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94-517: Improvements in powerful automotive propulsion and suspension systems following World War II allowed modern main battle tanks to incorporate progressively thicker and heavier armor, while maintaining considerable maneuverability and speed on the battlefield. As a result, achieving deep armour penetration with gun-fired ammunition required even longer anti-armour projectiles fired at even higher muzzle velocity than could be achieved with stubbier APDS projectiles. Armour-piercing discarding sabot (APDS)

188-424: A DU penetrator cannot simply be used to launch a substitute WHA penetrator, even of exactly the same manufactured geometry. The two materials behave differently under high pressure, high launch acceleration forces, such that entirely different sabot material geometries, (thicker or thinner in some places, if even possible), are required to maintain in-bore structural integrity. Often the greater engineering challenge

282-639: A belief that Soviet tanks had sufficient armour, the research was ended. No more research was conducted until 1974, when the Ministry of the Defensive Industry announced a contest to find the best tank protection . Picatinny Arsenal , an American military research and manufacturing facility experimented with testing linear cutting charges against anti-tank ammunition in the 1950s, and concluded that they may be effective with an adequate sensing and triggering mechanism, but noted "tactical limitations";

376-448: A bow. Horse-drawn carriages and Ford Model T used this system, and it is still used today in larger vehicles, mainly mounted in the rear suspension. Leaf springs were the first modern suspension system, and, along with advances in the construction of roads , heralded the single greatest improvement in road transport until the advent of the automobile . The British steel springs were not well-suited for use on America 's rough roads of

470-470: A high-power capacitor . In operation, a high-voltage power source charges the armour. When an incoming body penetrates the plates, it closes the circuit to discharge the capacitor, dumping a great deal of energy into the penetrator, which may vaporize it or even turn it into a plasma , significantly diffusing the attack. It is not public knowledge whether this is supposed to function against both kinetic energy penetrators and shaped charge jets, or only

564-463: A high-speed off-road vehicle encounters. Damping is the control of motion or oscillation, as seen with the use of hydraulic gates and valves in a vehicle's shock absorber. This may also vary, intentionally or unintentionally. Like spring rate, the optimal damping for comfort may be less, than for control. Damping controls the travel speed and resistance of the vehicle's suspension. An undamped car will oscillate up and down. With proper damping levels,

658-487: A layer of oxidiser, destroying the jet by burning it with oxidising agents. The earliest trials were done with small charges able to defeat 2 inch of steel plate which were readily defeated by a layer of explosive (Baratol, R.D.X., Cordite, etc.) or a vigorous oxidising medium. Subsequent trials with British No.68 and American M9A1 grenades were carried out. However trials were done in few numbers which caused varied results. A mixture of Sodium and Potassium Nitrates explosives

752-404: A penetrating weapon, the explosive detonates, forcibly driving the metal plates apart to damage the penetrator. The shaped charges on the other hand, each detonate individually, launching one spike-shaped plate each, meant to deflect, detonate or cut the incoming projectile. The disruption is attributed to two mechanisms. First, the moving plates change the effective velocity and angle of impact of

846-585: A smaller head on impact, though it will still be significantly "mushroomed". Tests have shown that the hole bored by a DU projectile is of a narrower diameter than for a similar tungsten projectile. Although both materials have nearly the same density, hardness, toughness, and strength, due to these differences in their deformation, depleted uranium tends to out-penetrate an equivalent length of tungsten alloy against steel targets. The use of depleted uranium, in spite of some superior performance characteristics, provokes political and humanitarian controversy, but remains

940-498: A spring rate close to the upper limit for that vehicle's weight. This allows the vehicle to perform properly under a heavy load, when control is limited by the inertia of the load. Riding in an empty truck meant for carrying loads can be uncomfortable for passengers, because of its high spring rate relative to the weight of the vehicle. A race car could also be described as having heavy springs, and would also be uncomfortably bumpy. However, even though we say they both have heavy springs,

1034-442: A strong, depleted uranium core. An important aspect of ERA is the brisance , or detonation speed of its explosive element. A more brisant explosive and greater plate velocity will result in more plate material being fed into the path of the oncoming jet, greatly increasing the plate's effective thickness. This effect is especially pronounced in the rear plate receding away from the jet, which triples in effective thickness with double

