The "Tommy" advanced biplane trainer was built in the US but was the brainchild of former Sopwith designer Benjamin Thomas. Most of the S4Cs had LeRhone C-9 engines in place of the original Gnome rotary.
Surplus S4Cs saw much use as barnstormers, as their large control surfaces and low wing loading made for sporty handling. The S-4E single seat derivative was lighter with a smaller wing, while the S5 trainer also shared the S4C's lines.
Photo: Frontal view of an S4C, front quarter shot of an S-6. Aviation April 1, 1919
Photo: Rear quarter view of a Thomas-Morse MB-3 fighter biplane. Aviation March 15, 1919 p.214
An RC conversion of the Guillows S4C kit