Working paper 169-LJ2.

Quote.

"The first two Little Joe boosters (Little Joe Nos. 6 and LJ1A) had the base area covered with a heat shield formed from stainless steel and called space metal. The shield was applied to prevent flame recirculation and heat radiation from injuring the boosters basic aluminum structure. The space metal installation proved unsatisfactory on the first two flights as reported in references 5 an 6. On Little Joe No.2, the space metal was replaced with a nominal 0.125-inch layer of a mixture of RTV 40, 60, and 90."

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