Drone Parasail

What seems confusing is the weight to sail area variability of the scaling down in size...a 10mph gust of wind at one size scale, is not the same as a smaller scale version, and speed to remain aloft comes into question regarding sail area vs weight relationship to thrust requirement....It would seem that the attitude controls would need to be quick and possibly auto computer controlled...What are your thoughts on this?....if you have any....

I see some simple modifications to some existing model rocketry designs that might be a good, frugal place to start exploring this idea.

It sounds like it should work.

With either a parasail or quadrotors, lift is generated by directing air downward. You can either push a little air down fast with a quadrotor or a lot of air down slowly with a parafoil to get the same lift. Lift is proportional to v² but the amount of power consumed is proportional to v³ so that a large airfoil is indeed more efficient than quadrotors.

The trick is going to be converting from "drone mode" to "hang glider mode". Maybe the drone can lift the parasail up to altitude and then fly around underneath it. Once it is suspended, it can rotate so it is facing forward. There is no reason it cannot maintain that orientation just as it maintains a horizontal orientation normally.

You'll probably need ducts around the fans to keep the lines to the parasail safe.

This appears to be a complex solution without a corresponding problem. This has already been done with small blimp shaped helium balloons so there is neither a need nor a market. You must have forward motion to deploy the parasail and that provides the lift, so why would you need the quad rotors? Vertical take off is not an option because the weight of the sail will flip the quad assembly. If you are insistent on making this drone, just scale down the existing powered parasail design and replace the pilot with controls that allow you to operate it from the ground.

This would be for surveillance, rapidly flying around and spotting a target of interest, then powering down for prolonged flight to observe the target, then jettison the sail and rapidly flying back...