Photograph of a man working on the nose section of a SAAC-23 mockup, circa 1961.Stamped on verso: "Rohcopie / Hans Entzeroth Fotograf / Zurich Bederstrasse 119."
Photograph of a man working on the wing section of the Learjet 23 prototype, July 25, 1963. The forward fuselage section is visible in the background.Inscription on verso: "P3-E / July 25, 1963."
Memorandum to Lear Jet employees from Bob Hagan, Manufacturing Superintendent and Chief of Flight Test, October 9, 1963. Sends thanks and congratulations to employees for a job well done and shares highlights from the test flight of the Learjet 23.…
Photograph of three men conducting tests on the Learjet 23 prototype, March 16, 1964.Inscription on verso: "Flight test instruction for ground test / T-76-3A / 3-16-64."
Photograph of men installing a new engine in the Learjet 23 prototype, February 21, 1964.Inscription on verso: "Installing new engine on Jet #1 / 2-21-64."
Photograph of two men looking at the door of the Learjet 23 prototype, February 18, 1964. A third man is visible inside the aircraft performing a test with an oscillograph.Inscription on verso: "Direct read out oscillograph loaned from Century…