1. Norden Bombsight For Sale

Bombardier with the Norden Bombsight on after the dropping of The Norden Mk. XV, known as the Norden M series in Army service, was a used by the (USAAF) and the during, and the in the and the. It was the canonical design, a system that allowed it to directly measure the aircraft's ground speed and direction, which older bombsights could only measure inaccurately with lengthy in-flight procedures. The Norden further improved on older designs by using an that constantly calculated the bomb's impact point based on current flight conditions, and an that let it react quickly and accurately to changes in the wind or other effects. Together, these features seemed to promise unprecedented accuracy in day bombing from high altitudes; in peacetime testing the Norden demonstrated a (CEP) of 23 metres (75 ft), an astonishing performance for the era.

This accuracy allowed direct attacks on ships, factories, and other point targets. Both the Navy and the AAF saw this as a means to achieve war aims through high-altitude bombing; for instance, destroying an invasion fleet by air long before it could reach US shores. To achieve these aims, the Norden was granted the utmost secrecy well into the war, and was part of a then-unprecedented production effort on the same scale as the. Ranked 46th among United States corporations in the value of World War II military production contracts. In practice it was not possible to achieve the expected accuracy in combat conditions, with the average CEP in 1943 of 370 metres (1,200 ft) being similar to Allied and German results. Both the Navy and Air Forces had to give up on the idea of pinpoint attacks during the war. The Navy turned to and to attack ships, while the Air Forces developed the concept to improve accuracy, while adopting area bombing techniques by ever larger groups of aircraft.

Nevertheless, the Norden's reputation as a pin-point device lived on, due in no small part to Norden's own advertising of the device after secrecy was reduced late in the war. The Norden saw some use in the post-World War II era, especially during the. Post-war use was greatly reduced due to the introduction of radar-based systems, but the need for accurate daytime attacks kept it in service for some time. The last combat use of the Norden was in the 's squadron, which used them to drop sensors onto the as late as 1967. The Norden remains one of the best-known bombsights of all time. A page from the Bombardier's Information File (BIF) that describes the components and controls of the Norden Bombsight. The separation of the stabilizer and sight head is evident.

1. The Norden M-1 Bomb-Sight. Although the Norden bomb-sight was superior to other bombsights, it was not the first. Elmer Sperry, who had invented the gyroscopic compass, had developed the Sperry Gyroscope bombsight for the U.S. Army Air Force.
2. The Norden bombsight was just one step, but a giant step, in the evolution of bombsights, dating back to World War I, when pilots used a simple crosshairs telescope to help bring their bombs close to their designated target. The World War II Norden bombsight consisted of two main parts, a stabilizer and a sight-head.

This is a much less common and less understood part of the Norden Bombsight system. The Sighhead rested on the stabilizer, and was connected to it by a long stem protruding underneath the Sighthead, as well as through a connecting rod which went to the Bombsight Clutch.

Background Typical bombsights of the pre-war era worked on the 'vector bombsight' principle introduced with the. These systems consisted of a -type calculator that was used to calculate the effects of the wind on the bomber based on simple. The mathematical principles are identical to those on the calculator used to this day. In operation, the bombardier would first take a measurement of the wind speed using one of a variety of methods, and then dial that speed and direction into the bombsight. This would move the sights to indicate the direction the plane should fly to take it directly over the target with any cross-wind taken into account, and also set the angle of the to account for the wind's effect on ground speed. These systems had two primary problems in terms of accuracy. The first was that there were several steps that had to be carried out in sequence in order to set up the bombsight correctly, and there was limited time to do all of this during the bomb run.

As a result, the accuracy of the wind measurement was always limited, and errors in setting the equipment or making the calculations were common. The second problem was that the sight was attached to the aircraft, and thus moved about during maneuvers, during which time the bombsight would not point at the target. As the aircraft had to maneuver in order to make the proper approach, this limited the time allowed to accurately make corrections. This combination of issues demanded a long bomb run. Experiments had shown that adding a stabilizer system to a vector bombsight would roughly double the accuracy of the system.

This would allow the bombsight to remain level while the aircraft maneuvered, giving the bombardier more time to make his adjustments, as well as reducing or eliminating mis-measurements when sighting off of non-level sights. However, this would not have any effect on the accuracy of the wind measurements, nor the calculation of the vectors. The Norden attacked all of these problems.

