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Comment by ashhimself | Hacker News Reader

Serious question, what advantage would this even have over a standard helicopter.

Retrograde advantage. I listen to my scanner and have some aviation interests and it seems a depressing truism that nobody ever needs helicopter ambulance service right next to a wanna be helipad in perfect weather. The human pilots are quite skilled and seem to fly almost by feel in the worst conditions. Lots of on site judgment calls about winds and power lines and trees and obstacles.

Something I think likely / inevitable is assistant drones flying in formation with a rescue chopper very closely coupled to the chopper autopilot. Its easy for a surprise wind gust to kill a chopper, but if you have a perimeter drone force hovering in perfect formation 100 meters away, you have 100 meters warning for the autopilot to react and prepare. Not to mention the usefulness of a drone for exotic rescue (ferry that rope down the gully for us to climb down and reach the victim) or accident scene lighting under bad conditions.

In theory it should be cheaper to fly, there's much less going on mechanically in a fixed rotor and there doesn't seem to be a pilot. However, I'm pretty sure that people have shown that creating human-scale quads is actually impossible with current battery tech. So, IMHO this is just another design that doesn't have anything to do with what is possible in the real world today.

Who says they have to use battery tech? On a human scale drone I'm sure they could find room for a gas tank.

For a quadcopter you need very fine control of the rotors, making a combustion engine hard to use. So then you will need to do combustion -> dynamo -> electricity -> electric motor.

A helicopter is controlled in a completely different way.

Larger multicopters are free to use alternative control methods. The method used in toy multicopters is both inexpensive and cheap yet other options do exist.

It would look like a quadrotor, and therefore be more hip and attract more press and possibly more investments.

If I'm being generous, I'd say the advantages are:

- Safer than a helicopter due to rotor redundancy

- Easier to pilot

Disadvantages

- More expensive to build

- Less stable in flight

- Probably can't glide down with autorotation as well in case of engine failure

- Probably needs to run with a turbine generating electricity rather than directly using the engine to drive the rotor

- The ease of flying benefit can be solved in software anyway.

A quadrotor doesn't have any sort of 'redundancy'. If you lose a rotor, you've lost control, and will be hitting the ground in pretty short order. I see multiple rotors as a disadvantage... more things to go wrong.

It depends on your design. You can build it with separate engines and manage to land safely on two diagonally opposite engines.

I'm not sure that's feasible. I've been flying multi-rotors for quit some time and if you lose a motor on a quad it's nearly instantaneously on a collision course with the ground. Y-6 or Hexacopter would be more feasible from a redundancy standpoint.

Quadroter no, but multirotor yes. DJI's S900 and S1000 are designed such that two props can fail and it stays in the air.

That depends heavily on your control system and how well you've tested it. In theory, a control system for a quadcopter that has independently controllable rotors could keep itself stable if one goes out. In practice, any control path you haven't tested probably won't work.

The biggest issue I see is dealing with the unbalanced torque... You could probably manage a 'controlled crash', but that's about it.

Potentially allow the vehicles to go to hostile environments (battlezones), bad weather conditions, and of course, epidemic zones (like ebola-struck regions). It will save pilot lives (crucial when there is a major event and many pilots are needed). And it will help contain disease.

Greater pool of potential pilots - ex-military, etc. vs. helicopter pilots.

It's a drone so we can assume that at least most of the piloting will be done by the computer. So you could have EMT just enter the address press "Fly", adjust lever to Fast and wait.

Having four independently controllable rotors is probably a lot more stable.

Having four independently controllable rotors makes it inherently unstable, needing a real time computer to keep it from flipping.

Helicopters, on the other hand, have positive stability.

Nope, it's less stable as the giant rotor acts as a large gyroscope. Quad copters work well with ultra-light weight electric motors, but the concept is focused on quickly changing how fast the blades spin so it does not scale very well.

@lultimouomo having a real-time computer to control four rotors in not something unachievable with current technology :) I would say that it's becoming almost a DIY tech.

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