page_title: Project Isinglass
section_title: The McDonnell proposal
hierarchical_section_title: Project Isinglass / The McDonnell proposal
caption_attribution_description: A B-52 carrying two D-21 reconnaisance drones. Photo was most likely taken by the same crewman who photographed the plane while it was refueling.
context_page_description: Project Isinglass was the code name given to two heavily classified, crewed reconnaissance aircraft studied by the Central Intelligence Agency as potential replacements for the Lockheed A-12 and SR-71 during the mid-1960s. The first proposal under the Isinglass name, a high-altitude plane to fly at Mach 4–Mach 5, was considered an insufficient advancement over existing aircraft; the second, much more advanced design, sometimes referred to as Project Rheinberry, was an air-launched, Mach 20 rocket-powered boost-glide aircraft that would use a very-high-altitude trajectory to avoid defenses. This aircraft was considered too costly for development, and the project was abandoned in 1967.
caption: A B-52 carrying two D-21 drones; Isinglass would have been carried and launched in this fashion
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