until the middle of the 20th century there was military interest in parasite fighters – fighter aircraft intended to be carried into a combat zone by a larger aircraft, such as a bomber. if the bomber were threatened, the parasite would be released to defend it. parasite fighters have never been highly successful and have seldom been used in combat. a major disadvantage of a parasite aircraft was that it reduced the payload capacity of the carrier aircraft. projects for this type were designed to overcome the great disparity in range between bombers and their escort fighters. development of aerial refueling has made parasite fighters obsolete.