真实飞行物理

飞行模拟器和空战游戏最大的区别在于物理系统的深度。这里我们不只是"升力=常数×速度²"，而是要考虑迎角（AoA）、翼型特性、发动机扭矩等更接近真实的因素。但不用担心——我们会用工程师风格的简化，让物理感觉真实又不让代码复杂到无法维护。

本章你将学到

• 迎角（AoA）：决定升力的关键因素
• 更完整的飞机气动力模型
• 螺旋桨飞机的发动机扭矩效应
• 失速：速度过低时飞机失去控制
• 地效：降落时接近地面的特殊升力效应

什么是迎角？

迎角（Angle of Attack，AoA）是机翼弦线（机翼前后缘连线）与来流方向之间的夹角。

    来流方向 →→→
              /
             /  ← 迎角（这个角度）
            /─────────────── 机翼弦线

• 迎角增大 → 升力增大（但阻力也增大）
• 迎角超过临界值（约15°） → 气流分离，失速，升力突然骤降
• 迎角为0° → 仍有少量升力（翼型不对称）

完整气动力控制器

GDScript

extends RigidBody3D

## 真实感飞行物理控制器（简化版）
class_name RealisticFlightController

# === 飞机参数（在编辑器调整）===
@export_group("发动机")
@export var max_engine_power: float = 134000.0  ## 最大功率（瓦特，约180马力）
@export var propeller_efficiency: float = 0.85  ## 螺旋桨效率

@export_group("翼型参数")
@export var wing_area: float = 16.2    ## 机翼面积（平方米）
@export var aspect_ratio: float = 7.3  ## 展弦比（翼展²/机翼面积）
@export var max_cl: float = 1.5        ## 最大升力系数（超过则失速）
@export var stall_angle: float = 15.0  ## 失速迎角（度）

@export_group("操控面")
@export var elevator_effectiveness: float = 1.0   ## 升降舵效果
@export var aileron_effectiveness: float = 0.8    ## 副翼效果
@export var rudder_effectiveness: float = 0.5     ## 方向舵效果

# === 内部状态 ===
var throttle: float = 0.0       ## 油门（0~1）
var airspeed: float = 0.0       ## 真空速（米/秒）
var altitude: float = 0.0       ## 高度（米）
var aoa: float = 0.0            ## 当前迎角（弧度）
var is_stalled: bool = false    ## 是否失速

## 空气密度（随高度变化，海平面约1.225 kg/m³）
func _get_air_density() -> float:
    var density_sl := 1.225
    # 简化的标准大气模型：每1000米密度降低约12%
    return density_sl * pow(1.0 - altitude / 44300.0, 4.256)

func _physics_process(delta: float) -> void:
    _update_flight_state()
    _apply_engine_thrust()
    _apply_aerodynamics()
    _apply_control_surfaces(delta)

func _update_flight_state() -> void:
    airspeed = linear_velocity.length()
    altitude = global_position.y

    # 迎角：速度向量与机翼弦线（飞机前向）之间的夹角
    if airspeed > 1.0:
        var forward := -global_transform.basis.z
        var vel_normalized := linear_velocity.normalized()
        # 取垂直平面内的角度（俯仰方向的迎角）
        aoa = forward.angle_to(vel_normalized)
        # 判断是仰头（正迎角）还是俯头（负迎角）
        var up := global_transform.basis.y
        if vel_normalized.dot(up) < 0:
            aoa = -aoa
    else:
        aoa = 0.0

    is_stalled = abs(rad_to_deg(aoa)) > stall_angle

func _apply_engine_thrust() -> void:
    if airspeed < 0.1:
        return
    # 推进功率 = 发动机功率 × 螺旋桨效率
    # 推力 = 功率 / 速度
    var thrust := max_engine_power * throttle * propeller_efficiency / maxf(airspeed, 10.0)
    var forward := -global_transform.basis.z
    apply_central_force(forward * thrust)

func _apply_aerodynamics() -> void:
    if airspeed < 1.0:
        return

    var air_density := _get_air_density()
    var dynamic_pressure := 0.5 * air_density * airspeed * airspeed

    # 升力系数：随迎角线性增加直到失速
    var aoa_deg := rad_to_deg(aoa)
    var cl: float
    if is_stalled:
        # 失速后升力系数骤降
        cl = max_cl * 0.3 * sign(aoa_deg)
    else:
        cl = clampf(aoa_deg / stall_angle * max_cl, -max_cl, max_cl)

    # 诱导阻力系数（升力的副产品）
    var cd_induced := cl * cl / (PI * aspect_ratio * 0.9)
    # 寄生阻力（与升力无关的摩擦阻力）
    var cd_parasitic := 0.025
    var cd_total := cd_induced + cd_parasitic

    # 升力：垂直于速度方向，偏向机翼上方
    var lift_dir := global_transform.basis.y
    var lift := dynamic_pressure * wing_area * cl
    apply_central_force(lift_dir * lift)

    # 阻力：与速度方向相反
    var drag := dynamic_pressure * wing_area * cd_total
    apply_central_force(-linear_velocity.normalized() * drag)

func _apply_control_surfaces(delta: float) -> void:
    var pitch := Input.get_action_strength("pitch_up") - Input.get_action_strength("pitch_down")
    var roll := Input.get_action_strength("roll_left") - Input.get_action_strength("roll_right")
    var yaw := Input.get_action_strength("yaw_left") - Input.get_action_strength("yaw_right")

    # 操控效果随速度增加（速度越快舵面越有效）
    var control_authority := clampf(airspeed / 50.0, 0.1, 1.0)
    if is_stalled:
        control_authority *= 0.3  ## 失速时操控大幅降低

    apply_torque(global_transform.basis * Vector3(
        pitch * elevator_effectiveness * control_authority,
        yaw * rudder_effectiveness * control_authority,
        roll * aileron_effectiveness * control_authority
    ))

