My first door (42x12) was a vertical folding door, mounted on an external horizontal track, looked good, cost was around $3000. Totally mechanical open and close, just raise the locking pins from holes in the concrete floor and push it from center to each side. The problem was 5 knots of wind made the task very dicey. On a couple of occasions the entire half sections nearly got wrapped around the side of the building before the locking pins found the external locking holes. When it was fully open or closed the wind did not matter so much, but in between I found myself being dragged across the ramp trying to control it. You'd be amazed how much force a little wind has on a big door surface. The process of open and close was a royal pain in the butt in anything but calm conditions.
After 5 years of wrestling with this thing, I bit the bullet last summer and went for a one piece overhead hydraulic door. I figured if ever this place ever goes on the market, that cheap vertical bi-fold door will have to go, why not do it now and enjoy the benefits of a decent door.
What a difference, just push the button and up goes the door.
You get what you pay for in hangars doors.