Bombsight - Knowledge (XXG)

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long "sighting" ranges being considered, the radar antenna would need to be very large to offer the required resolution, yet this ran counter for the need to develop an antenna that was as small as possible in order to reduce drag. They also pointed out that many targets would not show up directly on the radar, so the bombsight would need the ability to drop at points relative to some landmark that did appear, the so-called "offset aiming points". Finally, the group noted that many of the functions in such a system would overlap formerly separate tools like the navigation systems. They proposed a single system that would offer mapping, navigation, autopilot and bomb aiming, thereby reducing complexity, and especially the needed space. Such a machine first emerged in the form of the

1028:(CSBS), called "the most important bomb sight of the war". Dialling in the values for altitude, airspeed and the speed and direction of the wind rotated and slid various mechanical devices that solved the vector problem. Once set up, the bomb aimer would watch objects on the ground and compare their path to thin wires on either side of the sight. If there was any sideways motion, the pilot could slip-turn to a new heading in an effort to cancel out the drift. A few attempts were typically all that was needed, at which point the aircraft was flying in the right direction to take it directly over the drop point, with zero sideways velocity. The bomb aimer (or pilot in some aircraft) then sighted through the attached iron sights to time the drop. 964:, which added a simple system for directly measuring the wind speed. The bomb aimer would first dial in the altitude and airspeed of the aircraft. Doing so rotated a metal bar on the right side of the bombsight so it pointed out from the fuselage. Prior to the bomb run, the bomber would fly at right angles to the bomb line, and the bomb aimer would look past the rod to watch the motion of objects on the ground. He would then adjust the wind speed setting until the motion was directly along the rod. This action measured the wind speed, and moved the sights to the proper angle to account for it, eliminating the need for separate calculations. A later modification was added to calculate the difference between 830: 1218:. The Mk. XIV featured a stabilizing platform and aiming computer, but worked more like the CSBS in overall functionality – the bomb aimer would set the computer to move the sighting system to the proper angle, but the bombsight did not track the target or attempt to correct the aircraft path. The advantage of this system was that it was dramatically faster to use, and could be used even while the aircraft was manoeuvring, only a few seconds of straight-line flying were needed before the drop. Facing a lack of production capability, Sperry was contracted to produce the Mk. XIV in the US, calling it the Sperry T-1. 902:

based on eyesight. As aircraft speeds increase, there is less time available after the initial spotting to carry out the calculations and correct the aircraft's flight path to bring it over the proper drop point. During the early stages of bombsight development, the problem was addressed by reducing the allowable engagement envelope, thereby reducing the need to calculate marginal effects. For instance, when dropped from very low altitudes, the effects of drag and wind during the fall will be so small that they can be ignored. In this case only the forward speed and altitude have any measurable effect.

111:, which were pre-set to an estimated fall angle. In some cases, they consisted of nothing more than a series of nails hammered into a convenient spar, lines drawn on the aircraft, or visual alignments of certain parts of the structure. They were replaced by the earliest custom-designed systems, normally iron sights that could be set based on the aircraft's airspeed and altitude. These early systems were replaced by the vector bombsights, which added the ability to measure and adjust for winds. Vector bombsights were useful for altitudes up to about 3,000 m and speeds up to about 300 km/h. 929:

10,000 feet would fall at an average rate of 400 fps, allowing easy calculation of the time to fall. Now all that remained was a measurement of the wind speed, or more generally the ground speed. Normally this was accomplished by flying the aircraft into the general direction of the wind and then observing motion of objects on the ground and adjusting the flight path side to side until any remaining sideways drift due to wind was eliminated. The speed over the ground was then measured by timing the motion of objects between two given angles as seen through the sight.

873:'s FAR Part 63 suggests 5 to 10% accuracy of these calculations, the US Air Force's AFM 51-40 gives 10%, and the US Navy's H.O. 216 at a fixed 20 miles or greater. Compounding this inaccuracy is that it is made using the instrument's airspeed indication, and as the airspeed in this example is about 10 times that of the wind speed, its 5% error can lead to great inaccuracies in wind speed calculations. Eliminating this error through the direct measurement of ground speed (instead of calculating it) was a major advance in the tachometric bombsights of the 1930s and 40s. 1198:. Both systems were generally similar; a bomb sight consisting of a small telescope was mounted on a stabilizing platform to keep the sighting head stable. A separate mechanical computer was used to calculate the aim point. The aim point was fed back to the sight, which automatically rotated the telescope to the correct angle to account for drift and aircraft movement, keeping the target still in the view. When the bombardier sighted through the telescope, he could see any residual drift and relay this to the pilot, or later, feed that information directly into the 1280:", these forces were strategic in nature, largely a deterrent to the other force's own bombers. However, new engines introduced in the mid-1930s led to much larger bombers that were able to carry greatly improved defensive suites, while their higher operational altitudes and speeds would render them less vulnerable to the defences on the ground. Policy once again changed in favour of daylight attacks against military targets and factories, abandoning what was considered a cowardly and defeatist night-bombing policy. 1684: 1069: 41: 886: 1021:. Wimperis was very familiar with these techniques, and would go on to write a seminal introductory text on the topic. The same calculations would work just as well for bomb trajectories, with some minor adjustments to account for the changing velocities as the bombs fell. Even as the Drift Sight was being introduced, Wimperis was working on a new bombsight that helped solve these calculations and allow the effects of wind to be considered no matter the direction of the wind or the bomb run. 1005: 707:, the first constant, and the second varying with the square of velocity. For an aircraft flying straight and level, the initial vertical velocity of the bomb will be zero, which means it will also have zero vertical drag. Gravity will accelerate the bomb downwards, and as its velocity increases so does the drag force. At some point (as speed and air density increase), the force of drag will become equal to the force of gravity, and the bomb will reach 1032:

British use. Thousands were sold to foreign air forces and numerous versions were created for production around the world. A number of experimental devices based on a variation of the CSBS were also developed, notably the US's Estoppey D-1 sight, developed shortly after the war, and similar versions from many other nations. These "vector bombsights" all shared the basic vector calculator system and drift wires, differing primarily in form and optics.

1695: 1047:, and was the main sight in British service until 1942. This was in spite of the introduction of newer sighting systems with great advantages over the CSBS, and even newer versions of the CSBS that failed to be used for a variety of reasons. The later versions of the CSBS, eventually reaching the Mark X, included adjustments for different bombs, ways to attack moving targets, systems for more easily measuring winds, and a host of other options. 1202:. Simply moving the telescope to keep the target in view had the side effect of fine-tuning the windage calculations continuously, and thereby greatly increasing their accuracy. For a variety of reasons, the Army dropped their interest in the Sperry, and features from the Sperry and Norden bombsights were folded into new models of the Norden. The Norden then equipped almost all US high-level bombers, most notably the 854:

this would result in an error around 10 to 15 feet. A 5% error in airspeed, 10 mph, would cause an error of about 15 to 20 feet. In terms of drop timing, errors on the order of one-tenth of a second might be considered the best possible. In this case, the error is simply the ground speed of the aircraft over this time, or about 30 feet. All of these are well within the lethal radius of the bomb.

