C3-1 (Approved Type Certificate (ATC) 71)1928 125 horsepower Ryan-Siemens Sh-14 7 cylinder radial - 15+ built Juptner, 1962, p.180-182 Some sources suggest over 100 of the Ryan-Siemens powered C3s were built, however surviving records do not bear this out, per Juptner, 1964, p.278.