AMAZON VIDEO DEPICTION
You've probably seen the Amazon conceptual video where a small drone helicopter swoops down onto someone's driveway or backyard, lands, releases a small package, and takes off. Then the resident comes out and claims his package.
Well, I don't know about you, but I do not think it likely that we'll see this type of drone helicopter flying at ground level in residential neighborhoods, given the fact it has sharp, rapidly spinning rotors, exposed on each side and at a perfect height to injure any person or pet who happens to be in the way.
There is great danger in having any aircraft flying below tree or rooftop level except at an airport or helicopter landing pad!
Imagine a distracted motorist swerving into pedestrians or other cars when the Amazon Prime Air helo zooms across the street and lands on someone's lawn! Or some resident who comes out to claim his or her package and gets nicked by the helo rotor as it takes off. And what about the danger of the drone getting snagged by the branches of a tree, or a fence, or a troublemaker seizing it just for fun?
A BETTER CONCEPT (IMHO)
As illustrated in the above image, I think it makes much more sense for the drone aircraft to hover above tree and rooftop level and use a cable to lower the package to the customer's driveway or backyard, or to the flat roof of an apartment house or office building. Don't you?
Once the package is safely on the ground, an automated hook will release it and the cable will be pulled back up to the drone. This kind of implementation would allow the safe use of larger drones, with the capability to carry larger packages or multiple packages, more economically.
If the hook or cable gets tangled in a tree or fence, or grabbed by some troublemaker, it could be automatically detached at the drone end, and the drone could safely fly away. The company would send out a crew to retrieve the cable, and, if it was a troublemaker, summon the police.
EVERYTHING OLD IS NEW AGAIN
As the song says, "No need to remember when/'Cause everything old is new again". Many years ago, some rural towns in Australia got their mail and small packages via a fixed-wing aircraft that loitered in a tight orbit and lowered a basket on a cable. The locals would retrieve the incoming mail, and place outgoing mail in the basket, as depicted in the image below. (I have not been able to locate any information on the Internet about this method of air delivery and would appreciate it if anyone can supply more specific information or, even better, a photograph.)
The image above, showing the Kaman K-Max carrying a heavy tethered load, is from this video. According to the video, there is an unmanned version of this helicopter and some of the systems work for this project is being done at my old work location, Owego, NY (now Lockheed-Martin).
According to Wikipedia this helicopter "can be used in combat to deliver supplies to the battlefield, as well as civilian situations involving chemical, biological, or radiological hazards".