Skip to main content

Archives at The Museum of Flight

Series I. Lear Developments, 1907-1944, 1979, undated

Series I: Lear Developments provides insight into one of WPL’s earliest companies, Lear Developments, whose main focus was aircraft radio development and production. The company was established in 1931 and continued through 1939, when it changed its name to Lear Avia Inc. The series includes materials from the lifespan of the company as well as collected items dating earlier and some items dated later due to the restructure.

The series is broken down into eight subseries: administrative records, correspondence, financial records, legal records, photographs, publicity materials, research materials, and technical files. Some series are further subdivided for clarity and are detailed below. Materials are generally, but not always, arranged by date, with undated items at the end of each series. When able, circa dates have been provided.

Note that some folders are specifically marked as “[RM files]” by the Processing Archivist. These are the former office files of Richard Marsen, patent attorney and engineer for Lear Development. Because Marsen was involved in many different areas of the business, the folders were integrated into the appropriate subseries rather than left as a stand-alone series.

Subseries A: Administrative records holds only a small amount of correspondence and an undated map of Roosevelt Field that shows the location of Learadio Laboratories.

Subseries B: Correspondence contains assorted general correspondence, primarily from Richard Marsen to assorted Lear Developments employees, including WPL. Topics cover the day-to-day business, financial matters, patent processes, and ongoing work matters in all areas. Also included is a small batch of correspondence from May – October 1938 between WPL and Cass Hough in which the men discuss the installation, troubleshooting and payment for Lear Developments products, including WPL’s first radio compass installation. Included with these letters is a 1979 note from Hough to MOL referencing the older correspondence hoping she will “get a laugh” from it.

Subseries C: Financial records includes a few files from late in the company’s history: balance sheets, disbursement statements, and a license agreement between AT&T and Lear Developments.

Subseries D: Legal records is further divided into two subseries; legal cases and patent documents. Legal cases is comprised of a small amount of material from 1939-1940 related to the possible infringement around the Learadio streamline loop antenna. Patent documents, the largest of the subseries, includes patent applications, primarily by WPL; correspondence between patent attorney Gordon Scheibell, his partner Irl Goshaw, and Lear Developments personnel regarding patent applications; patent case assignments; and progress reports. It appears Scheibell may have passed away around 1938 and was succeeded by Marsen as evidenced by a power of attorney change and notice of estate closure. Of particular note is the patent application for the Model L radio compass, which Lear Developments marketed as the “Lear-O-Scope.” It was the first radio compass marketed towards non-commercial pilots and was used by Amelia Earhart in a record-breaking flight from Mexico City to New York.

Subseries E: Photographs contains 151 black-and-white photographic prints, primarily 8x10”. Seven prints depict aircraft and cockpit panels with Lear equipment, including the installation of the Lear-O-Scope on a TWA plane that flew coast to coast in just 11 hours and five minutes on April 30, 1935. Eighty-eight images depict assorted Lear Developments company products and parts. Identified items include the first car radio, the T-40 transmitter, the loop antenna, the hand reel, the antenna reel, T-30 and R-3 equipment, and the Lear-O-Scope. Seventeen prints feature company facilities and personnel, such as a work loft in New York that both WPL and Lear Developments shared with Fred Link, a staff group portrait at the Garden City, Long Island facility, and the outdoors testing of a portable unit, likely also at Garden City. Thirty-nine prints depict WPL with company products, primarily the Lear-O-Scope, but also the Radio-Aire, an early version of a dry battery radio transmitter and receiver. He is also pictured in or near aircraft, including a Monocoupe and Waco Model UIC, which have Lear Developments products installed. One image shows him with Clarence Clabaugh, one of the pilots who taught him to fly.

Some images do have identifying information, such as date, location, and names, but most do not. Some duplication occurs. While the bulk of photographs are found within this subseries, note that some photographs and negatives are also present in other subseries, usually in context with a press release or product information, and are noted when included in other folders.

Subseries F: Publicity materials includes product brochures, such as for the ARC-6 radio compass, the AMRL-1 marine radio direction finder, and an automatic landing field orientation device, among others. Also included are price lists, parts catalogs, and the company logo. One letter of note from Richard Marsen to Lear suggests using a more general tone (instead of a technical one) when announcing products in order to protect patents. The Learadio airport localizer is represented in this series with a Library of Congress certificate of copyright for the publication a diagram, correspondence, and clipping.

Subseries G: Research materials features items that were created by other companies used by LD staff to inform manufacture and/or design of Lear Developments products. Types of material include correspondence, diagrams, articles, and reports on wireless telegraphy, Sperry Gyroscope’s aircraft “homing device,” and tensioning devices. Also included are unsigned blank license agreements between contemporaneous companies, possibly used as templates for Lear license agreements.

The final subseries, Subseries H: Technical files consists of documents created in the course of product development by Lear Developments. Materials include instruction manuals and specifications for the Lear-O-Scope, T-120 transmitter, R-3 receiver, Unihand reel, and the ARL-48 motor reel. Also included are assorted technical diagrams, notes and sketches as well as notes on the ADF-6; an AMR-1 wiring diagram, and a letter to WPL from Richard Marsen discussing the radio altimeter and its use with the blind landing approach system.


  • 1907-1944, 1979, undated

Language of the Materials

Most materials are in English, but some materials are in other languages, including Bengali, French, German, Italian, Japanese, Romanian, and Spanish. When non-English language materials are present, it is noted on the individual folder.

Conditions Governing Access

A computer hard drive is not accessible, pending digital preservation procedures. The rest of the collection is open for research and is accessible in the Dahlberg Research Center by appointment. For more information contact us.


From the Collection: 285 Cubic Feet (190 legal size full-width document boxes (15 ½” x 10 ¼” x 5”), 2 legal size half-width document boxes (15 ½” x 10 ¼” x 2 ½”), 6 record cartons, 2 card boxes (12” x 4 ½” x 5 ½”), 9 oversize boxes (19” x 4” x 15”), 7 oversize boxes (20 ½” x 3" x 16 ½”), 7 oversize boxes (24 ½”x 3” x 20 ½”), 2 oversize boxes (40” x 2 ½” x 32”), 9 oversize rolled storage boxes (40” x 9” x 9”), 21 oversize folders (30” x 40”), 50 oversize folders (35 ¾” x 47 ¾”), 1 oversize folder (24” x 75”), 38 bagged rolled storage (60” x 5” x 5”), 1 Quadruplex tape (15 ¼” x 15 ½” x 3"))

The Museum of Flight | 9404 E. Marginal Way South | Seattle WA 98108-4097 | 206-764-5874
Contact us with a research request