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1128-400: A suspension system. In 1922, independent front suspension was pioneered on Lancia Lambda , and became more common in mass market cars from 1932. Today, most cars have independent suspension on all four wheels. The part on which pre-1950 springs were supported is called a dumb iron . In 2002, a new passive suspension component, the inerter , was invented by Malcolm C. Smith . This has

1222-547: A vehicle with zero sprung weight. They are then put through the same dynamic loads. The weight transfer for cornering in the front would be equal to the total unsprung front weight times the G-force times the front unsprung center of gravity height divided by the front track width. The same is true for the rear. Sprung weight transfer is the weight transferred by only the weight of the vehicle resting on its springs, and not by total vehicle weight. Calculating this requires knowing

1316-416: A vehicle's sprung mass to roll. It is expressed as torque per degree of roll of the vehicle sprung mass. It is influenced by factors including but not limited to vehicle sprung mass, track width, CG height, spring and damper rates, roll centre heights of front and rear, anti-roll bar stiffness and tire pressure/construction. The roll rate of a vehicle can, and usually, does differ front-to-rear, which allows for

1410-537: A wheel are less severe, if the wheel lifts when the spring reaches its unloaded shape than they are, if travel is limited by contact of suspension members (See Triumph TR3B .) Many off-road vehicles , such as desert racers, use straps called "limiting straps" to limit the suspensions' downward travel to a point within safe limits for the linkages and shock absorbers. This is necessary, since these trucks are intended to travel over very rough terrain at high speeds, and even become airborne at times. Without something to limit

1504-410: Is explosive reactive armour (ERA), but variants include self-limiting explosive reactive armour (SLERA), non-energetic reactive armour (NERA), non-explosive reactive armour (NxRA), and electric armour. NERA and NxRA modules can withstand multiple hits, unlike ERA and SLERA. When a shaped charge strikes the upper plate of the armour, it detonates the inner explosive, releasing blunt damage that

1598-422: Is a component in setting the vehicle's ride height or its location in the suspension stroke. When a spring is compressed or stretched, the force it exerts, is proportional to its change in length. The spring rate or spring constant of a spring is the change in the force it exerts, divided by the change in deflection of the spring. Vehicles that carry heavy loads, will often have heavier springs to compensate for

1692-414: Is a practical application of the phenomenon of hydro-dynamic penetration. Despite practical penetrator and target materials not being fluids before impact, at sufficiently high impact velocity even crystalline materials begin to behave in a highly plastic fluid-like manner, so many aspects of hydro-dynamic penetration do apply. Long rod projectiles penetrate a fluid in the literal sense, based simply on

1786-419: Is a simplified method of describing lateral load transfer distribution front to rear, and subsequently handling balance. It is the effective wheel rate, in roll, of each axle of the vehicle as a ratio of the vehicle's total roll rate. It is commonly adjusted through the use of anti-roll bars , but can also be changed through the use of different springs. Weight transfer during cornering, acceleration, or braking

1880-413: Is complex, and is determined by many factors; including, but not limited to: roll center height, spring and damper rates, anti-roll bar stiffness, and the kinematic design of suspension links. In most conventional applications, when weight is transferred through intentionally compliant elements, such as springs, dampers, and anti-roll bars, the weight transfer is said to be "elastic", while the weight which

1974-455: Is designing an efficient sabot to successfully launch extremely long penetrators, now approaching 80 cm (31 in) in length. The sabot, necessary to fill the bore of the cannon when firing a long, slender flight projectile, is parasitic weight that subtracts from the potential muzzle velocity of the entire projectile. Maintaining the in-bore structural integrity of such a long flight projectile under accelerations of tens of thousands of g's

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2068-412: Is determined by the instantaneous front view swing arm (FVSA) length of suspension geometry, or in other words, the tendency of the tire to camber inward when compressed in bump. Roll center height is a product of suspension instant center heights and is a useful metric in analyzing weight transfer effects, body roll and front to rear roll stiffness distribution. Conventionally, roll stiffness distribution

2162-413: Is insensitive to impact by kinetic projectiles up to 30 mm in caliber. A 20 mm APIT autocannon round penetrates a Serbian ERA sample but fails to detonate it. However, computer simulations indicate that a small caliber (30 mm) HEAT projectile will detonate an ERA, as would larger shape charges and APFSDS penetrators. NERA and NxRA operate similarly to explosive reactive armour, but without

