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PFI 1972 - February - Preliminary Designs

Preliminary design was performed in 4 books. The first contained the basic information: a summary of the prepared plane and its flight characteristics, study the dimension of the aircraft, the lists of installed equipment, some data on the combat capabilities and the general concept underlying the during its development. The second book contained data on the composition of the special equipment and weapons, the third - data about aerodynamics, and the fourth - on the design and on-board aircraft systems.

Given in the preliminary design of parametric calculations takeoff weight change gradients justify the need for strictly keeping the weight limits when designing the new aircraft. For example, it was found that the weight increase of only 1 kg in avionics increased takeoff weight of the aircraft by an average of 9 kg, the gradient for the engine is equal to 4 kg and for aircraft systems - 6.7 kg. In this regard, it stressed that carrying out tough policies to create a weight PFI should be the responsibility of not only General Designer, but the main designers of the aircraft, at all levels of cooperation.

Materials included preliminary design study of both aircraft layout options and integrated traditional. The initial data common to both layout variants, was the value of the take-off weight of 18 tons, installed TTZ, and selected on the basis of the analysis of the required level of flight performance, the starting values of the parameters (takeoff) thrust-weight ratio equal to 1.15 and a specific wing loading of 350 kg / m g. Usually, due to the long manufacturing cycle test models and, in step the materials cited in the preliminary design data obtained only on the basis of aerodynamic characteristics calculations. In this case, the calculation for both LTH layout options have been based on data obtained as a result of purging models in the wind tunnel of TsAGI.

It is interesting to note that all the flight characteristics of the aircraft were calculated for the version with the "truncated" combat load in the 2 medium-range missiles and six short-range missiles, which was explained by the complexity of the implementation of the requirements of the TTZ range.

So, in February 1972, preliminary design of the Su-27 was presented for consideration by the court. These proposals were presented and other participants of the competition. Complete armament of the Su-27, in accordance with the recommendations NIIAS, included up to 6 SD-class "air-air" medium (such as K-25 or K-23) and up to 6 SD small (K-60) range in a variety of possible combinations and built-in gun AO-17A with 250 rounds ammunition.

OKB Mikoyan opted for aircraft smaller dimension. The project is a light fighter MiG-29A provided, in accordance with the recommendations of the TsAGI, the creation of a normal scheme of the aircraft with a wing of moderate sweep, flat side adjustable air intakes and two engines R67-300 with a thrust in afterburner at 7500 kg. Normal take-off weight of the aircraft with acceptance option arms (2 SD medium-range K-25, UR 4 short-range type K-60 and gun ammunition 150 rounds) was 13,750 kg, while providing a starting thrust-weight ratio of 1.1.

Projects Yak-45I and the Yak-47 only differed in dimensions, the layout of both aircraft were almost identical. The Yak-45I provided for the installation of two engines R53F-300 with afterburner thrust of 8,200 kg, while the Yak-47 - with two engines R57F2-300 thrust in afterburner at 12500 kg. Normal take-off weight with acceptance option of weapons for the Yak-45I was 13,900 kg, and for the Yak-47 - 22800 kg, starting thrust-weight ratio - 1.17 and 1.1 respectively.

The Yak-45I and Yak-47 did not receive a positive recommendation. In the choice between the MiG-29 and Su-27 the customer did not say categorically what the plane was preferred - for the right of final selection, scientists had provided input to the Air Force commission.

The TsAGI generalized conclusion on all three projects OKB was signed June 29, 1972. Presumably, such a later date issue a report was due to the fact that the MAP and the Air Force needed to finalize all the details between themselves agreements on PFI program division into two separate directions.