Working with John Boyd and Thomas P. Christie at the Pentagon, he was associated with the self-dubbed 'Fighter Mafia', which advocated the use of energy–maneuverability theory in fighter jet design.

[8][9][10] Sprey would also became friends with Avery Kay, with whom he was involved with work on design concepts for a large caliber ground attack aircraft that would result in the A-10.

[12][13][14] Sprey also expressed his dissatisfaction with the size and complexity of the A-10, proposing a concept he called a blitzfighter, an extremely small aircraft with a cannon and no other armaments.

[16] He claimed that the F-35 is a poor replacement for the A-10 in the close air support (CAS) role, alleging it flies too fast for pilots to spot targets by eye and lacks maneuverability at low speeds,[17] lacks the necessary radios,[18] cannot survive small arms fire (or anti-aircraft guns), and has poor loiter time.

[20] Sprey was interviewed about his views of the F-35 multiple times: by the popular press,[21][22] on the politics and policy news network C-SPAN,[23] and at a meeting of the activist group "Stop the F-35".