2256-441: Is key information used in finding the force-based roll center as well. In this respect, the instant centers are more important to the handling of the vehicle, than the kinematic roll center alone, in that the ratio of geometric-to-elastic weight transfer is determined by the forces at the tires and their directions in relation to the position of their respective instant centers. Anti-dive and anti-squat are percentages that indicate

2350-422: Is more important than impact velocity; as exemplified by the fact that the base model M829 flies nearly 200 m/s (656 ft/s) faster than the newer model M829A3, but is only about one half the length, wholly inadequate for defeating state-of-the-art armor arrays. Complicating matters, when foreign deployment of military forces or export sales markets are considered, a sabot designed specifically to launch

2444-431: Is not a trivial undertaking, and has brought the design of sabots from employing in the early 1980s readily available low cost, high strength aerospace-grade aluminums, such as 6061 and 6066-T6, to high strength and more expensive 7075-T6 aluminum, maraging steel , and experimental ultra-high strength 7090-T6 aluminum, to the current state-of-the-art and expensive graphite fiber reinforced plastics, in order to further reduce

2538-405: Is squared because it has two effects on the wheel rate: it applies to both the force and the distance traveled. Wheel rate on independent suspension is fairly straightforward. However, special consideration must be taken with some non-independent suspension designs. Take the case of the straight axle. When viewed from the front or rear, the wheel rate can be measured by the means above. Yet, because

2632-415: Is that, during impact, fractures along these bands cause the tip of the penetrator to continuously shed material, maintaining the tip's conical shape, whereas other materials such as unjacketed tungsten tend to deform into a less effective rounded profile, an effect called "mushrooming". The formation of adiabatic shear bands actually means that the sides of the "mushroom" tend to break away earlier, leading to

2726-410: Is the "bump-stop", which protects the suspension and the vehicle (as well as the occupants) from the violent "bottoming" of the suspension, caused when an obstruction (or a hard landing) causes suspension to run out of upward travel without fully absorbing the energy of the stroke. Without bump-stops, a vehicle that "bottoms out", will experience a very hard shock when the suspension contacts the bottom of

2820-412: Is transferred through more rigid suspension links, such as A-arms and toe links, is said to be "geometric". Unsprung weight transfer is calculated based on weight of the vehicle's components that are not supported by the springs. This includes tires, wheels, brakes, spindles, half the control arm's weight, and other components. These components are then (for calculation purposes) assumed to be connected to

2914-660: Is tuned adjusting antiroll bars rather than roll center height (as both tend to have a similar effect on the sprung mass), but the height of the roll center is significant when considering the amount of jacking forces experienced. Due to the fact that the wheel and tire's motion is constrained by the vehicle's suspension links, the motion of the wheel package in the front view will scribe an imaginary arc in space with an "instantaneous center" of rotation at any given point along its path. The instant center for any wheel package can be found by following imaginary lines drawn through suspension links to their intersection point. A component of

Armour-piercing fin-stabilized discarding sabot - Misplaced Pages Continue

3008-486: Is usually calculated per individual wheel, and compared with the static weights for the same wheels. The total amount of weight transfer is only affected by four factors: the distance between wheel centers (wheelbase in the case of braking, or track width in the case of cornering), the height of the center of gravity, the mass of the vehicle, and the amount of acceleration experienced. The speed at which weight transfer occurs, as well as through which components it transfers,

3102-454: The De Dion tube , which is sometimes called "semi-independent". Like true independent rear suspension, this employs two universal joints , or their equivalent from the centre of the differential to each wheel. But the wheels cannot entirely rise and fall independently of each other; they are tied by a yoke that goes around the differential, below and behind it. This method has had little use in

3196-568: The Landau . By the middle of the 19th century, elliptical springs might additionally start to be used on carriages. Automobiles were initially developed as self-propelled versions of horse-drawn vehicles. However, horse-drawn vehicles had been designed for relatively slow speeds, and their suspension was not well suited to the higher speeds permitted by the internal combustion engine. The first workable spring-suspension required advanced metallurgical knowledge and skill, and only became possible with

3290-506: The United States . Its use around 1900 was probably due to the poor quality of tires, which wore out quickly. By removing a good deal of unsprung weight , as independent rear suspensions do, it made them last longer. Rear-wheel drive vehicles today frequently use a fairly complex fully-independent, multi-link suspension to locate the rear wheels securely, while providing decent ride quality . The spring rate (or suspension rate)

