Tank Tests of a 1/7-Size Powered Dynamic Model of the Grumman XJR2F-1 Amphibian: Spray Characteristics, Take-Off and Landing Stability in Smooth Water - Langley Tank Model 212, TED No. NACA 2378

Tests of a model of the XJR2F-Y amphibian were made in Langley tank no. to determine the spray characteristics and the take-off and landing stability. At a gross load of 22,000 pounds full size, spray entered the propeller disk only at a very narrow range of speeds. The spray striking the flaps was not excessive and no appreciable wetting of the tail surfaces was noted. The trim limits of stability appeared to be satisfactory and the upper-limit porpoising was not violent. The stable range of center-of-gravity locations with flaps set 20deg was well aft of the desired operating range. However, with flaps up, the forward limit was about 18 percent mean aerodynamic chord and the aft limit about 28.5 percent mean aerodynamic chord at a load of 26,000 pounds and with elevators deflected -10deg. Under these conditions the location of the step is considered satisfactory. Tests showed that the effect of water in the nose-wheel well would be to move the forward limit aft about 2-percent mean aerodynamic chord. Without ventilation of the main step, the model skipped during landing at most trims, but this skipping was not violent. With the ventilation, the model skipped lightly only at trims where the afterbody keel was approximately parallel to the water (around 7.5 deg).