Unity Drone Stabiliser

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(Rigidbody))]
public class Drone : MonoBehaviour
{
    const float MAX_FORCE = 50;
    const float MAX_TILT = 60;
    const float STEER_FORCE = .05f;
    const float MAX_SPIN = .5f;
    Vector3 frontLeft, frontRight, rearLeft, rearRight;

    Rigidbody body;
    Transform mTransform;
    void Awake()
    {
        body = GetComponent<Rigidbody>();
        mTransform = GetComponent<Transform>();
        frontLeft = new Vector3(-mTransform.localScale.x, 0, mTransform.localScale.x);
        frontRight = new Vector3(mTransform.localScale.x, 0, mTransform.localScale.x);
        rearLeft = new Vector3(-mTransform.localScale.x, 0, -mTransform.localScale.x);
        rearRight = new Vector3(mTransform.localScale.x, 0, -mTransform.localScale.x);
    }

    // Update is called once per frame
    void FixedUpdate ()
    {
        float forward = Input.GetAxis("Vertical");
        float right = Input.GetAxis("Horizontal");
        float up = Input.GetAxis("Trigger") * 20;
        float spin = Input.GetAxis("Horizontal2") * 3.5f;

        Vector3 orientation = mTransform.localRotation.eulerAngles;
        orientation.y = 0;
        FixRanges(ref orientation);

        Vector3 localangularvelocity = mTransform.InverseTransformDirection(body.angularVelocity);

        float velY = body.velocity.y;

        float desiredForward = forward * MAX_TILT - ( orientation.x + localangularvelocity.x * 15 );
        float desiredRight = -right * MAX_TILT - ( orientation.z + localangularvelocity.z * 15 );
        float desiredSpin = spin - localangularvelocity.y;

        ApplyForces( desiredForward / MAX_TILT, desiredRight / MAX_TILT, up - velY, desiredSpin );
    }

    void ApplyForces( float forward, float right, float up, float spin )
    {
        //need to maintain this level of upwards thrust to gain/lose altitude at the desired rate
        float totalY = Mathf.Min( (up * 100) + 9.81f, MAX_FORCE );

        if (totalY < 0) totalY = 0;

        //distribute according to forward/right (which are indices based on max tilt)
        //front left
        body.AddForceAtPosition( mTransform.up * ( totalY * .25f - forward * STEER_FORCE - right * STEER_FORCE ), mTransform.position + mTransform.TransformDirection( frontLeft ) );

        //front right
        body.AddForceAtPosition( mTransform.up * ( totalY * .25f - forward * STEER_FORCE + right * STEER_FORCE ), mTransform.position + mTransform.TransformDirection( frontRight ) );

        //rear left
        body.AddForceAtPosition( mTransform.up * ( totalY * .25f + forward * STEER_FORCE - right * STEER_FORCE ), mTransform.position + mTransform.TransformDirection( rearLeft ) );

        //rear right
        body.AddForceAtPosition( mTransform.up * ( totalY * .25f + forward * STEER_FORCE + right * STEER_FORCE ), mTransform.position + mTransform.TransformDirection( rearRight ) );

        spin = Mathf.Min(MAX_SPIN, spin);

        //Front
        body.AddForceAtPosition( mTransform.right * spin, mTransform.position + mTransform.forward );
        //Rear
        body.AddForceAtPosition( -mTransform.right * spin, mTransform.position - mTransform.forward );
    }

    void FixRanges( ref Vector3 euler )
    {
        if (euler.x < -180)
            euler.x += 360;
        else if (euler.x > 180)
            euler.x -= 360;

        if (euler.y < -180)
            euler.y += 360;
        else if (euler.y > 180)
            euler.y -= 360;

        if (euler.z < -180)
            euler.z += 360;
        else if (euler.z > 180)
            euler.z -= 360;
    }
}