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94-534: Most versions of the T1 series of light tanks shared the same basic layout, with the engine mounted in the front and the turret, transmission and final drive all located in the rear. The exceptions were the T1E4 and T1E6, which moved the turret to the middle, the engine to the rear, and the transmission and final drive to the front, a configuration similar to later tanks. All T1 versions had a manually traversed turret armed with

188-421: A 37 mm (1.46-inch) main gun and a coaxially mounted .30 caliber (7.62 mm) M1919 Browning machine gun , and all carried a crew of two: a commander who sat within the turret and worked the guns, and a driver seated just in front of the turret. The single T1 prototype was built in 1927. Its main gun was a 37 mm M1918 short tank gun , a U.S. version of a French infantry support gun of World War I. This

282-485: A better ride. Examples include the various rear suspensions of Austin-Healey 3000s and Fiat 128s . The earliest known leaf springs began appearing on carriages in France in the mid-17th century in the form of the two-part elbow spring (as the illustrated example from Lisbon), and later migrated to England and Germany, appearing on the carriages of the wealthy in those countries around 1750. Dr. Richard Lovell Edgeworth

376-503: A central plotting station deep within the ship. There the fire direction teams fed in the location, speed and direction of the ship and its target, as well as various adjustments for Coriolis effect , weather effects on the air, and other adjustments. The resulting directions, known as a firing solution, would then be fed back out to the turrets for laying. If the rounds missed, an observer could work out how far they missed by and in which direction, and this information could be fed back into

470-530: A contract for six of their rangefinders. The device, operated by one person, brought two images from a distance object into coincidence allowing the distance to be calculated from their relative motions. Now that the barrel remained aligned with the target after firing, the more primitive tangent sight was replaced with the rocking-bar sight for direct-fire sighting. These were installed on QF 4.7-inch Gun Mk I–IV quick firing gun from 1887. The rocking-bar (or 'bar and drum') sight had an elevation scale, could mount

564-602: A correction for the cross level of the gun and used feedback from electro-mechanical devices , such as gyroscopes and electronic clinometers , aligned to the axis of the bore. These devices were subsequently replaced by ring laser gyros. Most coastal artillery was in fixed defences, "fortresses" in some form. Their targets moved in two dimensions, and the gun had to be aimed at the target's future position. Some guns were relatively small calibre and dealt with relatively close targets, others were much larger for long-range targets. Coast artillery employed direct fire , and until

658-594: A favourite material for blacksmiths . In countries such as India , Nepal , Bangladesh , Philippines , Myanmar and Pakistan , where traditional blacksmiths still produce a large amount of the country's tools, leaf springs from scrapped cars are frequently used to make knives, kukris , and other tools. They are also commonly used by amateur and hobbyist blacksmiths. Leaf springs have also replaced traditional coil springs in some trampolines (known as soft-edge trampolines), which improves safety for users and reduces risk of concussion. The leaf springs are spaced around

752-406: A full, practicable fire control system for World War I ships, and most RN capital ships were so fitted by mid 1916. The director was high up over the ship where operators had a superior view over any gunlayer in the turrets . It was also able to co-ordinate the fire of the turrets so that their combined fire worked together. This improved aiming and larger optical rangefinders improved the estimate of

846-512: A leaf spring usually are formed into round eyes or eyelets, through which a fastener connects each end of the spring to the vehicle frame or body . Some springs terminated in a concave end, called a spoon end (seldom used now), to carry a swivelling member instead. One eye is usually fixed but allowed to pivot with the motion of the spring, whereas the other eye is fastened to a hinge mechanism that allows that end to pivot and undergo limited movement. A leaf spring can either be attached directly to

940-421: A means of aiming off for target movement and graticules marked for different ranges. Tank sights were of two general types. Either the sight was in fixed alignment with the axis of the bore with ranges marked in the sight, and the gunner laid the range mark on the target. Or during laying the gunner physically set the range to offset the axis of the bore from the axis of the sight by the correct amount and laid using

1034-665: A much higher muzzle velocity of 2,000 ft/s (610 m/s), though later the old M1918 model was reinstalled. In 1930 the Ordnance Department modified one of the T1E1 tanks to create the T1E3 . In some ways this was a hybrid of the T1E1 and T1E2; it had the high-velocity long-barreled Browning gun, thickened armor, and more powerful engine of the T1E2, but it retained the hull, turret, dimensions, and transmission gear ratios of

