3 decal variants:
1. Messerschmitt Bf 109X, experimental prototype, Luftwaffe, 1940 /alternate marking/
2. Messerschmitt Bf 109X, Luftwaffe, 1941 /alternate marking/
3. Messerschmitt Bf 109X, Slovak A.F., 1941 /alternate marking/
A new forward fuselage was designed from frame no.6 forwards, enabling the fitting of the radial engine. A new full vision "bubble" canopy was fitted. The aircraft flew in 1939. The second radial engined 109 was a modified F-1 airframe, fitted with a fuselage similar to the V-21 with the BMW 139 engine. The Me-109X used the BMW 801 however. The aircraft flew in September 1940 and was tested by the RLM. The RLM decided however that the FW-190 was performing well and that there was no need for a similar powered fighter. Therefore the program was ended in 1941.