CIA/CSI/ History Staff Monograph, The Central Intelligence Agency and Overhead Reconnaissance: The U-2 and Oxcart Programs, 16 July 2002.

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Chapter 6
important design features that contributed to a small radar return were
fiberglass engine inlets and wings whose leading edges were made of
-
Pyroceram.14
Lockheed's new entry was much like its first, but with several
modifications and a new designator, A-12. It, too, would employ two
of the powerful 158 engines. Lockheed's major innovation in reducing
radar return was a cesium additive in the fuel, which decreased the
radar cross section of the afterburner plume. This improvement had
been proposed by Edward Purcell of the Land committee. Desiring to
save weight, Kelly Johnson had decided not to construct the A-12 out
of steel. Traditional lightweight metals such as aluminum were out of
the question because they could not stand the heat that would be gen-
erated as the A-12 flew at Mach 3.2, so Johnson chose a titanium
alloy.
On 20 August 1959, Lockheed and Convair submitted their pro-
posals to a joint Department of Defense, Air Force, and CIA selection
panel. As the table shows, the two aircraft were similar in performance
Convair KINGFISH
" Convair Division, General Dynamics Corporation, "K14GFISH Summary Report.-
1959 (S). Kelly Johnson was very skeptical of the Convair design. noting in the Archangel
project log on 1-20 August 1959: "Convair have promised substantially reduced radar
cross section on an airplane the size of our A-I2. They are doing this, in my view, with
total disregard for aerodynamics. inlet and afterburner performance."
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