The files given
here were provided by Gene Rock (rchopper56@aol.com),
who reports coming across the Chupp Roto-Flyer in 1996 - the original seems
to date from the '40s. He has documented it in the form of these excellent
plans. The original Chupp Rotor was supposedly a stable flyer, however,
Gene reports that his model, built to the plans though with a few short-cuts,
requires a steady wind.
The plans are provided as a CADKEY file (right-click on the link to download, then unzip), which may be viewed, scaled and printed with the free CADKEY viewer. Alternatively, they may be viewed and printed as a PDF file, scaled for printing on A4 paper. But you will do best to print it on a laser printer and enlarge it on a photocopier.
Assembly instructions are given in PDF format.
Adi Shavit has details of the original Chupp patent (long since expired) on his Kite Patent Blog.