Vehicles

Rules (DESIGN §18)

Reference: research/bf3-vehicles.md (public numbers from Battlefield 3, clean-room). Our rules, in our words:

Roster by map tier (DESIGN §4: small maps = infantry, big maps = vehicles). Numbers scale with sector area, never with headcount alone.

Health, disable, repair. Hull HP is per class (truck 500, APC 600 as built, mobile AA 1000, MBT 1000, transport heli 750, attack heli / jet 500). Below the disable threshold (armour 50 %, air 34 %) the vehicle burns, crawls at 30 % speed and cannot regenerate; it is dead 20 s later unless an engineer repairs it. Above the threshold it regenerates 2 %/s after 8 s without damage. Repair tool: 25 HP/s, needs the engineer within 3 m, interrupted by damage.

Angle multipliers. Hits on armour are multiplied by facing: front 0.6, side 1.0, rear 1.6, top 1.3. A rear rocket hit disables an MBT in one hit; a frontal one takes four. Positioning is the tank fight.

Counters cost less than the vehicle. Every vehicle has an infantry answer in the default kits: anti-tank rocket (3 per resupply, 450 dmg × angle, drop like a slow bullet), lock-on MANPADS vs air (2.5 s lock the pilot hears, short range 300 m, one hit disables), laser designation by the squad leader doubles guided damage and lets rockets hit air. Smoke breaks designation for 5 s.

Air is glass, countermeasures have holes. One countermeasure per vehicle: flares (11 s cooldown, spoof missiles in flight, never break a lock) or jammer (5 s on, 10 s off). No stacking across seats.

Seats. Driver, gunner, up to 4 passengers; enclosed seats cannot be suppressed, open seats can. Enter within 2.5 m with E, exit anywhere; a vehicle with no driver stops in 2 s. Bots use the same rules: a squad leader claims the nearest free vehicle for a move longer than 150 m.

Spawn and logistics. Heavy assets spawn at the home camp on timers (MBT 60 s, helis 60–90 s, AA 120 s); captured zones give trucks (40 s) and AT emplacements (30 s). Driving the asset to the front is part of the game. Transport helicopters and the APC are the mobile squad spawns; the OIC's drone abilities (DESIGN §7a) replace BF's gunship: the strongest asset is gated behind a contested zone.

Netcode. Vehicles are entities like soldiers (position, yaw, pitch, hp, seat map); the driver predicts locally with the shared move model; passengers interpolate. Vehicles sit above enemies and below damage events in snapshot priority (research/bf3-netcode-and-scale.md §6).

What BF4's data says (§20.1)

• Damage is a linear ramp: StartDamage → EndDamage between two distances (every bullet row in weapons.md).
• Armour is 1000 HP per zone plus a 175 shield buffer; air is 500; transports and MRAPs 750 (vehicles.md).
• BF4's disable threshold reads 10 % of max HP, cleared at 15 % (m1abrams 100/150, ah1z 50/75, venom 75/112.5). That is lower than the BF3 notes (50 % armour, 34 % air). We keep the BF3-style thresholds (20.2).
• Regen: armour 14 s delay then 10 HP/s (m1abrams, lav25); air 10 s then 10 HP/s (ah1z, f35b); light cars 10 s then 25 HP/s (vdv_buggy, us_mrap-cougar); transport heli 10 s then 12.5 HP/s (venom).
• Front/rear/side/top angle multipliers are curves (angledamage_mbt_front/rear/sides/top, m1abrams). The curve points are not in data. Only "TopHitAngle 30" and "ForceMinDamageAngleRadius 7 m" are (m1abrams).

Decisions (§20.2)

Decisions that apply to every row:

• One HP pool per vehicle, no per-side zones. BF4 shares damage across zones anyway (HealthZonesShareDamage true, m1abrams).
• No shield buffer. We fold BF4's 175 shield (m1abrams) into the front multiplier instead.
• Disable thresholds are 50 % for armour and 34 % for air and soft vehicles. Below the threshold the vehicle burns, crawls at 30 % speed and does not regen. It dies 20 s later unless repaired (DESIGN §18).
• Regen starts only above the threshold, after the delay.
• Faction flavour: HALCYON vehicles have −10 % HP and +10 % speed. VRG vehicles have +10 % HP, −10 % speed and main gun ×1.1. MERIDIAN is the baseline. The table shows MERIDIAN.
• Top hit means the shot comes from more than 30° above the hull plane. That is BF4's TopHitAngle (m1abrams).
• Within 7 m, angle multipliers clamp to 1.0, so point-blank shots ignore angle. That is BF4's ForceMinDamageAngleRadius (m1abrams).
• No economy, so every timer is a flat respawn after destruction.