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1128-467: A plotting unit (or plotter) to capture this data. He added a gyroscope to allow for the yaw of the firing ship. Again this required substantial development of the, at the time, primitive gyroscope to provide continuous reliable correction. Trials were carried out in 1905 and 1906, which although completely unsuccessful showed promise. He was encouraged in his efforts by the rapidly rising figure of Admiral Jackie Fisher , Admiral Arthur Knyvet Wilson and

1222-498: A simple clutch-brake steering system which led to a loss of power while turning. The T1E5 replaced this with a controlled differential steering system from the Cleveland Tractor Company (a so-called "Cletrac" system). The engine was also replaced with the same 140 hp (104 kW) version as in the T1E4. Testing showed the controlled differential steering to be clearly superior to the clutch-brake system, and

1316-399: A telescope as well as the open sight, and provided a small amount of horizontal deflection. These provided 'independent line of sight' because they enabled data to be set on the mount and the telescope (or open sight) aimed at the target independent of the barrel elevation. A related problem, particularly for large and longer range guns, was that the wheels could be at different heights due to

1410-403: A totally unsprung suspension which used multiple equalizing links between the bogies to spread out impacts from rough terrain. This still gave a very rough ride. The T1E3's suspension had coil springs and hydraulic shock absorbers , and its ride was much smoother. The T1E4 , introduced in 1932, was another alteration of a T1E1 tank. Its transformation was much more radical, however, because

1504-405: A wide variety of guns, including the culverin , demiculverin , falconet and Saker . From the results of these trials, he produced range tables for elevations up to 10 degrees for each type with a standard propelling charge weight. A problem affecting gun laying, was the tapered external barrel shape. This affected elevation when the gun was aimed by sighting along the top of the barrel. In

1598-507: Is characterized by fewer leaves whose thickness varies from centre to ends following a parabolic curve . The intention of this design is to reduce inter-leaf friction, and therefore there is only contact between the leaves at the ends and at the centre, where the axle is connected. Spacers prevent contact at other points. Aside from weight-saving, the main advantage of parabolic springs is their greater flexibility, which translates into improved ride quality , which approaches that of coil springs;

1692-402: Is determined from the information or data that is collected, calculated, and applied to physical coordinates to identify the location of the target by the user. The term includes automated aiming using, for example, radar-derived target data and computer-controlled guns. Gun laying is a set of actions to align the axis of a gun barrel so that it points in the required direction. This alignment

1786-406: Is in the horizontal and vertical planes. A gun is "traversed" (rotated in a horizontal plane) to align it with the target, and " elevated " (moved in the vertical plane) to range it to the target. Gun laying may be for direct fire, where the layer sees the target, or indirect fire , where the target may not be visible from the gun. Gun laying has sometimes been called "training the gun". Laying in

1880-415: Is not well controlled, resulting in stiction and irregular suspension motions. For this reason, some manufacturers have used mono-leaf springs. A leaf spring takes the form of a slender arc -shaped length of spring steel of a rectangular cross-section. In the most common configuration, the centre of the arc provides the location for the axle , while loops formed at either end provide for attaching to

1974-480: Is specified by the Stubbs or Birmingham gauge , with typical thicknesses ranging between 0.203 to 0.375 in (5.2 to 9.5 mm) (6 to 3/8 or 00 gauge). The material and dimensions should be selected such that each leaf is capable of being hardened to have a fully martensitic structure throughout the entire section. Suitable spring steel alloys include 55Si7, 60Si7, 65Si7, 50Cr4V2, and 60Cr4V2. The two ends of

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2068-411: Is the process of aiming an artillery piece or turret, such as a gun , howitzer , or mortar , on land, at sea, or in air, against surface or aerial targets. It may be laying for either direct fire , where the gun is aimed directly at a target within the line-of-sight of the user, or by indirect fire , where the gun is not aimed directly at a target within the line-of-sight of the user. Indirect fire

2162-608: The Hotchkiss drive . That employed the lower arc, hence its name. "Quarter-elliptic" springs often had the thickest part of the stack of leaves stuck into the rear end of the side pieces of a short ladder frame, with the free end attached to the differential, as in the Austin Seven of the 1920s. As an example of non-elliptic leaf springs, the Ford Model T had multiple leaf springs over its differential that were curved in