3384-505: The American General Dynamics KEW-A1 has a muzzle velocity of 1,740 m/s (5,700 ft/s). This compares to ~914 m/s (3,000 ft/s) for a 5.56mm round fired from an M16 rifle. APFSDS rounds generally operate in the range of 1,400 to 1,800 m/s (4,593 to 5,906 ft/s). Above a minimum impact velocity necessary to overcome target material strength parameters significantly, penetrator length

3478-502: The ability to increase the effective inertia of wheel suspension using a geared flywheel, but without adding significant mass. It was initially employed in Formula One in secrecy, but has since spread to wider motorsport. For front-wheel drive cars , rear suspension has few constraints, and a variety of beam axles and independent suspensions are used. For rear-wheel drive cars , rear suspension has many constraints, and

3572-414: The actual spring rates for a 2,000 lb (910 kg) racecar and a 10,000 lb (4,500 kg) truck are very different. A luxury car, taxi, or passenger bus would be described as having soft springs, for the comfort of their passengers or driver. Vehicles with worn-out or damaged springs ride lower to the ground, which reduces the overall amount of compression available to the suspension, and increases

3666-483: The additional weight that would otherwise collapse a vehicle to the bottom of its travel (stroke). Heavier springs are also used in performance applications, where the loading conditions experienced are more significant. Springs that are too hard or too soft cause the suspension to become ineffective – mostly because they fail to properly isolate the vehicle from the road. Vehicles that commonly experience suspension loads heavier than normal, have heavy or hard springs, with

3760-522: The advent of industrialisation . Obadiah Elliott registered the first patent for a spring-suspension vehicle; each wheel had two durable steel leaf springs on each side and the body of the carriage was fixed directly to the springs which were attached to the axles . Within a decade, most British horse carriages were equipped with springs; wooden springs in the case of light one-horse vehicles to avoid taxation , and steel springs in larger vehicles. These were often made of low-carbon steel and usually took

3854-436: The amount of body lean. Performance vehicles can sometimes have spring rate requirements other than vehicle weight and load. Wheel rate is the effective spring rate when measured at the wheel, as opposed to simply measuring the spring rate alone. Wheel rate is usually equal to or considerably less than the spring rate. Commonly, springs are mounted on control arms, swing arms or some other pivoting suspension member. Consider

Armour-piercing fin-stabilized discarding sabot - Misplaced Pages Continue

3948-461: The armour. This is almost the same as the second mechanism that explosive reactive armour uses, but it uses energy from the shaped charge jet rather than from explosives. Since the inner liner is non-explosive, the bulging is less energetic than on explosive reactive armour, and thus offers less protection than a similarly-sized ERA. However, NERA and NxRA are lighter, safe to handle, safer for nearby infantry, can theoretically be placed on any part of

4042-417: The best choice for a particular anti-armor application. Depleted uranium alloy, for example, is pyrophoric ; the heated fragments of the penetrator ignite after impact in contact with air, setting fire to fuel and / or ammunition in the target vehicle, contributing significantly to behind-armour lethality. Additionally, DU penetrators exhibit significant adiabatic shear band formation. A common misconception

4136-428: The car will settle back to a normal state in a minimal amount of time. Most damping in modern vehicles can be controlled by increasing or decreasing the resistance to fluid flow in the shock absorber. See dependent and independent below. Camber changes due to wheel travel, body roll and suspension system deflection or compliance. In general, a tire wears and brakes best at -1 to -2° of camber from vertical. Depending on

4230-704: The counterpart of APFSDS in rifle ammunition. A rifle for firing flechettes, the Special Purpose Individual Weapon , was under development for the US Army, but the project was abandoned. Suspension system Suspension is the system of tires , tire air, springs , shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/ handling and ride quality , which are at odds with each other. The tuning of suspensions involves finding

4324-495: The degree to which the front dives under braking, and the rear squats under acceleration. They can be thought of as the counterparts for braking and acceleration, as jacking forces are to cornering. The main reason for the difference is due to the different design goals between front and rear suspension, whereas suspension is usually symmetrical between the left and the right of the vehicle. The method of determining anti-dive or anti-squat depends on whether suspension linkages react to

4418-513: The density of the target armour and the density and length of the penetrator. The penetrator will continue to displace the target to a depth of the penetrator length times the square root of the penetrator to target densities. One observes immediately that longer, denser penetrators will penetrate to deeper depths, and this forms the basis for the development of long-rod anti-armour projectiles. The important parameters for an effective long-rod penetrator, therefore, are very high density with respect to

