home while he design the Mark XV bombsight. When he returned in 1930 to demonstrate a prototype, Lieutenant Frederick Entwistle, the Navy's chief of bombsight development, judged it as revolutionary. The most significant improvement was that one simple adjustment by the bombardier measured the aircraft's ground speed and locked the target under the sight's horizontal crosshair. Norden's sight also calculated true air speed, wind speed, and angle of drift. It then automatically dropped the bomb load at the right moment, eliminating a significant source of human error.

In 1932 the Army and Navy finally consulted with each other and discovered that between them they had the makings of an excellent bomb aiming system. By combining the Navy's Norden Mark XV design with the Army's Sperry A-1 autopilot, they could create a fully integrated system comprising a stabilised bombing platform and a superb optical aiming device.

However the interservice rivalry continued until the Second World War - the Navy insisted that all the Army's Norden bombsights had to be procured through them and went to extreme lengths to hoard bombsights and even create artificial shortages by monopolising production for their own requirements - then putting them into storage - surely an example of interservice stupidity taken to the extreme.

A legend is born

With the development of the B-17 bomber and its introduction into service in 1939, the Army finally had the makings of a completely integrated bombing system. The new Flying Fortress was the perfect platform for the Norden bombsight and the combination was soon receiving the attention of Hollywood and eager journalists. It was a publicity agent's dream and with the outbreak of war the hype was notched up to plant the mystique of the Norden firmly in the minds of the American public as being capable of dropping a bomb in a "pickle barrel" from 20,000 feet.

The Norden in a B-17

In 1941 the Army Air Force commisioned novelist John Steinbeck to write a recruitment documentary, Bombs Away, in which he noted, "The bombsight has become the symbol of responsibility. It is never left unguarded for a moment. On the ground, it is kept in a safe and under constant guard. It is taken out of its safe only by a bombardier on a mission, and he never leaves it. He is responsible not only for its safety but its secrecy. Should his ship be shot down, he's taught how quickly and effectively to destroy it." (by shooting it with a Colt 45!)

Hollywood added to this hype in the 1943 epic "Bombardier", a film hailing the Norden sight as the ultimate in accuracy, extolling the courage of the bombardiers who used them without even showing a glimpse of the actual instrument.

There is little doubt that the Norden was probably the finest bombsight of the war, however claims as to its accuracy were way beyond its actual capability. Under perfect conditions the sight was capable of being very accurate, however the problem lay in the accuracy of the information being fed to it - garbage in, garbage out. This included actual wind conditions over the target - something that could only be predicted, guessed, or calculated for the altitude the aircraft was flying at. During the war with high altitude bombing there was no way to integrate in real time the various layers of wind velocities that the bombs passed through on their way to the target.

Accuracy could also be affected by aircraft movement. While the integration of the bombsight with Sperry's autopilot greatly helped, the effect of flack bursts, turbulence and evasive manouvres all contributed to throwing bombs off target. From 25,000ft it doesn't take much deflection to send a bomb a long way off course by the time it reaches the ground . In many ways the Norden was perfection in its own right, let down to some extent by deficiencies in the systems supporting it.

Many bomb aimers took their responsibilities extremely seriously, studying the workings of the Norden and perfecting their aiming techniques to gain better accuracy. By understanding its workings they also understood its weaknesses and were able to compensate accordingly and there were instances reported where bombs aimed from over 20,000 feet were on target. However as history shows the theory of area bombing had its flaws and generally due to a combination of factors - none the least being enemy action, most results left much to be desired.

The configuration of the Norden, except for development changes, remained the same throughout its life. Later several improvements were added to make it more accurate - new optics were developed, ballistic charts updated and electrical system refined. Electronics were first used in the C-1 auto pilot in 1941 and radar was also later used with the Norden.

The ulitmate use of the Norden came in August 1945 when it was used by the bombardier of the Enola Gay to drop the first nuclear weapon on Hiroshima, a strange contrast as the first bomb being a weapon of mass destruction hardly needed pin-point accuracy and probably would've been equally effective if aimed with a grease pencil cross on the windshield.

By war's end nearly 90,000 bombsights had been constructed by Norden and other contractors at a cost of $1.1 billion to the U.S. government. The Norden soldiered on in service until the Vietnam war when it was used by B-52s in the war against the North.

The ultimate irony concerning the secrecy surrounding the Norden, was that in 1938, an employee of the Norden Company named Lang, stole blueprints for the bombsight and sold them to the Luftwaffe for $3000. Goerring admitted that it was a clever device, however as the Luftwaffe's policy was centred on dive bombing to achieve accuracy, they had no need for such a bombsight.

Part 2: We reveal the Norden's Secret.