Basic operation To improve the calculation time, the Norden used a inside the bombsight to calculate the range angle of the bombs. By simply dialing in the aircraft's altitude and heading, along with estimates of the wind speed and direction (in relation to the aircraft), the computer would automatically, and quickly, calculate the aim point. This not only reduced the time needed for the bombsight setup but also dramatically reduced the chance for errors. This attack on the accuracy problem was by no means unique; several other bombsights of the era used similar calculators.

It was the way the Norden used these calculations that differed. Conventional bombsights are set up pointing at a fixed angle, the range angle, which accounts for the various effects on the trajectory of the bomb. To the operator looking through the sights, the crosshairs indicate the location on the ground the bombs would impact if released at that instant. As the aircraft moves forward, the target approaches the crosshairs from the front, moving rearward, and the bombardier releases the bombs as the target passes through the line of the sights. One example of a highly automated system of this type was the RAF's. The Norden worked in an entirely different fashion, based on the 'synchronous' or 'tachometric' method.

Internally, the calculator continually computed the impact point, as was the case for previous systems. However, the resulting range angle was not displayed directly to the bombardier or dialed into the sights. Instead, the bombardier used the sighting telescope to locate the target long in advance of the drop point. A separate section of the calculator used the inputs for altitude and airspeed to determine the angular velocity of the target, the speed at which it would be seen drifting backward due to the forward motion of the aircraft.

The output of this calculator drove a rotating at that angular speed in order to keep the target centered in the. In a properly adjusted Norden, the target remains motionless in the sights. The Norden thus calculated two angles: the range angle based on the altitude, airspeed and ballistics; and the current angle to the target, based on the ground speed and heading of the aircraft. The difference between these two angles represented the 'correction' that needed to be applied to bring the aircraft over the proper drop point.

Norden Bombsight For Sale

If the aircraft was properly aligned with the target on the bomb run, the difference between the range and target angles would be continually reduced, eventually to zero (within the accuracy of the mechanisms). At this moment the Norden automatically dropped the bombs. In practice, the target failed to stay centered in the sighting telescope when it was first set up. Instead, due to inaccuracies in the estimated wind speed and direction, the target would drift in the sight. To correct for this, the bombardier would use fine-tuning controls to slowly cancel out any motion through. These adjustments had the effect of updating the measured ground speed used to calculate the motion of the prisms, slowing the visible drift. Over a short period of time of continual adjustments, the drift would stop, and the bombsight would now hold an extremely accurate measurement of the exact ground speed and heading.

Better yet, these measurements were being carried out on the bomb run, not before it, and helped eliminate inaccuracies due to changes in the conditions as the aircraft moved. And by eliminating the manual calculations, the bombardier was left with much more time to adjust his measurements, and thus settle at a much more accurate result. The angular speed of the prism changes with the range of the target: consider the reverse situation, the apparent high angular speed of an aircraft passing overhead compared to its apparent speed when it is seen at a longer distance. In order to properly account for this non-linear effect, the Norden used a system of slip-disks similar to those used in.

However, this slow change at long distances made it difficult to fine-tune the drift early in the bomb run. In practice, bombardiers would often set up their ground speed measurements in advance of approaching the target area by selecting a convenient 'target' on the ground that was closer to the bomber and thus had more obvious motion in the sight. These values would then be used as the initial setting when the target was later sighted. System description The Norden bombsight consisted of two primary parts, the gyroscopic stabilization platform on the left side, and the mechanical calculator and sighting head on the right side. They were essentially separate instruments, connecting through the sighting prism.

The sighting eyepiece was located in the middle, between the two, in a less than convenient location that required some dexterity to use. Before use, the Norden's stabilization platform had to be righted, as it slowly drifted over time and no longer kept the sight pointed vertically. Righting was accomplished through a time consuming process of comparing the platform's attitude to small seen through a glass window on the front of the stabilizer.

In practice, this could take as long as eight and a half minutes. This problem was made worse by the fact that the platform's range of motion was limited, and could be tumbled even by strong turbulence, requiring it to be reset again. This problem seriously upset the usefulness of the Norden, and led the RAF to reject it once they received examples in 1942. Some versions included a system that quickly righted the platform, but this 'Automatic Gyro Leveling Device' proved to be a maintenance problem, and was removed from later examples.

