SAMPE Journal - January/February 2011 - 8

Figure 3. Progression of out of autoclave maturation. Experimentation Developmental Approach By October 2009, each of the floors of the launching pad in Figure 3 was under development. Plans were underway for efforts in automated placement of out-of-autoclave (OOA) materials on other government-funded programs, coordinated by government/industry advisory boards. The additional effort on this program provided for fabrication of a flight worthy boom and empennage with Cycom®5320 (and some Cycom®5320-1, when it went through production scale-up in time) for Boeing’s Phantom Eye aircraft, which is scheduled to fly in early 2011. Aurora Flight Sciences and HITCO Carbon Composites, Inc. were part of a technology transition and replication task, constructing an 11.6 m (38 ft) wing spar and a hat stiffened wing skin, respectively. These tasks led to the launching of the design efforts for tooling and parts for three 21 m (68 ft) wing skin configurations and a 21 m (68 ft) structural spar, which began in January 2010.

Materials Figure 4 illustrates the progression of materials development within the program. Starting with the resin development illustrated on the right side of the arrow, three sequential resins candidates were evaluated to provide the basis for selection of a systems for commercialization. These culminated in an experimental resin, X5320, which was highlighted to people interested in exploring OOA prepreg in late 2008. At a government/industry discussion in Memphis in September 2008, participants surveyed stressed interest in a resin system with sufficient out-time to facilitate the construction of very large structures, on the order of 10 meters. By mid-year 2009, multiple evaluators of Cytec’s Cycom®5320 system, the commercialized product conceived from X5320, discovered that the reactivity of Cycom®5320 was greater than its experimental predecessor, X5320, and the goal of 20 day shop life and 30 day out-time was not achievable with the system. That is when the Air Force Non-Autoclave Manufacturing Technology program decided not to compromise on its goals for program expediency. Thus, the transition and replication efforts at HITCO (wing skin), Aurora (spar), and Boeing (Phantom Eye boom and empennage) continued with Cycom®5320, but a resin system meeting the shop life and out time goals was to be used for the large scale fabrication efforts in the overall program plans. Cycom®5320-1 was manufactured on production equipment in the Greenville, TX, to an approved process control document in January 2010. The technical data sheet for the Cycom®5320-1 epoxy resin systems was released on 12 May 201024. The image in the arrowhead of Figure 4 is the c-scan from a 32 ply unidirectional tape, 30 day out-time panel which averaged 10.0 dB attenuation and percent void volume of less than 0.04 percent by acid digestion. The lay-up technicians reported a reduced, but still acceptable tack level after 15 days and a significantly reduced (but not zero) tack after 30 days. Further information regarding Cycom®5320-1 is discussed in reference6. Having a family of materials is important for most designs. As a result, fiber product form evaluations (shown in the upper left of the arrow in Figure 4) were performed with T40-800 for an early candidate and the crowfoot satin weave (CSW)

Figure 4. Materials technology developments.
SAMPE Journal, Volume 47, No. 1, January/February 2011

SAMPE Journal - January/February 2011

Table of Contents for the Digital Edition of SAMPE Journal - January/February 2011