2256-618: The Light Tank, M1 , but this was revoked after only a couple of months. The T1E1 had a few minor changes from the T1: the hull no longer projected forward of the tracks, and the fuel tanks were moved above the tracks. The top speed was reduced to 18 mph (29 km/h). The next version, the T1E2 , was built in 1929, again as a single prototype. It had heavier armor, varying from 0.25 in (6.4 mm) to 0.625 in (15.9 mm) thick, and

2350-419: The frame at both eyes or attached directly at one end, usually the front, with the other end attached through a shackle: a short swinging arm. The shackle takes up the tendency of the leaf spring to elongate when compressed and thus makes the suspension softer. The shackle provides some degree of flexibility to the leaf spring so that it does not fail when subjected to heavy loads. The axle is usually fastened to

2444-412: The 15th century. Two large-diameter wheels, axle-tree and a trail became the standard pattern for field use. The barrel was mounted in a wooden cradle with trunnions to mount it on the carriage. As technology improved, the trunnions became part of the barrel and the cradle was abandoned. Nevertheless, they were relatively large and heavy. Horizontal alignment was a matter of moving the trail. To achieve

2538-433: The 20th century. However, in the 1990s new or modified guns started adopting digital sights, following their successful use in the multi-launch rocket system developed in the 1970s. In these the azimuth and elevation were entered manually or automatically into a layers computer, then guided the layer's use of horizontal and elevation controls until the barrel was in the required horizontal and vertical alignment. This computed

2632-459: The British inventor Obadiah Elliott , referred to two circular arcs linked at their tips. This was joined to the frame at the top centre of the upper arc, the bottom centre was joined to the "live" suspension components, such as a solid front axle. Additional suspension components, such as trailing arms , would usually be needed for this design, but not for "semi-elliptical" leaf springs as used in

2726-660: The Director of Naval Ordnance and Torpedoes (DNO), John Jellicoe . Pollen continued his work, with tests carried out on Royal Navy warships intermittently. Meanwhile, a group led by Dreyer designed a similar system. Although both systems were ordered for new and existing ships of the Royal Navy, the Dreyer system eventually found most favour with the Navy in its definitive Mark IV* form. The addition of director control facilitated

2820-658: The Ordnance Department recommended its use for all tracked vehicles that could exceed six mph (ten km/h). The final T1 version produced, the T1E6 , was introduced in 1932 as a further alteration of the T1E4. The Cunnigham V8 engine was replaced with a 244-horsepower (182 kW) V12 made by the American-LaFrance and Foamite Corporation . Even though the tank's weight increased to 9.95 short tons (9.03 metric tons), its more powerful engine gave it

2914-423: The T1E1. The T1E3 weighed 8.5 short tons (7.7 metric tons). Since it had the T1E2's more powerful engine and the T1E1 gearing, this gave it both a higher power-to-weight ratio and greater speed than any previous T1 version, with a maximum speed of 21.9 miles per hour (35.2 km/h). The most important feature of this version, however, was its suspension, which was completely redesigned. All previous T1 versions had

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3008-401: The T1E4 retained the engine from the T1E1, but this proved to be underpowered, so it was replaced by an improved Cunningham V8 producing 140 horsepower (104 kW), giving the T1E4 a top speed of 20 miles per hour (32 km/h). The T1E5 , introduced around the same time as the T1E4, was yet another conversion of a T1E1, in this case with a new steering system. All previous T1 versions used

3102-400: The advantage of spreading the load more widely over the vehicle's chassis, whereas coil springs transfer it to a single point. Unlike coil springs, leaf springs also locate the rear axle, eliminating the need for trailing arms and a Panhard rod , thereby saving cost and weight in a simple live axle rear suspension. A further advantage of a leaf spring over a helical spring is that the end of

3196-462: The aircraft. However, the target is moving in three dimensions and this makes it a difficult target. The basic issue is that either the layer aims at the target and some mechanism aligns the gun at the future (time of flight) position of the target or the layer aims at the future position of the aircraft. In either case the problem is determining the target's height, speed and direction and being able to 'aim-off' (sometimes called deflection laying) for

3290-458: The anti-aircraft projectile time of flight. Leaf spring A leaf spring is a simple form of spring commonly used for suspension in wheeled vehicles . Originally called a laminated or carriage spring , and sometimes referred to as a semi-elliptical spring , elliptical spring , or cart spring , it is one of the oldest forms of vehicle suspension. A leaf spring is one or more narrow, arc-shaped, thin plates that are attached to

