I have been so impressed with my first version of this quad that I built a second one and on maiden, I would say it flies even better. Fast, smooth and agile, at the weekend just gone I flew alternate lipos on the other air-ro and a 5 inch racer, the air-ro made the 5 inch feel like a bus. Flight testing (first half is 3cell, second half is 4cell):

Edit build guide including wiring diagram and config, may be of use for beginners
https://www.electricwingman.com/img/cd/air-ro_builders_guide.pdf