Can someone please help me with this problem! :O

Hey im a Unity and C# beginner, today I started the development of my first ever unity game.

At first you might be like "What problem? I don't see it!"
well, it's not a REAL problem but it's just not what i want but since im a beginner i need a little help on this as i don't know much about Unity and C# yet, so basically I have a rocket in the game it's a 3d game and theres a rocket right, i set up controls (WAD) with .AddForce() W to fly, and A and D to go to the sides, the problem is W works perfectly fine but whenever I do A or D it just tilts the rocket to the side and makes it drop, instead, i want it to just shift left and right not tilt left and right. going up is exactly how i want it but i wanna move the rocket left and right so it's not just like "-tilts- AHHHHHH- (rocket falls to the floor and camera thats attached shakes violently and i can't get up again)"

I can't send it for some reason because I don't know how to but yea hope you understand it also heres the code I used it's force based

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class FlyingScript : MonoBehaviour
6. {
7.     public Rigidbody rb;
8.     // Start is called before the first frame update
9.     void Start()
10.     {
11.      
12.     }
13.  
14.     // Update is called once per frame
15.     void FixedUpdate()
16.     {
17.         if (Input.GetKey("w"))
18.         {
19.             rb.AddForce(0, 40, 0 * Time.deltaTime);
20.         }
21.  
22.         if (Input.GetKey("a"))
23.         {
24.             rb.AddForce(-4, 0, 0 * Time.deltaTime);
25.         }
26.  
27.         if (Input.GetKey("d"))
28.         {
29.             rb.AddForce(4, 0, 0 * Time.deltaTime);
30.         }
31. }
32.  

 

The code is pretty simple but I think a good solution would be like making the W to fly addforce physics based but then maybe have A and D controlled in another way? Is that even possible? If it is, can someone help me with it.

 

Ok i found the solution i have borders around the area so the rocket cant go free roaming it has to stay in a certain area and i removed the deltatime so it's all good now