Plug Construction

The Phoenix airframe parts will be constructed using molded composite sandwich panels (the “bread” consists of layers of carbon/epoxy fabric and the “meat” consists of foam core). All molded composite airframes begin life with a male plug.  From the male plug comes the female molds and it’s within these female molds that the airframe parts are fabricated.  So, the first step in the process is to create the male plugs.

We’ve begun the process of creating the male plugs with the fabrication of the fuselage plug. This is exacting work since the symmetry and alignment of the aircraft ultimately depends on the accuracy of the plug. The process begins with the construction of an internal keel. From the computer CAD files, closely spaced slices are taken through the fuselage, along the fuselage length. These cross-sectional slices define the fuselage shape. These CAD cross-sections are then scaled up to full size and the full size formers are cut using a laser. The formers are then attached to the keel and the space in between the formers is filled with polyurethane foam. The foam is then cut and sanded (by hand) to the final fuselage shape taking numerous measurements to assure accurate fuselage definition. Once accuracy has been established, fiberglass/epoxy layers are applied to the formers/foam and the fiberglass layers are filled in and sanded (by hand) until the desired smoothness is obtained.

The fuselage plug shown in the pictures below was fabricated at our facility in San Luis Obispo, California over a period of 4 months by one of our guys, working part time.

GALLERY (Click to enlarge)

Figure 1 - The Keel	Figure 2 - The Cross-Sections	Figure 3 - Cutting the Foam
Figure 4 - Fitting the Foam	Figure 5 - Fitting the Foam	Figure 6 - Sanding the Foam
Figure 7 - Laying the Fiberglass	Figure 8 - Finished	Figure 9 - Finished