The J-3 Kitten is a cub inspired US Ultralight with an empty weight of under 254 Lbs. It features a single seat and tube and fabric construction. First Flight was in 1986.
Power comes from a Rotax 277 / 28 hp or similar power.
Plans are still available on: https://buildandfly.shop/product/j3-kitten/
The J-3 Kitten has decent YouTube coverage:
For RC options Outerzone has one hit on the search:
https://outerzone.co.uk/plan_details.asp?ID=14993
No hits directly for the J-3 Kitten but plenty for the J3 Cub
J-3 Cub Airplane “Live to Fly” Vintage Pilot T-shirt T-Shirt
J3 RC Plane, 5 Channel RC Airplane
J-3 Cub Pilot Front with Floats Vinyl Sticker
Gould Aero 