Active Control of Performance and Vibratory Loads Using Leading Edge Slats

The comprehensive rotorcraft analysis UMARC was modified to calculate the capabilities of leading-edge slats for helicopter performance improvement in moderate to high-speed forward flight. Leading-edge slats were shown to enhance the maximum rotor thrust by 15-30% at advance ratios larger than 0.2 and reduce power requirements by 10-20% at high thrust levels. 20% span slats offered a good compromise between power reductions and adverse effect on vibratory hub loads. The rotor with leading-edge slats could be trimmed at a maximum forward speed that was about 20 knots greater than for the baseline rotor with no slats.