Mechanic deep dive
How AA Actually Works in WoWs Legends: Mounts, Auras, and Dual-Purpose Guns
The AA card on a ship's spec screen lists a handful of gun families. Each row has a DPS number and a range, and the per-family numbers can look arbitrary at first. They are not. A small set of damage auras drives every value on the card, and once you know the formula behind the auras, the gap between ships with dual-purpose guns and ships without becomes obvious.
What AA actually does
When an enemy aircraft enters your AA bubble, your continuous AA damage starts ticking against it. Each gun mount contributes to one or more damage auras: short, medium, or far range bands centered on your ship. The aura's job is to dump damage on every aircraft inside its radius for as long as they stay there.
Two numbers per aura govern how much damage actually lands:
- Continuous damage. The raw per-second value the aura outputs when it engages. Set by the game per ship, scaled by the mounts attached to the aura.
- Hit probability. How reliably each tick of damage connects. Usually 0.75 to 1.0 across Legends ships.
The displayed per-family DPS on the in-game AA card is:
displayed_dps = continuous_damage × 3.5 × hit_probability
displayed_dps = the per-family number on the AA spec card · continuous_damage = the aura's raw DPS value in the game files · hit_probability = the aura's hit chance, typically 0.75 to 1.0 · 3.5 = an empirical scaling constant the game applies to every aura, the same multiplier whether it is a 20 mm Oerlikon aura or a 5"/38 secondary aura.
A worked check on California's 5"/38 secondaries: the aura's continuous damage is 40, hit probability 0.75. 40 × 3.5 × 0.75 = 105 DPS, which is exactly what the in-game card shows for California's 127 mm row. Iowa's 5"/38 aura: 50 × 3.5 × 0.75 = 131 DPS, again matching the printed value.
The basics: mounts feed auras
Every AA mount on the ship is bound to an aura by hardpoint. When the game lights up your AA, it sums every mount's contribution into its assigned aura. Most fittings produce two or three auras: a short-range "near" aura around 2 km, a "medium" aura around 2.5 to 3.5 km, and (on ships with dual-purpose secondaries) a "far" aura at 4.5 to 5 km.
Take Hawkins as a concrete example. The Tier IV RN heavy cruiser carries three AA gun families:
- 13 mm Hotchkiss light AA. Four quad mounts, 16 barrels total. Bound to a near aura at 1.2 km.
- 40 mm 2-pdr Pom-Pom medium AA. Four quad mounts, 16 barrels total. Bound to a medium aura at 2.5 km.
- 102 mm/45 Mk V dual-purpose secondary. Four twin mounts, 8 barrels total. Bound to a far aura at 3.5 km.
Hawkins's three AA auras at scale. A plane crossing each ring picks up the next family's damage.
None of these mounts contribute outside their aura's radius. A torpedo bomber releasing at 3.5 km is right at the edge of the 102 mm DP secondary's far aura — only the DP secondary is engaging. The 40 mm Pom-Pom and 13 mm Hotchkiss are still out of range. Once the plane crosses 2.5 km, the 40 mm joins in; under 1.2 km, the 13 mm adds the last layer.
The aura's range is the gate. Iowa's point-blank AA total is 674 DPS, but only 131 of that reaches the 5 km edge of her bubble. The 5"/38 secondaries are the only family with that reach. Closer in, the 40 mm and 20 mm join in and the stack jumps to 409 DPS at 3.5 km, then to the full 674 DPS once a plane crosses the 2 km Oerlikon ring.
Reading the in-game AA card
The card lists every gun family and the range it reaches. To work out the effective DPS at a given distance, sum the rows whose range is at least that distance.
Continuing with Hawkins:
| Family | Mounts | DPS | Range |
|---|---|---|---|
| 13 mm Vickers | 4 × 4 | 21 | 1.2 km |
| 40 mm Bofors | 4 × 3 | 117 | 2.5 km |
| 102 mm 4"/45 | 4 × 2 | 54 | 5.0 km |
At 5 km, only the 102 mm reaches: 54 DPS of pressure as the bomber starts its run. At 2.5 km, the 40 mm Bofors joins in for 171 DPS. At 1.2 km, the 13 mm light AA stacks on top for the full 192 DPS, but most strike aircraft have already dropped by then.
Read the AA card right to left. The longest-range family decides whether a CV's strike package can even close to drop range. The short-range families decide what reaches the carrier afterward.
Dual-purpose guns
A dual-purpose mount fires at both surface targets and aircraft. Its physical gun is on the secondary (or main) battery, but the same mount has an AA aura bound to it, so it shows up on the AA card alongside dedicated AA mounts.
The cleanest examples in Legends:
- Bismarck's 105 mm L/65 C/37 and C/31. The C/37 mount is the dual-purpose secondary (six twin mounts, surface plus AA); the C/31 mount is AA-only (two twin mounts). Both carry a 4.5 km far aura. The in-game AA card splits them as two rows: roughly 93 DPS from the C/37 line and 31 DPS from the C/31 line at the upgraded hull, for a combined ~124 DPS @ 4.5 km, on top of the 37 mm and 20 mm dedicated AA at shorter range.
