We decided to take part in a competition in which we were
required to build a remotely piloted lighter than air craft. As it said lighter
than air so we began to look at helium balloon option with propellers for
guidance etc. but the tournament rules were a bit confusing and after three
weeks of intense research we had decided that a helium balloon of required
dimensions (2 ft. diameter/flying indoors) would at best float) i.e. it could
not have the guidance system attached and still be expected to be lighter than
air. Apparently the tournament supervisors realized this and they altered the
rules cutting the lighter than air. Then our best option was of course to go
for a quadcopter. Now we didn’t know anything about quadcopters. So we embarked
on a mission to build a quadcoter. So this article is about how to make a
quadcopter for amateurs.
What is a quadcopter?
It is a flying craft with 4 propellers. The rpm of the
propellers needs only be changed to achieve the funtions of forward, backward,
sideways, rotational flying.
Parts Needed:
As we went for the hobby part of quadcopters so we used all
ready made parts from the hobby shops and hobbyist. It was basically a kit with
mismatch parts.
List of Parts Required:
4 motors
Quadcopter frame (you can buy readymade or you can make
yourself)
Flight controller board (FCB) (it is basically a circuit board
with all the functions required by a quacopter pre feeded into it.)
Propellers (should be compatible with the motors, more on
this later)
Battery (should be of optimum capacity, not too large not too
small)
Electronic Speed Controllers (can be obtained readymade or if
you are an electronics student you can design your own)
Radio Controller/ Transmitter/ TX-RX
Wires (different voltage capacities for attaching all the
circuitry)
Power Distribution board (needed if you build the frame
yourself)
Screws, /nuts and bolts (you’ll have to purchase from hobby
shops because they are hexagonal shape not readily available in market)
Our build:
First of all I would suggest search the hobby forums and get
in touch with a hobbyist, it’ll save you a lot of time and trouble.
We went for a hobbyking FS450 frame which is a 450 size (450
mm) quadcopter frame and comes ith a PCB for power distribution. For motors we
went for the Turnigy 950 KV brushless outrunners. These can spin at a maximum
rpm of 11000 rpm. By using online calculators we calculated that we would
require large props of 8-10 inch size. We went for 1045 props. 10 indicates
prop size and 45 indicated its pitch. These are relatively slow spinning motors
drawing large current so we had to go for ESCs over 25 amps. We went for Turnigy
plush 30 A ESCs. We got a 2200 mAh 3S LiPo battery of Turnigy. For the radio
controller I would suggest that go for a good and popular radio controller as
it would save you a lot of pain later. We went for a second hand Hobbyking
controller 6ch which comes on the very low quality chart. And it was a lot of
pain in the…well.
Item
|
Quantity
|
Turnigy Plush 30A
ESC
|
4
|
Turnigy 950 KV
motors
|
4
|
Hobbyking 6ch
TX-RX
|
1
|
Hobbyking slowfly
1045 Props
|
8
|
Kk 2.0 FCB
|
1
|
FS450 frame
|
1
|
Screws, Nuts,
Bolts
|
Unlimited
|
How to build:
1.First
have the following tools nearby. Solder iron, solder wire, cutter, hammer,
plier, tape, double tape
2.Solder
the bullet connectors on the ESCs (if not already done so)
3.Take
the ESCs one by one and solder them onto the connections on the PCB (frame)
4.Solder
the battery’s wires on the PCB on the allotted slots.
5.Fix
the motors on the motor mounts provided on the respective arm of the frame.
6.Fix
the arms of the frame on the frame board (PCB).
7.Attach
the battery and the receiver on the underside of PCB (or any feasible place)
8.Make
sure that the CG (center of gravity) of the whole assembly is on the exact
center of the PCB (frame board), if it is not then make corrections to do so.
9.You
can check the CG by tying a knot from the center of the assembly (PCB) and
suspending it in mid-air.
10.Take the 5V connecting wires or
jumpers and attach at respective slots of receiver and FCB.
11.Fix the props on the motors, make
sure they are fixed tightly. You don’t want the props flying off in mid-flight
(trust me it has happened)
12.Fix two bright LEDs or LED tape (it
is a piece of fabric with a lot of LEDs) on the front part of your quad copter
so that while flying you know which side is front and which is back. Take a
connection out to the battery wires for this tape.
13.Congratulations, your quad copter is
assembled.
How to fly:
Coming on to the flying bit, let me tell you clearly that it
will be a miracle if you get it right up in the air in the first try. If you
don’t want to take any risks (actually it is advisable) you should first
practice with a toy quadcopter to get a hang of this thing. For our part we
extensively tested for a day on mattresses spread out on the floor. First you will have to calibrate the ESCs
with the remote controller (TX) so that they (ESCs) know what the start and end
points of her TX are. Process of calibration varies with ESCs and FCB. You can
find it online.
After calibration you have to check whether each function on
your TX prompts exactly the same response on your quadcopters. For example if
you are giving throttle all the motors should speed up in unison, if you give
forward pitch the two forward designated motors should speed up and the two
backward designated motors should slow down.
Another thing to keep in mind is that some FCB come with a
safety mechanism. You have to arm them after switching on the power. Arming
process involves pulling both the knobs on the TX in the bottom right corner of
the screen. An indicator led will turn on the FCB to indicate that the board
has been armed. This prevents accidental starting of the motors.
Our Flight:
Unfortunately we were extremely short of time for the
competition so we couldn’t fly it to our fill. But the few test flights we did
after correcting all the glitches gave satisfactory results. We had to change
the ESCs from the OPTO to Hobbyking Plush because the former were apparently
not compatible with the kk2.0 FCB. Also we had earlier installed a MultiWii FCB
which is a much superior board compared to the kk2.0 but for reasons unknown
its accelerometer was behaving most weirdly.
Conclusion
I hope this article serves as a guide for any future
aspirants to this hobby