On the KM, the rear engines are the ones used in flight, and they're mounted well above the ground. The front engines are more of a booster to get it airborne,

On the KM, the rear engines are the ones used in flight, and they're mounted well above the ground. The front engines are more of a booster to get it airborne, but they are indeed incredibly vulnerable. You might be able to get it airborne without as much boost if you had the help of an intermediate phase of acceleration as a hydrofoil. The Orylonok uses a ski in this vein.