{"nrhp_refnum":"85002795","name":"Variable Density Tunnel","other_names":[],"category":"structure","location":{"address":"Langley Research Center","address_restricted":false,"city":"Hampton (Independent City)","county":"Hampton","state":"VA","lat":37.07880417300004,"lon":-76.34381827699997,"geom_source":"nps_gis"},"listed_date":"1985-10-03","is_nhl":true,"nhl_designated_date":"1985-10-03","areas_of_significance":["Other","Engineering","Science"],"significance_levels":["national"],"summary":{"what_it_is":"A riveted steel pressure tank housing a wind tunnel, located in Building 582 in the East Area of the Langley Research Center in Hampton, Virginia. It was built from 1921 to 1923 for the National Advisory Committee for Aeronautics (NACA).","why_significant":"The nomination argues that the tunnel was the first facility to establish NACA as a technically competent research organization. By varying air pressure, it let engineers match full-scale flight conditions using small scale models. Its data fed into designs of aircraft such as the DC-3, B-17 and P-38.","narrative":"Inside Building 582 at NASA's Langley Research Center in Hampton, Virginia, a large steel pressure tank holds the Variable Density Tunnel, built between 1921 and 1923 for the National Advisory Committee for Aeronautics. Newport News Shipbuilding & Dry Dock Co. made the riveted tank, which is 34.5 feet long and 15 feet in diameter and built to withstand 21 atmospheres. Its purpose was to solve a problem in aircraft testing: results from scale models in ordinary wind tunnels did not match full-size flight because the Reynolds number differed. Compressing the air let a small model reproduce full-scale conditions. Max Munk, a NACA technical assistant, advocated the concept. The tunnel gave NACA a research tool superior to any elsewhere, and its data on 78 airfoil sections influenced aircraft such as the DC-3, B-17 and P-38. A fire damaged the interior in 1927, and it was rebuilt by 1930. It was declared potentially unsafe in 1978 and now sits unused.","period_of_significance":"1921-1940","architect_builder":"Max Munk","architectural_style":null,"criteria":[],"status_note":"Basic structure remains intact; declared potentially unsafe for operations in 1978, with no plans for its use. Present use is listed as abandoned.","vacant_flag":true,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:51:57.143996-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/45/6790/41679045/content/electronic-records/rg-079/NPS_VA/85002795_NHL.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/85002795/7a433504ff-800.webp","url_1600":"https://nationalhistoricalregister.com/media/85002795/7a433504ff-1600.webp","licence":"Public domain","author":"NACA","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Variable_Density_Wind_Tunnel_-_GPN-2000-001242.jpg\" rel=\"noopener\">NACA</a>, Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Variable_Density_Wind_Tunnel_-_GPN-2000-001242.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/41679045","wikipedia":"https://en.wikipedia.org/wiki/Variable_Density_Tunnel","wikidata":"https://www.wikidata.org/wiki/Q7915697"},"indexable":true,"url":"https://nationalhistoricalregister.com/virginia/hampton/variable-density-tunnel-85002795/"}