It's a well known fact that the Yak was a straight copy of the Harvard, so an easy mistake to make, trashnav
Is it really a well known fact?
Apart from a radial-piston engine, low wing and a semi-elliptical fin I can't see many similarities. The Yak 52 was designed in the mid seventies, when Soviet mathematical aerodynamical modelling was a long way ahead of nascent US digital techniques - whereas the Harvard was designed in the 1940s with fairly primitive US aerodynamic modelling. And that's without even mentioning that the Harvard had a MTOW about five times higher than the Yak52...
FWIW, the Yak 52 is a superb aircraft that (as long as you can handle the oil consumption!) massively out-handles anything designed in the West during the 70s, thanks to exeptionial investment in mathematical modelling in the USSR. The Yak 52 must be one of the few piston aircraft ever designed that has the stability to be easily handed in IMC but still have the handling to be a world class aerobatic aircraft. It is definitely not a copy of the T-6!