The biggest challenge i see is the annoyance factor, but people have proven willing to put up with a fair bit of annoyance if it provides them with enough utility.
You mean like all of the cars and trucks that are rumbling around everywhere for no good reason? They roar around everywhere, are incredibly dangerous, require billions of dollars of government funded infrastructure, and destroy the environment. No one would ever allow them to become common, when we have such alternatives as walking, bikes, trains, and the like, right? They're just crazy inefficient; a bike is so much more energy efficient for a single person, and a train is faster, safer, and more efficient for moving large numbers around.
So yes, I think sans massive government corruption, we don't see these kinds of technologies that are intrusive and inefficient rising to prominence.
Also, trucks hit a technological sweet spot that I don't think drones sit in. They have predictable and easily controllable failure modes; they're always traveling at eye level where they're relatively (easier) to spot; they have relatively high transport capacity, enabling multiple visits; etc.
The problem with drones that replace trucks is that I'm not sure we've actually gained much by having flying trucks all over the place - the increase in delivery time (which I'm not sure would actually be very high in the average case) would easily be offset by the danger of many low flying trucks.
They may explain the US, although I doubt it. It doesn't explain literally every single other industrialized nation in the world, including the many ones without a powerful auto industry.
> They have predictable and easily controllable failure modes
So will drones, once they mature. And despite all the predictability and controllability, trucks still fall over or get themselves wedged under bridges etc, shutting down traffic for hours.
> they're always traveling at eye level where they're relatively (easier) to spot
Except when they're around a corner, and it's not much help to a cyclist about to be crushed by a turning truck.
> they have relatively high transport capacity
For drones to be competitive they will have to be competitive with this fact. If you're right, drones will never take off (pun intended). If you're wrong, you're wrong.
At 200ft with low KV motors and big props they are nearly silent or at least quiet enough that they blend into the background. If you fly following surface streets you remove a lot of the "drone falling on someone possibility" and insurance can handle damage to cars if something were to go wrong. Keep in mind they can also be fitted with parachutes and airbags that can be deployed for safety.
Right now the biggest holdbacks are losing GPS lock (flyaways are not fun) sense and avoid (don't hit stuff) and battery life.
You can easily build a multicopter with current tech able to fly 5km+ and back in under 10min (I've done it) the issue is that due to the weight of the batteries you don't end up with much payload left to speak of. As better battery tech is rolled out and other stated problems are solved drone based logistics will be viable, I give it 5 maybe 10 years max and am very bullish on it.
Are you expecting the drones to use hardened GPS modules resistant to hijacking and not get DDoS'd by someone broadcasting fake GPS at their take off area?
Aside from their main downside (energy density), which is improving each year and now reaching 265 Wh/g, electric batteries provide many improvements. First of all, electric motors are more efficient than gas-powered motors. Secondly, gas-powered motors are fairly heavy, so you need a bigger and thus more expensive quadcopter. Thirdly, it is difficult to control a gas-powered quadcopter at the speed of an electric quadcopter.
TL;DR It's possible but difficult to make a gas-powered quadcopter, since it'll be heavy and difficult to control. At that point, it doesn't make much sense to use a quadcopter, since two of their biggest advantages are how easy they are to control and how light they can be.
Also, it would make no sense for you to "DDoS" a GPS module. DDoS = distributed denial of service. You're probably thinking of jamming (broadcasting garbage data so the GPS can't receive anything) or spoofing (broadcasting fake data.)
I disagree with you there. Collective pitch quadcopters with combustion engines have been done. With CP quads you lose one benefit of traditional quadcopters, which is their simplicity (basically, they're four electric motors with a computer that tells each one how fast to spin), but that benefit is more applicable to hobbyists than to commercial package delivery.
Hold on, let me (get in my car/wait for the bus/walk a few miles/order it with my phone, take a nap, and wake up with it at my door).
http://en.wikipedia.org/wiki/Abraham_Lincoln#mediaviewer/Fil...
yet 180 years later hydrogen fuel cells still aren't a competitive energy storage strategy. Less spectacular examples include flying cars and speech recognition / AI.
You'd think they would have thought this through, but ya know, I'm not sure they thought the Fire Phone through.
People may like it for a about a week ("neato, I can get my package lickity-split!") and then will say screw this, those things are making a racket and driving me batty.
It's not like they can be used to deliver groceries. And they presumably have to return to the base after each delivery, because they can't carry that much. That's just crazy inefficient.
I could see small electric rolling vehicles that make automated deliveries. But noisy little helicopter drones? Not going to happen.