Once the stabilizer was righted, the bombardier would then dial in the initial setup for altitude, speed, and direction. The prism would then be 'clutched out' of the computer, allowing it to be moved rapidly to search for the target on the ground. Later Nordens were equipped with a to aid in this step. Once the target was located the computer was clutched in and started moving the prism to follow the target.

The bombardier would begin making adjustments to the aim. As all of the controls were located on the right, and had to be operated while sighting through the telescope, another problem with the Norden is that the bombardier could only adjust either the vertical or horizontal aim at a given time, his other arm was normally busy holding himself up above the telescope. On top of the device, to the right of the sight, were two final controls.

The first was the setting for 'trail', which was pre-set at the start of the mission for the type of bombs being used. The second was the 'index window' which displayed the aim point in numerical form. The bombsight calculated the current aim point internally and displayed this as a sliding pointer on the index.

The current sighting point, where the prism was aimed, was also displayed against the same scale. In operation, the sight would be set far in advance of the aim point, and as the bomber approached the target the sighting point indicator would slowly slide toward the aim point. When the two met, the bombs were automatically released. The aircraft was moving over 110 metres per second (350 ft/s), so even minor interruptions in timing could dramatically affect aim. Early examples, and most used by the Navy, had an output that directly drove a Pilot Direction Indicator meter in the cockpit. This eliminated the need to manually signal the pilot, as well as eliminating the possibility of error. Army Air Forces use, the Norden bombsight was attached to its autopilot base, which was in turn connected with the aircraft's autopilot.

The Honeywell C-1 autopilot could be used as an autopilot by the flight crew during the journey to the target area through a control panel in the cockpit, but was more commonly used under direct command of the bombardier. The Norden's box-like autopilot unit sat behind and below the sight and attached to it at a single rotating pivot. After control of the aircraft was passed to the bombardier during the bomb run, he would first rotate the entire Norden so the vertical line in the sight passed through the target.

From that point on, the autopilot would attempt to guide the bomber so it followed the course of the bombsight, and pointed the heading to zero out the drift rate, fed to it through a coupling. As the aircraft turned onto the correct angle, a belt and pulley system rotated the sight back to match the changing heading. The autopilot was another reason for the Norden's accuracy, as it ensured the aircraft quickly followed the correct course and kept it on that course much more accurately than the pilots could. Later in the war, the Norden was combined with other systems to widen the conditions for successful bombing. Notable among these was the system called the, which were used directly with the Norden bombsight. The radar proved most accurate in coastal regions, as the water surface and the coastline produced a distinctive radar echo.

Combat use Early tests The Norden bombsight was developed during a period of when the dominant U.S. Military strategy was the defense of the U.S. And its possessions.

A considerable amount of this strategy was based on stopping attempted invasions by sea, both with direct naval power, and starting in the 1930s, with USAAC airpower. Most air forces of the era invested heavily in or for these roles, but these aircraft generally had limited range; long-range strategic reach would require the use of an.

The Army felt the combination of the Norden and presented an alternate solution, believing that small formations of B-17s could successfully attack shipping at long distances from the USAAC's widespread bases. The high altitudes the Norden allowed would help increase the range of the aircraft, especially if equipped with a, as with each of the four radial engines of the B-17. In 1940, Barth claimed that 'we do not regard a 15 square feet (1.4 m 2). As being a very difficult target to hit from an altitude of 30,000 feet (9,100 m)'. At some point the company started using the pickle barrel imagery, to reinforce the bombsight's reputation. After the device became known about publicly in 1942, the Norden company in 1943 rented and folded their own show in between the presentations of the.

Their show involved dropping a wooden 'bomb' into a pickle barrel, at which point a pickle popped out. These claims were greatly exaggerated; in 1940 the average score for an Air Corps bombardier was a circular error of 120 metres (400 ft) from 4,600 metres (15,000 ft), not 4.6 m from 9,100 m. Real-world performance was poor enough that the Navy de-emphasized level attacks in favor of almost immediately.

