????? ??? ???? ???? ???? ?? ???????? ???? ??? ???? ??? ???? ???? ???? ???? ??????? ???? ??????? ???? ?????? ?????.??? ??? ????? ?? ???????? ?? ??? ?? ??? ???? ????? ???? ???? ?????? ???????????? ????? ?????? ?? ????? ?? ????? ??????? ???? ????????? ?? ???? ??????? ??????? ?????? ????? ???????.Most plane engines are either lightweight reciprocating