The Miller M-5 Belly Flopper was a 1940s American homebuilt aircraft. Its most notable feature was that the pilot flew in the prone position.
It was designed and built by Ervin A. Miller of Milwaukee, Wisconsin during the 1940s. The aircraft was a single-seat, low-wing cantilever monoplane. The pilot lay prone within a fully enclosed fuselage, the front of which was fitted with a transparent dome. The aircraft was equipped with a pair of Continental A40 engines, which powered two two-bladed propellers. There was a fixed conventional undercarriage, and a cruciform tail. The aircraft was given the FAA registration of N29113.
The M-5 first flew in 1946. It was reported that the airplane had accrued 300 hours of flight time. Miller sold the aircraft, and the new owner destroyed it in a crash.