Greetings, this is dslyecxi. In today's episode of Art of Flight we're going to go into the details of the most common weapon types available to helicopters, as well as talk about some gunnery terminology. The intent of this guide is not only to educate pilots, prospective pilots, or air-curious infantry on what their weapons can do, but also to provide a baseline of knowledge for future guides regarding air support.
We'll start with describing the different types of effects you'll see from helicopter weapons, then move on to the topic of weapon geometry, and finish up with a more detailed look at the employment and precision of different types of helo weapons.
Munition effects fall into two basic categories - kinetic and explosive.
Kinetic effects are from projectiles that have no inherent explosive capability and depend on impact to do their damage. This takes the form of machineguns, miniguns, and armor-piercing cannon shells.
With kinetic weapons, you see three different kinds of effect. You have the pure impact of the round hitting something, the possibility of ricochet, and also the possibility that the round will penetrate the surface it strikes.
Impact is of course the simplest aspect to consider. Bullets lose velocity over distance, which lessens their potential damage. However, in Arma terms, you're going to do a great deal of damage at any reasonable range with the typical rounds fired from miniguns or machineguns.
Ricochets happen when a round strikes a surface at an angle where it isn't outright stopped, doesn't penetrate or fragment, and has its energy redirected elsewhere. The velocity bullets tend to ricochet at are often significantly slower than pre-ricochet, and this lowered velocity greatly reduces the damage they can do. The exception to this is with cannon shells - if an explosive cannon round ricochets, regardless of how fast it's traveling, the damage it will do upon landing again and detonating will be significant.
Ricochets seem like they'd be a big concern with high rate of fire weapons like miniguns, but in practical usage and with correct employment techniques it's not something to overly worry about. While you can potentially strike a friendly with a ricocheting round, it's unlikely and the proper employment will make this a remote possibility. You can see here how most of the rounds are ricocheting high enough that there's little to worry about. Autocannons, due to the aforementioned issue, are worth carefully considering ricochets for - particularly when there's a background with friendlies on it, such as this hill.
Ricochets tend to happen when using shallow attack angles or grazing fire, which makes it possible to mitigate them by utilizing steeper attacks and plunging fire.
Penetration is the ability of a bullet to punch through a given object and deal damage on the other side. The faster and heavier the projectile, and the more square-on the impact is, the more likely this becomes. Penetration is what allows miniguns to still have effects against enemy occupying buildings or similar structures, most light vehicles, and even some kinds of bunkers. Due to this requiring high velocity and relatively square-on impact angles to be effective, it's rare for ricocheting rounds to penetrate anything aside from wood and other light surfaces.
Explosive effects come from weapons like rockets, cannons firing explosive ammo, and guided missiles. There are two primary types of damage they inflict - blast and fragmentation.
When an explosive projectile detonates, anything within clear line of sight of it out to a certain range will be subjected to blast effects. The bigger the munition, the larger the radius. Here we have a visualization of the blast effects for different munition types. The character icons indicate the stance of that unit, the red rings are what Arma considers the lethal zone, and the orange rings indicate the casualty radius. There's a 50-meter scale included as well.
Stance has a significant effect on damage with many of the munitions - standing is most vulnerable, then crouched, the prone's the safest by a considerable margin. Note that some munitions are configured such that they do lethal damage through a large part of the casualty zone, like the Mk82 and the 155mm artillery.
Artillery, mortars, and bombs do incredible damage, as you'd expect.
Getting to typical helicopter weapons, we see that the DAGR is very focused in what it does. Strike a vehicle with it and you're good, but it's less usable against clusters of infantry. By comparison, the FFARs are potent anti-infantry weapons.
Hellfires pack a good punch as well, but their anti-infantry effects are limited. The thermobaric version of the hellfire, however, is extremely effective against infantry out to roughly 40 meters, depending on stance.
A 20mm autocannon like the Cobra's does a good job of inflicting damage on infantry, though it's a bit less powerful against prone units. The 30mm cannon on the Apache, by contrast, is extremely potent against infantry in any stance, and bursts are devastating.
