This 1953 NACA High-Speed Flight Research Station photograph shows the wing chord extensions added to D-558-2 #3. The added width on the outer wing panels was one attempt made to solve the tendence of the D-558-2 aircraft to “pitch-up” during flight. Other modifications tested included fixed and free-floating slats, one- or two-wing fences, and a slat and wing fence. None of these additions proved truly effective, and the chord extension actually aggravated the pitch-up. The research program nevertheless added greatly to the store of knowledge about how to deal with pitch-up (as well as how not to deal with it, itself valuable information). The best solution was to place the horizontal stabilizer low on the aft fuselage, where it would be below the downwash from the wing and the wing wake.