Freelancer ship physics for Unity. Includes engine kill and thruster.

FreelancerShipPhysics.cs

// ====================================================================================================
// In my codebase, all ships have their own instance of this that they use to apply physics with.
// I'm using a struct mostly because I want to maintain copy semantics.
// ====================================================================================================

public struct FlightInput
{
    public float Pitch;
    public float Yaw;
    public float Roll;
    
    public float Throttle;
    public float StrafeHorizontal;
    public float StrafeVertical;
    
    public bool IsEngineKill;
    public bool IsThrusterActive;
    public bool IsReversing;
}

// ====================================================================================================
// These are the member variables used for physics. The values here are taken from 88 Flak's Defender.
// In the actual Unity C# class, these are all properties that are exposed to the Inspector.
// ====================================================================================================

// Physics
public float Mass = 150f;
public float LinearDrag = 155f;
public Vector3 AngularDrag = new Vector3(50000f, 50000f, 50000f);
public Vector3 AngularInertia = new Vector3(12500f, 12500f, 12500f);
public Vector3 SteeringTorque = new Vector3(120000f, 120000f, 120000f);
public float BankLimit = 80f;

// Engine
public float ThrustForce = 24000f;
public float BoosterForce = 12000f;
public float ReverseFraction = .5f;
public float StrafeForce = 18000f;

// ====================================================================================================
// These functions are the core of Freelancer's physics. It's pretty straightforward since it uses
// linear drag for everything. The actual application of of the physics forces (thrust etc) are handled
// by Unity's Rigidbody, and all that math works out the same because physics is just physics.
// ====================================================================================================

private void ConfigureRigidbody()
{
    Rigidbody = gameObject.AddComponent<Rigidbody>();
    Rigidbody.mass = Mass;
    Rigidbody.useGravity = false;
    Rigidbody.angularDrag = 0f;
    Rigidbody.drag = 0f;
    Rigidbody.inertiaTensor = AngularInertia;
    Rigidbody.centerOfMass = Vector3.zero;
}

private void RunShipPhysics()
{
    // Ship thrust
    if (GetIsEngineRunning())
    {
        var forwardThrustForce = FlightInput.IsReversing
            ? -ThrustForce * ReverseFraction
            : ThrustForce * FlightInput.Throttle;

        forwardThrustForce += FlightInput.IsThrusterActive ? BoosterForce : 0f;

        var appliedLinearForce = new Vector3(
            StrafeForce * FlightInput.StrafeHorizontal,
            StrafeForce * FlightInput.StrafeVertical,
            forwardThrustForce);
        Rigidbody.AddRelativeForce(appliedLinearForce, ForceMode.Force);

        // Linear drag forces
        var dragForce = -Rigidbody.velocity * LinearDrag;
        Rigidbody.AddForce(dragForce, ForceMode.Force);
    }

    // Ship rotation
    var appliedAngularForce = new Vector3(
        SteeringTorque.x * FlightInput.Pitch,
        SteeringTorque.y * FlightInput.Yaw,
        SteeringTorque.z * FlightInput.Roll);
    Rigidbody.AddRelativeTorque(appliedAngularForce, ForceMode.Force);

    // Angular drag forces
    var localAngularVelocity = transform.InverseTransformVector(Rigidbody.angularVelocity);
    var localAngularDragForce = Vector3.Scale(-localAngularVelocity, AngularDrag);
    Rigidbody.AddRelativeTorque(localAngularDragForce, mode: ForceMode.Force);
}

public bool GetIsEngineRunning()
{
    return !FlightInput.IsEngineKill
        || FlightInput.IsThrusterActive
        || FlightInput.IsReversing
        || Mathf.Abs(FlightInput.StrafeHorizontal) > .1f
        || Mathf.Abs(FlightInput.StrafeVertical) > .1f;
}