Bjorn’s Corner: Aircraft Structures Part 7. Fiberglass.

Fiberglass composites represent one of the foundational material technologies underlying modern aircraft construction, and Leeham News contributor Björn Fehrm's ongoing structures series traces their origins directly to mid-20th century industrial manufacturing. Owens-Corning, formed from a merger of Owens-Illinois and Corning Glass Works, commercialized glass fiber-reinforced plastic beginning in the mid-1940s, producing prototype boat hulls and eventually contributing to the body construction of the 1953 Chevrolet Corvette. Aviation adopted the technology early, applying it to engine cowlings, radomes, antenna structures, and fairings — applications where design flexibility, electrical transparency, or corrosion resistance mattered more than raw tensile strength. The article distinguishes between several glass fiber variants: E-glass, the most common in aviation, is non-conductive and cost-effective; S-glass offers roughly 30 percent higher tensile strength and greater stiffness but commands a price premium that has increasingly pushed structural applications toward carbon fiber instead.

For working pilots and aviation operators, this material taxonomy has direct practical implications. The prevalence of E-glass in radomes and antenna fairings means that any maintenance involving those structures requires care to avoid inadvertent introduction of conductive materials that could compromise RF transparency and degrade navigation or communication performance. Aircraft such as Diamond DA40s and DA42s — referenced directly in the article with a link to an AVweb production video — use hybrid glass and carbon fiber layups in their wing skins, with carbon fiber concentrated in tension-loaded lower surfaces. Understanding that composite panels are not monolithic but rather carefully engineered laminate stacks helps pilots and maintenance personnel appreciate why impact damage assessments on these surfaces are complex: a visible surface blemish may conceal subsurface delamination that compromises the designed load path entirely.

The article's emphasis on composite part design as a "multidimensional problem" — involving fiber type, matrix type, and manufacturing process — reflects a reality that increasingly touches every segment of aviation from piston singles to wide-body airliners. In general aviation, fiberglass remains the dominant composite material for non-structural components precisely because of its low cost and ease of repair using widely available materials and hand layup techniques. Glider manufacturers relied heavily on fiberglass for decades before carbon fiber became economically viable; that transition accelerated through the 1990s and 2000s as industrial carbon fiber production scaled up. Business jet and airline operators encounter this material hierarchy throughout their fleets: glass fiber in interior panels, fairings, and radomes; carbon fiber in primary structure; and aramid (Kevlar) fibers in impact-resistant applications such as engine containment rings and flooring panels.

The broader trend Fehrm's series is tracking — the progressive replacement of aluminum with composite structures — has reshaped airframe certification, maintenance requirements, and training curricula across the industry. Transport category aircraft such as the Boeing 787 and Airbus A350 use composite primary structure at a scale that was unimaginable when Owens-Corning was laying up prototype boat hulls in 1944. For Part 91, 91K, and 135 operators managing modern composite-heavy aircraft, the material science basics covered in this series are not merely academic: they underpin structural repair manual interpretation, damage tolerance assessments, and the increasingly specialized skill sets required of maintenance providers cleared to work on these airframes. As composite content continues to expand even in next-generation regional and single-aisle designs, the foundational distinctions between fiber types, matrix systems, and manufacturing processes will only grow in operational relevance.