Flight Model

Every helicopter in CZ Autoz is built on DayZ 1.29’s CarScript base — the correct script-driven aircraft foundation. No two aircraft fly the same way — a nimble MD500 and a heavy AW101 Merlin require very different technique, each tuned around its own mass, drag, and control parameters.

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How It Works

Since v0.2.8 the entire flight simulation runs on a true physics force model — lift, drag and control torques are applied as real forces each physics tick, with the pilot’s aircraft driven through DayZ’s native client-side prediction pipeline for instant, smooth response: no server round-trip feel, no rubber-banding, no stepping while holding a turn. Passengers, co-pilots and bystanders ride the network feed cleanly like native vehicle passengers (the airframe rumble non-pilots used to feel was fixed in v0.2.9), so everyone sees and hears the helicopter whether or not a pilot is seated.

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Flight Modes (Simple / Advanced)

The server’s gameplay.flightMode selects one of two flight personalities on the same physics:

• Simple (default) — assisted: altitude hold on collective release, coordinated turns, smoothed input. Attitude still holds on stick release, and full aerobatics work.
• Advanced — raw and manual: no altitude hold, minimal auto-coordination, crisper input — you fly the aircraft yourself. Release the collective in a climb or descent and the aircraft keeps going until you counter it. Since v0.3.0 the HUD shows a collective gauge (both modes) so you always know where your vertical power sits.

Since v0.2.9 each mode also has its own feature profile (featuresSimple / featuresAdvanced) covering Autohover, wind and the Advanced-only aerodynamics below — see Flight Mode Profiles.

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Wind Physics (v0.2.9, optional)

With windPhysicsEnabled on in the live profile, the world’s live weather wind physically pushes the aircraft — delivered as gust-driven buffeting rather than a constant shove. Weather fronts wobble and lean you, and a hover in a storm takes real stick work. Off by default; strength tunable via windStrength.

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Air Density (ISA) — new in v0.3.9

Air thins with altitude, and since v0.3.9 the rotor feels it. Lift is scaled by an ISA standard-atmosphere density model based on the aircraft’s height above sea level:

• About 9% of lift is gone by 1,000 m ASL, and about 18% by 2,000 m
• The scaling floors at 20% — extreme altitude never takes lift to zero on its own
• It stacks with the per-airframe service-ceiling curve below, which is a separate limit

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Advanced Flight Feel (v0.2.9, Advanced mode only)

Three real aerodynamic behaviours exist only in the Advanced profile:

• Vortex Ring State (vrsEnabled / vrsSeverity / vrsOnsetDescent) — descend too fast into your own downwash and the rotor loses its bite; recover by flying forward into clean air or reducing collective. It can only trigger below ETL speed and clear of ground effect — a fast descent with forward speed on, or one close enough to the ground to be in ground effect, never enters it
• Anti-torque coupling (antiTorque) — pulling collective kicks the nose like a real single-rotor helicopter; hold it on the pedals
• Blowback (blowback) — the nose wants to rise as airspeed builds; trim against it

All three were fixed and retuned in v0.3.0 after the Advanced model’s first full flight-testing pass (new defaults: blowback 0.08, antiTorque 0.04, vrsSeverity 0.22), and blowback/anti-torque are hard-capped at 25% of the pilot’s own control authority — no configured value can overpower the pilot. Existing servers keep their stored values through migration; see the retune note in Global Settings to adopt the new tuning.

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Control Response (Tau Smoothing)

Each control axis uses a time-constant (Tau) smoothing model under control.response — separate constants govern how quickly the axis ramps up to an input (accel) and how quickly it settles back when the input is released (decay). Lower values feel sharper and more immediate; higher values feel heavier and more damped. This replaces the old per-axis acceleration/decay multipliers.

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Ground Effect

When flying close to the ground, the helicopter receives additional lift:

• Configured via aerodynamics.groundEffectBonus — 0.10 (+10%) on the MD500, MH-6 and SA342M, 0.12 on the UH-1H, Blackhawk and Merlin, and 0.13 on the Chinook
• aerodynamics.groundEffectAlt sets the altitude below which the bonus applies — between 8 m and 15 m depending on airframe
• Fades linearly as altitude increases
• Makes low hovering feel slightly more stable

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Effective Translational Lift (ETL)

Forward flight generates extra lift:

• Configured via aerodynamics.etlBonus — MD500 0.12, MH-6 0.13, SA342M 0.11, UH-1H 0.09, Blackhawk 0.08, Merlin 0.07, Chinook 0.06
• aerodynamics.etlSpeed sets the speed (in knots) at which the full bonus applies — 45 · 45 · 48 · 50 · 52 · 55 · 58 in that same order
• A helicopter will fly more efficiently in forward flight than in a stationary hover
• Light scouts get the biggest ETL boost and reach it soonest; the heavies get less of it, later

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Tilt & Inverted Flight

Lift acts along the rotor’s axis, so the more the helicopter tilts, the less of that thrust holds you up. Tilt past vertical and the rotor can no longer hold you — you lose lift and fall under the helicopter’s own weight, just like real physics. It is fully recoverable: roll or pitch back toward upright and lift returns as the rotor comes back over you.