Less predictable than the blast are the fragmentation effects of an explosive. Fragments from the projectile casing or payload can be propelled much further than the blast effect, but the size of the fragments and their quantity mean that it's chance as to whether they actually strike anything. If they do, they can be severely damaging given the right fragment size and velocity. In ACE, only certain munitions will create fragmentation - FFARs for instance won't, but Hellfires like you see here will. In order to help performance, fragments are generally created only in the directions of things that can potentially be struck by them - that's why each of these explosions looks so directional, since they're gravitating towards my helo and the BMP in the target area.
The last effect to consider isn't actually from the munitions you can deliver, but rather from what they do to their targets. Hitting a BMP with an ATGM will destroy it, sure, but then what? The BMP has ammunition and fuel in it, and those will tend to - but not always - detonate in a secondary explosion. This secondary can be a much larger blast than what initially hit it, meaning that the considerations for the munition itself aren't necessarily the largest source of damage that will occur.
The next piece of the puzzle is the geometry involved when using these sorts of weapons. Here we'll be talking about three aspects of this - the milliradian, several types of ranges, and the beaten zone.
The angular unit of measure we'll be referencing at times here is the milliradian, or mil. In NATO terms, this is taking a circle and dividing it into 6400 parts, versus 360 for degrees.
Here we can see what degrees look like when projected into the world. By comparison, here are mils - a much finer measurement, where one degree is roughly equal to eighteen mils. Mils are used frequently in ballistics, such as scope adjustments, artillery, and similar.
The technical definition of a mil is that it's an angle where the size of the arc it subtends is equal to one-one-thousandth of the radius of that circle, which is to say that it's unit-agnostic and one mil will equal one unit at one thousand times that distance. So one mil at one thousand meters will equate to one meter, one mil at one thousand yards will equate to one yard, and so forth. Since we're in Arma, we're most concerned with meters, and that's the context of the term in this guide.
Since an angle of one mil at one thousand meters is equal to one meter, a weapon that has a dispersion of one mil means that barring other factors, all of the rounds from that weapon will land in a one meter wide grouping at one kilometer, two meters at two kilometers, and so forth. Obviously in actual employment there are a lot of things that alter this, but conceptually that's how it works.
Here I'm firing a SAW, and as you'll see, the shots have landed mostly in a seven mil wide area. At this range, 7 mils is equal to a three-meter wide area.
In this view, the ellipse represents a measurement in which the center green number is how many mils wide it is, and the smaller number below that is how wide it is in meters at that distance.
Slant range is a term used in discussing aerial weapons employment. It is simply a straight-line distance from your aircraft to whatever you're aiming at. While on the map you may be firing from a kilometer away, factoring your altitude into this means that the slant range will grow larger than the map range as altitude changes relative to the target altitude. This can be higher or lower than the target altitude, as it's only the absolute offset that matters.
Aircraft with forward-firing weapons that lack the ability to employ them through magnified sensors tend to have their accuracy potential directly related to their slant range to the target. Using a Littlebird as an example, distances roughly correlate to anything up to 800 meters being considered close, shown here in green, anything from 800 to 1300 meters being mid-range, shown here as white, and anything from 1300 meters up is long-range.
Accuracy depends on a combination of the slant range, attack geometry, and weapon type.
While slant range is a minor consideration in typical shallow employment aspects - here you can see that the slant and map range differ by only a few meters - it becomes a more noticeable factor the steeper the attack is.
The reason for this is that the map range is essentially the ballistic range, or rather, it's the range you factor in for projectiles dropping due to gravity. As the absolute difference between the slant and the map range grows, the amount of drop you will see is proportionally less - equal to the gravitational effect that would happen over the distance of the map range, which is why it becomes known as ballistic range.
Think of it this way: When you fire a rocket, for example, you see it rise, hit an apex, and then fall back down again. In this shot, you can see the rocket rise above the point of aim, stay steady, then fall before impacting. This is the tilt of the launcher and thus the launch angle sending it up, then gravity bringing it back down. However, if gravity has little influence on the projectile, such as when the slant range is long but the ballistic range is short, the projectile essentially never "drops" back down (relatively speaking) - in this one, the slant range is 1400 meters, but the ballistic range is only 700 due to the angle of the dive. This means that when you're doing steep plunging attacks, your bullets and rockets will strike higher than they otherwise would. You can see that here - the rockets rise but never fall, striking higher than they did from a shallow angle.
