CW Blog

A lot of research effort is occurring right now, focused on electric propulsion for aircraft. One US-based program is NASA’s Scalable Convergent Electric Propulsion Technology and Operations Research (SCEPTOR) subproject, which is developing the manned X-57 Maxwell experimental aircraft featuring a distributed electric propulsion system (more on that below).  SCEPTOR is part of NASA’s Convergent Aeronautics Solution (CAS) initiative, which falls under the agency’s Transformative Aeronautics Concepts Program. NASA’s goal of meeting and overcoming the challenges of today’s aviation starts with potentially revolutionary ideas, and CAS was instrumental in supporting the idea of zero-carbon-emitting distributed electric propulsion, says the agency.

Elemental rings are fitted to create a mandrel for the fuselage skin in this MTorres demonstrator fuselage.

Composite surfaces are subject to weathering, including rain erosion, as well as other environmental damage. To protect the underlying plies, the film must be strong enough to mitigate potential damage from mechanical abrasion, UV exposure, and must provide a barrier for subsequent processes like sanding or paint removal.

Surfacing films can also help address the effect of thermal cycling. Thermal cycling can create microcracking in the aircraft surface coating. These tiny cracks can allow moisture ingression, which can ultimately lead to corrosion or delamination. Microcracking can be minimized by closely matching coefficient of thermal expansion (CTE) of prepregs, surfacing film and paint coating systems.

The broader aerospace world might be patiently waiting for Boeing to officially announce plans to develop its New Middle-Market Airplane (NMA, or 797), tabbed as a replacement for the 757, but suppliers are not sitting on their hands. SAMPE 2018, May 21-24 (Long Beach, CA, US), proved that the aerospace composites supply chain has been busy developing new products for next-generation aircraft. Like the 797. 

The composites industry has embraced waterjet machining, thanks to its relatively low operating cost, fast cutting speed, fast set-up time and “cool” temperature, that is, the process does not create heat in the material or part being cut and is unaffected by the heterogeneity of composite materials. The use of jets or streams of water to cut materials goes back hundreds of years, but the concept of adding abrasives to water for cutting harder materials took off in the 1960s and early 1970s, with several companies contributing to the technology, developing pumps, nozzles, intensifiers and especially hardened orifices that could withstand the erosive action of the high-velocity abrasive grit. Waterjet precision has increased as well, as manufacturers have improved flow control.The number of companies that make and sell commercial waterjet machines is extensive; check out CW’s online SourceBook for a fairly complete list: https://www.compositesworld.com/suppliers/product/362.