AIC's 52nd Annual Meeting

The Smithsonian National Air and Space Museum is undergoing a multi-year renovation project that has enabled some of our aviation treasures to be thoroughly examined for the first time in decades. One such artifact is a glider built and sold by the German aviation pioneer, Otto Lilienthal. Lilienthal studied aerodynamics and methodically tested various wing designs through the 1890’s. He was a great inspiration to the Wright brothers, who adopted his experimental approach and built on his data. Lilienthal flew more than 2000 flights and established the first factory for gliders to be sold to the public. The Smithsonian National Air and Space Museum’s glider is one of the 9 “Normalsegelapparat” gliders Lilienthal sold to the public and is the only Lilienthal glider in the western hemisphere.

During the gallery renovation’s planning stages, an initial survey characterized the glider as needing only surface cleaning and stain reduction. Records indicated that the glider had gone through three previous restorations and that it was still in good condition. Upon closer inspection and during the more detailed treatment proposal phase, questions began to arise about the accuracy and structural stability of the glider. The fabric slated for stain reduction was a 1960’s replacement that was incorrectly constructed. The wood frame retained old repairs related to its first test flights alongside new breaks. The metal hardware was almost entirely replacements that mis-represented Lilienthal’s innovative design. The growing concerns warranted a thorough examination of the artifact. Traces of evidence extant on the original materials prompted extensive historical research and collaboration with Lilienthal experts in Germany. As we learned more about the artifact, our treatment protocol shifted towards reversing the previous ill-informed restorations and to embrace the new information derived from current collaborations and material analyses.

Navigating this changing course of the treatment plan yielded many pleasant surprises and some challenges. Newly revealed features of the glider, such as an early safety feature, a clearer understanding of the original hardware’s functional design, and the re-discovery of an original Lilienthal vertical stabilizer were all highlights of this process. However, the greatest challenge was in finding ways to “unrestore” the glider and reintegrate missing components without impacting the original elements. Historically relevant damages needed to be preserved while carefully retaining structural integrity with reversible repairs.

As we gained knowledge about our glider and considered our technical capabilities, we adjusted the treatment protocol. Guided by current ethical standards we utilized the highest level of craft skills to return the glider to its original configuration while expanding the field’s body of knowledge regarding Lilienthal gliders for all of the museums and scholars involved.