The key to developing a very strong overall structure lies in getting rid of voids that may form in the epoxy resin. NASHERO guarantees the lowest void content in its composite matrix structure thanks to a proprietary vacuum infusion process. “This also lets us get ideal fiber volume fractions depending on the interstitial gaps in the reinforcement stack,” Sharma says.
That process, and the engineering behind it, attracted the attention of R&M International, a supplier of textiles and plastics in Fort Washington, Pa. After evaluating NASHERO’s technology, R&M teamed up with the company in late 2015 to produce high-quality CFRP parts for sale in the United States.
According to R&M Partner Stephen Rawson, the NASHERO process features other impressive innovations aside from the low void content. One is its closed loop material management system that protects workers and the environment from the risks associated with chemicals and airborne fragments. It also reduces material scrap, which saves money. “NASHERO was able to reduce chemical waste down to percentage levels below two percent, whereas some sectors of the industry have percentages as high as 30 percent that ends up as production waste,” Rawson says.
Another innovation is the use of high-efficiency curing ovens to produce parts. The resulting components equal the quality usually only seen at large aerospace firms, according to Rawson. Sharma says the company developed its proprietary ovens out of necessity, as an extensive search-and-bid process involving multiple vendors failed to turn up anything suitable. NASHERO’s ovens measure 27.9 x 8.2 x 8.2 feet, enabling the curing of large airplane parts. They can hold a temperature differential of 230 F while consuming a tenth of the energy of the most other ovens, Sharma says.
He also notes that vacuum infusion for aerospace components requires care since it’s difficult to place dry fabric on inverted surfaces. Adhesives can’t be used because that would lead to impurities and potential defects. The company overcame this challenge through design and process adjustments.
As of early 2016, most of the primary structure of NASHERO’s plane is complete. Assembly and system integration is now underway, with flight testing soon to follow. The company’s current facility can support production of about 20 aircraft per year. After flight testing, NASHERO plans to move to a larger plant capable of manufacturing more than 200 aircraft annually. The new building will facilitate NASHERO’s long-term plans to produce three models of the aircraft, with at least one constructed with less expensive fiberglass composites.