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An ongoing NASA (Small Business Innovation Research) SBIR Phase II design and development program will produce the first lightning protected, fiberglass, General Aviation aircraft that is available as a kit. The results obtained so far in development testing of typical components of the aircraft kit, such as the wing and fuselage panels indicate that the lightning protection design methodology and materials chosen are capable of protecting such small composite material airframes from lightning puncture and structural damage associated with severe threat lightning strikes. The primary objective of the program has been to develop a lightning protection design for a full scale test airframe and verify its adequacy with full scale laboratory testing, thus enabling production and sale of owner-built, lightning-protected, Stoddard-Hamilton Aircraft, Inc. Glasair HI airplanes.

Presently, many manufacturers are replacing aluminium with fiberglass, Kevlar, and carbon fiber composites (CFC) to take advantage of the fuel savings allowed by weight reduction. It is well known that lightning strikes may cause severe damage to unprotected composites, so protective measures must usually be incorporated. Presently available methods involve application of a layer or ply of conductive material to the laminate, which compromises the original weight savings and sometimes imposes manufacturing and repair difficulties. These drawbacks have been especially severe for thin laminates, where the weight of the protective layer is a significant portion of the entire laminate. Thus, an effort was begun to develop more efficient lightning protective methods for CFC laminates. The outcome was a new CFC material that incorporates conductive filaments to disperse stroke and energies and to limit damage but retains the same physical and structural properties as unprotected CFC.

A series of measurements was made of voltages induced in electrical circuits within a metallic aircraft wing by full-scale simulated lightning currents flowing through its skin and structure. The measured data were mathematically analyzed to enable determination of voltages across load impedances to which the circuits might be connected elsewhere in the aircraft. Relationships between induced voltages and lightning current, wing structural, and circuit parameters were determined. Induced voltages of magnitudes likely to cause damage or interference with avionics were measured.