SERVO 10.2013 21
UAV HAS SOLAR FLAIR
The largest robot at the AUVSI expo held
recently belonged to Titan Aerospace. It was a model
of their Solara 50 robotic atmospheric satellite, and
they had to chop off the tail and most of the wings
to get it to fit inside the building. The Solara is
intended to lift a payload to 20,000 meters and then
keep it there for five years, running entirely on solar
power. It functions a bit like a satellite, except it is
substantially cheaper and much more versatile. Plus,
you can get it back when you're done.
It's a little hard to tell, but these UAVs are big.
The Solara 50 is 15 meters long with a wingspan of
50 meters, and there's an even larger one called the
Solara 60 with a 60 meter wingspan. Despite its size,
the Solara 50 only weighs 160 kilograms and it can
carry a 30 kg payload, which is fairly respectable.
What makes the Solara functional as an
atmospheric satellite are two things. The first is the
altitude that it's designed to fly at. At 20,000 meters,
you're pretty much above everything. You're looking
down on clouds and weather, and the winds and
temperatures are generally very stable — or at least
predictable. Being that high also gives you a field of
view encompassing about 45,000 square kilometers.
If you were to mount a cellular base station on a
Solara, it would take over for a hundred cell towers
on the ground.
The second thing that makes Solara work is that
it's solar powered. Every available surface on the
wings and tail are covered in solar panels, and there
are batteries inside the wings. During the day, Solara
generates kilowatts of power, and there's enough left
over in the batteries to provide hundreds of watts all
night. Because the UAV never requires refueling it
can stay aloft for five years, either circling over one
spot on the ground, or (if you want it to travel) it's
got an effective range of something like 4. 5 million
kilometers, cruising at just under 60 knots.
The five year life is based on components, so
Solara may very well be able to stay up for longer
and that’s what is so cool about Solara — the fact
you can bring it back down if something goes wrong.
Even if nothing goes wrong, you still get your payload
back at the end of five years — something usually
impossible with satellites. Solara is also much much
cheaper than a satellite, although the company isn't
quite ready to say how much.