We don't know how secret this was? Did the KGB / other spy orgs know? It's possible many UFO saucer sightings were test flights of this or similar craft. Al

We don't know how secret this was? Did the KGB / other spy orgs know? It's possible many UFO saucer sightings were test flights of this or similar craft. Also, I've heard of the Avro saucer car before.