Handling qualities assessment of the effects of tail boom strakes on the Bell 412 helicopter

Flight tests were recently conducted at the National Research Council of Canada Flight Research Laboratory on the Bell 412 helicopter to evaluate the effects of the Boundary Layer Research tailboom strakes on aircraft handling qualities and control margins. Handling qualities were assessed using a selection of the standard hover/low speed manoeuvres from ADS-33, while control margins were examined by collecting trim position data at various low airspeeds and relative wind azimuths. The results indicated that the strakes offer a 0.5 to 1.0 Cooper-Harper handling qualities rating improvement for most manoeuvres, particularly with the stability augmentation system turned off. The strakes also improved the pedal margins resulting in the pilot using less left pedal when flying at low speed and reduced pedal activity at the critical relative wind azimuth.