1898:, Matt Clairborne aerocorner.com, "Norden was one of the first companies to combine a mechanical computer’s qualities into the actual bombsight. These computers used wheels and dials to solve complex math problems. By setting a few known factors, in this case, airspeed, altitude, and wind drift, the computer could do all of the math for the bombardier. This type of tool was called a tachometric bombsight." 1056: 877:

20,000 feet is approximately 1,750 feet, an error that would place the bombs far outside their lethal radius. In tests, accuracies of 3 to 4 degrees were considered standard, and angles as high as 15 degrees were not uncommon. Given the seriousness of the problem, systems for automatic levelling of bombsights was a major area of study before World War II, especially in the US.

1108:, the most famous of all tachometric bombsights, was able to identify a target the bombsight was able, in perfect conditions, to fly the plane to it. In battle, complicated by anti-aircraft defenses, crosswinds and clouds, and the need for aircraft to stay in formation to avoid collisions, results were less ideal but as good as could be achieved with the technology under the circumstances. 715: 33: 1254: 679: 473: 857:

The wind affects the accuracy of the bomb in two ways, pushing directly on the bomb while it falls, as well as changing the ground speed of the aircraft before the drop. In the case of the direct effects on the bomb, a measurement that has a 5% error, 1.25 mph, that would cause a 5% error in the

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system to keep the bombsight pointed roughly downward during maneuvering or compensating for windage had been pursued for some time. Experiments as early as the 1920s had demonstrated that this could roughly double the accuracy of bombing. The US carried out an active program in this area, including

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If anything changed the aircraft's path during the bomb run, whether due to difficulty turning and a tendency to oscillate after levelling induced by the Dutch roll or evasive maneuvers forced by the enemy, bomb trajectory calculations had to be set up again. There simply was not time to do so with

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The CSBS Mk. IA, the first widely produced vector bombsight. The drift wires are visible on the right, the windage calculator on the left, and the altitude scale in the middle (vertical). The actual sights are the white rings near the top of the altitude slider and white dots mid-way along the drift

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The accuracy of the drop is affected both by inherent problems like the randomness of the atmosphere or bomb manufacture as well as more practical problems like how close to flat and level the aircraft is flying or the accuracy of its instruments. These inaccuracies compound over time, so increasing

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asked the Army Air Forces Scientific Advisory Group to study the problem of bombing from jet aircraft that would soon be entering service. They concluded that at speeds over 1,000 knots (1,900 km/h), optical systems would be useless – the visual range to the target would be less than the range

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to automatically calculate the proper aim point in a few moments. Some of the traditional inputs, like airspeed and altitude, could even be taken directly from the aircraft instruments, eliminating operational errors, and allowing constant recalculation of essential target-tracking and bomb release

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The CSBS was introduced into service in 1917 and quickly replaced earlier sights on aircraft that had enough room – the CSBS was fairly large. Versions for different speeds, altitudes and bomb types were introduced as the war progressed. After the war, the CSBS continued to be the main bombsight in

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until it was directly below the aircraft. This revealed the ground speed, which was multiplied by the time taken to hit the ground, and then a pointer in the sight was set to an angle looked up on a table. The bomb aimer then watched the target in the sight until it crossed the pointer, and dropped

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Finally, consider errors of the same 5% in the equipment itself, that is, an error of 5% in the setting of the range angle, or a similar 5% error in the levelling of the aircraft or bombsight. For simplicity, consider that 5% to be a 5 degree angle. Using simple trigonometry, 5 degrees at

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It is useful to consider a single example of a bomb being dropped on a typical mission. In this case we will consider the AN-M64 500 lbs General-Purpose Bomb, widely used by the USAAF and RAF during World War II, with direct counterparts in the armouries of most forces involved. Ballistic data

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Finally, consider the effects of wind. The wind acts on the bomb through drag and is thus a function of the wind speed. This is typically only a fraction of the speed of the bomber or the terminal velocity, so it only becomes a factor if the bomb is dropped from altitudes high enough for this small

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is countered solely by drag, which starts to slow the forward motion. As the forward motion slows, the drag force drops and this deceleration diminishes. The forward speed is never reduced entirely to zero. If the bomb were not subject to drag, its path would be purely ballistic and it would impact

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with bomb loads similar to heavy bombers of a generation earlier. This generated demand for a new generation of greatly improved bombsights that could be used by a single-crew aircraft and employed in fighter-like tactics, whether high-level, low-level, in a dive towards the target, or during hard

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At the attack ranges being considered, thousands of miles, radio navigation systems would not be able to offer both the range and the accuracy needed. This demanded radar bombing systems, but existing examples did not offer anywhere near the required performance. At the stratospheric altitudes and

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These early systems operated independently of any existing optical bombsight, but this presented the problem of having to separately calculate the trajectory of the bomb. In the case of Oboe, these calculations were carried out before the mission at the ground bases. But as daylight visual bombing

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Although the US put the most effort into development of the tachometric concept, they were also being studied elsewhere. In the UK, work on the Automatic Bomb Sight (ABS) had been carried on since the mid-1930s in an effort to replace the CSBS. However, the ABS did not include stabilization of the

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Assuming errors of 5% in every major measurement, one can estimate those effects on accuracy based on the methodology and tables in the guide. A 5% error in altitude at 20,000 feet would be 1,000 feet, so the aircraft might be anywhere from 19 to 21,000 feet. According to the table,

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can be used to convert this point into an angle relative to the ground. The bombsight is then set to indicate that angle. The bombs are dropped when the target passes through the sights. The distance between the aircraft and target at that moment is the range, so this angle is often referred to as

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When windage is accounted for, the calculations become more complex. As the wind can operate in any direction, bombsights generally break the windage into the portions that act along the flight path and across it. In practice, it was generally simpler to have the aircraft fly in such a way to zero

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All of the calculations needed to predict the path of a bomb can be carried out by hand, with the aid of calculated tables of the bomb ballistics. However, the time to carry out these calculations is not trivial. Using visual sighting, the range at which the target is first sighted remains fixed,

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flying at 322 km/h (200 mph) at an altitude of 20,000 feet in a 42 km/h (26 mph) wind. Given these conditions, the M64 would travel approximately 10,000 feet (3,000 m) forward from the drop point before impact, for a trail of about 305 m (1,001 ft) from the

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In the absence of wind, the bombsight problem is fairly simple. The impact point is a function of three factors, the aircraft's altitude, its forward speed, and the terminal velocity of the bomb. In many early bombsights, the first two inputs were adjusted by separately setting the front and back