3384-497: The axle and chassis in a way that allows the leaf spring to flex vertically in response to irregularities in the road surface. Lateral leaf springs are the most commonly used arrangement, running the length of the vehicle and mounted perpendicular to the wheel axle, but numerous examples of transverse leaf springs exist as well. Leaf springs can serve multiple suspension functions: location, springing, and to some extent damping as well, through interleaf friction. However, this friction

3478-425: The barrel assembly (called the ordnance in some countries). Early guns could only be traversed by moving their entire carriage or mounting, and this lasted with heavy artillery into World War II. Mountings could be fitted into traversing turrets on ships, coast defences or tanks. From circa 1900 field artillery carriages provided traverse without moving the wheels and trail. The carriage, or mounting, also enabled

3572-422: The barrel to be set at the required elevation angle. With some gun mounts it is possible to depress the gun, i.e., move it in the vertical plane to point it below the horizon. Some guns require a near-horizontal elevation for loading. An essential capability for any elevation mechanism is to prevent the weight of the barrel forcing its heavier end downward. This is greatly helped by having trunnions (around which

3666-477: The best power-to-weight ratio of the entire T1 series. However, the maximum speed was still 20 miles per hour (32 km/h), and the larger V12 engine severely crowded the engine bay, making maintenance troublesome. The T1E6 kept the armament of the T1E4; the armor's maximum thickness remained unchanged, but the minimum thickness increased from 0.25 inches (6.4 mm) to 0.375 inches (9.5 mm). The T1E2 has been preserved, though without its guns. Previously it

3760-419: The bracket. The bar was marked in yards or degrees. This direct-fire sight was aimed at the target by moving the trail horizontally and elevating or depressing the barrel . By the late 19th century the simple open tangent sights were being replaced by optical telescopes on mounts with an elevation scale and screw aligned to the axis of the bore. Rifled and breech loading artillery were introduced from

3854-400: The centre mark in the sight. Some sights had a means of estimating the range, for example using a stadiametric method. Other tanks used an optical coincident range-finder or after World War II, a ranging machine gun. From the 1970s these were replaced by laser range finders. However, tank guns could not be fired accurately while moving until gun stabilisation was introduced. This appeared at

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3948-434: The change in warship armament from hull-mounted to turreted guns . However, ships had a complication compared to land based guns: they were firing from a moving platform. This meant that their laying calculations had to predict the future position of both ship and target. Increasingly sophisticated mechanical calculators were employed for proper gun laying, typically with various spotters and distance measures being sent to

4042-529: The computer along with any changes in the rest of the information and another shot attempted. Rudimentary naval fire control systems were first developed around the time of World War I . Arthur Pollen and Frederic Charles Dreyer independently developed the first such systems. Pollen began working on the problem after noting the poor accuracy of naval artillery at a gunnery practice near Malta in 1900. Lord Kelvin , widely regarded as Britain's leading scientist first proposed using an analogue computer to solve

4136-458: The conflict that could use the technique effectively, in many subsequent battles, British commanders nonetheless ordered artillery to be "less timid" and to move forward to address troops' concerns about their guns abandoning them. The British used improvised gun arcs with howitzers; the sighting arrangements used by the Boers with their German and French guns is unclear. Optical sights appeared in

4230-574: The early 17th century, 'dispart sights' compensated for this. This was a piece of metal placed on the muzzle to make the line of sight parallel to the axis of the bore. Another technique involved measuring the depth of the barrel through the touchhole and at the muzzle, the difference being the wedge size needed to compensate for the tapered barrel. The ballistic pendulum was invented in 1742 by English mathematician Benjamin Robins , and published in his book New Principles of Gunnery , which revolutionized

4324-464: The effects of barrel wear in changing muzzle velocity were fully recognised. This meant that different guns needed a different elevation angle for the same range. This led many armies to use an elevation angle calculated in a battery command post . However, in the 1930s the British adopted calibrating sights in which range was set on the sight, which automatically compensated for the difference of muzzle velocity from standard. An alternative to this

4418-499: The elevating mass rotates vertically) at the centre of gravity, although a counterbalance mechanism can be used. It also means the elevation gear has to be strong enough to resist considerable downward pressure but still be easy for the gun layer to use. Until recoil systems were invented in the late 19th century and integrated into the gun carriage or mount, guns moved substantially backwards when they fired, and had to be moved forward before they could be laid. However, mortars, where

