First M-4 was flown on May 1, 1954. The aircraft went through a number of improvements with 201M being one of the more successful ones. M-4 set a world record by taking 55220 kg to the altitude of 13121 m on October 29, 1959. The fuselage is round with a large, swept tail fin, and a small canopy overlooking the pointed nose. A pair of jet engines is mounted on pylons under the wings with the second pair attached to the wingtips.
Tailplane is swept and tapered.
Main landing gear retracts into the fuselage with small support wheels retracting into the wingtips just inboard of the outside engines. It was first flown in 1961. 200000 kg Max.