WITHIN-CANOPY AIR-FLOWS AND SPRAY MOVEMENT FOR FIXED-WING AIRCRAFT

Studies determined the effects of airspeed and spray height of a Cessn a AgHusky on airflow and temporal spray deposits in cotton and cantalo upe canopies. Analyses of covariance selected significant covariants w hich were used to adjust treatment means. Ambient velocity and turbule nce intensity in the canopies were used to adjust for aircraft induced airflows. None of the variables studied covaried significantly with d eposits in the cantaloupe canopy. Canopy size had the greatest impact on canopy airflows, deposits, and longevity of aircraft effects in cot ton. Deposits and mean airflows were greatest in the smaller canopy. D eposits in small cotton for an airspeed of 145 km/h were significantly greater than those for an airspeed of 185 km/h. There were no signifi cant effects on deposit in large cotton. Based on mean and rms velocit y in crop canopies, wake effects were significantly greater than ambie nt for about 5 s in both cotton and cantaloupe canopies. An airspeed o f 145 km/h resulted in higher mean air velocities and greater deposits in cantaloupe than an airspeed of 185 km/h. Spray height of 1.8 m res ulted in greater mean air velocities but less spray deposited in canta loupe than a 3.7 m height.