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This is a special purpose slide rule, which was used by pilots to determine true airspeed, based on indicated air speed, altitude, and other instrument readings. It is typical of the many specialized slide rules used for air navigation and flight management, before the advent of electronic calculators and satellite-based navigation systems.

The slide rule was found with a collection of paper archives that were donated to the Smithsonian in 1957.

 Display Status

This object is not on display at the National Air and Space Museum. It is either on loan or in storage.
Object Details
Country of Origin United States of America Type INSTRUMENTS-Computers, General Purpose Manufacturer G. Felsenthal & Sons Inc.
 Dimensions 3-D (Diameter x Depth): 0.6 × 20.3cm (1/4 × 8 in.)
Storage: 25.4 × 5.7 × 25.4cm (10 in. × 2 1/4 in. × 10 in.)
 Materials Plastic
Ink
Steel
Non-Magnetic Metal Alloy
Paint
 Inventory Number A19970199000 Credit Line Bequest of the Estate of E.L. Jones. Data Source National Air and Space Museum Restrictions & Rights Usage conditions apply
For more information, visit the Smithsonians Terms of Use.