A flight test evaluation of seaplane takeoff performance with respect to delta ratio

Research in seaplane takeoff performance is rare, due to the limited number of seaplanes and the difficulty in measuring takeoff distance on the water. This thesis presents an evaluation of a seaplane takeoff performance metric referred to as delta ratio (D_r), a rule of thumb technique for determining whether or not enough distance is available to make a successful departure from an unfamiliar or obstructed body of water regardless of aircraft weight, and examines D_r as a function of technique. Delta ratio is defined, by previous research, as the water-run distance over the total distance to clear a 50-foot obstacle. ^{(DeRemer, 1988)} In order to evaluate the viability of the D_r, flight tests were conducted by the University of Tennessee Space Institute at the Woods Reservoir, Tullahoma, TN during day VMC for 1.8 hours. Numerous takeoffs were performed at weights of 3050 lb. (light) and 3400 lb. (gross) using three takeoff techniques; conventional (baseline), float-lift, and flap-input. A one-way ANOVA was performed, in conjunction with Duncan's New Multiple Range Test for planned comparison, on the resulting distance information to determine the significance of D_r across weight and technique. It was determined that D_r should not be applied to takeoff maneuvers using the flap- input technique. However, it was found that the D_r is consistent across weight and technique during takeoff maneuvers that employed the conventional or float-lift technique. It was also determined that the flap-input technique was the only technique that proved to significantly reduce the takeoff distance when a seaplane is heavily loaded. The flap-input technique demonstrated no significant benefit when lightly loaded. Based on the data gathered and the experience gained from this flight test, recommend the flap-input technique not be employed by novice or minimum currency seaplane pilots.