Full Details

Name and Model Number The Hoffman airplane calculator
Country of Origin USA
Date of Manufacture 1918
Front Scales Specialized aviation parameters (see photo)
Back Scales N/A
Scale Length 32 cm (outside scale)
Type of Rule Other
Construction A cardboard circular slide rule, instruction book and charts in a cardboard cover
Area of Use Aviation
Comment Performs numerous calculations for the design of flying machines.
For details see https://www.nzeldes.com/HOC/Hoffman.htm
Rarity RRRR
Donor Collection of Nathan Zeldes
Match Number 415
(Click Picture for Details)

In conjunction with our 'donors' we assign a rarity rating to each item, based on the system devised by Herman van Herwijnen
(1929 - 2004), renowned Dutch collector, author, and creator of Herman's Archive, a collection of 5,000 slide rule images on CD.
• RR = Rare - 1 of 25 collectors has one; it may take a year to find an example in the marketplace.
• RRR = Very Rare - only a few known to collectors; may be several years before it comes up for sale.
• RRRR = Extremely Rare - a museum piece; unlikely that an example will come up for sale.