Complex sentence: To boost take-off performance two JATO bottles could be attached to the rear fuselage, performance was also improved when Lyulka AL-5F (forseerovannyy-afterburning) engines were fitted.
Split into simpler sentences: To boost takeoff performance, two JATO bottles could be attached to the rear fuselage. Performance was also improved when Lyulka AL-5F (forseerovannyy-afterburning) engines were fitted.