Ever wondered were the electricity
that charges your phone on a plane, actually comes from? If so, then keep
reading because it’s definitely simpler than you think.
First of all, depending on the
different stages of the flight; there are many ways to supply power to an
aircraft. Such as, when on the ground and you’re about to get off, the engines
are hopefully off and can’t make electricity. Therefore, a large generator
called a GPU, is towed to the aircraft and plugged in to a socket, hidden
underneath. As a result, keeping the AC blowing on a hot summers day.
In addition, that annoying whining
noise you hear when climbing the rear steps of the plane is the APU. Even
though it sounds like a monster vacuum cleaner, its actually a tiny jet engine
that makes electricity using the fuel onboard and helps start the bigger
engines when needed.
However, later on in the flight, when
the GPU isn’t an option, the engines provide electricity by using their kinetic
energy, created by the spinning fan, and turning a generator. There are as many
generators onboard as there are engines, so it really isn’t a big deal if one
fails…unless you only have one engine.
Now, some diligent readers might
realise that an engine doesn’t always spin at the same rate. Therefore, doesn’t
create the same amount of electricity all the time. But, as ever, engineers,
thought about that before you and therefore created a Constant Speed Drive.
This drive, is normally part of the mentioned generator and provides a constant
output frequency of electricity, no matter how fast or slow the engines are
Just like anywhere else, aircraft
have their fair share of hassle when its come to A.C. or D.C. current. Just a
reminder that A.C. is when the electric current alternates its charge from
positive to negative and back. Whereas, D.C. is just a continuous stream of
either positive or negative current. Which, surprisingly enough both have their
Nevertheless, before the electricity
is connected, all the necessary systems are routed through two copper busbars;
respectively A.C. or D.C. These busses are simply a hub for all appliances
requiring electrical power and avoids any additional confusion with wires,
inside the aircraft.
Still, the purpose of separating A.C.
and D.C. current into their respective busses is that due to the nature of A.C.
current, it is used to power heavier loads such as fuel and hydraulic pumps. In
contrast to, D.C. which makes it vital to power most electronic equipment such
as computers, radios and even the oven.
In case the unimaginable happens, and
the plane loses all its engines and APU, the aircraft still has an ace up its
sleeve: well, in regards to electricity and not gravity.
Conveniently hidden in the shadow of the main landing gear, lies a little turbine
that’s fittingly called the RAT. This is dropped as soon as electricity cuts
out and is attached to a small generator which creates just enough electricity
to power yet another bus: the essential bus. Connected to the essential bus are
the most critical systems such as communications, radios and navigation. As a
result, ensuring that even when the worst happens, the pilots may still be able
to bring the aircraft down in relatively one piece.