The need for a new easy impact machine for the Soviet Air Forces appeared in the second half of 1960-s when the military and political leadership of the country had to draw a conclusion that, besides a general missile - nuclear war with the USA, the USSR should be also aware of local conflicts with use of the ordinary weapon.
Meanwhile experience of wars in Vietnam, Hindustan and the Near East testified that the Air Forces require, first of all, rather easy impact plane which is able to operate over a line of contact of ground forces, to struggle with tanks and other mobile targets, to strike impacts in close rear of the enemy, to strike its communications, isolating a battlefield from the approach of the enemy reserves. Such plane should have carried a big number of freely - fallen bombs of a small caliber (in fact to destroy an enemy tank or an automobile is not necessary to have "500". It will be enough to have ammunition of caliber 50-100 kg). It was necessary for a new fighter- bomber to have an improved review forward - downwards allowing a pilot to find out independently small sized ground targets. Besides the plane should have carried perspective equipment and arms, in particular - aim - navigating system, a laser range finder and guided missiles of a class air -to- surface.
As well as MiG- 23B, a plane MiG- 27 intended for actions on the stationary and mobile ground targets. Bombing was carried out even during absence of visibility of the target, including during complicated kinds of maneuver. The opportunity of using of two various kinds of weapon in one approach was provided. Repeated automatic approach on the target was supposed also because its coordinates "were reordered" by an onboard computer.
Fighting survivability of MiG- 27, besides installation of armored overlays (as well as for MiG- 23?) on each side of cabin of the pilot was increased due to forced aspiration of fuel tanks by neutral gas (this innovation was fulfilled for MiG- 23?? for the first time ).
In 1973 the first fighter - bomber MiG- 27raised in 1974 in air by pilot - verifier V.E.Menitskii was constructed. The serial production of MiG- 27 began at Irkutsk an aircraft factory in 1973 and proceeded till 1977. All 560 planes of this type were made.
MiG- 27 became one of the most mass and successful planes of domestic tactical aircraft and began to be issued on license abroad. The wing of changeable geometry which was accepted as rather disputable innovation on a fighter the Instant - 23 appeared to be more suitable in a design of the tactical impact plane optimized for flights at small altitude and basing at front air stations with Ascent Landing Band (VPP) of the limited length. MiG- 27 got on arms a missile UR of a class air -to- surface X-23 (?-23?) with radiocommand system of aiming that increased opportunities of the plane on struggle with small ground targets. Among the advantages of this missile, in comparison with previous X-66, was the opportunity to strike the enemy not only from a diving, but also in a horizontal flight. Besides new UR had the increased accuracy. As to the disadvantages of X-23 (and of other tactical missiles of a class air -to- surface of the first generation) they are low noise immunity of channels of the communication line, necessity of practically straight-line flight of the plane from the moment of start before undermining of Fighting Part (BC), impossibility of battery launch, and also strong dependence of results of shooting on qualification of the pilot.
MiG- 27 could place up to three pendant fuel tanks by capacity of 790 l on two underwing and under-fuselage unit of a suspension bracket. The design of a glider remained practically constant, that provided excellent access to the weapon and simplified the decision of a problem of cooling of the block of the trunks.
