Editing Lockheed X-7 (section)

==Construction==
The X-7 was constructed from steel, unlike its successors such as the A-12 and YF-12 which used titanium. These X-7 planes had wings constructed from stainless steel and a fuselage made from a nickel alloy. The use of steel was due to the inability of aluminum to endure air friction heating at hypersonic speeds, years before the widespread introduction of titanium.

The engines developed for the X-7/AQM-60 were designed to operate for a short time, to test the design for the [[CIM-10 Bomarc]]. They were redesigned with better materials for use on the hypersonic [[Lockheed D-21]] drone launched from the back of a [[Lockheed M-21]], a derivative of the [[Lockheed A-12]], or from under the wing of a [[Boeing B-52 Stratofortress]].<ref>Goodall and Goodall 2002, p. 106.</ref>