A quadcopter is perhaps the simplest flying machine requiring minimum amount of aerodynamic accuracy and complications, and therefore it's no surprise, it could gain an immense popularity among the various hobbyists who could successfully build this....a machine that they could actually fly and control at their own will.
The Quadcopter Dynamics
The fact that a quadcopter drone is the simplest in terms of technicality and dynamics is actually due to the involvement of 4 propellers and a balanced frame structure, which enable the machine to fly with relatively good equilibrium, even in difficult climatic conditions.
However simplicity also implies that the system might not be as efficient as the conventional airplane and chopper models which are intricately designed for exhibiting extreme efficiency in terms of speed and fuel consumption, and of course load bearing capability...all of these could be essentially lacking in a typical quadcopter system.
Nevertheless, as far as a hobby project is concerned, this machine becomes the ideal choice for most enthusiasts who find it very amusing and intriguing to build a flying machine of their own, at home, which ultimately "listens" and flies to whatever direction the user prefers it to move.
However, for a new player, who may be technically not so informed may find even this simple machine extremely complicated to understand, simply because most of the related info presented across the many websites fail to discuss the concept lucidly and in a "language" that might suit a layman.
This article has been specifically written for those not-so technical folks who are interested to build a magnificent flying machine but find the subject too difficult to digest.
How Quadcopter Flies
So let's jump right way and understand what are the essential things required to make a quadcopter fly successfully. Here are the basics to successfully make the machine fly smoothly:
1) Basically the machine requires a firm and strong body, but extremely light in weight. This could be fabricated or assembled using hollow square aluminum extrusion pipes, by suitably drilling holes and fixing the frame with nuts and bolts.
2) The structure should be in the form of a perfect "+" or a perfect "x", it doesn't make a difference as long as the angle between the "crossing" pipes are at 90 degrees each.
Basic elements needed for constructing a quadcopter can be seen in the following image:
Part Assembly Simulation
The rough animated simulation below shows regarding how to assemble the above shown elements together:
How to Construct Quadcopter Framework
The aluminum for the "+" frame can be acquired by appropriately cutting and sizing ready made aluminum extrusion tubing, as shown below:
The size of the frame is relative and therefore is not crucial, you can build a wide frame with the motors fitted wide apart or build a rather compact frame structure where the motors are not too wide apart...although it must be ensured that the propellers are well aloof from each other for enabling better equilibrium and balance.
3) The "+" frame structure must be fitted with a square platform at the central section where the frame arms meet and cross each other. It could be simply a well polished aluminum plate appropriately dimensioned for comfortably accommodating all the necessary electronics and wiring.
Thus this central plate or the platform is basically required for installing and housing the electronics of the system which would ultimately be responsible for controlling your quadcopter.
4) Once the above framework is completed, the motors are required to fixed across the ends of the cross bars, as shown in the above figures.
5) It's needless to say that all the fitting work needs to be done with utmost accuracy, and perfect alignment, this might require the association of an experienced fabricator for the job.
Since everything in the design is in pairs, aligning the elements accurately won't be actually too difficult, it's just about sizing and fitting the pairs with as much similarity as possible, which will in turn ensure a maximum level of balance, equilibrium and sync for the system.
Once the framework is built, it's time to integrate the electronic circuits with the relevant motors. This will need to be done as per the instructions provided in the given circuit manual.
The circuit boards could be fitted on the bottom side of the central plate with appropriately housing or over the plate, again with an appropriate cabinet for enclosing it tightly.
Understanding the Rotational Direction of the Propellers
Analyzing the direction of Rotation of the Motor propellers for a Balanced Lift-of:
Referring to the above animated simulation, the direction of rotation of the motor propellers should be aligned in the following manner:
It simply needs to be such that the motors at the ends of one rod should be identical but different to the other rod motor direction, meaning if one rod has the motors spinning in the clockwise direction, then the motors at the ends of the other complimenting rod must be tuned to spin in the anti-clockwise. direction.
Please refer to the simulation above to correctly understand the counter-acting movement of the motors that may be needed to be assigned to the motors for ensuring a balanced take of
How to Control the direction of the quadcopter by controlling the speed of the motors.
Yes, the flying direction of the quadcopter can be tweaked and controlled as per your own wish and will by simply applying different speeds (RPMs) to the concerned motors.
The following images show how the basic speed transmission may be applied to the relevant motors in order to achieve and execute any desired flying direction to the machine:
As indicated in the above diagrams, by appropriately decreasing the speed of a set of motors, or increasing the speed of the opposite set of motors, or tweaking the speeds as per ones own preference the quadcopter can be made to travel in the air in any desired specific direction.
The above images indicate the basic directions, such as forward, reverse, right, left etc...however any other odd direction can also be efficiently implemented by suitably adjusting the speeds of the relevant motors or may be just a single motor.
For example in order to force the machine to fly towards the N/W direction, the speed of only the S/E motor may be increased, and for enabling the machine to fly at the N/E direction, the speed of the S/W motor may be increased...and so on. It just needs to be practiced until the full control of the quadcopter becomes achievable and mastered by the user.
Soon I would be presenting an article explaining the construction details of the electronic circuit and the remote control integration for a quadcopter...without using any microcontroller IC.