Boost Glider Duration Competition comprises nine events open to any model rocket, one portion of which returns to the ground in stable, gliding flight supported by aerodynamic lifting surfaces which sustain that portion against gravity. If the entry is staged, the gliding portion must be part of the uppermost stage, and must not be deployed until that stage has burned out. The entry may separate into multiple pieces; only the gliding portion is timed. Models whose gliding surfaces are made of flexible materials (e.g., plastic film or cloth) are prohibited from this event. The purpose of this competition is to achieve the longest flight duration time.