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As bombers grew and multi-place aircraft became common, it was no longer possible for the pilot and bombardier to share the same instrument, and hand signals were no longer visible if the bombardier was below the pilot in the nose. A variety of solutions using dual optics or similar systems were

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bombing was almost always carried out by eye, dropping the small bombs by hand when the conditions looked right. As the use and roles for aircraft increased during the war, the need for better accuracy became pressing. At first this was accomplished by sighting off parts of the aircraft, such as

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systems to allow accurate bombing through clouds or at night. When postwar studies demonstrated that bomb accuracy was roughly equal either optically or radar-guided, optical bombsights were generally removed and the role passed to dedicated radar bombsights. Finally, especially since the 1960s,

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Analysis of the results of bombing attacks carried out using radio navigation or radar techniques demonstrated accuracy was essentially equal for the two systems – night time attacks with Oboe were able to hit targets that the Norden could not during the day. With the exception of operational

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the bomb target and recalculated the release point based on input that included horizontal deviations induced by minor aircraft maneuvering or wind drift. In their most advanced form the incorporated sophisticated optics, data derived directly from the aircraft's flight instruments, compact

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For higher altitude drops, the effect of wind and bomb trajectory could no longer be ignored. One important simplification was to ignore the terminal velocity of the bomb, and calculate its average speed as the square root of the altitude measured in feet. For instance, a bomb dropped from

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the weapon of choice was a nuclear one, and accuracy needs were limited. Development of tactical bombing systems, notably the ability to attack point targets with conventional weapons that had been the original goal of the Norden, was not considered seriously. Thus when the US entered the

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The strategic bombing role was following an evolution over time to ever-higher, ever-faster, ever-longer-ranged missions with ever-more-powerful weapons. Although the tachometric bombsights provided most of the features needed for accurate bombing, they were complex, slow, and limited to

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that may be considered, but they are concerns only for bombs that spend a significant portion of a minute falling through the air. Those effects can be minimized by reducing the fall time by low-level bombing or by increasing the speed of the bombs. Those effects are combined in the

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drift, which would be 17.5 feet. However, that 1.25 mph error, or 1.8 fps, would also be added to the aircraft's velocity. Over the time of the fall, 37 seconds, that would result in an error of 68 feet, which is at the outside limit of the bomb's performance.

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to allow accurate navigation when far from land. These systems quickly improved in accuracy, and eventually became accurate enough to handle the bomb dropping without the need for a separate bombsight. This was the case for the 1,500 feet (460 m) accuracy demanded of the

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vacuum range, and impact with a velocity of 351 m/s (1150 fps) at an angle of about 77 degrees from horizontal. A 42 km/h (26 mph) wind would be expected to move the bomb about 91 m (299 ft) during that time. The time to fall is about 37 seconds.

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However, low-level bombing also increases the danger to the bomber from ground-based defences, so accurate bombing from higher altitudes has always been desired. That has led to a series of increasingly sophisticated bombsight designs dedicated to high-altitude level bombing.

142:, as the aircraft manoeuvres, and add the ability to adjust for weather, relative altitude, relative speeds for moving targets and climb or dive angle. That makes them useful both for level bombing, as in earlier generations, and tactical missions, which used to bomb by eye. 1063:

is the canonical tachometric bombsight. The bombsight proper is at the top of the image, mounted on top of the autopilot system at the bottom. The bombsight is slightly rotated to the right; in action the autopilot would turn the aircraft to reduce this angle back to

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struts and engine cylinders, or drawing lines on the side of the aircraft after test drops on a bombing range. These were useful for low altitudes and stationary targets, but as the nature of the air war expanded, the needs quickly outgrew these solutions as well.

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All of the USAAC's pre-war bombsights featured some system for automatically levelling the sight; the Estopery D-series used pendulums, Sperry designs used gyroscopes to stabilize the entire sight, and the Norden used gyroscopes to stabilize the optics. See

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further improved the bomber's abilities, allowing direct attack of targets without the need of remote radio transmitters, which had range limited to the line-of-sight. By 1943 these techniques were in widespread use by both the RAF and USAAF, leading to the

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on this bomb can be found in "Terminal Ballistic Data, Volume 1: Bombing". Against men standing in the open, the 500 lbs has a lethal radius of about 107 m (351 ft), but much less than that against buildings, perhaps 27 m (89 ft).

1170:-like device, and the manual calculation though a series of gears or slip wheels. Originally limited to fairly simple calculations consisting of additions and subtractions, by the 1930s they had progressed to the point where they were being used to solve 479: 273: 909:. This was a simple device with inputs for airspeed and altitude which was hand-held while lying prone on the wing of the aircraft. After considerable testing, he was able to build a table of settings to use with these inputs. In testing at 785:

sights of an iron sight, one for the altitude and the other for the speed. Terminal velocity, which extends the fall time, can be accounted for by raising the effective altitude by an amount that is based on the bomb's measured ballistics.

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The way the line of bombs falling from this B-26 goes towards the rear is due to drag. The aircraft's engines keep it moving forward at a constant speed, while the bombs slow down. From the bomber's perspective, the bombs trail behind the

1265:) but finding its target was a major problem. In practice, only large targets such as cities could be attacked. During the day the bomber could use its bombsights to attack point targets, but only at the risk of being attacked by enemy 1159:, which could be used to directly dial in the required path and have the aircraft fly to that heading with no further input. A variety of bombing systems using one or both of these systems were considered throughout the 1920s and 30s. 949:

the bombs. Similar bombsights were developed in France and England, notably the Michelin and Central Flying School Number Seven bombsight. While useful, these sights required a time-consuming setup period while the movement was timed.

711:. As the air drag varies with air density, and thus altitude, the terminal velocity will decrease as the bomb falls. Generally, the bomb will slow as it reaches lower altitudes where the air is denser, but the relationship is complex. 995:

grew more effective, they would often pre-sight their guns along the wind line of the targets they were protecting, knowing that attacks would come from those directions. A solution for attacking cross-wind was sorely needed.

1174:. For bombsight use, such a calculator would allow the bomb aimer to dial in the basic aircraft parameters – speed, altitude, direction, and known atmospheric conditions – and the bomb sight would use tacheometrically-based 1336:

retained their optical systems, but these were often considered secondary to the radar and radio systems. In the case of the Canberra, the optical system only existed due to delays in the radar system becoming available.

913:, Scott was able to place two 18 pound bombs within 10 feet of a 4-by-5 foot target from a height of 400 feet. In January 1912, Scott won $ 5,000 for first place in the Michelin bombing competition at 1206:. In tests, these bombsights were able to generate fantastic accuracy. In practice, however, operational factors seriously upset them, to the point that pinpoint bombing using the Norden was eventually abandoned. 1320:

was still widely used, conversions and adaptations were quickly made to repeat the radar signal in the existing bombsights, allowing the bombsight calculator to solve the radar bombing problem. For instance, the

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As electronics improved, these systems were able to be combined, and then eventually with systems for aiming other weapons. They may be controlled by the pilot directly and provide information through the

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of the bomb at any given instant. If the bomb is released at low altitudes and speeds the bomb will not reach terminal velocity and its speed will be defined largely by how long the bomb has been falling.