The could mount the Norden, like the preceding, but combat use was disappointing and eventually described as 'hopeless' during the. In spite of giving up on the device in 1942, bureaucratic inertia meant they were supplied as standard equipment until 1944. USAAF anti-shipping operations in the Far East were generally unsuccessful. In early operations during the, B-17s claimed to have sunk one minesweeper and damaged two Japanese transports, the cruiser, and the destroyer. However, all of these ships are known to have suffered no damage from air attack during that period. In other early battles, including the or, no claims were made at all, although some hits were seen on docked targets. The USAAF eventually replaced all of their anti-shipping B-17s with other aircraft, and came to use the technique in direct low-level attacks.

Air war in Europe As U.S. Participation in the war started, the U.S. Army Air Forces drew up widespread and comprehensive bombing plans based on the Norden. They believed the B-17 had a 1.2% probability of hitting a 30 metres (100 ft) target from 6,100 metres (20,000 ft), meaning that 220 bombers would be needed for a 93% probability of one or more hits. This was not considered a problem, and the AAF forecast the need for 251 combat groups to provide enough bombers to fulfill their comprehensive pre-war plans.

After earlier combat trials proved troublesome, the Norden bombsight and its associated AFCE were used on a wide scale for the first time on the 18 March 1943 mission to Bremen-Vegesack, Germany; The dropped 76% of its load within a 300 metres (1,000 ft) ring, representing a CEP well under 300 m (1,000 ft) As at sea, many early missions over Europe demonstrated varied results; on wider inspection, only 50% of American bombs fell within a 400 metres ( 1⁄ 4 mi) of the target, and American flyers estimated that as many as 90% of bombs could miss their targets. The average CEP in 1943 was 370 metres (1,200 ft), meaning that only 16% of the bombs fell within 300 metres (1,000 ft) of the aiming point. A 230-kilogram (500 lb) bomb, standard for precision missions after 1943, had a lethal radius of only 18 to 27 metres (60 to 90 ft).

Faced with these poor results, started a series of reforms in an effort to address the problems. In particular, he introduced the 'combat box' formation in order to provide maximum defensive firepower by densely packing the bombers.

As part of this change, he identified the best bombardiers in his command and assigned them to the lead bomber of each box. Instead of every bomber in the box using their Norden individually, the lead bombardiers were the only ones actively using the Norden, and the rest of the box followed in formation and then dropped their bombs when they saw the lead's leaving his aircraft. Although this spread the bombs over the area of the combat box, this could still improve accuracy over individual efforts. It also helped stop a problem where various aircraft, all slaved to their autopilots on the same target, would drift into each other.

These changes did improve accuracy, which suggests that much of the problem is attributable to the bombardier. However, precision attacks still proved difficult or impossible. When took over command of the from in early 1944, precision bombing attempts were dropped. Area bombing, like the RAF efforts, were widely used with 750 and then 1000 bomber raids against large targets. The main targets were railroad marshaling yards (27.4% of the bomb tonnage dropped), airfields (11.6%), oil refineries (9.5%), and military installations (8.8%).

To some degree the targets were secondary missions; Doolittle used the bombers as an irresistible target to draw up fighters into the ever-increasing swarms of Allied long-distance fighters. As these missions broke the Luftwaffe, missions were able to be carried out at lower altitudes or especially in bad weather when the could be used. In spite of abandoning precision attacks, accuracy nevertheless improved.

By 1945, the 8th was putting up to 60% of its bombs within 300 metres (1,000 ft), a CEP of about 270 metres (900 ft). Still pursuing precision attack, various remotely guided weapons were developed, notably the and bombs and similar weapons. Adaptations The Norden operated by mechanically turning the viewpoint so the target remained stationary in the display. The mechanism was designed for the low angular rate encountered at high altitudes, and thus had a relatively low range of operational speeds. The Norden could not rotate the sight fast enough for bombing at low altitude, for instance. Typically this was solved by removing the Norden completely and replacing it with simpler sighting systems.

A good example of its replacement was the refitting of the with a simple iron sight. Designed by Capt. Ross Greening, the sight was mounted to the existing pilot direction indicator, allowing the bombardier to make corrections remotely, like the bombsights of an earlier era. However, the Norden combined two functions, aiming and stabilization.

