One of the Air Trails descendants (Air Trails Hobbies for Young Men?) had an article and an interview with the designer in the 50s. Nice picture on the cover, too. I think there was a kit, possibly by Berkely for a CL/FF/RC version that may not have sold well. There have also been several plans published, mostly controline, using the principal.

A later article on the concept said the main problem with the idea was the uneven loading on the props and subsequent high vibration with one blade in the channel area and the other in open air damaging to wood props, and also to the engine bearings and mounting structure.

Thinking back to the original article, I think the designer spent a lot of time explaining that "Nature abhors a vacuum", and may have mistated some Bernoulli theorems in the interview. Might have helped reduce the take off run by a couple yards, but that was the designer's subjective opinion, and may never have actually been objectively measured.