I think it says he designed it in this book: Stalking Louis Curtiss, by Wilda Sandy and Larry Hancks, which is available at the KC public library. I haven't looked at that book in a long time, so I don't know if they provide a lot of references in the end notes, and used Curtiss' papers to document it.
Curtiss' papers are kept at the Kenneth Spencer Research Library Archival Collections at the University of Kansas.