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because the bomb appears to trail behind the aircraft as it falls. The trail and range differ for different bombs due to their individual aerodynamics and typically have to be measured on a bombing range.

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All of these bombsights shared the problem that they were unable to deal with wind in any direction other than along the path of travel. That made them effectively useless against moving targets, like

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In the pre-World War II era there had been a long debate about the relative merits of daylight versus night-time bombing. At night the bomber is virtually invulnerable (until the introduction of

1237:, the world's first operational jet bomber. During the war the RAF had the need for accurate high-altitude bombing and in 1943 introduced a stabilized version of the earlier ABS, the hand-built 696:

is the air density. These equations show that horizontal velocity increases vertical drag and vertical velocity increases horizontal drag. These effects are ignored in the following discussion.

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During the early 1930s the debate had been won by the night-bombing supporters, and the RAF and Luftwaffe started construction of large fleets of aircraft dedicated to the night mission. As "

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sighting system, nor the Norden's autopilot system. In testing the ABS proved to be too difficult to use, requiring long bomb runs to allow the computer time to solve the aim point. When

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considerations – limited resolution of the radar and limited range of the navigation systems – the need for visual bombsights quickly disappeared. Designs of the late-war era, like the

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The main problem in completely separating the motion into vertical and horizontal components is the terminal velocity. Bombs are designed to fly with the nose pointed forward into the

1233:. The basic mechanism was almost identical to the Norden, but much smaller. In certain applications the Lotfernrohr 7 could be used by a single-crew aircraft, as was the case for the 1084:

The limitations of vector bombsights (which required a long straight run before dropping the bombs to accommodate windage) led to the development of bombsights based on the field of

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system, first used operationally in early 1943, offered real-world accuracies on the order of 35 yards, much better than any optical bombsight. The introduction of the British

991:. Unless the target just happened to be travelling directly in line with the wind, their motion would carry the bomber away from the wind line as they approached. Additionally, as 2106: 674:{\displaystyle {\begin{aligned}d_{h}&=CA\rho {\frac {v_{h}}{\sqrt {v_{v}^{2}+v_{h}^{2}}}}(v_{v}^{2}+v_{h}^{2})\\&=CA\rho v_{h}{\sqrt {v_{v}^{2}+v_{h}^{2}}}\end{aligned}}} 468:{\displaystyle {\begin{aligned}d_{v}&=CA\rho {\frac {v_{v}}{\sqrt {v_{v}^{2}+v_{h}^{2}}}}(v_{v}^{2}+v_{h}^{2})\\&=CA\rho v_{v}{\sqrt {v_{v}^{2}+v_{h}^{2}}}\end{aligned}}} 821:

and similar terms are often used as well. In practice, some or all of these calculations are carried out using angles and not points in space, skipping the final conversion.

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at the bottom that allowed the sight to be rotated fore and aft. After zeroing out sideways motion the sight was set to a pre-set angle and then an object was timed with a

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Both the British and Germans would later introduce Norden-like sights of their own. Based at least partially on information about the Norden passed to them through the

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is the calculation of the location in space where the bombs should be dropped in order to hit the target when all of the effects noted above are taken into account.

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complained that even the CSBS had too long a run-in to the target, efforts to deploy the ABS ended. For their needs they developed a new vector bombsight, the

732:. In practice, drag means that the impact point is short of the vacuum range, and this real-world distance between dropping and impact is known simply as the 757:

influence to noticeably affect the bomb's path. The difference between the impact point and where it would have fallen if there had been no wind is known as

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with the performance needed to solve the equations of motion started to be incorporated into the new tachometric bombsights, the most famous of which is the

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Bombsights are sighting devices that are pointed in a particular direction, or aimed. Although the solution outlined above returns a point in space, simple

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Through the 1950s and 1960s, radar bombing of this sort was common and the accuracy of the systems were limited to what was needed to support attacks by

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Modern aircraft do not have a bombsight but use highly computerized systems that combine bombing, gunnery, missile fire and navigation into a single

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out any sideways motion before the drop, and thereby eliminate this factor. This is normally accomplished using a common flying techniques known as

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was used to combine the output from the AN/APQ-7 with the Norden, allowing the bomb aimer to easily check both images to compare the aim point.

1821: 1384: 1374:(CEP) of about 3,000 feet (910 m) was considered adequate. As mission range extended to thousands of miles, bombers started incorporating 1283:

In spite of this change, the Luftwaffe continued to put some effort into solving the problem of accurate navigation at night. This led to the

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Now consider the horizontal motion. At the instant it leaves the shackles, the bomb carries the forward speed of the aircraft with it. This

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during the opening stages of the war. The RAF returned in force in early 1942 with similar systems of their own, and from that point on,

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A bombsight has to estimate the path the bomb will take after release from the aircraft. The two primary forces during its fall are

897:. The lever just in front of the bomb aimer's fingertips sets the altitude, the wheels near his knuckles set the wind and airspeed. 1606: 1424:, something that required only middling accuracy but a very different trajectory that initially required a dedicated bombsight. 1127:

made it impossible to sustain long straight-and-level bombing runs without excessive loss of aircraft and their valuable crews.

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To start with, consider only the vertical motion of a bomb. In this direction, the bomb will be subject to two primary forces,

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bombers made manual adjustments to keep a plane on target more difficult. Large monoplanes suffered from an effect known as "

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Bombsights were first used before World War I and have since gone through several major revisions. The earliest systems were

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the altitude of the bomb run, thereby increasing the fall time, has a significant impact on the final accuracy of the drop.

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procedure that compares measured movement over the ground with the calculated movement using the aircraft instruments. The

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or a video display on the instrument panel. The definition of bombsight is becoming blurred as "smart" bombs with

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fully computerized bombsights were introduced, which combined the bombing with long-range navigation and mapping.

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Calculating the effects of an arbitrary wind on the path of an aircraft was already a well-understood problem in

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One of the earliest recorded examples of such a bombsight was built in 1911 by Lieutenant Riley E. Scott, of the

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Geoffery Perrett, "There's a War to Be Won: The United States Army in World War II", Random House, 1991, p. 405

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is proportional to the relative air speed squared. If the vertical component of the velocity is denoted by

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Two real-world considerations accelerated the development of tachometric bombsights: the introduction of

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suggested in the post-war era, but none of these became widely used. This led to the introduction of the

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in France, scoring 12 hits on a 125-by-375 foot target with 15 bombs dropped from 800 meters.

