Joining of Different Type “Wing-Body” Surfaces of Aircraft Structure K. Leonavičius, Vilnius Gediminas Technical University, Antanas Gustaitis Aviation Institute Riga 2002

Contents Introduction 3D models in aviation Modern modeling methods Joining of Different “Wing-Body” surfaces of Aircraft Structures 2 Contents Introduction 3D models in aviation Modern modeling methods Basic types of surfaces Types of surfaces joining FUSELAGE – fin joining fuselage - FIN joining FUSELAGE – FIN joining Examples of models Conclusion

Joining of Different “Wing-Body” surfaces of Aircraft Structures 3 Introduction Development of the 3D model – one of the most important stage of a design process in aviation. Complex shapes in aviation - new possibilities of high technology: Modern computer aided design (CAD) and analysis (CAE) software Computerised manufacturing (CAM), new composite materials and technology There is the strong demand of new 3D design methods of complex shape objects in aviation

Some features of aircraft modeling Joining of Different “Wing-Body” surfaces of Aircraft Structures 4 Some features of aircraft modeling Differences between aircrafts and other objects (cars, ships) shapes One “Skin” instead of separate “Faces” Development of aircrafts shapes Lines, arcs - Conic curves – splines, Bezier curves Assimilation of separate airplane shapes (nose-cabin-tail) into one smooth surface. Joining of fuselage and wing surfaces

3D design of light airplane Joining of Different “Wing-Body” surfaces of Aircraft Structures 5 3D design of light airplane Shape is closely related to form of internal content – crew, load, powerplant, etc. Influence of aerodynamic – max laminar flow, min drag area Influence of strength – optimization of shape and weight Influence of high tecnology - CAM New composite materials Curve of Zmax

Basic methods of airplane shape design Joining of Different “Wing-Body” surfaces of Aircraft Structures 6 Basic methods of airplane shape design Buttock-planes method Radiusography Method of Conic curves Splain, NURBS curves methods

Method of 3D design using spline curves Joining of Different “Wing-Body” Surfaces of Aircraft Structures 7 Method of 3D design using spline curves Step – by – step explanation Draft project Shape editing Contour editing Results Numerical mock-up Flow analysis Strength analysis Surface lofting Temporary sections Izocurves Basic sections Contours Coordinate system Internal components Initial layaut Main views

Types of surfaces Lifting surface (wing, fin, stabilizer) Joining of Different “Wing-Body” Surfaces of Aircraft Structures 8 Types of surfaces Lifting surface (wing, fin, stabilizer) Curves or surfaces composed by “clouds of points” (airfoils). Geometry is parameterized by coordinates of points. “Free Form” surface (fuselage, fairing, cowling). The geometry of such surfaces is parameterized by mathematical functions (Conic curves, polynomic spline curves - NURBS).

“FUSELAGE – fin” type joining Joining of Different “Wing-Body” Surfaces of Aircraft Structures 9 “FUSELAGE – fin” type joining Fin airfoil Fin surface model Fuselage surface model Fillet Blend Transition zone (fairing)

“fuselage – FIN” type joining Joining of Different “Wing-Body” Surfaces of Aircraft Structures 10 “fuselage – FIN” type joining Fin airfoil Fin surface model Fuselage surf. model Fillet Blend Transition zone (front edge fairing)

“FUSELAGE – FIN” type joining Joining of Different “Wing-Body” Surfaces of Aircraft Structures 11 “FUSELAGE – FIN” type joining Fin rooth airfoil Fin airfoil Fuselage geometry Contour Fin geometry Transition zone geometry Blend Loft UV

Joining of Different “Wing-Body” Surfaces of Aircraft Structures 13 Conclusions Modern high technology in aviation allows very complex shapes to be developed and manufactured. The “Free Form” surfaces of double curvature are typical for a light and sport airplanes. There are two basic methods of aircraft surface parameterization – numerical (fuselages, fairings, etc.) and geometric (wings). Development of the transition zones between them creates an additional problems. There are some typical ways to connect a surfaces of different type - “Fuselage-fin”, “fuselage – Fin”, “Fuselage-Fin”. Proper CAD technique is recommended for every type of joining. It is objective to change geometrically parameterized (by coordinates) curves into mathematically determined curves (Conic, NURBS). Special methods and software would be created and integrated with modern CAD-CAE packages. Development of transition zones is possible by joining the design CAD software with the CAE strength (FEM) and flow (CFD) analysis software.