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J U L Y 2 0 1 4 | 3 9 the dish rim, also a composite. The rim is molded separately and bonded to a vertical fange at the edge of the dish. Lacy in cooperation with NRC-Canada partner Profle Composites' (Kingston, Wash.) CEO Geoff Wood, worked on a dish rim connector (DRC). It features a unique ball-and-joint design that clev- erly and securely anchors the dish to the support structure. There are several types and sizes of DRC, depending on the DRC's location and whether or not it's accommodating one or two support structure tubes. A 10.2-inch/259-mm long threaded stainless steel bolt, with a 4-inch/102-mm ball on one end, is enclosed in the DRC, which has two primary parts, the DRC in- ner and the DRC outer. The DRC inner is a compression-molded carbon fber base that contains half of the ball socket(s) for one or two bolts. The DRC outer is Step 3 The primary dish, during preparations for infusion. NRC-Canada says surface error of the mold is less than 0.5 mm/0.02 inch, producing a final part with a surface error of just. 0.9 mm/0.04 inch. Step 8 An NRC-Canada employee bags a DRC in preparation for infusion. Step 9 A fully molded DRC, with two threaded bolts emerging from the composite ball- and-socket joint. The DRC will be bonded into the DVA-1 rim; the metallic bolts will be used to attach the dish to its primary support structure. Source (all step photos): NRC-Canada Step 4 DVA-1 primary dish, bagged and beginning infusion. The dish comprises a thin layer of aluminum, backed by glass and carbon fiber. The resin is a vinyl ester, chosen because of its ability to maintain dimensional tolerance. Infusion takes about an hour. Step 5 Primary dish rim sections, prior to bonding to the primary dish. Note the pockets in some of the rims, which will house the dish rim connectors. Step 10 A finished DRC sits next to the pocket in the dish trim into which it will be adhesively bonded. glass fber to protect against galvanic corrosion, and several plies of A&P; Tech- nology's (Cincinnati, Ohio) QISO triaxi- al braided carbon fber — in this case, Toray's (Tokyo, Japan) T700 material. The entire layup is bagged and the resin, HE- TRON 922 vinyl ester from Ashland Per- formance Materials (Columbus, Ohio), is infused in one shot, in about an hour. Lacy reports that infusion provides the greatest process control most affordably. "It's such a large part that infusion gave us the best trade-off in terms of perfor- mance and cost." Infusion modeling was done by Lacy with Polyworx (Nijverdal, The Netherlands) software. On the downside, Lacy points out that the vinyl ester was chosen in 2007, but that Ashland technically no longer man- ufactures the 922 grade. Therefore, there is some pressure to switch to a more contemporary matrix resin. "The prob- lem is that to switch resins is a bit of a big deal," he reports, "because we have to requalify everything. We're not quite aerospace, but we have a similar prob- lem. This is critical — we're concerned about shrinkage, warpage, radio trans- parency. There's a whole suite of things that all have to be right." Clever connectors The main refector, when installed, must be anchored to the primary support structure, a latticework of metallic tubes that joins the refector to the mecha- nized pedestal on which it rests. Each dish must connect to 14 tubes at eight connection points (some connection points receive two tubes). Each connec- tion must be adjustable as the dish is erected, and then tightened and secured when it is properly positioned. Connec- tion points are built into what's called 0714HPC IM_NRC-OK.indd 39 6/17/2014 10:56:38 AM