Sukhoi T10-24

Purpose: To evaluate Su-27 foreplanes. Design Bureau: P O Sukhoi, Moscow, General Designer M P Simonov.

In 1977 Simonov authorised studies into the possibility of adding foreplanes (canard sur­faces) to the Su-27. Such surfaces appeared to offer improved controllability, especially in extreme manoeuvres at high AOA (angle of attack), when flight testing had shown that the tailerons were in the wake of the wing. Following tunnel testing of models work con­tinued in 1979 in collaboration with CAHI
(TsAGI). This research revealed that in some flight conditions there were longitudinal-con­trol problems. A canard system free from these problems was devised in 1982, and in May 1985 flight testing of the T10-24 began.

The Tl 0-24 was fitted with the PGO (Pered – neye Gorizontal’noye Opereniye, front hori­zontal tail). After prolonged research this was fitted not on the forward fuselage, as in most other canard aircraft, but to the leading edges of the modified centroplan (centre wing). The two surfaces had a cropped-delta plan shape, with a thickness/chord ratio of 3 per
cent, and they were mounted horizontally and pivoted at about 60 per cent root chord. They were driven by power units linked to the FBW flight-control system. Depending upon the flight regime they increased stability in pitch and roll and also instability in pitch. They significantly reduced trim drag, and they increased the maximum attainable lift coeffi­cient (at an AOA of 30°) from 1.75 to 2.1.

Testing the T10-24 substantiated the pre­dicted advantages and supported develop­ment of later fighters, beginning with the navalSu-27K.