Why doesn't everyone have a jetpack? - Richard Browning
On April 12, 1961,
Soviet cosmonaut Yuri Gagarin
piloted a 2,400 kilogram spacecraft
in humanity’s first manned space flight.
One week later, Bell Aerosystems debuted
another advancement in aviation:
the gas-powered rocket pack.
Capable of flying 35 meters
in just 13 seconds,
the rocket pack thrilled onlookers.
But the device’s engineers
were less enthused.
Despite years of cutting-edge work,
they knew this short flight was all
the rocket pack could muster.
So why was a massive spacecraft easier
to send flying than a single pilot?
According to Newton's laws of motion,
the physics behind flight are
actually quite simple.
All you need is a powerful enough
upward force
to counteract the downward force
of gravity.
And since objects with more mass
experience stronger gravitational forces,
lighter objects should be easier
to get off the ground.
However, modern jet engines,
our primary tool for flight,
actually get more efficient
the larger they are.
Jet engines work by sucking in huge
volumes of air,
and then expelling that air
as quickly as possible.
While most of this actually bypasses
the inner machinery,
it still contributes to a huge portion
of the engine's thrust.
But the air that does enter
the engine’s core gets compressed
by a series of tightly packed blades.
That compressed air then enters
the combustion chamber,
where it is injected with jet fuel
and ignited.
The heat causes the compressed air
to rapidly expand,
bursting out of the exhaust
and propelling the engine forward.
As air leaves the engine it also turns
a turbine embedded in the exhaust nozzle.
This turbine powers the fan
and the compressor blades,
creating a cycle that maintains thrust
for as long as there’s fuel to burn.
The more air an engine can take in and
expel the more thrust it can produce.
On a modern jet, the diameter
of a frontal fan is larger than a truck.
And even spinning
at relatively low speeds,
these engines produce more than enough
thrust to maintain the necessary speed
for flying a passenger aircraft.
But smaller engines simply can’t
take in this much air.
For most of the 20th century,
engineers couldn’t produce an engine
small and light enough
for an individual to wear,
yet powerful enough to lift itself
alongside its pilot and fuel.
Designs could only carry enough fuel
for 30 seconds of flight,
and when airborne,
the powerful thrust in a single direction
made jetpacks difficult
and dangerous to control.
But the new millennium brought advances
in materials, manufacturing,
and computing technology,
including systems which could manage
fuel injection with incredible precision.
Together, these dramatically improved
the fuel efficiency
and power-to-weight ratio of jet engines.
By 2016, micro-engines the size
of a coffee can
and weighing less than 2kg
could achieve 220 Newtons of force.
This was when an English engineer
named Richard Browning
saw the opportunity to create
a new kind of lightweight jetpack.
In addition to a single engine
strapped to the back,
this so-called Jet Suit involved a pair
of micro-engines on each arm
to split and balance the thrust.
Working with the back engine,
these provided three-points of stability,
which some pilots describe as being
akin to comfortably leaning on crutches
while a friend supports your back.
It may seem complicated to manage
all these engines at once,
but many pilots master
it in less than a day
with the help of another
advanced computer system— their brain.
Various brain regions
and multiple sensory systems
perfectly calibrate our sense of balance
and spatial orientation,
helping pilots smoothly
direct their flights.
Slight movements of the arms allow
operators to increase and decrease lift,
quickly turn in mid-air,
or glide forward for up to 5 minutes.
This technology is still fairly new,
and without major advances
in fuel efficiency and engine technology,
don’t expect to have a jetpack
of your own any time soon.
But if reaching for the sky
already got us this far,
who knows where we'll fly next?
