Project Isinglass

Project Isinglass was the code name given to two heavily classified, crewed reconnaissance aircraft studied by the Central Intelligence Agency (CIA) as potential replacements for the Lockheed A-12 and SR-71 during the mid-1960s.

[3] The Isinglass/Rheinberry concept was considered to be superior to spy satellites in a number of ways, including rapid turnaround time and quick response capability.

[3] Following fourteen months of work, McDonnell had developed the aircraft to the point where serious proposals were made for its construction.

[3] When the CIA failed to receive approval for funding, McDonnell approached the U.S. Air Force with the project.

[3] Although the development of the Isinglass/Rheinberry aircraft was conducted using McDonnell's own funding,[7] the United States Air Force's Air Force Rocket Propulsion Laboratory did fund the development of the aircraft's intended engine, the Pratt & Whitney XLR-129, intended to be a reusable rocket engine.