While the former was not useful at low altitudes, the latter could be even more useful, especially if flying in rough air near the surface. This led James 'Buck' Dozier to mount a Doolittle-like sight on top of the stabilizer in the place of the sighting head in order to attack German in the. This proved extraordinarily useful and was soon used throughout the fleet. Wartime security. Photo of the AFCE and Bombsight shop ground crew in the 463rd Sub Depot affiliated with the USAAF 389th Bomb Group based at Hethel, Norfolk, England Since the Norden was considered a critical wartime instrument, bombardiers were required to take an oath during their training stating that they would defend its secret with their own life if necessary.

In case the bomber plane should make an emergency landing on enemy territory, the bombardier would have to shoot the important parts of the Norden with a gun to disable it. As this method still would leave a nearly intact apparatus to the enemy, a grenade was installed; the heat of the chemical reaction would melt the Norden into a lump of metal. The was originally equipped with flotation bags in the wings to aid the aircrew's escape after, but they were removed once the began; this ensured that the aircraft would sink, taking the Norden with it. After each completed mission, bomber crews left the aircraft with a bag which they deposited in a safe ('the Bomb Vault'). This secure facility ('the AFCE and Bombsight Shop') was typically in one of the base's (Quonset hut) support buildings. The Bombsight Shop was manned by enlisted men who were members of a Supply Depot Service Group ('Sub Depot') attached to each. These shops not only guarded the bombsights but performed critical maintenance on the Norden and related control equipment.

This was probably the most technically skilled ground-echelon job, and certainly the most secret, of all the work performed by Sub Depot personnel. The in charge and his staff had to have a high aptitude for understanding and working with mechanical devices.

As the end of World War II neared, the bombsight was gradually downgraded in its secrecy; however, it was not until 1944 that the first public display of the instrument occurred. Main article: In spite of the security precautions, the entire Norden system had been passed to the Germans before the war started.

Lang, a German spy, had been employed by the Carl L. Norden Company. During a visit to Germany in 1938, Lang conferred with German military authorities and reconstructed plans of the confidential materials from memory. In 1941, Lang, along with the 32 other German agents of the, was arrested by the and convicted in the largest prosecution in U.S. He received a sentence of 18 years in prison on espionage charges and a two-year concurrent sentence under the.

German instruments were actually fairly similar to the Norden, even before World War II. A similar set of gyroscopes provided a stabilized platform for the bombardier to sight through, although the complex interaction between the bombsight and autopilot was not used. The, or Lotfe 7, was an advanced mechanical system similar to the Norden bombsight, although in form it was more similar to the Sperry S-1.

It started replacing the simpler Lotfernrohr 3 and BZG 2 in 1942, and emerged as the primary late-war bombsight used in most level bombers. The use of the autopilot allowed single-handed operation, and was key to bombing use of the single-crewed. Postwar analysis Postwar analysis placed the overall accuracy of daylight precision attacks with the Norden at about the same level as radar bombing efforts.

The 8th Air Force put 31.8% of its bombs within 300 metres (1,000 ft) from an average altitude of 6,400 metres (21,000 ft), the 15th Air Force averaged 30.78% from 6,200 metres (20,500 ft), and the 20th Air Force against Japan averaged 31% from 5,000 metres (16,500 ft). Many factors have been put forth to explain the Norden's poor real-world performance. Over Europe, the cloud cover was a common explanation, although performance did not improve even in favorable conditions. Over Japan, bomber crews soon discovered strong winds at high altitudes, the so-called, but the Norden bombsight worked only for wind speeds with minimal wind shear. Additionally, the bombing altitude over Japan reached up to 9,100 metres (30,000 ft), but most of the testing had been done well below 6,100 metres (20,000 ft). This extra altitude compounded factors that could previously be ignored; the shape and even the paint of the bomb mantle greatly changed the aerodynamic properties of the weapon, and, at that time, nobody knew how to calculate the of bombs that reached supersonic speeds during their fall.

Unable to obtain the Norden, the RAF continued development of their own designs. Having moved to, where visual accuracy was difficult under even the best conditions, they introduced the much simpler. This was designed not for accuracy above all, but ease of use in operational conditions. In testing in 1944, it was found to offer a CEP of 270 metres (890 ft), about what the Norden was offering at that time.

