Danny Deger wrote:
Why does the shuttle throttle to 3 Gs on ascent?

Danny Deger

Because structurally the shuttle vehicle is only stressed for 3 g's. If
they didn't throttle back in the late stages of the ascent when the
fuel is almost gone and the vehicle is light, it would exceed this
level of acceleration. Since the engines are liquid fueled, they can
hold full thrust until the fuel is gone.

Bud