LENShere was a time when remote-
controlled aeroplanes were
expensive and difficult to fly, and
remote-controlled helicopters
were unaffordable and near
impossible to fly. Those of us with
dreams of flying our own machines
were left to look on from the sidelines, unable
to participate.
We have been fortunate then, over the last couple
of decades, to witness a technological revolution in
manufacturing that has brought flight to within the
reach of almost anyone. Powerful yet lightweight
electric motors, coupled with batteries that have
undreamed-of capacities, on machines made from
advanced materials by precision mass production
techniques, have given us aircraft for pocket money
prices. Not only has
this been a revolution
in terms of cost, it has
also given us entirely
new craft that would
have been impossible
to fly before the advent
of the computing power
required to keep them
in the air. A multirotor,
commonly referred to as a drone, would have been
impossible to fly by any other means than with the
help of a computer to keep it in trim, yet now, due
to their very low moving parts count, they are the
cheapest and most commonly seen form of remote-
controlled flight. Multirotors have become a part of
hackspace culture in a way that other craft have not,
so let’s take an in-depth look at them and understand
how they are built.BUILDING BLOCKS
A multirotor has a central fuselage, around which
are positioned a set of motors with fixed propellers,
or rotors, whose thrust points downwards. A
computerised controller monitors a gyroscope and
accelerometer, and constantly adjusts the thrust
from each motor to maintain the craft in level
flight. The vast majority of multirotors have an
even number of rotors, so you will commonly see
quadcopters with four rotors, hexacopters with six,
and octocopters with eight.
There are many different types of multirotor,
each of which has its own characteristics andapplications. A racing quadcopter with extreme
manoeuvrability, for example, will be completely
different to an octocopter used by a broadcaster to
carry a TV camera that requires stability and long
flight time. It’s time to look at just a few of the types
you will commonly find.SMALL BEGINNINGS
If there is a bottom of the heap in terms of
multirotors, it’s probably to be found in your local toy
store. Toy micro-quadcopters have been on every
child’s Christmas list for a few years now and, while
they may be cheap, they are no less fun to fly than
their larger counterparts. About ten pounds will snag
you the most basic, a tiny quadcopter that will sit in
the palm of your hand and has about five minutes’
flight time from a small lithium polymer battery.These machines invariably have little brushed DC
motors and very limited outdoor capability, but their
flight characteristics are such that, if you can master
one, you should find flying a more capable machine
to be no problem.
As the budget increases in the field of ready-to-fly
multirotors, so do the capabilities of the models in
question. The more expensive toy machines now
have on-board first-person-view video transmitters
and, as the price increases, there is a transition
from the world of toys to that of serious machines.
The motors have become brushless, the batteries
much larger, they are likely to have GPS units
and much better quality FPV video cameras, and
accessories such as a camera on a gimbal can be
slung underneath. The sky is the limit when it comes
to high-end multirotor hardware.
This article however is about building a multirotor,
and in it we shall look at all aspects of a simple
build using off-the-shelf parts. We’ll produce a
machine that is a serious aircraft, that’s fun to fly and
expandable in different ways as you increase your
multirotor flying experience.T
MULTIROTORS HAVE BECOME A
PART OF HACKSPACE CULTURE IN A
WAY THAT OTHER CRAFT HAVE NOT
Jenny List
Jenny is the creator of
the @LanguageSpy
ele ctronics kit and
a key member of
Oxford Hackspace.
@Jenny_Alto