4512-415: The development of the superior, but more expensive independent suspension layout has been difficult. Henry Ford 's Model T used a torque tube to restrain this force, for his differential was attached to the chassis by a lateral leaf spring and two narrow rods. The torque tube surrounded the true driveshaft and exerted the force to its ball joint at the extreme rear of the transmission, which

4606-528: The differential of the live axle . These springs transmit torque to the frame. Although scorned by many European car makers of the time, it was accepted by American car makers, because it was inexpensive to manufacture. Also, the dynamic defects of this design were suppressed by the enormous weight of U.S. passenger vehicles before the implementation of the Corporate Average Fuel Economy (CAFE) standard. Another Frenchman invented

4700-627: The early development of APFSDS ammunition, existing rifled barrel cannons were used, (and are still in use), such as the 105 mm M68/M68E1 cannon mounted on the M60/A1/A3 main battle tank or the British 120 mm Royal Ordnance L30 of the Challenger 2 tank. To reduce the spin rate when using a rifled barrel, a "slip obturator" (slip obturation ring) is incorporated that allows the high pressure propellant gasses to seal, yet not transfer

4794-653: The eastern-European military inventory today has either been manufactured to use ERA or had ERA tiles added to it, including even the T-55 and T-62 tanks built forty to fifty years ago, but still used today by reserve units. The U.S. Army uses reactive armour on its Abrams tanks as part of the TUSK (Tank Urban Survivability Kit) package and on Bradley vehicles and the Israelis use it frequently on their American built M60 tanks. ERA tiles are used as add-on (or appliqué ) armour to

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4888-580: The effective plate thickness during the impact. To be effective against kinetic energy projectiles, ERA must use much thicker and heavier plates and a correspondingly thicker explosive layer. Such heavy ERA , such as the Soviet-developed Kontakt-5 , can break apart a penetrating rod that is longer than the ERA is deep, again significantly reducing penetration capability. Modern APFSDS however, can not be broken apart by ERA, as it usually has

4982-468: The example above, where the spring rate was calculated to be 500 lbs/inch (87.5 N/mm), if one were to move the wheel 1 in (2.5 cm) (without moving the car), the spring more than likely compresses a smaller amount. If the spring moved 0.75 in (19 mm), the lever arm ratio would be 0.75:1. The wheel rate is calculated by taking the square of the ratio (0.5625) times the spring rate, thus obtaining 281.25 lbs/inch (49.25 N/mm). The ratio

5076-417: The explosive liner. Two metal plates sandwich an inert liner, such as rubber. When struck by a shaped charge's metal jet, some of the impact energy is dissipated into the inert liner layer, and the resulting high pressure causes a localized bending or bulging of the plates in the area of the impact. As the plates bulge, the point of jet impact shifts with the plate bulging, increasing the effective thickness of

5170-411: The express purpose of firing APFSDS ammunition. KE penetrators for modern tanks are commonly 2–3 cm (0.787–1.18 in) in diameter, and can approach 80 cm (31.5 in) long. As more structurally efficient penetrator-sabot designs are developed their length tends to increase, in order to defeat even greater line-of-sight armour depth. The concept of armour defeat using a long rod penetrator

5264-414: The form of multiple layer leaf springs. Leaf springs have been around since the early Egyptians . Ancient military engineers used leaf springs in the form of bows to power their siege engines , with little success at first. The use of leaf springs in catapults was later refined and made to work years later. Springs were not only made of metal; a sturdy tree branch could be used as a spring, such as with

5358-430: The frame or body, which is transferred to the occupants and every connector and weld on the vehicle. Factory vehicles often come with plain rubber "nubs" to absorb the worst of the forces, and insulate the shock. A desert race vehicle, which must routinely absorb far higher impact forces, might be provided with pneumatic or hydro-pneumatic bump-stops. These are essentially miniature shock absorbers (dampers) that are fixed to

5452-414: The latter. As of 2005, this technology had not yet been introduced on any known operational platform. Another electromagnetic alternative to ERA uses layers of plates of electromagnetic metal with silicone spacers on alternate sides. The damage to the exterior of the armour passes electricity into the plates, causing them to magnetically move together. As the process is completed at the speed of electricity