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of the wind speed is a more serious concern. Early navigation systems generally measured it using a

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put any concerted effort into development. During the 1920s, the Navy funded development of the

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In ballistics terms, it is traditional to talk of the calculation of aiming of ordnance as the

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systems of increasing accuracy allowed bombing in any weather or operational conditions. The

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In spite of early examples like Scott's prior to the war, during the opening stages of the

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A Forgotten Offensive: Royal Air Force Coastal Command's Anti-shipping Campaign, 1940-1945

2121: 2023: 2004: 1939: 1825: 1429: 1167: 1077: 921: 749: 156: 135: 61: 1162:

During the same period, a separate line of development was leading to the first reliable

972:, which grows with altitude. This version was the Drift Sight Mk. 1A, introduced on the 1793: 1421: 1367: 1134:

One solution was to stabilize the bombsight independent of the aircraft. The use of a

1014: 953: 941: 866: 704: 139: 65: 1985: 932:

One of the most fully developed examples of such a sight to see combat was the German

2236: 1475: 1230: 965: 745: 2217: 1166:. These could be used to replace a complex table of numbers with a carefully shaped 748:, normally through the use of fins at the back of the bomb. The drag depends on the 1493: 1445: 1417: 1379: 1234: 1175: 1055: 801: 123: 1420:

also developed in order to allow aircraft to escape the blast radius of their own

2111:(Technical report). US Army Office of the Chief of Ordnance. 1944. Archived from 2016: 1895: 1401: 1085: 961: 890: 846: 108: 97: 88: 57: 2017:"Royal Air Force Bomber Command 60th Anniversary, Campaign Diary November 1943" 1009:

wires. The drift wires are normally taut, this example is almost a century old.

1861: 1849: 1837: 1116: 894: 1411:

At the same time, the ever-increasing power levels of new jet engines led to

1123:

predecessors. Also, intense ground-based anti-aircraft defenses and improved

1321: 1305: 1301: 1296: 1226: 1199: 1156: 1148: 1112: 1098: 984: 945: 937: 1101:

to guide the aircraft to a its target and automatically release its bombs.

736:. The difference between the vacuum range and actual range is known as the 1182:

Although these developments were well known within the industry, only the

17: 2101:(Technical report). US Army Office of the Chief of Ordnance. August 1944. 1396: 1309: 724: 84: 80: 2120:

United States Naval Academy, Department of Ordnance and Gunnery (1958).

1187: 1120: 1119:", and were not able to slip-turn to correct for it as easily as their 833:

US Navy dive bomber pilot flying the airplane at an angle of about 75°.

714: 700: 138:. The systems have the performance to calculate the bomb trajectory in 76: 1155:. These same developments led to the introduction of the first useful 32: 1775:

The Encyclopedia of Military Aircraft, 2006 Edition, Jackson, Robert

1481: 1140: 1135: 1043:

Vector bombsights remained the standard by most forces well into the

2209: 1257:

The AN/APS-15 radar bombing system, a US version of the British H2S.

1253: 1884:"Despatch on war operations, 23rd February, 1942, to 8th May, 1945" 1262: 1252: 1067: 1054: 1003: 957: 884: 828: 713: 127: 39: 31: 1850:"Pilot Direction Instrument and Bomb Dropping Sight for Aircraft" 988: 976:

heavy bomber. Variations on the design were common, like the US

92: 53: 2038: 2036: 2034: 2032: 1548: 1546: 1544: 1441: 1725: 1723: 1721: 1719: 1717: 1910:, Henry Black, 2001 aviatorsdatabase.com, (posted July 2013) 267:

and the vertical and horizontal components of the drag are:

56:

accurately. Bombsights, a feature of combat aircraft since

1531: 1529: 1408:

equipped with the Norden. Such a solution was inadequate.

83:, which make the path of the bomb through the air roughly 1657: 1655: 1147:'s experiments with US versions of the CSBS mounted to a 72:

as those aircraft took up the brunt of the bombing role.

2070:, 101 Great Bombers, Rosen Publishing Group, 2010, p. 80 1759: 1757: 1755: 1753: 956:, better known for his later role in the development of 952:

A great upgrade to the basic concept was introduced by

2055:"Biographical memoirs of fellows of the Royal Society" 1351:

of a bomb being dropped at high altitudes and speeds.

1674:"Federal Aviation Regulations, Navigator Flight Test" 1577: 1575: 1573: 482: 276: 219: 192: 165: 1131:

the bombsights and mechanical computers of the day.

