| Name and Model Number | Hoffman Airplane Designer No. 458 |
| Country of Origin | USA |
| Date of Manufacture | c. WW I |
| Front Scales | 25 various |
| Back Scales | none |
| Scale Length | Varies |
| Type of Rule | Disc |
| Construction | Printed cardboard, celluloid indicator |
| Area of Use | Aviation |
| Comment | For calculations related to the design of biplane aircraft, No. 458, price $3.50.
Appears to be for military biplanes; includes information for machine gun, ammunition, and gun turret weights. Will calculate 33 different components of airplane construction and performance. |
| Rarity | RRRR |
| Donor | Collection of Mike Frey |
| Match Number | 231 |
| 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. |