The Thorp T-18 was designed in 1963 and is still a common home-built aircraft to see at airshows like Airventure & Sun-N-Fun. Over 400 examples have flown.
John Thorp the designer worked on many aircraft during his career i`ncluding the Piper PA-28 Cherokee series.
The T-18 was originally an open cockpit aircraft powered by a 0-290G ground power unit. But evolved into a closed cockpit with a O-360 for power.
It paved the way for the Van’s RV series of kitplanes. Used T-18 finished aircraft and projects come up from time to time. kits / plans are are difficult to see if they are still around. One resource is: https://www.homebuilt.org/kits/elkund/elkund2.html
A few other websites to check out:
https://www.eaa.org/eaa/aircraft-building/kits-and-plans/t—z/thorp-t-18
A few YouTube videos on the aircraft:
Outerzone has 3 T-18 plan options for anyone looking to build a RC model.
https://outerzone.co.uk/plan_details.asp?ID=9236
https://outerzone.co.uk/plan_details.asp?ID=2403
https://outerzone.co.uk/plan_details.asp?ID=10701
Gould Aero 