M-55 supersonic passenger planehttp://alternathistory.com/m-55-sverkhzvukovoi-passazhirskii-samolet
"late in 1959 OKB V.m. Myasischev studies on passenger sverhzvukovomu launched the "55".
Study several options showed that the most appropriate variant based on the m-50 bomber with M16-17. But already in the following year over the preferred layout by type of aircraft considered m-56 bomber.
In fact, it was the development of the project "53(bottom two pictures)".
Considered 3 options:
: designed to 40 passengers, had two engines
: designed to 85 passengers, had four engines
(Top picture? This design seems to have 4 engines. Air intake shape is little different compared with "53" SST, and this design had a single vertical tail stabilizer.)
: high-wing monoplane with a forward horizontal plumage. Under the triangular wing,
on the sides of the fuselage in two packages were placed six engines
The plane was calculated at the speed of 2300-2650 km/h at altitudes of up to 22 km. In the shipping version (takeoff weight 245 t) he could be operated on routes with a length of 6000-6500 km with 5% fuel. While the total number of passengers must not exceed 50. Takeoff was 3500 m, mileage-1500-1700 m With 100-120 passengers was within the range 3500-4000 km.
These were the first in the USSR passenger supersonic aircraft projects. Low aerodynamic airframe and high unit costs of fuel engines prevented the boundary of 1950-60-ies to create a supersonic airliner, competitive dozvukovym machines."
Bottom drawing shows M-55B which Triton-san already showed us.http://www.secretprojects.co.uk/forum/index.php/topic,3767.0.html
So 55A is mystery.