The MagPi - July 2018

(^12) July 2018 raspberrypi.org/magpi
News
zzy Brand, a student at
Brown University, USA,
created a clever system
to recover the data from his
high-altitude balloon (HAB).
Rather than use a parachute and
geolocator, he instead fitted the
data module to a glider set to land
at preprogrammed co-ordinates.
Izzy reveals, “I had the idea
a long time ago – maybe early
high school (2013).” Initially the
idea was just to find a way to fly a
glider, dropping it from a hot-air
balloon, as Izzy’s “nearby hills
weren’t steep enough.”
The glider uses a Raspberry
Zero W and a Pixhawk, a flight
controller powered by an ARM
processor. “I chose the Zero W,”
Izzy explains, “because it can run
MAVProxy, essentially a terminal
version of the GUI-based ground
station software used to control
the Pixhawk.” Izzy chose the
Pixhawk due to his familiarity with
its predecessor, the ArduPilot.
At 10 000 m, the Zero W turned
on the autopilot mode and
“triggered a solid-state relay to
burn the nickel-chromium wire
and release the glider.”
Guided landing
Izzy explains that the Pixhawk
module’s autopilot mode operates
on a system of waypoints, so he set
“only one waypoint co-ordinate at
the target landing location, with
an elevation of zero.”
In addition, the Pixhawk doesn’t
have a glider mode, so Izzy had to
“set the maximum ascent angle
to zero so the glider wouldn’t
try to climb without a motor and
thereby stall.”
Amazingly, after launching the
balloon and driving to the landing
site 122 miles away, the glider
was waiting just 10 m from the
target location.
“We were astonished,” Izzy
tells us. “This project failed
miserably in 2015, [as] the glider
landed in a forest about ten miles
from its target.”
Izzy would like to thank his
friends Luke Fisher and Nick Menz
for their help “in testing the glider
and on the launch day.” You can
find the source code and flight logs
at magpi.cc/qkqKXj.
I
HIGH-ALTITUDE RASPBERRY PI GLIDER
HIGH-ALTITUDE
RASPBERRY PI
GLIDER
I had the idea a long time ago –
maybe early high school (2013)
Left Izzy’s glider isn’t
anything fancy –
mainly foam board and
corrugated plastic,
with handwarmers to
keep the electronics
inside from freezing
Above The day of
the launch, using a
$60 military surplus
sounding balloon to
send the glider into
the atmosphere
Effortless HAB data recovery