1387:, which lacked any sort of conventional bombsight. 673: 467: 259: 205: 178: 126:, tachometric bombsights were often combined with 87:. There are additional factors such as changes in 1896:History of The Norden Bombsight and How It Works 1304:and then a series of improved versions like the 2164:, June 1945, pp. 70–73, 220, 224, 228, 232 2128:. Vol. 2. U.S. Government Printing Office. 1807:"De Havilland Mosquito: An Illustrated History" 155:The drag on a bomb for a given air density and 1886:, Routledge, 1995. See Appendix C, Section VII 52:is a device used by military aircraft to drop 1346:straight-line and level attacks. In 1946 the 940:. The Görtz used a telescope with a rotating 260:{\displaystyle {\sqrt {v_{v}^{2}+v_{h}^{2}}}} 8: 2136:Development of Airborne Armament 1910 - 1961 2108:Terminal Ballistic Data, Volume III: Effects 1564: 1552: 1535: 2098:Terminal Ballistic Data, Volume I: Bombing 2152:. Bonnier Corporation: 116–119, 212, 214. 1416:maneuvering. A specialist capability for 1194:while the Army funded development of the 659: 654: 641: 636: 630: 624: 592: 587: 574: 569: 553: 548: 535: 530: 519: 513: 491: 483: 481: 453: 448: 435: 430: 424: 418: 386: 381: 368: 363: 347: 342: 329: 324: 313: 307: 285: 277: 275: 249: 244: 231: 226: 220: 218: 197: 191: 170: 164: 2158:"How the Norden Bombsight Does Its Job" 1763: 1661: 1646: 1634: 1622: 1593: 1581: 1509: 60:, were first found on purpose-designed 2191:"The bombsight war: Norden vs. Sperry" 1963: 1951: 1919: 1696:"Visual Flight Planning and Procedure" 960:in England. In 1916 he introduced the 2079: 2042: 1933:"The Differential Analyser Explained" 1809:, MBI Publishing Company, 2006, p. 68 1729: 1519: 1517: 1515: 1513: 1472:(RAF) less accurate, for area bombing 44:1923 Norden MK XI Bombsight Prototype 7: 1819:"Interwar Development of Bombsights" 1685:"Precision Dead Reckoning Procedure" 1249:Radar bombing and integrated systems 1139:Estoppey sights mounted to weighted 2146:"How Our Bombsight Solves Problems" 2122:"Chapter 23: Aircraft Fire Control" 1942:, Auckland Meccano Guild, July 2009 1828:, US Air Force Museum, 19 June 2006 728:at an easily calculable point, the 2057:, Royal Society, Volume 52, p. 234 1278:the bomber will always get through 25: 2168:Goulter, Christina J. M. (1995). 2068:"BAe (English Electric) Canberra" 1404:, their weapon of choice was the 692:is the cross-sectional area, and 2144:Raymond, Allan (December 1943). 2139:. Vol. 1 - Bombing Systems. 1359:, and later the "K-System", the 186:and the horizontal component by 27:Aircraft system for aiming bombs 2026:, Royal Air Force, 6 April 2005 1744:Society of Automotive Engineers 1464:Stabilized Automatic Bomb Sight 1239:Stabilized Automatic Bomb Sight 907:U.S. Army Coast Artillery Corps 871:Federal Aviation Administration 845:The M64 will be dropped from a 598: 562: 392: 356: 1: 2189:Searle, L. (September 1989). 1838:"Target Following Bomb Sight" 1074:Low Level Bombsight, Mark III 1794:"A Primer of Air Navigation" 1607:"Daylight Precision Bombing" 688:is the coefficient of drag, 1882:Sir Arthur Travers Harris, 2264: 2126:Naval Ordnance and Gunnery 1908:World War II Bomber Sights 1523:See diagrams, Torrey p. 70 893:mounted on the side of an 2003:30 September 2013 at the 1986:"The T-1 Bombsight Story" 1334:English Electric Canberra 1314:Boeing B-29 Superfortress 1038:pilot direction indicator 1026:Course Setting Bomb Sight 36:An early bombsight, 1910s 1938:24 November 2018 at the 1792:Harry Egerton Wimperis, 1783:Parragon Publishing 2002 1072:Bomb aimer's window and 1998:"The Duquesne Spy Ring" 1824:11 January 2012 at the 1372:circular error probable 1271:anti-aircraft artillery 1104:Once the operator of a 993:anti-aircraft artillery 2133:Perry, Robert (1961). 1746:: 63–64. January 1922. 1258: 1172:differential equations 1081: 1065: 1051:Tachometric bombsights 1017:, one requiring basic 1010: 911:College Park, Maryland 898: 834: 720: 675: 469: 261: 207: 180: 45: 37: 2227:on 30 September 2011. 1864:, US Patent 1,360,735 1862:"Airplane Bomb Sight" 1852:, US Patent 1,510,975 1840:, US Patent 1,389,555 1613:, October 2008, p. 61 1330:Boeing B-47 Stratojet 1256: 1071: 1058: 1007: 915:Villacoublay Airfield 888: 832: 769:The bombsight problem 717: 676: 470: 262: 208: 206:{\displaystyle v_{h}} 181: 179:{\displaystyle v_{v}} 43: 35: 2022:11 June 2007 at the 1796:, Van Nostrand, 1920 1406:Douglas A-26 Invader 1341:Postwar developments 1243:No. 617 Squadron RAF 1204:B-17 Flying Fortress 1164:mechanical computers 1095:mechanical computers 936:, developed for the 480: 274: 217: 190: 163: 116:mechanical computers 1470:Mark XIV bomb sight 1285:Battle of the Beams 1024:The result was the 938:Gotha heavy bombers 664: 646: 597: 579: 558: 540: 458: 440: 391: 373: 352: 334: 254: 236: 2243:Optical bombsights 1611:Air Force Magazine 1499:Aircraft periscope 1438:laser-guided bombs 1434:in-flight guidance 1259: 1245:, The Dambusters. 1212:RAF Bomber Command 1082: 1076:in the nose of an 1066: 1019:vector mathematics 1011: 978:Estoppey bombsight 974:Handley Page O/400 970:indicated airspeed 899: 835: 721: 671: 669: 650: 632: 583: 565: 544: 526: 465: 463: 444: 426: 377: 359: 338: 320: 257: 240: 222: 213:then the speed is 203: 176: 64:and then moved to 46: 38: 2181:978-0-7146-4617-6 2115:on 7 August 2010. 1742:"Bomb Dropping". 