5546-503: The mushrooming deformation, which was a chronic problem for conventional tungsten alloys, increasing penetration by 8–16% and impact toughness by 300%. This results in the microparticle tungsten penetrator causing self-sharpening behavior equivalent to that of the DU penetrator. Typical velocities of the APFSDS rounds vary between manufacturers and muzzle length/types. As a typical example,

5640-402: The parasitic sabot mass, that could be nearly half the launch mass of the entire projectile. The discarding sabot petals travel at such a high muzzle velocity that, on separation, they may continue for many hundreds of feet at speeds that can be lethal to troops and damaging to light vehicles. For this reason, tank gunners have to be aware of danger to nearby troops. The saboted flechette was

5734-497: The performance of these rounds (rifling adds friction and converts some of the linear kinetic energy to rotational kinetic energy, thus decreasing the round's velocity, range and impact energy). A very high rotation on a fin-stabilized projectile can also increase aerodynamic drag, further reducing impact velocity. For these reasons APFSDS projectiles are generally fired from smoothbore guns, a practice that has been taken up for tank guns by western and eastern blocs . Nevertheless, in

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5828-449: The platform swing on iron chains attached to the wheeled frame of the carriage. This system remained the basis for most suspension systems until the turn of the 19th century, although the iron chains were replaced with the use of leather straps called thoroughbraces by the 17th century. No modern automobiles have used the thoroughbrace suspension system. By approximately 1750, leaf springs began appearing on certain types of carriage, such as

5922-499: The portions of an armoured fighting vehicle that are most likely to be hit, typically the front ( glacis ) of the hull and the front and sides of the turret. Their use requires that a vehicle be fairly heavily armoured to protect itself and its crew from the exploding ERA. A further complication to the use of ERA is the inherent danger to anyone near the tank when a plate detonates, though a high-explosive anti-tank (HEAT) warhead explosion would already cause great danger to anyone near

6016-491: The preferred material for some countries due to lower cost and greater availability than tungsten. Tungsten itself has been found to be biologically hazardous and creates exposure hazards only somewhat milder than depleted uranium. In some countries, such as South Korea , specific heat treatment processes such as multi-stage cyclic heat treatment and microstructure control are applied to tungsten penetrators to finely separate metallic grain structures, significantly improving

6110-595: The report was declassified in 1980. A West German researcher, Manfred Held, carried out similar work with the IDF in 1967–1969. Reactive armour created on the basis of the joint research was first installed on Israeli tanks during the 1982 Lebanon war and was judged very effective. An element of explosive reactive armour (ERA) is either made out of a sheet or slab of high explosive sandwiched between two metal plates, or multiple "banana shaped" rods filled with high explosive which are referred to as shaped charges. On attack by

6204-421: The rifling of the gun barrel, which imparts a spin to the round. Up to a certain limit, this is effective, but once the projectile's length is more than six or seven times its diameter, the gyroscopic effect imparted by barrel rifling becomes less effective. Adding fins to the base of the round like the fletching of an arrow instead gives the round its stability in flight. The spin from standard rifling decreases

6298-461: The right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible, because all the road or ground forces acting on the vehicle do so through the contact patches of the tires . The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different. An early form of suspension on ox -drawn carts had

6392-590: The same spot twice is much more difficult. The Australians were the first recorded to have conceptualized and developed methods to disrupt and spread the jet of a hollow charge shell to reduce its penetrating power. In a June 1944 report from the Explosives Manufacturing Practices Laboratory of the Explosives Factory Maribyrnong, an operational requirement for the defence against shaped charges

6486-401: The shaped charge jet, reducing the angle of incidence and increasing the effective jet velocity versus the plate element. Second, since the plates are angled compared to the usual impact direction of shaped charge warheads, as the plates move outwards the impact point on the plate moves over time, requiring the jet to cut through fresh plates of material. This second effect significantly increases

6580-457: The spring as close to the wheel as possible. Wheel rates are usually summed and compared with the sprung mass of a vehicle to create a "ride rate" and the corresponding suspension natural frequency in ride (also referred to as "heave"). This can be useful in creating a metric for suspension stiffness and travel requirements for a vehicle. Roll rate is analogous to a vehicle's ride rate, but for actions that include lateral accelerations, causing

6674-472: The sprung center of gravity height is the roll moment arm length. The total sprung weight transfer is equal to the G-force times the sprung weight times the roll moment arm length divided by the effective track width. The front sprung weight transfer is calculated by multiplying the roll couple percentage times the total sprung weight transfer. The rear is the total minus the front transfer. Jacking forces are

