At the University of Michigan, Johnson conducted wind tunnel tests of Lockheed's proposed Model 10 airliner. He found the aircraft did not have adequate directional stability, but his professor felt it did and told Lockheed so. Upon completing his master's degree in 1933, Johnson joined Lockheed as a tool designer on a salary of $83 a month. Shortly after starting, Johnson convinced Hall Hibbard, the chief Engineer, the Model 10 was unstable. Hibbard sent Johnson back to Michigan to conduct more tests. Johnson eventually made multiple changes to the wind tunnel model, including adding an "H" tail, to address the Problem. Lockheed accepted Johnson's suggestions and the Model 10 went on to be a success. This brought Johnson to the attention of company management, and he was promoted to aeronautical Engineer.