1565:Fire Control 1958 1553:Fire Control 1958 1536:Fire Control 1958 1444:, replace "dumb" 1376:inertial guidance 1348:US Army Air Force 1223:Duquesne Spy Ring 1184:US Army Air Corps 1153:inertial platform 1000:Vector bombsights 779:bombsight problem 709:terminal velocity 665: 560: 559: 459: 354: 353: 255: 70:tactical aircraft 16:(Redirected from 2255: 2228: 2226: 2220:. Archived from 2195: 2185: 2153: 2140: 2129: 2116: 2102: 2083: 2077: 2071: 2066:Robert Jackson, 2064: 2058: 2052: 2046: 2040: 2027: 2014: 2008: 1995: 1989: 1982: 1976: 1973: 1967: 1961: 1955: 1949: 1943: 1929: 1923: 1917: 1911: 1905: 1899: 1893: 1887: 1880: 1874: 1871: 1865: 1859: 1853: 1847: 1841: 1835: 1829: 1816: 1810: 1803: 1797: 1790: 1784: 1773: 1767: 1761: 1748: 1747: 1739: 1733: 1727: 1712: 1704: 1698: 1693: 1687: 1682: 1676: 1671: 1665: 1659: 1650: 1644: 1638: 1632: 1626: 1620: 1614: 1603: 1597: 1591: 1585: 1579: 1568: 1562: 1556: 1550: 1539: 1533: 1524: 1521: 1458:Norden bombsight 1413:fighter aircraft 1289:radio navigation 1192:Norden bombsight 1145:Sperry Gyroscope 1045:Second World War 695: 691: 687: 680: 678: 677: 672: 670: 666: 663: 658: 645: 640: 631: 629: 628: 604: 596: 591: 578: 573: 561: 557: 552: 539: 534: 525: 524: 523: 514: 496: 495: 474: 472: 471: 466: 464: 460: 457: 452: 439: 434: 425: 423: 422: 398: 390: 385: 372: 367: 355: 351: 346: 333: 328: 319: 318: 317: 308: 290: 289: 266: 264: 263: 258: 256: 253: 248: 235: 230: 221: 212: 210: 209: 204: 202: 201: 185: 183: 182: 177: 175: 174: 151:Forces on a bomb 21: 2263: 2262: 2258: 2257: 2256: 2254: 2253: 2252: 2233: 2232: 2231: 2224: 2210:10.1109/6.90187 2193: 2188: 2182: 2167: 2162:Popular Science 2150:Popular Science 2143: 2132: 2119: 2105: 2095: 2091: 2086: 2078: 2074: 2065: 2061: 2053: 2049: 2041: 2030: 2024:Wayback Machine 2015: 2011: 2005:Wayback Machine 1996: 1992: 1983: 1979: 1974: 1970: 1962: 1958: 1950: 1946: 1940:Wayback Machine 1931:William Irwin, 1930: 1926: 1918: 1914: 1906: 1902: 1894: 1890: 1881: 1877: 1872: 1868: 1860: 1856: 1848: 1844: 1836: 1832: 1826:Wayback Machine 1817: 1813: 1804: 1800: 1791: 1787: 1774: 1770: 1762: 1751: 1741: 1740: 1736: 1728: 1715: 1705: 1701: 1694: 1690: 1683: 1679: 1672: 1668: 1660: 1653: 1645: 1641: 1633: 1629: 1621: 1617: 1604: 1600: 1592: 1588: 1580: 1571: 1563: 1559: 1551: 1542: 1534: 1527: 1522: 1511: 1507: 1490: 1488:Similar devices 1454: 1440:or those using 1430:head-up display 1422:nuclear weapons 1393: 1368:nuclear weapons 1343: 1251: 1078:Avro Shackleton 1053: 1002: 934:Görtz bombsight 922:First World War 883: 827: 771: 750:angle of attack 693: 689: 685: 668: 667: 620: 602: 601: 515: 497: 487: 478: 477: 462: 461: 414: 396: 395: 309: 291: 281: 272: 271: 215: 214: 193: 188: 187: 166: 161: 160: 157:angle of attack 153: 148: 136:head-up display 66:fighter-bombers 62:bomber aircraft 28: 23: 22: 15: 12: 11: 5: 2261: 2259: 2251: 2250: 2245: 2235: 2234: 2230: 2229: 2186: 2180: 2165: 2156:Volta Torrey, 2154: 2141: 2130: 2117: 2103: 2092: 2090: 2087: 2085: 2084: 2072: 2059: 2047: 2028: 2009: 1990: 1988:, 26 July 2001 1977: 1968: 1956: 1944: 1924: 1912: 1900: 1888: 1875: 1866: 1854: 1842: 1830: 1811: 1798: 1785: 1768: 1749: 1734: 1713: 1699: 1688: 1677: 1666: 1664:, p. 119. 1651: 1639: 1627: 1615: 1605:John Correll, 1598: 1586: 1569: 1557: 1540: 1525: 1508: 1506: 1503: 1502: 1501: 1496: 1489: 1486: 1485: 1484: 1479: 1473: 1467: 1461: 1453: 1450: 1392: 1391:Modern systems 1389: 1342: 1339: 1250: 1247: 1229:developed the 1149:gyroscopically 1052: 1049: 1015:air navigation 1001: 998: 954:Harry Wimperis 882: 879: 867:dead reckoning 826: 823: 811:dropping angle 770: 767: 682: 681: 662: 657: 653: 649: 644: 639: 635: 627: 623: 619: 616: 613: 610: 607: 605: 603: 600: 595: 590: 586: 582: 577: 572: 568: 564: 556: 551: 547: 543: 538: 533: 529: 522: 518: 512: 509: 506: 503: 500: 498: 494: 490: 486: 485: 475: 456: 451: 447: 443: 438: 433: 429: 421: 417: 413: 410: 407: 404: 401: 399: 397: 394: 389: 384: 380: 376: 371: 366: 362: 358: 350: 345: 341: 337: 332: 327: 323: 316: 312: 306: 303: 300: 297: 294: 292: 288: 284: 280: 279: 252: 247: 243: 239: 234: 229: 225: 200: 196: 173: 169: 152: 149: 147: 144: 114:In the 1930s, 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 2260: 2249: 2246: 2244: 2241: 2240: 2238: 2223: 2219: 2215: 2211: 2207: 2203: 2199: 2198:IEEE Spectrum 2192: 2187: 2183: 2177: 2174:. Routledge. 2173: 2172: 2166: 2163: 2159: 2155: 2151: 2147: 2142: 2138: 2137: 2131: 2127: 2123: 2118: 2114: 2110: 2109: 2104: 2100: 2099: 2094: 2093: 2088: 2082:, Chapter VI. 2081: 2076: 2073: 2069: 2063: 2060: 2056: 2051: 2048: 2045:, Chapter II. 2044: 2039: 2037: 2035: 2033: 2029: 2025: 2021: 2018: 2013: 2010: 2006: 2002: 1999: 1994: 1991: 1987: 1984:Henry Black, 1981: 1978: 1972: 1969: 1966:, p. 63. 1965: 1960: 1957: 1954:, p. 61. 1953: 1948: 1945: 1941: 1937: 1934: 1928: 1925: 1922:, p. 60. 1921: 1916: 1913: 1909: 1904: 1901: 1897: 1892: 1889: 1885: 1879: 1876: 1870: 1867: 1863: 1858: 1855: 1851: 1846: 1843: 1839: 1834: 1831: 1827: 1823: 1820: 1815: 1812: 1808: 1802: 1799: 1795: 1789: 1786: 1782: 1781:1-4054-2465-6 1778: 1772: 1769: 1766:, p. 27. 1765: 1760: 1758: 1756: 1754: 1750: 1745: 1738: 1735: 1731: 1726: 1724: 1722: 1720: 1718: 1714: 1711:for examples. 1710: 1703: 1700: 1697: 1692: 1689: 1686: 1681: 1678: 1675: 1670: 1667: 1663: 1658: 1656: 1652: 1649:, p. 23. 1648: 1643: 1640: 1637:, p. 39. 1636: 1631: 1628: 1625:, p. 10. 1624: 1619: 1616: 1612: 1608: 1602: 1599: 1596:, p. 13. 