6768-419: The sum of the vertical force components experienced by suspension links. The resultant force acts to lift the sprung mass, if the roll center is above ground, or compress it, if underground. Generally, the higher the roll center , the more jacking force is experienced. Travel is the measure of distance from the bottom of the suspension stroke (such as when the vehicle is on a jack, and the wheel hangs freely) to

6862-460: The tank can absorb. Reactive armour is intended to counteract anti-tank munitions that work by piercing the armour and then either killing the crew inside, disabling vital mechanical systems, or creating spalling that disables the crew—or all three. Reactive armour can be defeated with multiple hits in the same place, as by tandem-charge weapons, which fire two or more shaped charges in rapid succession. Without tandem charges, hitting precisely

6956-476: The tank. Although ERA plates are intended only to bulge following detonation, the combined energy of the ERA explosive, coupled with the kinetic or explosive energy of the projectile, will frequently cause explosive fragmentation of the plate. The explosion of an ERA plate creates a significant amount of shrapnel, and bystanders are in grave danger of fatal injury. Thus, infantry must operate some distance from vehicles protected by ERA in combined arms operations. ERA

7050-698: The target, high hardness to penetrate hard target surfaces, very high toughness (ductility) so the rod does not shatter on impact, and very high strength to survive gun launch accelerations, as well as the variabilities of target impact, such as hitting at an oblique angle and surviving counter-measures such as explosive-reactive armor. While penetrator geometry has adapted to reactive armour counter-measures, tungsten heavy alloy (WHA) and depleted uranium (DU) alloy continue to be preferred materials. Both are dense, hard, tough, ductile, and strong; all exceptional qualities suitable to deep armor penetration. Each material exhibits unique penetration qualities that may make it

7144-516: The time, so the Abbot-Downing Company of Concord, New Hampshire re-introduced leather strap suspension, which gave a swinging motion instead of the jolting up-and-down of spring suspension. In 1901, Mors of Paris first fitted an automobile with shock absorbers . With the advantage of a damped suspension system on his 'Mors Machine', Henri Fournier won the prestigious Paris-to-Berlin race on 20 June 1901. Fournier's superior time

7238-476: The tire and the road surface, it may hold the road best at a slightly different angle. Small changes in camber, front and rear, can be used to tune handling. Some racecars are tuned with -2 to -7° camber, depending on the type of handling desired, and tire construction. Often, too much camber will result in the decrease of braking performance due to a reduced contact patch size through excessive camber variation in suspension geometry. The amount of camber change in bump

7332-435: The tire's force vector points from the contact patch of the tire through instant center. The larger this component is, the less suspension motion will occur. Theoretically, if the resultant of the vertical load on the tire and the lateral force generated by it points directly into the instant center, the suspension links will not move. In this case, all weight transfer at that end of the vehicle will be geometric in nature. This

7426-414: The top of the suspension stroke (such as when the vehicle's wheel can no longer travel in an upward direction toward the vehicle). Bottoming or lifting a wheel can cause serious control problems, or directly cause damage. "Bottoming" can be caused by the suspension, tires, fenders, etc. running out of space to move, or the body or other components of the car hitting the road. Control problems caused by lifting

7520-428: The torque of braking and accelerating. For example, with inboard brakes and half-shaft-driven rear wheels, the suspension linkages do not react, but with outboard brakes and a swing-axle driveline, they do. Reactive armour Reactive armour is a type of vehicle armour used in protecting vehicles, especially modern tanks, against shaped charges and hardened kinetic energy penetrators . The most common type

7614-476: The total spin rate of the rifling into the projectile. The projectile still exits the barrel with some residual spinning, but at an acceptably low rate. In addition, some spin rate is beneficial to a fin-stabilized projectile, averaging out aerodynamic imbalances and improving accuracy. Even smooth-bore fired APFSDS projectiles incorporate fins that are slightly canted to provide some spin rate during flight; and very low twist rifled barrels have also been developed for

7708-413: The travel, the suspension bushings would take all the force, when suspension reaches "full droop", and it can even cause the coil springs to come out of their "buckets", if they are held in by compression forces only. A limiting strap is a simple strap, often from nylon of a predetermined length, that stops downward movement at a pre-set point before theoretical maximum travel is reached. The opposite of this

