So, I’m planning to make a realistic flight simulator with Jump Trajectory(gasgiant on Github)'s Airplane physics, here’s the link to the project:

So, his project mostly cover the whole physics, but if you notice closely when playing, when the plane’s speed is about 55-60km/h, the nose plane is stabilized, the plane doesn’t lean to any side and you’re not control the plane. Then you can easily see that the plane will automatically goes up and down, and that’s not correct according to the design of a Cessna. Of course when flying, the airplane can tilt up and down a little bit but not that much, see in this video to see how the plane will actually work when stabilized at a certain high speed:

So can you guys help me to fix the physics in his code, the plan here is to make the plane stabilized at a speed of 55-60km/h and at a certain angle like the actual Cessna in real life. Pleaseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee. I will be very appreciate your help!