<div class="htmlview paragraph">Based on a comparative study of competing V/STOL concepts, the folding tiltrotor offers many advantages for missions requiring long endurance combined with a speed capability in excess of 400 knots. Folding tiltrotor technology development began in 1967 and the results of wind tunnel tests and design studies show no significant technical obstacles to the development of a folding tiltrotor aircraft. The convertible fan/shaft CTFS-34 engine can be used to power a technology demonstrator aircraft. The next step in the development of tiltrotor technology should be a folding tiltrotor technology demonstrator based on either the V-22 or the S-3A.</div>