One-line decisions:

• Thresholds are not BF4's. BF4 disables at 10 % (m1abrams 100/1000). We keep 50 % / 34 % so engineers get a rescue window and attackers get a chase window (bf3-vehicles.md §6.3).
• Rocket math. The AT rocket does 350 direct (20.3). Against an MBT that is 262 front (4 hits kill, 2 disable), 350 side (3 kill), 612 rear (1 disables, 2 kill). Against a 500 HP aircraft one hit leaves 150 HP, below the 34 % line (170 HP), so the aircraft is disabled.
• Spawn timers are ours. BF4 per-spawner respawn delays are not in data. The shared prefab only shows InitialSpawnDelay 15 s, SpawnDelay 0, TimeUntilAbandoned 10 s, abandoned→destroyed 20 s (maps.md legend). We adopt the abandon rule: an empty vehicle is destroyed 30 s after its last occupant leaves, if it is more than 30 m from its spawner (SpawnProtectionRadius 30, maps.md).
• Crit time. BF4 attack helis keep 2.75 s of control after the killing hit (ah1z CriticalDamageTime). We give every aircraft 2.5 s so pilots can bail.
• Upside-down / water. BF4 deals 250 HP/s to an upside-down MBT and 30–50 HP/s in deep water (m1abrams). Ours: 100 HP/s upside-down after 3 s, and water kills ground vehicles in 5 s.
• Models we have (ASSETS.md): the 4 Animated Tanks give MBT, IFV/APC and mobile AA. The armoured pickup is the light and heavy car. The Ships pack gives the RHIB and the attack boat. Helicopters and the jet are Blender work.

Lock-on, countermeasures, designation (§20.4)

What BF4's data shows:

• Signatures. Jets and helis have heat 10 and radar 1. Ground vehicles have heat −1 (cannot be heat-locked) and radar 10 (ah1z, f35b, m1abrams).
• Low altitude. Under 25 m (helis) or 50 m (jets), an aircraft's heat signature drops from 10 to 1 (ah1z, f35b LowAltitudeHeight / LowAltitudeHeatSignature).
• Vehicle missile locks. Heat-seekers lock in 1.5 s at 6.5° out to 1000 m, fly 50→250 m/s and do 195 (heatseeking_missile). Radar missiles do 135, fly 350 m/s and seek on their own at 1.8° out to 650 m (activeradar_missile_land).
• Locks and warnings. The Stinger's lock gives the target no warning. Only its missile warns (fim92a: asset WarnLock none, projectile wtWarnVehicle). The IGLA and Javelin warn while locking (sa18igla, fgm148_javelin).
• Flares. 9 per load, back 14.8 s after use. A flare lives 2.5 s and decoys within 10 m (heli_flares, jet_flare).
• ECM. Back 19.8 s after use (ecm_trigger). It jams for 7 s in a 45° cone out to 50 m (ah1z AirMissileJamming). It is off on transports and ground vehicles (venom, m1abrams).
• Smoke. Ground smoke jams locks for 7 s within 15 m of the vehicle, 20 m for attack boats (m1abrams, us_fac-cb90 SmokeJamming). It is back 11.8 s after use (tank_smoke).
• Active protection. Back 22.3 s after use (tank_ironfist).
• Laser designator. Locks in 1.5 s at 4° out to 500 m (soflam_portable).
• Spotting. Active spot 12 s, passive 1.5 s (every vehicle).

Our rule set:

1. Signature per vehicle: {heat, radar, low_alt_m, low_alt_heat}. Air: heat 10, radar 1. Helis go low at 20 m, jets at 40 m, and drop to heat 1 there. Ground: heat 0, radar 10.
2. Heat locks need heat ≥ 5. So MANPADS and AA missiles cannot lock a heli flying below 20 m. Only guns, rockets and designation reach it.
3. Lock timers. MANPADS 2.5 s, AA vehicle missile 1.5 s, guided AT 1.5 s, designated 1.0 s. Cones: AA 6°, AT 4°. Ranges: MANPADS 400 m, AA vehicle 1000 m, guided AT 350 m (600 m designated).
4. Two audible stages. The target hears "locking" for the whole timer, then "missile". The Stinger's silent lock is not copied. Every lock on a crewed vehicle warns (bf3-vehicles.md §6.7).
5. Missile speeds. MANPADS 250 m/s, AA missile 300 m/s, guided AT 200 m/s. Each turns at most 60°/s. The flight is short, so a dodge is a decision, not a reflex test.
6. One countermeasure per vehicle, chosen at spawn. No stacking across seats (bf3-vehicles.md §6.6).
   • Flares (air default): spoof missiles already in flight within 10 m. They never break a lock that is still building. 11 s cooldown.
   • Jammer (air or ground option): breaks locks and blinds missile seekers for 5 s, then 10 s cooldown. It does nothing to unguided rockets.
   • Smoke (ground default): breaks locks and designation inside 15 m for 7 s. 12 s cooldown.
7. Laser designation (squad leader tool, IFV/MBT gunner seat). It locks in 1.5 s at 4° out to 500 m and holds while the laser stays on the target. While held:
   • guided weapons do ×2 damage and lock in 1.0 s;
   • AT rockets home on air;
   • the target hears a warning. Smoke or a jammer breaks the laser for 5 s.
8. Designation counts as a spot. The target is spotted for 12 s, like BF4's active spot (vehicles.md Spotting).