7802-579: The tuning ability of a vehicle for transient and steady-state handling. The roll rate of a vehicle does not change the total amount of weight transfer on the vehicle, but shifts the speed and percentage of weight transferred on a particular axle to another axle through the vehicle chassis. Generally, the higher the roll rate on an axle of a vehicle, the faster and higher percentage the weight transfer on that axle . By 2021, some vehicles were offering dynamic roll control with ride-height adjustable air suspension and adaptive dampers. Roll couple percentage

7896-429: The vehicle in a location, such, that the suspension will contact the end of the piston when it nears the upward travel limit. These absorb the impact far more effectively than a solid rubber bump-stop will, essential, because a rubber bump-stop is considered a "last-ditch" emergency insulator for the occasional accidental bottoming of the suspension; it is entirely insufficient to absorb repeated and heavy bottoming, such as

7990-453: The vehicle's sprung weight (total weight less the unsprung weight), the front and rear roll center heights, and the sprung center of gravity height (used to calculate the roll moment arm length). Calculating the front and rear sprung weight transfer will also require knowing the roll couple percentage. The roll axis is the line through the front and rear roll centers that the vehicle rolls around during cornering. The distance from this axis to

8084-457: The vehicle, and can be packaged in multiple spaced layers if needed. A key advantage of this kind of armour is that it cannot be defeated via tandem warhead shaped charges, which employ a small forward warhead to detonate ERA before the main warhead fires. Electric armour or electromagnetic armour is a proposed reactive armour technology. It is made up of two or more conductive plates separated by an air gap or by an insulating material, creating

8178-487: The velocity. ERA also counters explosively forged projectiles, as produced by a shaped charge. The counter-explosion must disrupt the incoming projectile so that its momentum is distributed in all directions rather than toward the target, greatly reducing its effectiveness. Explosive reactive armour has been valued by the Soviet Union and its now-independent component states since the 1980s, and almost every tank in

8272-402: The wheels are not independent, when viewed from the side under acceleration or braking, the pivot point is at infinity (because both wheels have moved) and the spring is directly inline with the wheel contact patch. The result is often, that the effective wheel rate under cornering is different from what it is under acceleration and braking. This variation in wheel rate may be minimised by locating

8366-533: Was 11 hours 46 minutes and 10 seconds, while the best competitor was Léonce Girardot in a Panhard with a time of 12 hours, 15 minutes, and 40 seconds. Coil springs first appeared on a production vehicle in 1906 in the Brush Runabout made by the Brush Motor Company. Today, coil springs are used in most cars. In 1920, Leyland Motors used torsion bars in

8460-482: Was attached to the engine. A similar method like this was used in the late 1930s by Buick and by Hudson 's bathtub car in 1948, which used helical springs that could not take fore-and-aft thrust. The Hotchkiss drive , invented by Albert Hotchkiss, was the most popular rear suspension system used in American cars from the 1930s to the 1970s. The system uses longitudinal leaf springs attached both forward and behind

8554-403: Was initially the main design of the kinetic energy (KE) penetrator. The logical progression was to make the shot longer and thinner to increase its sectional density , thus concentrating the kinetic energy in a smaller area. However, a long, thin rod is aerodynamically unstable; it tends to tumble in flight and is less accurate. Traditionally, rounds were given gyroscopic stability in flight from

8648-461: Was laid out. The focus was in regard to Japanese 75 mm hollow charge shells used against Allied tanks in the Pacific. The destructive effect of the shaped charge was identified as a jet moving at high velocities, consisting out of particles from the liner. The two methods developed were to destroy the jet by forcing it to act through a layer of explosives, disrupting the jet, and to make it act through

8742-541: Was proposed in the USSR by the Scientific Research Institute of Steel (NII Stali) in 1949 by academician Bogdan Vjacheslavovich Voitsekhovsky . The first pre-production models were produced during the 1960s. However, insufficient theoretical analysis during one of the tests resulted in all of the prototype elements being detonated. For a number of reasons, including the aforementioned accident and

8836-460: Was seen as the most practical option due to their casting properties. The mixture acted as an oxidiser which may explode when dispersed and heated. The Explosives Manufacturing Practices Laboratory seemingly developed a more middle road between chemical armor and explosive reactive armor concepts to counter the hollow charge threat. The idea of counterexplosion ( kontrvzryv in Russian) in armour

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