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Tests, using small scale models of the Curtiss-Wright X-100 and X-19 aircraft, have been carried out to investigate the disturbance and spray caused by VTOL aircraft hovering above water. Full scale disc loadings in the range 20 to 70 lb./sq.ft. were represented. Correlation of the model test results with full scale testing of the X-100 airplane over water at a disc loading of 23 lb.sq.ft. and height of 21 feet show excellent agreement. Downwash effects on objects floating below the X-19 model were also demonstrated. Spray is shown to rise to considerable heights at the higher disc loadings with the models close to the water surface, and floating objects may be subjected to severe buffeting under these conditions. LIST OF ILLUSTRATIONS Figure Page 1 General View of Test Area 26 2 Wave Maker 27 3 Nozzle Instrumentation 28 4 X-100 Model 29 5 X-19 Model 30 6 Spray Characteristics of a 4 Inch Diameter 31 Nozzle and 16 Inch Ducted Fan Data from NASA TN D-56 7 Spray Characteristics of 1 Inch, 2 Inch and 32 4 Inch Width Nozzles Data from IAS Taper Number 60-14 8 Variation of Surface Dynamic Pressure 33 with Nozzle Dynamic Pressure 9 Spray Characteristics of 10 Inch, 5 Inch 34« and 2.5 Inch Diameter Nozzles 35 10 Spray Characteristics of the X-100 Model 36 11 Predicted Spray Heights for the X-100 37 Aircraft 12 X-100 Aircraft Hovering Over Water 38 13 Photographs of X-100 Tests 39«40 14 Spray Characteristics of the X-19 Model 41«42 15 Predicted Spray Heights for the X-19 43 Aircraft 16 Photographs of X-19 Tests 44,45 17 Photographs of X-19 Tests with Model 46 Life Rafts