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A higher harmonic control (HHC) investigation was conducted on a full-scale, isolated XV-15 rotor in helicopter modein the NASA Ames 80by 120-Foot Wind Tunnel to independently control noise and vihration. The higher harmonic blade pitch was generated using swashplate oscillations. The radiated hlade-vortex interaction (RVI) noise footprint was measured on 11 plillie I~r~~r r l h the rotor uith an act~artir tra\rrpr.'li.st results showed lhi~t IIHC is highly efYecliv~ in reducin(: I!VI naoise, arhirvinv il I2 dl! redurlinn in nrak n18isu level within lhe noiw fntttnrint. Nt~ire r c d u r t i t~~~ wit11 IIIIC renlains eITecliv~cvrn with perturbations in rotor trim and flight conditions. Blade pressure feedback was demonstrated to be a viahle method for closed-loop noise control. Some noise reduction mas achieved with no increase in vibratory huh loads. Increases in control loads due to HHC generally limited further noise reduction. The vibration controller achieved about 50 percent reduction in vibratory huh loads with control loads limiting the HHC amplitude.

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