Lightweight fiberglass structures have been designed and produced to create subscale models of both manned and unmanned air vehicles. These fiberglass structures were produced using CNC machined molds and incorporate special features for bondline joggles, wing installation, internal equipment mounting, disassembly and shipment. Many different types of molds and fixtures have been designed and produced at Lucas Industries to support the unmanned air vehicle market. Functional tools such as lamination molds, braiding mandrels, trim fixtures, drill templates and inspection gages have all been designed and delivered to different customers. Lucas has such broad capability that project tasks such as prototyping of low quantity parts can be accomplished very cost effectively while at the same time, durable metal molds can be produced for later phases of the program. UAV Case Study 1 - Global Hawk Lucas Industries has produced several lightweight air frame structures for special test models on existing unmanned air vehicles. The CATIA® design system was used to properly scale a full size engineering model of the Global Hawk system down to a specific size for testing purposes. A high fidelity electronic model was designed with structural split lines, assembly features and critical bonding interfaces that allowed efficient fabrication of the fiberglass composite sections. Layup molds were designed as female cavities controlling the outer mold line surfaces to within 0.010" of the electronic model. Computer numerical control machining (CNC) techniques were applied to precisely sculpt high density polyurethane tooling materials selected for the project. The wings were made as separate upper and lower skins for each of the left and right hand airfoil shapes. Interior ribs were installed at several locations to increase bonding surfaces and at critical attachment interfaces for higher strength. Metallic pin stub spars were used to attach the wings to prepositioned tube receptors mounted in the fuselage. Attachment hardware was arranged to allow easy removal and installation of the wings for shipment and storage. The fuselage was also designed in two halves to allow ease of manufacture and insertion of stiffening frames prior to final assembly, photo 2573. A special feature was incorporated on top the fuselage to transfer structural mounting loads into the frame and skin assembly. This single point attachment pad allowed all sensor, control and data acquisition cabling to enter the model internally while still withstanding the motion and other mechanical stresses to the airframe. After layup, a composite stiffening frame was adhesively bonded along the primary fuselage interface on each half. This frame served as a central load bearing keel for the thin outer skin structures. A pair of composite tube sections was bonded into each wing root socket area for eventual use in attaching the wings. Locking set screws were used to fix the metal pin stub spars into both the wing roots and into the fuselage. A similar technique was employed to mount the separately laminated vee tail control surfaces to the aft fuselage. All the detail parts on this project were composed of E type fiberglass laminated with room temperature curing epoxy from PTM&W(PR2114). Vacuum bag processing was the standard method for applying pressure during cure. A filled epoxy surfacing coat yielded superb finish quality off of the direct CNC milled molds. This surface material was further enhanced by the application of a thin metallic coating via electroless plating techniques. Final polishing steps brought the already accurate shapes to an extremely fine level of precision and surface roughness prior to delivery. This level of contour consistency and electrical surface continuity had never been achieved before in this type of test model. The general approach has become the standard at Lucas Industries for fabricating this type of product. Here are some photos of our recent R&D projects: