| Name and Model Number | Russian Pilot's Slide Rule NL-7 |
| Country of Origin | Soviet Union |
| Date of Manufacture | 1937 |
| Front Scales | Different scales needed in aviation |
| Back Scales | Different scales needed in aviation |
| Scale Length | Scales of variable lengths, length of the slide rule 21 cm |
| Type of Rule | Slide Rule |
| Construction | Celluloid on wood |
| Area of Use | Aviation |
| Comment | The first version of Soviet pilot rule was originally designed by L. S. Popov in 1927 and the last version NL-10u was introduced as late as 1978. This NL-7 (Navigatsionnaya Linejka) was produced in Leningrad at Prometei factory of Latvian cultural-educational society Prometejs. As explained in the user handbook Nikol'skoi M.N. & Blinov V. Ya.: Aeronavigatsionnaya linejka, 1939, 88 p., which can be uploaded at http://www.amyat.narod.ru/theory/nl/nl.djvu , following operations can be performed: a) normal arithmetic and trigonometric calculations, b) navigational calculations, c) bombing calculations, d) photogrammetric calculations. See also Leipälä Timo: Soviet Prometei slide rules 1931–1937 at http://www.rechenschieber.org/BochumPrometeirevised2013.pdf and Kormashov V.A.: Navigatsionnaya schetnaya linejka NL-10, 1956, 100 p., the reprint of which can be bought from Amazon. |
| Rarity | RR |
| Donor | Collection of Timo Leipälä |
| Match Number | 397 |
| 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. |