the Mirage fighter jet's delta wing whilst very efficient at high speed generates enormous drag at low speeds, should the donk(s) stop then it needs a ridiculous amount of speed (190Kts) to glide (at roughly 45 degrees nose down). There was even an old joke that developed which recommended that if the engine stopped then open the canopy, throw out a brick and follow it down
Flt Lt. Garry Cooper dead sticked Mirage A3-29 into a crop dusting airstrip after swallowing a bird. Severe bollocking I believe.