- USN 5"/38 Mark 12. The standard WW2 dual-purpose mount. Present as a secondary on California, Iowa, Baltimore, and Cleveland, and as main battery on the universal destroyers (Fletcher, Sumner, Gearing). Iowa's 10 mounts deliver 131 DPS at 5 km; California's 8 give 105 DPS; Baltimore's 6 give 98 DPS.
- IJN Type 89 127 mm/40. The Japanese DP secondary, on Mogami, Atago, Kaga, Yamato, and most modern IJN BB and CA hulls.
- RN 4.5"/45 Mark III. KGV-class secondary, dual-purpose by design.
- RN 4"/45 QF Mark V and XIX. The British WW2 cruiser DP standard, on Edinburgh, Belfast, Devonshire, and Hawkins.
The opposite case is the single-purpose secondary: an older surface-only gun. Texas's 5"/51 Mk 7 is the textbook example, same caliber as California's 5"/38 but it only fires at ships. Texas's AA card has no 5"/51 entry at all. Agincourt's 6"/50 BL Mk XIII and 76 mm QF 12-pdr secondaries are the same story, classic pre-DP-era casemate guns that contribute zero to her AA total. Bismarck's own 150 mm SK C/28 main secondaries land in the same category. They are on the ship. They are not on the AA card.
The difference shows on the AA card: California's eight twin mounts of the 5"/38 add 105 DPS at 5 km that Texas's eight twin mounts of the 5"/51 do not provide, even though the two ships are sister-tier with similar gun counts.
A brief history of dual-purpose
The dual-purpose gun is a 1930s engineering answer to a 1920s problem. Pre-WW1 battleships carried casemate secondaries: surface-only, mounted low in the hull behind shielded openings, limited elevation. Their job was to swat torpedo boats sneaking in past the main battery.
By the late 1920s, aircraft had become the bigger threat, and casemates could not elevate enough to engage them. Navies started bolting separate AA mounts on top of existing secondaries, doubling the gun count and weight for no improvement against either threat.
The 1932 design of the 5"/38 Mark 12 mount was the first widely-deployed answer: one gun, one mount, both jobs. Open-top pedestal mount, full elevation, fast traverse, and a fire-control system that could track both ship and air targets. Every US Navy capital ship laid down or refit after 1937 carried it. The same gun later equipped destroyers (Fletcher class onward) as their main battery, because a dual-purpose 5" was a better destroyer gun than a dedicated surface 4.7".
Other navies followed:
- Royal Navy. 4.5"/45 Mark III (KGV class, 1937) and 4"/45 QF Mk XVI (cruisers, early 1930s).
- Kriegsmarine. 105 mm SK C/33 (Bismarck, 1936), derived from the contemporary Flak 38 anti-aircraft gun.
- Imperial Japanese Navy. Type 89 127 mm/40 (1932) on Mogami-class and later.
- Italian Navy. 90 mm/50 OTO M1939, the late-1930s DP secondary on Littorio and follow-on designs.
By 1945 a "secondary" gun on any modern warship was assumed to be dual-purpose. The exceptions were heavy 150 mm-and-up classes kept for surface fire. Anything smaller had been converted or replaced. Legends reflects this faithfully: ships designed before the DP transition (Texas, Florida, Agincourt, Kawachi, Cavour) carry only their dedicated AA mounts on the AA card. Everything after gets the secondary battery line as a bonus AA layer.
Practical takeaways
- Look at the longest-range family first. It tells you whether your AA bubble reaches strike aircraft at all. Ships with 5 km secondary DP guns force the CV to drop earlier or eat your damage on the run-in.
- Stacked auras matter more on aggressive ships. A brawler that lives at 4 to 6 km from enemy ships also lives close to incoming planes, and the close-range AA stack does most of the work. A kiting cruiser may never see the inner aura activate.
- Dual-purpose secondaries roughly double the AA on classes that have them. A Bismarck-line BB with 105 mm DP secondaries has materially better AA than a US Standard-class BB with the same nominal AA mount count.
- AA modifications boost auras, not mount counts. If a ship's relevant aura is already weak, the mod helps proportionally. It does not invent new range bands.
The 3.5 scaling constant in the displayed-DPS formula was derived empirically by comparing in-game AA spec card captures to the raw continuous_damage and hit_probability values from WoWs Legends in-game data, across multiple ships and gun families. Exact match on California, Sumner, Manfred von Richthofen, and Dante Alighieri; within ±17% on the other verified ships, likely from in-game UI splitting one aura across multiple gun families. Aura, mount, and dual-purpose classifications are read from each ship's in-game data. The dual-purpose vs single-purpose roles for each gun family are cross-checked against Wikipedia's naval-gun entries (5"/38, 5"/51, 5"/25, 4"/45 QF, 4.5"/45, 8.8 cm SK L/45, 10.5 cm SK C/33, 15 cm SK C/28, BL 6"/50).