The unusual delta aircraft is the Heuberger-Rinker H-5 Stinger and love it that that this one-of-a-kind aircraft still exists in pretty good condition, Did you notice any registration? (it originally was N3638G). The Stinger was an original design of Mr. Larry (Lawrence K) Heuberger who started construction around the early-1960s. Prior completion the project was acquired (around 1968) by Mr.
Bud Rinker (Santa Barbara, Ca) who almost certainly did some limited testing in 1970.
Some details: Two-seat and one 140hp Lycoming O-290-G engine.
wingspan 16ft 6 inch, length 14ft 8 inch
Theoretical max. speed 180 mph, cruise 160 mph, ceiling 10,500ft and climbrate 1.200ft/minute.
Sorry no info on the twin Ercoupe
Regards, Walter (van Tilborg) from the Netherlands