4512-409: The end of World War II. Some were hydraulic, while others used electrical servos. During the 1970s tanks started being fitted with digital computers. The need to engage balloons and airships, from both the ground and ships, was recognised at the beginning of the 20th century. Aircraft were soon added to the list and the others fell from significance. Anti-aircraft was direct fire, the layer aiming at

4606-421: The enemy's position at the time of firing. The system was eventually replaced by the improved " Admiralty Fire Control Table " for ships built after 1927. By the 1950s gun turrets were increasingly unmanned, with gun laying controlled remotely from the ship's control centre using inputs from radar and other sources. Telescopic sights for tanks were adopted before World War II , and these sights usually had

4700-445: The equations which arise from the relative motion of the ships engaged in the battle and the time delay in the flight of the shell to calculate the required trajectory and therefore the direction and elevation of the guns. Pollen aimed to produce a combined mechanical computer and automatic plot of ranges and rates for use in centralised fire control. To obtain accurate data of the target's position and relative motion, Pollen developed

4794-475: The first years of the 20th century, and the German Goerz panoramic sight became the pattern for the rest of the 20th century. They were graduated in degrees and 5 minute intervals, decigrads or mils (4320, 4000 or 6000/6300/6400 to a circle). A feature of 20th-century laying was the use of one- or two-man laying. The US was notable for using two-man laying, horizontal on one side of the gun, elevation on

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4888-523: The following decade. By the early 1900s the open sight was sometimes replaced by a telescope and the term goniometer had replaced "lining-plane" in English. The first incontrovertible, documented use of indirect fire in war using Guk's methods, albeit without lining-plane sights was on 26 October 1899 by British gunners during the Second Boer War . Although both sides demonstrated early on in

4982-451: The front suspension of the 1983 Corvette . This arrangement uses a straight leaf spring that is tightly secured to the chassis at the centre; the ends of the spring are bolted to the wheel suspension, allowing the spring to work independently on each wheel. This suspension is smaller, flatter and lighter than a traditional setup. Multi-leaf springs are made as follows. Because leaf springs are made of relatively high quality steel, they are

5076-487: The gun cradle. Despite this effort, nothing followed from it, and it was only with the introduction of the French 75 mm in 1897, that recoil systems started to become normal. The gun's barrel slid back on rollers, pushing a piston into an oil-filled cylinder. This action absorbed the recoil progressively as the internal air pressure rose and, at the end of recoil, generated a strong, but decreasing, back pressure that returned

5170-401: The gun did not have to be repositioned after each time it was fired. An early prototype incorporating this design feature was built in 1872 by Russian engineer, Vladimir Stepanovich Baranovsky. His 2.5-inch rapid-firing gun was also equipped with a screw breech, a self-cocking firing mechanism and it fired a fixed round (shell and cartridge case together). The recoil mechanism was contained in

5264-515: The gun forward to its original position. By this time smokeless powder had replaced gunpowder as the standard propellant. The first practical rangefinder was developed by Barr & Stroud a pioneering Scottish optical engineering firm. Archibald Barr and William Stroud became associated from 1888. In 1891 they were approached by the Admiralty to submit a design for a short-base rangefinder for trial, and in 1892 they were awarded with

5358-590: The guns in the right direction. However, various aids emerged. Horizontal aiming involved sighting along the barrel, this was enhanced by a notch made in the ring around the barrel at the breech end and an 'acorn' on the ring around the muzzle . This was still used in the 19th century in some instances. The range with a flat trajectory was called 'point blank' range. However, while point blank may have been enough for some purposes, field artillery (whether mobile or static) and guns in fortresses needed longer range. This required ways to measure elevation angles and know

5452-585: The late 19th century laying had changed little, apart from gaining telescopic sights , over the centuries. Nineteenth-century improvements in gun design and ammunition greatly extended their effective range. In 1879, Major HS Watkins of the Royal Garrison Artillery invented the depression range finder , the position-range finder and associated fire control systems . His description explains its essence: It took almost 20 years to get it to full effectiveness, but its general principle became

5546-504: The latter half of the 19th century as well, making the manufacture of leaf springs more consistent and less expensive. Leaf springs were very common on automobiles until the 1970s when automobile manufacturers shifted primarily to front-wheel drive , and more sophisticated suspension designs were developed using coil springs instead. Today leaf springs are still used in heavy commercial vehicles such as vans and trucks , SUVs , and railway carriages . For heavy vehicles, they have

