CompositesWorld
Issue link: https://cw.epubxp.com/i/919214
NEWS 31 CompositesWorld.com Diamond Aircraft Austria impregnation by hand or automated means and must be hand cut. Bausek says the company is researching automated cutting solutions for its in-house manufactured wet-preg, but the tech- nology readiness level is not high enough yet for serial production. Smaller parts and structures, including nacelles (Fig. 2, p. 30), are laid up in the cutting area immediately after they are cut. Ply schedules associated with each mold specify which material to place where and specify periodic quality- control steps to check accuracy. Bausek notes that Diamond's common platform concept is operative here. erefore, one mold can be used to make parts for several different aircraft, but that means the materials, fiber orientation and/or thickness vary by aircraft type. Making sure that a layup meets the require- ments of the intended part is critical. "We must make sure the right material is used for the right aircraft," he sums up. Carbon fiber is supplied to Diamond Aircraft by Toho Tenax Europe GmbH (Wuppertal, Germany) and Mitsubishi Chemical Carbon Fiber & Composites (Irvine, CA, US). Format is either UD, 2x2 twill or plain weave. A carbon fiber/aluminum weave or a carbon fiber/copper weave is used for the lightning strike protec- tion layer. e epoxy resin for all of Diamond Aircraft's parts and structures is supplied by Hexion (Columbus, OH, US), including a "legacy" epoxy still used on the DA40 and DA42, and a newer epoxy for the DA62. Bausek says Diamond Aircraft has enjoyed a long relationship with Hexion, which has been a partner to the company since 1997. Indeed, Hexion technical personnel are frequently at Diamond's facilities and provide support for all aspects of composites manufacturing. Large parts Bausek leads the way into an adjacent room where parts too large for the cutting/kitting room are laid up. Here, a wide variety of molds and other equip- ment are in several stages of production. Of particular interest is the lower shell of a DA42 mid-section, which features a spar bridge that connects the wings to the plane's primary struc- ture. Part of this structure includes the landing gear rib, fabricated from a glass fiber composite, which will better show cracks if it is damaged. At the next mold, a technician is working on an engine reinforcement structure and has applied adhesive paste to the mating surfaces in advance of bonding. FIG. 3 C-spar: The most complex aerocomposite Infusion of the DART 450 C-spar is one of Diamond's most technical, if unusual, composites fabrica- tion operations. Production head David-Alexander Bausek calls it the company's most complex, labor-intensive layup and says managing resin flow during injection is the key. For that, he uses a Membrane Tube Infusion (MTI) resin flow promoter, from DD | Compound (Ibbenbüren, Germany). Source | CW / Photo | Jeff Sloan FIG. 4 Interchangeable bonded wing structures A fully assembled DART 450 wing spar structure, featuring two C-spars (Fig. 3, above), in a bonding fixture. All Diamond Aircraft wings are interchangeable. Source | CW / Photo | Jeff Sloan