You don't have to stress much about the ballistic range in typical employment, but do remember that when you're doing steep plunging attacks, you'll want to aim slightly lower because of this effect.
A helo firing its weapons, whether those are miniguns, rockets, or similar, produces a cone of fire. Where that cone intersects the target area becomes the beaten zone, or the area in which the munitions are striking. This beaten zone can take two basic forms based on whether it's the result of plunging or grazing fire.
Grazing fire occurs when the projectile is approaching the target from a shallow angle. This causes the beaten zone to become highly elliptical, exaggerating the vertical spread of munitions due to aiming error or dispersion.
Using this infantryman as a demonstrator, here's what exactly grazing fire entails. Red dots indicate parts of the trajecatory where the bullet is within 1.7 meters of the ground - which is about eye level for an Arma soldier. This is known as danger space. Black dots are when it's above that. You can see that as the bullet travels here, it goes above the terrain for a period of time where it can't strike any infantry, then as it falls back towards the terrain you can see that the area in which it can potentially strike a soldier - the danger space - is significantly lengthy and includes an area in front of the actual beaten zone. Anyone in that red zone can potentially be struck by the bullet.
Helicopters usually aren't firing quite as close to the ground as that, but the effect still occurs. Here you can see how a shallow attack angle leads to an elongated beaten zone and danger space.
Let's look at that in more detail from a helo's perspective. This is a Littlebird with a .50cal GAU-19. The dispersion of this particular weapon is roughly 6 mils - so six meters at one kilometer. This ellipse is twelve mils wide. You can see that from this perspective, the shot grouping - the yellow dots - looks tight. Here's the same thing, but showing a six-mil-wide center section. While some shots hit outside the six mil region, the bulk of the impact area is within it. As we move to look at it from a different perspective, you can see how elliptical and lengthy the beaten zone actually is. Watching the fire from this perspective, note how much coverage of this patch of ground the bullets have and how long the danger zone is. Anyone in this area - standing, prone, whatever - is very likely to be hit by this.
The alternative to grazing fire is plunging fire. This happens when firing from steeper attack angles relative to the target.
With the same helo and GAU-19, this is what plunging fire looks like at a slant range of 510 meters. The danger space - the total distance at which an infantryman would be at risk - is much smaller than the grazing example we saw previously, due to the projectiles entering the beaten zone at that steeper angle. This causes the danger space to be confined entirely to the beaten zone.
Understanding the beaten zone, grazing and plunging fire, and how these relate to the orientation of the aircraft relative to the target area helps both pilots and FACs plan for how to best utilize weapons, as well as how to safely do so in complex environments.
Now that we understand the types of damage weapons can do as well as terminology and concepts related to how the geometry of weaponry works, let's close out by talking about the main kinds of weapons you'll see, how they're employed, what they're used against, and how precise they can be.
The typical kinetic weapon you'll see is a minigun. These come in a few different forms, but the two types you'll see most often are 7.62 and .50cal variants in forward-firing fixed mounts. These have high rates of fire that allow them to saturate an area from a distance, but don't let that description fool you: Miniguns can be used to place very precise fire on targets.
While most miniguns in this context are fixed forward, you will find some gunships like the Venom that have crew members operating swivel-mounted miniguns on either side of the aircraft, giving them the ability to orbit and engage a target on the inside of the orbit.
Miniguns are used primarily against infantry, light vehicles, and structures - they're reasonably effective against infantry, though the targeting can be difficult, but highly effective against light vehicles. Heavy miniguns like the .50 caliber GAU-19 can be used to penetrate light armored vehicles such as BRDMs, BTRs, and even BMPs and BMDs on the sides and top deck.
Here you can see how an M134's 7.62mm bullet can pen a BRDM and injure the crew and passengers inside, though it doesn't have enough energy to make it back out the other side.
The GAU-19's .50 caliber bullets punch clear through a BTR-80 from the side, shredding anything inside in the process. This makes it possible to target the forward section of the vehicle in order to kill the gunner, commander, and driver.
The GAU-19 can also pen the side of a BMP-2, injuring anything in the passenger compartment.
When firing from above, the GAU-19 is more than capable of severely damaging or even destroying a BMP.
The ballistics and maximum effective range of a minigun depends on the caliber of it.
