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The Museum Conservation Institute


SCMRE Investigation Reveals Pioneering Feature of U.S. First Guided Missile

Smithsonian Center for Materials Research and Education staff, led by Walter Hopwood (Organic Chemist) and Jia-sun Tsang (Senior Paintings Conservator), assisted NASM conservators in the recovery of the unique guided missile's materials and appearance.

The Gorgon II-A is the United States' first liquid-fueled rocket powered, guided air-to-air missile. It is a rare surviving example, one of 21 missiles of this type ever built (1943-1946). Launched 12 miles from the target at 140 miles per hour, fitted with a 200 lb. warhead, it could accelerate to a velocity of 525 miles per hour. It was controlled by the pilot in the cockpit of the plane from which it was launched using radio signals and had the additional feedback of a camera positioned in the nose. This could locate a target in mid-air within a distance of 18 miles. It is very likely that this is the first example of the incorporation of television into missile technology. Unfortunately, the early technology, poor equipment resolution, and lack of control at high speeds resulted in inadequate operational performance.

The original transparent tip of the missile was later over-painted with a yellow paint, obscuring the important design innovation. The goal of the analysis and treatment was to restore the original appearance of the missile. Removal of the overpaint without affecting the under layer was problematic: the first step was to identify the original paint materials. This evaluation would ensure that the method devised to remove the over-paint would not affect the original transparent plastic. A small sample of the under layer was taken for Fourier Transform Infrared Analysis (FTIR) and it was identified as acrylic resin. The next step was to identify the paint. The paint was examined on the spot using SCMRE's new portable X-ray fluorescence spectrometer (XRF), providing an immediate identification of lead. A sample was taken for binder examination with FTIR and was shown to be alkyd, an early synthetic oil paint. Use of organic solvents for alkyd paint removal could have been disastrous to the clear acrylic nose. Following paint solubility testing, it was found that the alkyd could be removed with no effect on the acrylic using 30% aqueous potassium hydroxide (KOH). Using these analyses and treatment guidelines the missile was restored to its original appearance.

Gorgon guided missle