This project is mentioned in the Wikipedia page ("Project 1794")--it actually predates the Avrocar. The attitude/flight control design was slightly different: where the Avrocar had an asymmetrical rotating ring around the edge to provide attitude control, the earlier design used thrust vector nozzles like those used in the Harrier and F-35.
It seemed the project failed due to engineering problems unrelated to the design: it had oil leaks, and at one point an engine broke free from the aircraft and launched off on its own, endangering the test engineers.
Had these unrelated problems not occurred, it's possible that they could have succeeded where the later Avrocar failed, since the control principles in the earlier project were sound and eventually successfully used in modern VTOL aircraft.
It seemed the project failed due to engineering problems unrelated to the design: it had oil leaks, and at one point an engine broke free from the aircraft and launched off on its own, endangering the test engineers.
Had these unrelated problems not occurred, it's possible that they could have succeeded where the later Avrocar failed, since the control principles in the earlier project were sound and eventually successfully used in modern VTOL aircraft.