Hydro-Aerodynamic Design And Water Landing Load Reduction For An Amphibious Aircraft Fuselage

The 21st century is the ocean century,large amphibious aircraft will play an important role in the fields such as transportation,offshore patrol and anti-submarine,forest fire rescue,which puts forward new and higher requirements for the range and anti-wave performance of amphibious aircraft.According to aerodynamic and hydrodynamic requirements,this paper carries out research on the hull fuselage design,the drag reduction by retractable step configuration and the water loading reduction by strutted-submerged hydro-ski.Engineering method and numerical simulation are employed to calculate and analyze the hydro and aerodynamics of the designed fuselage,which provides an important reference for the design and research of a new generation of amphibious aircraft.To meet the demand of the mission,the parameters of hull fuselage and wave suppression groove are reasonably selected by referring to the shape of the existing seaplanes and the design manual of the seaplane.The CAD model is formed as the original fuselage configuration in this paper.The retractable step configuration is designed to reduce the cruise aerodynamic resistance.The result by numerical simulation shows that the optimal shape of retractable step can reduce the drag by up to 24percent.Compared with the original hull fuselage,the retractable step configuration brings about the negative impact of hydrodynamic stability and resistance.To improve the hydrodynamic performance of the retractable step configuration,the blowing jets with 10m³ gas output per hour are equipped at the place of the original step.The strutted-submerged hydro-ski is installed at the bottom of the fuselage near the longitudinal position of the center of gravity to reduce the water loading of fuselage.Obvious effect of water loading reduction can be shown with the hydro-ski by the method of engineering estimation and numerical simulation,comparing the original fuselage with the same initial attitude and landing speed.Further calculation shows that the optimal shape of the hydro-ski(when the beam loading coefficient C_?0 is equal to 100,the length-beam ratio l/b is equal to 5 and the dead-rise angle?is equal to 20°)can cut down the water loading by at least 63.8%.