飞机设计导论（第三章）.ppt

Introduction to Aircraft Design
Chapter 3
Why is that shape?
Civil Aircraft
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隐身技术
Background
There is almost no limit to the variety of the shapes of aircraft.
This chapter gives a brief introduction describing wing, fuselage and powerplant arrangements followed by descriptions of the characteristics of civil, military and rotorcraft types(next chapter).
Aircraft are essentially aerodynamic vehicles and every aircraft designer must develop considerable aerodynamic skills.
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Introduction to Aircraft Design
Background
The aerodynamic shape of the aircraft will determine aircraft speeds, manoeuvrability, flying qualities, range, field performance, costs, altitudes and many other parameters.
There is a close interaction between such disciplines as aerodynamics, structures, propulsion and aircraft systems.
An optimum shape must be determined to maximize a chosen performance parameter.
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Introduction to Aircraft Design
Wing and tail
The wing is the main lift source and it must be carefully designed to optimize its lift/drag ratio over the whole flight envelope.
Figure shows definitions of the main wing geometrical characteristics.
The parameters are defined as following.
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Introduction to Aircraft Design
Wing and tail
There are some more important aerodynamic parameters. They are:
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Introduction to Aircraft Design
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Introduction to Aircraft Design
Wing and tail
The stall speed may be reduced by use of leading or trailing edge devices. These increase camber and area.
Wing design is to choose the correct parameters of the wing platform and the aerofoil section.
Table highlights the main wing aerodynamic variables, and their effects on different categories of aerodynamic performance.
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Introduction to Aircraft Design
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Introduction to Aircraft Design
Propeller-driven Aircraft
Mach No. is not higher than and wing swee