Unity 3D Hovercraft c# script

using UnityEngine;
using System.Collections;

public class Hovercraft : MonoBehaviour {

    Transform fan;
    Transform fanBlades;

    void Start () {
        fan = transform.Find("Fan");
        fanBlades = fan.Find("Fan Blades");
    }

    void Update () {

        float r = Input.GetAxis("Horizontal") * -25;

        fan.localRotation = Quaternion.Euler(0,r,0);

        float force = Input.GetAxis("Vertical") * 4;

        rigidbody.AddForceAtPosition( fan.forward * force, fan.position );

        fanBlades.RotateAroundLocal(Vector3.forward, force * 10 * Time.deltaTime);

        Camera.main.transform.LookAt(transform);
    }
}