5640-412: The leaf both supports an axle and locates/partially locates the axle. This can lead to handling issues (such as "axle tramp"), as the flexible nature of the spring makes precise control of the unsprung mass of the axle difficult. Some suspension designs use a Watts link (or a Panhard rod ) and radius arms to locate the axle and do not have this drawback. Such designs can use softer springs, resulting in

5734-416: The leaf spring is also serving to hold the axle in position, soft springs—i.e. springs with low spring constant—are not suitable. The consequent stiffness, in addition to inter-leaf friction, makes this type of suspension not particularly comfortable for the riders. There are a variety of leaf springs, usually employing the word "elliptical". "Elliptical" or "full elliptical" leaf springs, patented in 1804 by

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5828-465: The leaf spring may be guided along a definite path. In many late 1990s and early 2000s trucks, the leaf spring is connected to a Hinkle Beam ball joint. The leaf spring also has seen modern applications in cars. For example, the 1963 Chevrolet Corvette Sting Ray uses a transverse leaf spring for its independent rear suspension. Similarly, 2016 Volvo XC90 has a transverse leaf spring using composite materials for its rear suspension, similar in concept to

5922-425: The line of sight to the target, although the layer may make allowance for the wind, and with rifled guns the sights may compensate for projectile "drift". With indirect fire the horizontal angle is relative to something, typically the gun's aiming point, although with modern electronic sights it may be a north-seeking gyro . Depending on the gun mount, there is usually a choice of two trajectories that will result in

6016-466: The mass of the ejecta, the velocity of the bullet could be approximated. The second, and more accurate method, was to directly measure the bullet momentum by firing it into the pendulum. Robins experimented with musket balls of around one ounce in mass (30 g), while other contemporaries used his methods with cannon shot of one to three pounds (0.45 to 1.36 kg). The first system to supplant ballistic pendulums with direct measures of projectile speed

6110-401: The mid-19th century, notably by William Armstrong , whose gun equipped Royal Navy warships from the 1850s. An important advance in the art of gun laying came with the introduction of the first recoil mechanisms . The barrel recoil was absorbed by hydraulic cylinders and then the barrel was returned to its firing position by a spring that had stored some of the recoil energy . This meant

6204-400: The middle of the spring by U-bolts . The leaf spring acts as a linkage to hold the axle in position and thus separate linkages are not necessary. The result is a suspension that is simple and strong. Inter-leaf friction dampens the spring's motion and reduces rebound, which, until shock absorbers were widely adopted, was a very significant advantage over helical springs . However, because

6298-570: The norm for heavy artillery fire control and laying. Shorter-range guns retained conventional direct-fire laying with telescopes for much longer. In the 20th century, coast artillery, like field and the larger anti-aircraft guns, included corrections for non-standard conditions such as wind and temperature in their calculations. Naval artillery on board capital ships soon adopted gunlaying arrangements broadly similar to Major Watkins' coast artillery pattern. The introduction of breech-loading guns , then recoil systems and smokeless powder , completed

6392-613: The other leaves are tapered at each end. Sometimes auxiliary or rebound leaves are part of the main spring pack, in which case the auxiliary leaf closest to the main leaf is No. 1, the next closest is No. 2, etc. The leaves are attached to each other through the centre bolt, which is at or near the mid-point along the length of the leaf spring. To ensure that leaves remain aligned laterally, several methods can be used, including notches and grooves between leaves or external clips. Spring steels were discovered to be most efficient at approximately 1% carbon content. Individual leaf thickness

6486-470: The other. Most other nations mostly used one-man laying. The laying drill, dealing with all three axes, typically adopted this sequence: "roughly for line, roughly for elevation, cross-level, accurately for line, accurately for elevation". The other main difference in sighting arrangements was the use of an elevation angle or alternatively the range. This issue became more complicated in World War I when

6580-407: The recoil forces were transferred directly into the ground (or water, if mounted on a ship), did not always require such movement. With the adoption of recoil systems for field artillery, it became normal to pivot the saddle on the lower carriage, initially this "top traverse" was only a few degrees but soon offered a full circle, particularly for anti-aircraft guns. The introduction of recoil systems

6674-467: The relationship between the elevation angle and the range. The first recorded device to measure an elevation angle was Niccolò Tartaglia 's invention of a gunners' quadrant circa 1545. This device had two arms at right angles connected by an arc marked with angular graduations. One arm was placed in the muzzle, and a plumb bob suspended against the arc showed the elevation angle. This led to many calculations relating elevation angle to range. The problem

