Real Armor Mod Wiki/Real World FAQ

HEAT Warheads
There is a lot of misinformation about how HEAT warheads work--to the point that documentaries, and even government documents, routinely repeat the most common misconceptions.
 * "HEAT" stands for "High Explosive Anti-Tank". It is a type of "shaped" or "hollow" charge warhead.
 * It is not so named for high temperatures and its mechanism of attack has absolutely nothing to do with "melting its way through armor" or "molten hot jets of gas" or any other such nonsense.
 * HEAT warheads are a special type of shaped charge warhead developed during WW2 as an anti-tank weapon. Their innovation involves adding a metal liner to the concave portion of the shaped charge. Via "Munroe effect", the explosive compresses the metal liner into an ultra high-speed spike of metal that shoots forward.
 * The temperatures involved are well under the melting point of the metal liners used. The operative properties are ductility and density--not melting point--which is why copper is a popular liner.
 * The metal spike forms, achieves maximum penetration potential and then dissipates into a weaker, discontinuous stream within a few meters of the detonation point. While the spike penetrates armor in a manner similar to a kinetic round (e.g. sabot), it's unique properties make it sensitive a wider array of mechanical disruption. These methods generally involve preventing the spike from forming optimally, reducing its penetration power. [NB: There is a considerable speed gradient during the spike formation--with the tip travelling much faster than the tail. Think of the liner not as a "jet" but as a rapidly stretching metal spike. The spike eventually stretches beyond its ductile limits and breaks into pieces, losing most of its penetrating power at this point].
 * The significance of HEAT warheads is that they allow for high penetration power in something other than a large, heavy tank cannon firing kinetic shot. They are extremely useful for launchers which must be light and/or guided: man-portable anti-tank missiles and rockets, aircraft fired missiles, and the like. Their penetrative power is also not diminished with range as is the case with kinetic warheads.
 * The power of HEAT warheads sparked a considerable effort in armor designed to protect against them (what RAM calls "CE armor"). As a consequence kinetic penetrators have (again) become the preferred round for the tank canon, while HEAT warheads remain in use for anti-tank missiles and rockets.

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Ammunition Storage & Survivability
Combat vehicles carry two main explosive hazards once their armor is penetrated:
 * fuel
 * ammunition

Of the two, ammunition (stored internally) is the larger hazard--particularly the propellant charges which make up the bulk of the explosive material. This is especially true of large caliber ammunition (e.g. tank main gun) which is powerful enough to blow apart the vehicle that carries it. Fuel--while always a fire hazard--is not very explosive by comparison, and can be better mitigated by fire suppression systems.

Depleted Uranium
Along with tungsten, one of the two high-density metals cheap and common enough for use in armor-penetrating kinetic rounds (in alloyed form). Of the two, DU is cheaper and has superior penetrating properties* due to its tendency to retain a sharper tip as it travels through armor. Tungsten's more "mushroom"-shaped tip during penetration spreads out its energy over a larger area, reducing performance. Additionally, on impact DU readily erodes into small particles that are "pyrophoric"--they spontaneously combust in air. This increases the damage caused from a penetrating hit --igniting internally stored ammunition, for example. DU is a toxic heavy metal and weakly radioactive (both problems being significantly exacerbated when the dust from expended munitions is inhaled or otherwise ingested).

* DU alloys can outperfrom tungsten ones by up to 25% or so in penetration, but only at slower impact velocities. At typical APFSDS impact speeds, the improvement is probably in the 5-10% range.

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Range and the European Battlefield
In considering the

Strategy
The Soviets evolved an "offensivist" strategy dating back to the early 1930's. This was not a pro-war doctrine, rather it meant that attacks and movement were favored over defensive postures once a war had started. The doctrine evolved through WW2 to influence the Soviet approach to the Cold War and a potential conflict against NATO in Europe.

Overall, the Soviets designed their army around the "blitzkreig": concentration of combined arms to produce/exploit breakthroughs and rapid movement far into the enemy's rear areas. This offered several advantages in a ground war with NATO. Rapidly closing and intermingling with the enemy line reduced the value of NATO's "standoff" arsenal: air support, artillery, and potential use of nuclear weapons. The Soviets emphasized offensive capability, mobility, and 'quantity over quality'.

NATO doctrine evolved over time from a more defensive strategy, to a more dynamic counter-attack orientation. But the general emphasis was on a numerically inferior force fighting a large enemy within a shallow defensive front (it was not politically viable within NATO to plan for defense in depth). NATO emphasized "assault breaker" systems: long-range, rapid reaction, and precision guided weapons designed to concentrate firepower on attacking Soviet formations, degrading them before they could mass their power on the frontline. This translated roughly into 'quality over quantity' and an emphasis on things like superior fire control and precision munitions.

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Sabot (APFSDS)
[NB: APFSDS rounds coincide with the modern smoothbore canon because their long, thin design cannot be spin-stabilized, requiring fins instead. (Rifled canon can fire such rounds with the inclusion of a "slip-ring" to reduce the excessive spin that would otherwise interfere with the fin-stabilization). The discarding sabot 'shell' allows them to be fired from large caliber guns--gaining the benefit of the canon's power, which keeping the sub-caliber penetrator itself appropriately light and thin to maximize armor penetration.]

The Soviets--who pioneered this type of round--adopted the smaller "ring"-style sabot, while NATO rounds use the more bulky "spindle" design. Each approach has advantages and disadvantages, although the traditional ring design has been largely abandoned in more recent rounds.
 * Spindle sabot are larger and heavier than ring sabot, and will result in a slower muzzle velocity all other things being equal.
 * However, they allow the round to have sub-caliber fins--which results in much lower air resistance.
 * Ring sabot are smaller and lighter allowing a higher muzzle velocity.
 * However, they require full-caliber fins--which results in considerably higher drag (about double that of a sub-caliber fin round).

Soviet ring designs prioritized short range penetration at the cost of higher drag--and thus poorer penetration at longer ranges (2km+). This fit with their overall emphasis on the Central European battlefied, where long range engagements would be rare.

NATO spindle designs allow the round to maintain penetration power at longer distances. This gives them an edge in longer range battlefieds, e.g. desert combat.

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