The conceptual design phase is the most important part of the design process. It consists of:
- Making a wish list of what the aircraft will do. This is a preliminary specification.
- Size lifting and control surfaces.
- Select and design airfoils. Many projects such as; the variable wing geometry, high speed aircraft, the Lancair and Stallion, the jump start gyroplane, the Acro 1 have required special airfoils.
- Make a three view drawing of aircraft.
- Make an inboard profile layout showing location of all major components.
- Perform a weight and balance and stability check and rearrange components to meet requirements.
- Calculate performance.
- Make an isometric drawing to show what aircraft looks like.
- Final aircraft specification.
Once the conceptual design is completed, the structural design can be started. This includes:
- Perform structural design, sizing and optimization.
- Design fixed or retractable landing gear.
- Design pressurized hull and system.
- Make detailed layouts using drafting and CAD systems.
- Perform loads and stress analysis.
- Perform finite element analysis for composites, metallic structures, buckling, linear/nonlinear static, eigenvalue and mode shapes, transient thermal analysis, shock analysis, sin sweep, random vibration.
- Perform flutter analysis.
- Design lightning strike protection.
- Design icing protection system design.
- Design drive shaft and propeller if necessary.
- Perform material testing at ambient and elevated temperature.
- Complete fabrication of composite aircraft parts and prototyping.
Since composite materials and fabrication techniques may vary from design to design and result in different material properties, it is important to perform material testing at room and elevated temperature. Aircraft Designs has a series 1220 universal test machine. The following composite material tests are used at ADI. The material properties from these tests are used in sizing the final structure.
- Inplane Rail Shear Test per North American Rockwell set up
- Inplane Shear per ASTM D3518
- Tensile Test per ASTM D3039
- Compression Test similar to ASTM D695 and Boeing set up
- Honeycomb core Shear per ASTM C273
- Honeycomb core Flatwise Tension per ASTM C297
- Honeycomb core Compression per ASTM C365
 Much of the aerodynamic work done by Aircraft Designs, Inc. has been performed by Rick and Susie McWilliams. Rick is a brilliant designer of airfoils, wings, and computer programs. One of the programs that Rick wrote is the Oshkosh Airfoil program which he has been using to design the airfoils of the Stallion, Lancair IV, ES, Acro 1 and many others. On the left is Susie and Rick in front of their new Zlin aerobatic aircraft. Monterey, 2005. In addition to flying acrobatics, Rick loves to fly helicopters and has just received his helicopter rating from his instructor Dan Gray. Here is a video of Susie picking up her R22 helicopter. Click here to view. Major Structural Repair of Composite Structures by Martin Hollmann. A very detailed article for the step by step procedure of repairing composite aircraft structures. This is the only article that has ever been published on this most important topic. Click here to download free pdf file.
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