6768-452: The required elevation angle, various arrangements were used. At the simplest, it was wedges or quoins between the breech and the trail, but wooden quadrants , or simple scaffolds mounted on the trail, were also used to support the breech and provided larger choice of elevation angle. Screw elevation devices were also used as early as the 16th century. However, naval and some fortress carriages and mounting evolved differently. Field mobility

6862-407: The science of ballistics , as it provided the first way to accurately measure the velocity of a bullet. Robins used the ballistic pendulum to measure projectile velocity in two ways. The first was to attach the gun to the pendulum, and measure the recoil . Since the momentum of the gun is equal to the momentum of the ejecta, and since the projectile was (in those experiments) the large majority of

6956-420: The shape of a yoke . As a substitute for dampers ( shock absorbers ), some manufacturers laid non-metallic sheets in between the metal leaves, such as wood. Elliot's invention revolutionized carriage design and construction, removing the need for a heavy perch and making transportation over rough roadways faster, easier, and less expensive. A more modern implementation is the parabolic leaf spring. This design

7050-490: The shot landing in the same spot. The dividing angle between the trajectories is about 45 degrees (usually between 0 degrees and 90 degrees), it varies slightly due to gun dependent factors. Below 45 degrees the trajectory is called "low angle" (or lower register), above 45 degrees is "high angle" (or upper register). The differences are that low angle fire has a shorter time of flight, a lower apex, and flatter angle of descent. All guns have carriages or mountings that support

7144-563: The slope of the ground, which caused inaccuracy. Before the First World War , the British BL 60-pounder gun was fitted with oscillating (reciprocating) sights, using sighting telescopes, a sight clinometer and range scale as well as a deflection drum for the telescope. These mounts could be cross-leveled, which removed the need for the gun commander to calculate a deflection correction for uneven wheels. Cross-leveling introduced

7238-415: The tank's weight rose to 8.9 short tons (8.1 metric tons). The Cunningham V8 engine had its power boosted to 132 hp (98 kW), giving the T1E2 a slightly higher power-to-weight ratio than its predecessors; despite this, the maximum speed was only 16 mph (26 km/h) because of changes in the gear ratios. The 37 mm main gun was changed to a long-barreled Browning semi-automatic type, having

7332-407: The third axis into laying. Modern indirect fire dates from the late 19th century. In 1882, Russian Lt Col KG Guk published Field Artillery Fire from Covered Positions that described a better method of indirect laying (instead of aiming points in line with the target). In essence, this was the geometry of using angles to aiming points that could be in any direction relative to the target. The problem

7426-575: The trade-off is reduced load carrying capability. They are widely used on buses for improved comfort. A further development by the British GKN company and by Chevrolet, with the Corvette, among others, is the move to composite plastic leaf springs. Nevertheless, due to the lack of inter-leaf friction and other internal dampening effects, this type of spring requires more powerful dampers/shock absorbers. Typically when used in automobile suspension

7520-413: The vehicle chassis. For very heavy vehicles, a leaf spring can be made from several leaves stacked on top of each other in several layers, often with progressively shorter leaves. The longest leaf is also known as the main, master, or No. 1 leaf, with leaves numbered in descending order of length. The eyes at the end of the leaf spring are formed into the master leaf. In general, aside from the main leaf,

7614-638: The vehicle's layout was completely changed. The engine was moved to the rear, the transmission and final drive to the front, and the turret to the middle of the body. At 15 ft 5 in (4.70 m) in length, the T1E4 was nearly a quarter longer than preceding T1 versions. The T1E4 also got a new suspension copied exactly from the British Vickers 6-Ton light tank, which the Army had recently tested. It featured semi-elliptic leaf springs and articulated four-wheel bogies. Harry Knox even dared to patent

7708-405: The vehicle, infringing on John Valentine Carden 's patent from 1929. The main gun was replaced by the 37 mm semi-automatic gun M1924, whose muzzle velocity of 1,350 feet per second (410 m/s) was lower than that of the long-barreled Browning in the T1E2 and T1E3. The armor thickness was similar to the T1E2 and T1E3. The T1E4 had an overall weight of 8.6 short tons (7.8 metric tons). At first

7802-405: The vertical plane (elevation angle) uses data derived from trials or empirical experience. For any given gun and projectile types, it reflects the distance to the target and the size of the propellant charge. It also incorporates any differences in height between gun and target. With indirect fire, it may allow for other variables as well. With direct fire, laying in the horizontal plane is merely