C

using Godot;

public partial class RealisticFlightController : RigidBody3D
{
    [ExportGroup("发动机")]
    [Export] public float MaxEnginePower = 134000f;
    [Export] public float PropellerEfficiency = 0.85f;

    [ExportGroup("翼型参数")]
    [Export] public float WingArea = 16.2f;
    [Export] public float AspectRatio = 7.3f;
    [Export] public float MaxCl = 1.5f;
    [Export] public float StallAngle = 15f;

    [ExportGroup("操控面")]
    [Export] public float ElevatorEffectiveness = 1f;
    [Export] public float AileronEffectiveness = 0.8f;
    [Export] public float RudderEffectiveness = 0.5f;

    public float Throttle { get; set; } = 0f;
    public float Airspeed { get; private set; } = 0f;
    public float Altitude { get; private set; } = 0f;
    public float Aoa { get; private set; } = 0f;
    public bool IsStalled { get; private set; } = false;

    private float GetAirDensity()
    {
        return 1.225f * Mathf.Pow(1f - Altitude / 44300f, 4.256f);
    }

    public override void _PhysicsProcess(double delta)
    {
        UpdateFlightState();
        ApplyEngineThrust();
        ApplyAerodynamics();
        ApplyControlSurfaces((float)delta);
    }

    private void UpdateFlightState()
    {
        Airspeed = LinearVelocity.Length();
        Altitude = GlobalPosition.Y;

        if (Airspeed > 1f)
        {
            var forward = -GlobalTransform.Basis.Z;
            var velNorm = LinearVelocity.Normalized();
            Aoa = forward.AngleTo(velNorm);
            if (velNorm.Dot(GlobalTransform.Basis.Y) < 0) Aoa = -Aoa;
        }
        else Aoa = 0f;

        IsStalled = Mathf.Abs(Mathf.RadToDeg(Aoa)) > StallAngle;
    }

    private void ApplyEngineThrust()
    {
        if (Airspeed < 0.1f) return;
        float thrust = MaxEnginePower * Throttle * PropellerEfficiency / Mathf.Max(Airspeed, 10f);
        ApplyCentralForce(-GlobalTransform.Basis.Z * thrust);
    }

    private void ApplyAerodynamics()
    {
        if (Airspeed < 1f) return;
        float airDensity = GetAirDensity();
        float dynamicPressure = 0.5f * airDensity * Airspeed * Airspeed;
        float aoaDeg = Mathf.RadToDeg(Aoa);

        float cl = IsStalled
            ? MaxCl * 0.3f * Mathf.Sign(aoaDeg)
            : Mathf.Clamp(aoaDeg / StallAngle * MaxCl, -MaxCl, MaxCl);

        float cdInduced = cl * cl / (Mathf.Pi * AspectRatio * 0.9f);
        float cdTotal = cdInduced + 0.025f;

        ApplyCentralForce(GlobalTransform.Basis.Y * dynamicPressure * WingArea * cl);
        ApplyCentralForce(-LinearVelocity.Normalized() * dynamicPressure * WingArea * cdTotal);
    }

    private void ApplyControlSurfaces(float delta)
    {
        float pitch = Input.GetActionStrength("pitch_up") - Input.GetActionStrength("pitch_down");
        float roll = Input.GetActionStrength("roll_left") - Input.GetActionStrength("roll_right");
        float yaw = Input.GetActionStrength("yaw_left") - Input.GetActionStrength("yaw_right");

        float authority = Mathf.Clamp(Airspeed / 50f, 0.1f, 1f);
        if (IsStalled) authority *= 0.3f;

        ApplyTorque(GlobalTransform.Basis * new Vector3(
            pitch * ElevatorEffectiveness * authority,
            yaw * RudderEffectiveness * authority,
            roll * AileronEffectiveness * authority
        ));
    }
}

失速警告系统

失速是飞行中最危险的状态，游戏里需要明确提示：

GDScript

extends Node

## 失速警告系统
class_name StallWarning

@onready var aircraft: RealisticFlightController = get_parent()
@onready var warning_audio: AudioStreamPlayer = $StallWarningBeep

var is_warning_active: bool = false

func _process(_delta: float) -> void:
    ## 在接近失速迎角（80%）时触发警告
    var aoa_ratio := abs(rad_to_deg(aircraft.aoa)) / aircraft.stall_angle

    if aoa_ratio > 0.8 and not is_warning_active:
        is_warning_active = true
        warning_audio.play()  ## 播放"叮叮叮"的失速警告音
    elif aoa_ratio <= 0.7 and is_warning_active:
        is_warning_active = false
        warning_audio.stop()

C

using Godot;

public partial class StallWarning : Node
{
    private RealisticFlightController _aircraft;
    private AudioStreamPlayer _warningAudio;
    private bool _isWarningActive = false;

    public override void _Ready()
    {
        _aircraft = GetParent<RealisticFlightController>();
        _warningAudio = GetNode<AudioStreamPlayer>("StallWarningBeep");
    }

    public override void _Process(double delta)
    {
        float aoaRatio = Mathf.Abs(Mathf.RadToDeg(_aircraft.Aoa)) / _aircraft.StallAngle;
        if (aoaRatio > 0.8f && !_isWarningActive)
        {
            _isWarningActive = true;
            _warningAudio.Play();
        }
        else if (aoaRatio <= 0.7f && _isWarningActive)
        {
            _isWarningActive = false;
            _warningAudio.Stop();
        }
    }
}

下一步

飞行物理完成后，搭建 机场与地形系统。