Air & Space Magazine Vortex Studies A Learjet and a Cessna T-37 chase a Boeing B-747 to investigate its vortex trails, made visible with smoke generators, in the sky over NASA’s Dryden (now Armstrong) Flight Research Center in 1974. NASA September 17, 2014 ShareCopy linkEmailSMSFacebookXRedditLinkedInBlueskyPrintAdd as preferred source You Might Also Like Gravity Testing July 22, 2013 Milestone Earth Viewing July 25, 2014 Typhoon Season May 25, 2016 Sewing the Sunshade July 8, 2016 Eyes on the Earth December 15, 2011 Get the latest stories in your inbox every weekday. Email Powered by Salesforce Marketing Cloud (Privacy Notice / Terms & Conditions)