Can quadcopters carry humans anytime soon? Manned aerial vehicles of today are either helicopters or planes. However, what about quadcopters and multirotors? Many attempts have been made in the past to build life sized multirotors capable of heavy payloads and human carrying capacity. But can quadcopters carry a human in the near future?
In this post we shall look at some of the factors that will determine whether or not you will be seeing life sized quadcopters carrying humans around all over city skies (like in sci-fi movies).
Stability
Quadcopters and multirotors are inherently very unstable. The reason you see plenty of these flying machines in the small scale is because they provide agility and maneuverability and this is particularly useful for specific tasks like photography, spying and scouting in search and rescue operations.
With scaling up, most of these benefits are outweighed by the fact that it is very difficult to maintain stability without the aid of a complex software system. With present day software advancements, it may very well be possible to build such a software system (as we can already witness in the small scale – flight control and stabilizing software), but even then, the question to ask is – is it worth it?
It is easy to imagine helicopters and planes maintaining at least most of the altitude and direction, even if the controls were let go. But with quadcopters and multirotors, all you can expect is to crash and burn without a sophisticated flight control system.
Safety
Although one might imagine that it is easier to gain control of the flight with more rotors, the fact remains that with more rotors, the likelihood of failure increase because any one of those motors could potentially fail.
Also, in case of a failure, it is easier to predict a helicopter or a plane crash behaviour. Multirotors can go down so violently and chaotically (spinning around and such) that it may be impossible for a last minute heroic endeavour to save lives.
This may not seem as important, but the placement of rotors is another factor that we must consider. With multirotors, the likelihood of a propeller based damage to the environment, people and to the passenger itself is higher. Extra care will have to be taken to ensure that such strikes are avoided.
Efficiency in scaling up
If you are familiar with the square cube law, then this point will immediately strike you. This is exactly why you don’t see giant spiders walking around the streets. If you scale up a spider that big, it will crumble down from its own weight.
When scaling up in size, the lift produced by the multirotor will scale up by a square factor because it grows in proportion to the area that the rotors take up. However, the overall weight or volume of the multirotor will scale up by a cube factor!
What this means is that due to inherent universal laws, it may be impossible to have a multirotor that is as efficient as a helicopter because having one large propeller on one large motor is way more efficient than having multiple smaller motors with smaller propellers.
This also means a bigger toll on the batteries or fuel. Even if it is possible to engineer a quadcopter capable of carrying a human, the flight times will probably be incredibly abysmal for practical purposes. Not to mention that it may be impossible for a multirotor to carry multiple humans.
Costs vs benefits
What are the benefits of having a full sized quadcopter or multirotor over the conventional helicopter or plane? One might think increased potential for maneuverability due to extended control over multiple motors and the ability to look cool. Again, is that enough and really worth it?
One might have a tendency to associate autonomous flight with quadcopters and multirotors, but it is important to note that autonomous flight can be achieved with any type of aircraft. That particular factor is not dependent on the type of the aircraft, but the software system that is implemented in it.
The cost of producing a passenger quadcopter/multirotor will obviously be high and due to inefficient fuel usage (refer to the last section), the cost per flight will also go up, not to mention higher costs of maintaining.
We must think of the benefits of quadcopters and multirotors over helicopters in the life-size scale that will outweigh the costs of producing and maintaining them before we go about mass producing them.
In Closing
With all that said, one might think that passenger quadcopters and multirotors may very well be impractical. But with further advancements, who knows what exactly the future holds!
Here is a promotional video from a Chinese based company that seems to be taking that bold move:
What do you think? Drop your comments below!
