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US 6,308,913 B1Granted
Method for reducing wave resistance in airplane
AssigneeHonda Giken Kogyo Kabushiki Kaisha
InventorsMichimasa Fujino, Yuichi Kawamura
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AssigneeHonda Giken Kogyo Kabushiki Kaisha
InventorsMichimasa Fujino, Yuichi Kawamura
Estimating the term…
It is an object of the present invention to reduce the wave resistance by disposing a fluid element such as an engine nacelle in a predetermined position on the upper surface of the main wing, and positively superposing the air flow generated by the fluid element onto the air flow on the upper surface of the main wing, thereby reducing the peak of the negative pressure on the upper surface of the main wing to retard the generation of a shock wave. If the engine nacelle is disposed on the upper surface of the main wing, and the longitudinal position of the front end of the engine nacelle is established in a range of 63% to 100% from the front end of a wing chord of the main wing (see b and i in FIG. 9), a shock wave is generated on the upper surface of the main wing in a range of transonic speed to inhibit an increase in wave resistance, whereby the cruising speed can be increased, while avoiding an increase in amount of fuel consumed. If the front end of the engine nacelle is in front of a position corresponding to 63% of the wing chord (see e and f in FIG. 9), a shock wave inhibiting effect is not exhibited, and the wave resistance is increased.
A method for reducing a wave resistance in an airplane, which comprises disposing a substantially cylindrical engine nacelle covering a gas turbine engine within a main flow above a rear portion of an air flow on an upper surface of a main wing of an airplane, for generating a negative pressure on the upper surface of the main wing of the airplane cruising at a transonic speed, superposing a decelerated region of the main flow generated in front of the engine nacelle onto the air flow on the upper surface of the main wing to decelerate the air flow on the upper surface of the main wing, defining the negative pressure when the air flow on the upper surface of the main wing becomes sonic speed, as a critical pressure coefficient, establishing on the wing chord a reference point at which the profile of pressure on the upper surface of the main wing is changed from a state equal to or larger than the critical pressure coefficient to a state smaller than the critical pressure coefficient, and disposing a front end of the engine nacelle to the rear of a position in front of the reference point by 5% of the length of the wing chord, thereby reducing the negative pressure on the upper surface of the main wing to inhibit the generation of a shock wave.
A method for determining a position of an engine nacelle in an airplane, which comprises disposing a substantially cylindrical engine nacelle covering a gas turbine engine within a main flow above a rear portion of the air flow on an upper surface of the main wing of the airplane, for generating a negative pressure on the upper surface of the main wing of the airplane cruising at a transonic speed, and superposing a decelerated region of the main flow generated in front of the engine nacelle onto the air flow on the upper surface of the main wing to decelerate the air flow on the upper surface of the main wing, thereby reducing the negative pressure on the upper surface of the main wing to inhibit the generation of a shock wave, the method comprising:
Dependencies are inferred from the claim text.