This led to a debate within the RAF whether to use their own tachometric design, the, or use the Mk. XIV on future bombers. XIV ultimately served into the 1960s while the SABS was removed from service almost immediately after the war.

Postwar use In the postwar era, the development of new precision bombsights essentially ended. At first this was due to the military drawdown, but as budgets increased again during the opening of the, the bomber mission had passed to nuclear weapons. These required accuracies on the order of 2,700 metres (3,000 yd), well within the capabilities of existing radar bombing systems. Only one major bombsight of note was developed, the Y-4 developed on the. This sight combined the images of the radar and a lens system in front of the aircraft, allowing them to be directly compared at once through a binocular eyepiece.

Bombsights on older aircraft, like the and the later, were left in their wartime state. When the opened, these aircraft were pressed into service and the Norden once again became the USAF's primary bombsight. This occurred again when the started; in this case retired World War II technicians had to be called up in order to make the bombsights operational again.

Its last use in combat was by the Naval Air Observation Squadron Sixty-Seven , during the Vietnam War. The bombsights were used in for implanting Air-Delivered Seismic Intrusion Detectors (ADSID) along the. See also., a German equivalent., whose hair was used for the bombsight crosshairs. Explanatory notes. & The Weapons Acquisition Process: An Economic Analysis (1962) p.619. ^., pp. 86-87., US Navy, 30 June 1997., Life, 30 August 1943, p.

Flight, August 1945, p. 180. ^, p. 64. TIME magazine.

The Norden company, ordered by the Navy Department to turn over bombsight plans to Remington Rand Inc., which was to build 8,500 'football units' (the main computing part),. ^ Ross: Strategic Bombing by the United States in World War II.

^, p. 61., Life, 26 April 1943, p. 27.

Alvin Kernan, Donald Kagan & Frederick Kagan, Yale University Press, 2007, p. 51. Barrett Tillman, 'Avenger at War', Ian Allan, 1979, p. 53. Robert Cressman, Naval Institute Press, 2000, p. 62. Gene Eric Salecker,., US Navy, 20 April 1999.

Neillands, Robin (2001). The Bomber War: The Allied Air Offensive against Nazi Germany. The Overlook Press, p.

Geoffery Perrett, 'There's a War to Be Won: The United States Army in World War II' (1991) p. 405. Edward K. Eckert, 'In War and Peace: An American Military History Anthology' (1990) p. 260. Michael C.C.

Adams, 'The Best War Ever: America in World War Two' (1994) p.54., p. 62. Matthews,. 'The Aviation Factfile: Aircraft of World War II' (2004) p.79.

(PDF). (publicly released on March 12, 1985 under the Freedom of Information Act).

Retrieved 2007-05-12. Wakelam, Randall Thomas (2009). University of Toronto Press. National Museum of the United States Air Force.

2 June 2015., Observation Squadron Sixty-Seven (VO-67), Bibliography. Stewart Halsey Ross: 'Strategic Bombing by the United States in World War II'. Albert L. Pardini: 'The Legendary Norden Bombsight', Schiffer Publishing, 1999., Turner Publishing, 1998. 'The Norden Bombsight. 'Bombing – Students' Manual'.

'Bombardier's Information File'. Stephen McFarland: 'America's Pursuit of Precision Bombing, 1910-1945'., University of Minnesota. Pasinski produced the prototype for the bombsight.

He designed production tools and supervised production of the bombsight., University of Minnesota. Information on the Norden bombsight, which Burroughs produced beginning in 1942. External links Wikimedia Commons has media related to. Torrey, June 1945 Popular Science. Popular Mechanics, February 1945, p. 7-10.

This was among the parts I was given a number of years ago from the wreckage of one of my uncle's B-17s. Most of the parts I was given I could identify from the numbers stamped in them, but this one remained a question. A friend who was a B-17 flight engineer thought it might be a servo for some part of the auto-pilot system, but I just saw an image elsewhere of what was identified as the gyro for a Norden bombsight, and it was very similar to this. Unfortunately I only have this one image of the part, which is about 4' across if I remember correctly. One of the other parts I was given was the remains of the mount for the bombsight, so I know they had the bombsight at some point.

Any bombsight experts out there who can tell just from this image?