If air taxi services ever take off, you might want to hold onto your hat very firmly. A new FAA report looking at various eVTOL prototypes shows that when they take off and land they have a downwash from rotors equivalent to hurricane-force wind.

Film buffs may remember the opening of the 1965 musical The Sound of Music where the camera swoops over the Austrian alps and zeros in on a distant Julie Andrews dancing in a mountain meadow. What was edited out was Miss Andrews getting knocked on her backside, thanks to the downwash from the camera helicopter.

These DownWash and OutWash (DWOW) effects are notorious for helicopters and are one of a number of reasons why helicopter air taxi services have never been very successful. Since eVTOLs are governed by the same laws of physics as helicopters, the US FAA is very interested in learning as much as possible about the DWOW effects of the new aircraft being developed for what is hoped will be the first truly successful air taxis.