7896-416: Was a sliding-gear type with three forward gears and one reverse gear. After the prototype was evaluated, it was stripped down to its chassis, which was reused to test other vehicle types. The T1 prototype was followed in 1928 by the very similar T1E1 . Four of these were built, making the T1E1 the only T1 version which was not built as a single prototype. The T1E1 was briefly standardized for production as

7990-468: Was a 'gun rule' at each gun; in this case the range was set on the rule and an elevation angle read and given to the layer to set on the sight. The issue was finally resolved by the introduction of digital computers in the battery command post that calculated the correct elevation angle for the range and muzzle velocity accurately and quickly. Apart from calibrating sights, there was no significant difference in field artillery laying arrangements for most of

8084-450: Was a relatively low-velocity weapon, with a muzzle velocity of 1,200 ft/s (370 m/s). The tank's armor ranged from 0.25 in (6.4 mm) to 0.375 in (9.5 mm) in thickness, and the tank's overall weight was 7.5 short tons (6.8 metric tons ). It was powered by a 105 hp (78 kW) Cunningham water-cooled V8 gasoline engine which gave it a top speed of 20 mph (32 km/h). The transmission, made by Cotta,

8178-416: Was an important milestone. The earliest guns were loaded from the muzzle. They were typically little more than bare barrels moved in wagons and placed on the ground for firing, then wooden frames and beds were introduced. Horizontal alignment with the target was by eye, while vertical laying was done by raising the muzzle with timber or digging a hole for the closed end. Gun carriages were introduced in

8272-859: Was awarded three gold medals by the Society of English Arts and Manufacturers in 1768 for demonstrating the superiority of sprung carriages. By 1796, William Felton 's A Treatise on Carriages showed that leaf springs were being marketed regularly by the late 18th century carriage industry. Obadiah Elliot is credited with inventing the modern leaf spring with his 1804 patent on elliptical leaf springs, which brought him significant recognition and revenue, and engineers began studying leaf springs to develop improved designs and manufacturing processes. The mechanics and deflection of leaf springs were developed by Clark (1855), Franz Reuleaux (1861), and G.R. Henderson (1894). Improved steel rolling processes, process instruments, and spring steel alloys were developed during

8366-423: Was interrupted by the bullet passing through two meshes of fine wires, again providing the time to traverse the given distance. Tangent sights were introduced in the 19th century. These provided the rear sight used with an 'acorn' or similar foresight at the muzzle. The tangent sight was mounted in a bracket beside or behind the breech, the eyepiece (a hole or notch) was atop a vertical bar that moved up and down in

8460-510: Was invented in 1808, during the Napoleonic Wars and used a rapidly rotating shaft of known speed with two paper disks on it; the bullet was fired through the disks, parallel to the shaft, and the angular difference in the points of impact provided an elapsed time over the distance between the disks. A direct electromechanical clockwork measure appeared in 1840, with a spring-driven clock started and stopped by electromagnets, whose current

8554-514: Was not required, so large wheels and trails were irrelevant. Headspace below decks was often low. This led to compact carriages, mostly on four small wheels. Obviously, large horizontal traverses were more difficult, but such things were unnecessary when shooting broadside. However, in fortresses wider traverse was required. One solution was platform and slide mountings. Wide traverse was also useful on some shipmounted guns . Laying required sights . At its simplest, this means nothing more than aiming

8648-488: Was on outdoor display at the U.S. Army Ordnance Museum at Aberdeen Proving Ground in Aberdeen , Maryland. Due to that museum's closure in 2010, it has been moved to the U.S. Army Ordnance Training and Heritage Center at Fort Lee , Virginia, where it is presently in indoor storage and not publicly accessible. Background: History of the tank , Tank classification , interwar period Gun laying Gun laying

8742-410: Was that these calculations assumed what today is called an " in vacuo " trajectory – they made no allowance for air resistance against the projectile. What was needed were range and accuracy trials to determine the actual relationship between range and elevation angle. The practical approach was conducted by William Eldred , Master Gunner at Dover Castle, in gunnery trials in 1613, 1617 and 1622. He used

8836-466: Was the lack of an azimuth instrument to enable it; clinometers for elevation already existed. The Germans solved this problem by inventing the Richtfläche, or lining-plane, in about 1890. This was a gun-mounted rotatable open sight, mounted in alignment with the bore, and able to measure large angles from it. Similar designs, usually able to measure angles in a full circle, were widely adopted over

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