| 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 |
| Thumbnail (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. |