• There is no artificial tilt limit in manual flight — loops, rolls and upside-down passes are all possible, in both flight modes. The one exception is Autohover, which hard-limits attitude to 40° of pitch and roll while it is engaged
• At 90° of tilt the rotor’s thrust points fully sideways — vertical lift is zero, thrust becomes speed, and gravity takes over until you right the aircraft
• Since v0.2.9 this is honest in Simple mode too: the Simple altitude assist is at full strength up to about 30° of tilt and has faded to nothing by about 63°, so steep dives and inverted flight genuinely cost altitude — everyday flying under ~30° is unaffected

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Autorotation

If the engine stops (fuel out, engine destroyed, or manually shut down), the rotor continues spinning through inertia:

• The helicopter enters a controlled descent rather than an immediate freefall
• Tilting the cyclic during autorotation now translates the helicopter — you can glide forward and steer the descent rather than only rotating in place
• autorotation.gravityFactor controls how much gravity is cancelled during the glide (default 0.60)
• autorotation.descentCap sets the maximum descent rate in knots — tuned per helicopter (see the table below)
• autorotation.flareStrength controls how much vertical lift a collective flare recovers (default 6.0)
• autorotation.coastMinutes sets how long the rotor keeps turning visually and audibly after a mid-air engine cut (default 4.0) — the rotor coasts down gradually instead of snapping to a stop, and engine and rotor audio fade together over that time
• A skilled pilot can perform a survivable landing using autorotation technique

Descent rate scales with helicopter mass. Heavier helicopters have higher rotor disc loading, so their rotors provide proportionally less lift during autorotation — they descend significantly faster than light scouts. The gravity factor and descent cap set the baseline, but the actual descent rate at any given rotor spool is heavier for larger aircraft. This reflects real-world rotor disc loading behaviour. Since v0.2.8 the autorotation glide is tuned per helicopter — light scouts autorotate gently, heavies drop fast:

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Service Ceiling

Each helicopter has a configurable altitude ceiling above which lift drops to zero: The lift reduction is gradual — performance starts degrading before the ceiling is hit, not suddenly at it.

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Never-Exceed Speed (VNE)

Each helicopter has a maximum airspeed — set per variant via flight.maxAirspeed (in knots) and shown on each helicopter’s page. Flying above this threshold causes the flight model to apply increasingly heavy drag that arrests further speed gain. The previous fixed hard cap has been removed — top speed is now tuned per variant — and the behaviour at the envelope boundary can be tuned separately: See Per-Helicopter Settings for default values and the full list of tunable flight parameters.

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Flying With a Sling Load

A slung load changes the flight envelope for as long as it is on the hook, scaled by how heavy the load is against the aircraft:

• VNE drops by up to 35% — a fully loaded hook takes a third off your top speed
• Vertical speed cap drops by up to 40% — climbs and descents are slower
• Forward drag rises by up to 80% — acceleration is sluggish and you decelerate faster off the stick
• The load’s weight is partly compensated by extra thrust — 85% of it in Simple mode, 55% in Advanced, so Advanced pilots genuinely feel the mass hanging under them

See Sling Loading for hooking, the per-airframe lift classes, and the winch.

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Ground Flip Recovery

If a helicopter ends up tipped on the ground — resting on its side, nosed over, or fully inverted — pressing X will flip it upright.

• Disabled by default — enable with groundFlipRecovery set to 1 in the live flight-mode profile (featuresSimple / featuresAdvanced) in mod_config.json — configurable per mode
• Works from any tipped attitude past roughly 70° (reworked in v0.3.0 — it previously required a ≥ 90° bank, which some airframe shapes never quite reached). An upright helicopter can never trigger it, even parked on the steepest usable slope
• Only activates on the ground (or settled against something) while effectively stationary — never in flight

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Pilot Exits In Flight

• If the pilot voluntarily exits while airborne — or uses Move to Cabin — Autohover engages automatically to hold position (autoHoverOnExit, on by default in both profiles)
• If the pilot is killed in their seat, the helicopter continues on its last heading with no Autohover snap — it will fly freely until it crashes or someone takes the pilot seat