R4D SkytrainThis Photograph taken in 1956 shows the first of three R4D Skytrain aircraft on the ramp behind the NACA High-Speed...This photograph taken in 1956 shows the first of three R4D Skytrain aircraft on the ramp behind the NACA High-Speed...NASA Flight Research Center's Douglas R4D-5/C-47H (Bu. No. 17136) in flight, with its landing gear extended, in 1963.