The M134's 7.62 bullets maintain their velocity moderately well, giving it a max effective range of about 1 to 1.5 kilometers. The accuracy of this weapon is about 6 mils, or six meters at one kilometer, with the main accuracy issue being the steepness of the trajectory as velocity is lost. The bullets slow down enough over distance that if they're still in the air after 2.3 kilometers, their time-to-live will expire and they'll be deleted.
The GAU-19's .50cal bullets retain their velocity extremely well by comparison, resulting in a flatter trajectory. The gun itself is capable of similar accuracy as the M134, but firing it at distance is made much easier by the flat trajectory. It's possible to hit targets out to a bit beyond two kilometers with this, and the round itself can travel over four kilometers.
If using a mod that supports vehicle weapon recoil, having a single minigun on one side of the aircraft can cause a significant yawing effect when firing. Pairing miniguns can help to mitigate this factor, changing the yaw into more of a downward pull which is easier to counteract.
Rockets are typically folding-fin aerial rockets, or FFARs, carrying a high-explosive or high-explosive, dual purpose warhead. A rocket pod can have as few as 7 and as many as several dozen rockets, and different types of aircraft can carry different sizes and quantities of pods. These can be used to saturate areas from a distance, or for more precise work at closer ranges.
Rockets have moderate blast ranges and are highly effective against clusters of infantry, light vehicles, structures, and most light armored threats. Some rockets have HEDP warheads that make them capable of dealing with light and medium armor more effectively.
Rockets typically have an accuracy of about 11 mils, or 11 meters of dispersion at one kilometer. They're effective on point targets at close to medium slant ranges, and can deal with area targets at longer ranges.
The maximum range of an FFAR is far beyond what you can accurately aim for in typical Arma contexts. Sitting off the south-eastern coast of Chernarus, it's entirely possible to lob a rocket (or several) 11 or so kilometers to impact on the north western airfield. Possible, yes. Practical? No.
Cannons are usually, but not always, associated with a turret that allows them to be fired offset from the aircraft's flight path. These tend to come in the form of 20 or 30mm cannons, and tend to use dual-purpose ammo that attempts to be effective against infantry and some types of armor.
Cannons are highly effective at clearing out clusters of infantry, obliterating light vehicles, dispatching light and medium armored threats, demolishing structures and fortifications, and depending on their size, are sometimes able to harass, track, or otherwise inconvenience heavier armor with sustained hits.
Ballistic computers calculate the necessary adjustments for range, offset, and aircraft speed, retaining a high level of accuracy even when firing offset from the aircraft's flight. When combined with powerful magnified optics, a cannon can be used to put precision fire on targets from long range, out to around 2.5 kilometers.
Cannons tend to have somewhat more dispersion than miniguns, but not tremendously so. The Apache's 30mm cannon produces a beaten zone that's about 10 mils wide, or about ten meters, at one kilometer. When combined with their often explosive munitions, this slightly larger dispersion makes for a wider coverage of the explosive effects of the ammo, putting more ground at risk in any given burst.
Guided missiles, typically refered to as ATGMs for Anti-Tank Guided Missiles, take a few different forms, with the two most common helo-launched examples being DAGRs - which are basically repurposed guided rockets - and Hellfires, which are beefier anti-tank or anti-structure munitions.
Heavier guided missiles like Hellfires are primarily used as anti-vehicle or anti-structure weapons and are capable of destroying all types of ground threats with their powerful terminal effects. In the event that one missile doesn't do the trick, two almost certainly will. Some missiles are intended for anti-infantry or anti-structure work, such as thermobaric warheads, and do those jobs well.
Guided missiles are highly accurate and can be finessed during their flight path to track a moving target or change the point of aim on the fly. Some, like Hellfires, can be fired in different trajectories to help mitigate overhead cover or strike from a more vertical aspect.
The maximum range of these varies, but in Arma terms, you're capable of striking something vehicle-sized at least five kilometers away with a Hellfire or similar, and can comfortably engage at closer ranges. Some types of ATGMs can even be remote designated, allowing infantry on the ground to laser designate a threat that the helo can fire at from an extended range.
And with that we're at an end. Hopefully this has helped to give you a better understanding of what your helo's weapons are capable of, what various terms actually mean in this context, as well as some considerations for how to employ your weapons most effectively. This is dslyecxi, and until next time, take care.