1595: 1590: 1587: 1583: 1578: 1576: 1574: 1570: 1566: 1561: 1558: 1554: 1549: 1547: 1545: 1541: 1537: 1532: 1530: 1526: 1520: 1518: 1516: 1514: 1510: 1504: 1500: 1497: 1495: 1492: 1491: 1487: 1483: 1480: 1477: 1476:Lotfernrohr 7 1474: 1471: 1468: 1465: 1462: 1459: 1456: 1455: 1451: 1449: 1447: 1446:gravity bombs 1443: 1439: 1435: 1431: 1425: 1423: 1419: 1414: 1409: 1407: 1403: 1398: 1390: 1388: 1386: 1385:B-70 Valkyrie 1381: 1380:star trackers 1377: 1373: 1369: 1364: 1362: 1358: 1352: 1349: 1340: 1338: 1335: 1331: 1325: 1323: 1317: 1315: 1311: 1307: 1303: 1298: 1294: 1290: 1286: 1281: 1279: 1274: 1272: 1268: 1264: 1255: 1248: 1246: 1244: 1240: 1236: 1232: 1231:Lotfernrohr 7 1228: 1224: 1219: 1217: 1213: 1207: 1205: 1201: 1197: 1193: 1189: 1185: 1180: 1177: 1173: 1169: 1165: 1160: 1158: 1154: 1150: 1146: 1142: 1137: 1132: 1128: 1126: 1122: 1118: 1114: 1109: 1107: 1102: 1100: 1096: 1091: 1087: 1079: 1075: 1070: 1062: 1057: 1050: 1048: 1046: 1041: 1039: 1033: 1029: 1027: 1022: 1020: 1016: 1006: 999: 997: 994: 990: 986: 981: 979: 975: 971: 967: 963: 959: 955: 950: 947: 943: 939: 935: 930: 926: 923: 918: 916: 912: 908: 903: 896: 892: 887: 881:Early systems 880: 878: 874: 872: 868: 864: 859: 855: 851: 848: 843: 839: 831: 824: 822: 820: 819:bombing angle 816: 812: 808: 803: 798: 796: 792: 786: 782: 780: 776: 768: 766: 764: 760: 754: 751: 747: 746:relative wind 742: 739: 735: 731: 726: 716: 712: 710: 706: 702: 697: 660: 655: 651: 647: 642: 637: 633: 625: 621: 617: 614: 611: 608: 606: 593: 588: 584: 580: 575: 570: 566: 554: 549: 545: 541: 536: 531: 527: 520: 516: 510: 507: 504: 501: 499: 492: 488: 476: 454: 449: 445: 441: 436: 431: 427: 419: 415: 411: 408: 405: 402: 400: 387: 382: 378: 374: 369: 364: 360: 348: 343: 339: 335: 330: 325: 321: 314: 310: 304: 301: 298: 295: 293: 286: 282: 270: 269: 268: 250: 245: 241: 237: 232: 227: 223: 198: 194: 171: 167: 158: 150: 145: 143: 141: 137: 132: 129: 125: 121: 117: 112: 110: 105: 101: 99: 94: 90: 86: 82: 78: 73: 71: 67: 63: 59: 55: 51: 42: 34: 30: 19: 2248:Aerial bombs 2222:the original 2204:(9): 60–64. 2201: 2197: 2170: 2161: 2149: 2135: 2125: 2113:the original 2107: 2097: 2089:Bibliography 2075: 2062: 2050: 2012: 1993: 1980: 1971: 1959: 1947: 1927: 1915: 1903: 1891: 1878: 1873:Torrey p. 72 1869: 1857: 1845: 1833: 1814: 1805:Ian Thirsk, 1801: 1788: 1771: 1764:Goulter 1995 1743: 1737: 1732:, Chapter I. 1708: 1702: 1691: 1680: 1669: 1662:Raymond 1943 1647:Bombing 1944 1642: 1635:Bombing 1944 1630: 1623:Bombing 1944 1618: 1610: 1601: 1594:Effects 1944 1589: 1582:Bombing 1944 1560: 1494:Reflex sight 1426: 1418:toss bombing 1410: 1394: 1365: 1353: 1344: 1326: 1318: 1312:used on the 1282: 1275: 1260: 1235:Arado Ar 234 1220: 1208: 1181: 1179:parameters. 1176:trigonometry 1161: 1151:-stabilized 1133: 1129: 1125:interceptors 1110: 1103: 1089: 1083: 1042: 1034: 1030: 1023: 1012: 982: 951: 931: 927: 919: 904: 900: 875: 862: 860: 856: 852: 844: 840: 836: 818: 815:aiming angle 814: 810: 806: 802:trigonometry 799: 787: 783: 778: 774: 772: 762: 758: 755: 743: 737: 733: 730:vacuum range 729: 722: 698: 683: 154: 133: 124:World War II 113: 106: 102: 74: 49: 47: 29: 1964:Searle 1989 1952:Searle 1989 1920:Searle 1989 1478:(Luftwaffe) 1402:Vietnam War 1395:During the 1086:tacheometry 962:Drift Sight 891:Drift Sight 863:measurement 847:Boeing B-17 809:, although 807:range angle 763:cross trail 122:. Then, in 109:iron sights 98:dive bomber 89:air density 68:and modern 58:World War I 2237:Categories 2080:Perry 1961 2043:Perry 1961 1730:Perry 1961 1505:References 1436:, such as 1196:Sperry O-1 1157:autopilots 1117:Dutch roll 1106:Norden M-1 1061:Norden M-1 985:submarines 895:Airco DH.4 18:Bomb sight 1361:AN/APA-59 1357:AN/APQ-24 1322:AN/APA-47 1306:AN/APQ-13 1297:H2S radar 1227:Luftwaffe 1200:autopilot 1113:monoplane 1099:autopilot 946:stopwatch 719:aircraft. 618:ρ 511:ρ 412:ρ 305:ρ 140:real time 85:parabolic 50:bombsight 2218:22392603 2020:Archived 2001:Archived 1936:Archived 1822:Archived 1709:Interwar 1452:See also 1397:Cold War 1310:AN/APQ-7 1267:fighters 889:A Mk. I 825:Accuracy 795:sideslip 791:crabbing 775:solution 725:momentum 81:air drag 1567:, 23D3. 1555:, 23D2. 1460:(USAAF) 1216:Mk. XIV 1188:US Navy 1141:gimbals 1121:biplane 1090:tracked 701:gravity 77:gravity 2216: 2178: 1779: 1482:SVP-24 1225:, the 1136:gimbal 1097:, and 777:. The 684:where 146:Theory 120:Norden 2225:(PDF) 2214:S2CID 2194:(PDF) 2007:, FBI 1466:(RAF) 1263:radar 1064:zero. 989:ships 958:radar 942:prism 761:, or 759:drift 738:trail 734:range 128:radar 54:bombs 2176:ISBN 1777:ISBN 1378:and 1370:– a 1332:and 1308:and 1293:Oboe 1269:and 1186:and 1143:and 1059:The 987:and 968:and 966:true 861:The 805:the 705:drag 703:and 93:wind 91:and 79:and 2206:doi 1442:GPS 1302:H2X 1168:cam 793:or 2239:: 2212:. 2202:26 2200:. 2196:. 2160:, 2148:. 2124:. 2031:^ 1752:^ 1716:^ 1654:^ 1609:, 1572:^ 1543:^ 1528:^ 1512:^ 1448:. 1363:. 1316:. 1273:. 980:. 817:, 813:, 797:. 765:. 100:. 48:A 2208:: 2184:. 1584:. 1538:. 1080:. 694:ρ 690:A 686:C 661:2 656:h 652:v 648:+ 643:2 638:v 634:v 626:h 622:v 615:A 612:C 609:= 599:) 594:2 589:h 585:v 581:+ 576:2 571:v 567:v 563:( 555:2 550:h 546:v 542:+ 537:2 532:v 528:v 521:h 517:v 508:A 505:C 502:= 493:h 489:d 455:2 450:h 446:v 442:+ 437:2 432:v 428:v 420:v 416:v 409:A 406:C 403:= 393:) 388:2 383:h 379:v 375:+ 370:2 365:v 361:v 357:( 349:2 344:h 340:v 336:+ 331:2 326:v 322:v 315:v 311:v 302:A 299:C 296:= 287:v 283:d 251:2 246:h 242:v 238:+ 233:2 228:v 224:v 199:h 195:v 172:v 168:v 20:)

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