Concorde is one of only two supersonic jetliner models to operate commercially; the other is the Soviet-built Tupolev Tu-144, which operated in the late 1970s.[277][278] The Tu-144 was nicknamed "Concordski" by Western European journalists for its outward similarity to Concorde.[279] It had been alleged that Soviet espionage efforts had resulted in the theft of Concorde blueprints, supposedly to assist in the design of the Tu-144.[280] As a result of a rushed development programme, the first Tu-144 prototype was substantially different from the preproduction machines, but both were cruder than Concorde. The Tu-144S had a significantly shorter range than Concorde. Jean Rech, Sud Aviation, attributed this to two things,[281] a very heavy powerplant with an intake twice as long as that on Concorde, and low-bypass turbofan engines with too-high a bypass ratio which needed afterburning for cruise.