I'm also "intimately familiar" with multi rotors, and I don't think any of these issues you've identified are valid, with the exception of regulations (which Amazon admits won't happen).
> Battery recharge time - out for 15 mins flight? Recharge for 2 hours.
So? Swap out batteries. The whole drone doesn't have to be grounded for 2 hours.
> Flight time / payload - pick one. (20 mins with no payload is a stretch. Add bigger batteries? Too much weight. Add bigger motors and props for more lift? now you need bigger batteries...
That's wrong, too. Multirotor flight speeds are 30+ knots. Modest wind is not a big deal.
> Unstable with a failed motor / prop. Will fall out of the sky under numerous failure scenarios.
Most robust multirotor platforms have 8 or more motors/props, and can trivially handle the failure of one or two. It's true that there are "numerous failure scenarios" which will result in a UAV falling out of the sky, but the same is true of passenger airliners: this will happen if the wings fall off. To suggest that a UAV can't be made as reliable as a typical manned helicopter is short-sighted.
> The blades are lethal - can be shielded, but will add weight and reduce efficiency.
This is only true in the absence of failsafe mechanisms: e.g. a device that brakes the motor when below a certain altitude. Also, as you mentioned, they can be shielded.
> GPS is unreliable at best, and is easily interfered with.
No, GPS is perfectly reliable "at best", and utterly nonfunctional at worst. Fortunately, there are lots of alternatives for GPS.
> Current regulations in countries that have them typically require line-of-sight operation; away from people and property (which rules out landing outside someone's front door); no over-flight of persons; restrictions around distances from the operator when taking off and landing. (And remember the battery / weight issue? Go over a certain weight [~8KG], and the regulations get even more onerous.)
The multirotor you cited has a no-load hover time of about 15 mins - hover n/e forward flight. It has a loaded flight time of about 5 mins. Like I said - pick one.
I didn't say wind, I said weather. That said, forward flight in even moderate wind draws considerably more current.
The motors are open for cooling and weight efficiency. They aren't waterproof. Try flying in snow, or dusty / sandy environments and see what happens!
If GPS accuracy randomly ranges between perfect and nonfunctional, then you have described unreliable. Please cite all these alternatives.
What do you imagine might happen if one were to 'brake the motors below a certain altitude'?
And I didn't say 'can't be made', I said the technology isn't there yet, nor by 2015 as Amazon suggest. I also said it will be eventually.
Inertial navigation systems[1] have been used for more years than GPS has existed. Even now almost all military drones / rockets / ICBMs use very precise inertial systems.
I'm the complete opposite - I've never even seen a drone-like machine.
Could you squeeze in any more minutes with solar panelling? I mean if they have to fly in decent weather anyway they may as well try to get a bit more charge in them while flying
That's 10 minutes each way. Assuming they fly at 30 mph, you get a range of 5 miles. That might work for big cities, assuming they can fly for 5 miles in a straight line, which they can't.
> No, GPS is perfectly reliable "at best", and utterly nonfunctional at worst. Fortunately, there are lots of alternatives for GPS.
GPS got hacked a long time ago, and even military drones got stolen using a fake GPS transmission.
There are not that many GPS alternatives. GLONASS. Maybe if you have some local towers, but that's a huge project in itself.
> Battery recharge time - out for 15 mins flight? Recharge for 2 hours.
So? Swap out batteries. The whole drone doesn't have to be grounded for 2 hours.
> Flight time / payload - pick one. (20 mins with no payload is a stretch. Add bigger batteries? Too much weight. Add bigger motors and props for more lift? now you need bigger batteries...
That's wrong. There are many off the shelf platforms which can easily handle 5+ lb payloads for 20+ minute flights. Here's one: http://www.freeflysystems.com/products/cinestarHL.php
> No good in 'weather' of pretty much any kind.
That's wrong, too. Multirotor flight speeds are 30+ knots. Modest wind is not a big deal.
> Unstable with a failed motor / prop. Will fall out of the sky under numerous failure scenarios.
Most robust multirotor platforms have 8 or more motors/props, and can trivially handle the failure of one or two. It's true that there are "numerous failure scenarios" which will result in a UAV falling out of the sky, but the same is true of passenger airliners: this will happen if the wings fall off. To suggest that a UAV can't be made as reliable as a typical manned helicopter is short-sighted.
> The blades are lethal - can be shielded, but will add weight and reduce efficiency.
This is only true in the absence of failsafe mechanisms: e.g. a device that brakes the motor when below a certain altitude. Also, as you mentioned, they can be shielded.
> GPS is unreliable at best, and is easily interfered with.
No, GPS is perfectly reliable "at best", and utterly nonfunctional at worst. Fortunately, there are lots of alternatives for GPS.
> Current regulations in countries that have them typically require line-of-sight operation; away from people and property (which rules out landing outside someone's front door); no over-flight of persons; restrictions around distances from the operator when taking off and landing. (And remember the battery / weight issue? Go over a certain weight [~8KG], and the regulations get even more onerous.)
This is 100% valid. Regulations are a concern.