Strategic placement of the rotors in a non-planar configuration in a multirotor vehicle can improve power efficiency. We extend our wind tunnel study on the investigation of the negatively staggered tandem propeller performance, aiming to validate the results through flight tests. The previous study conducted at the University of Dayton Low Speed Wind Tunnel (UD-LSWT) showed a power-saving benefit for the negatively staggered propeller configuration. An in-house-built flight test platform with various vertical propeller displacements was designed, built, and flown successfully in the current study. Flight test data confirmed up to 18% power saving for the negatively staggered propeller configuration when compared to the traditional non-staggered configuration, indicating the potential of the negatively staggered propeller configuration for practical applications. Furthermore, flight test data indicated that, at vertical offsets above 0.2dz, any increased power saving is minimal.