BallastHalo 3 Launch Monday 14:00 - 16:00 - Long Duration Floater

[James Coxon]

Hey All,
Apologies if you are subscribed to all the mailing lists and get this
3 times! Currently the plan is to launch BallastHalo 3 on Monday
(14/12/09) afternoon an hour or so before sunset (15:51GMT in
Cambridge). Using a 1.5kg balloon with a 1.5mm pinhole vent the aim is
to lift the payload to an altitude of between 18-24km where it should
float. After 30mins of floating the payload will then test its ballast
tanks and dump some ballast (all preprogrammed), this should cause the
balloon to rise until it reestablishes float, again after 30mins we'll
dump more ballast and so on. The dumping of ballast will probably
shorten the length of the flight rather then extend it.

The current flight path will take the balloon west and then around
Wiltshire it'll swing south and then pass out into the channel towards
the channel islands - these of course are forecasts so may change.
Due to the slightly unusual flight path those listeners in the South
of England will be very useful for this flight so please if you are
available volunteer to help track. The flight path will be mapped on
to http://spacenear.us/tracker and conversation will be on
irc.freenode.net #highaltitude .

The payload is quite complicated! Onboard is a master flight computer
pretty much identical to the one used on BallastHalo 1 and 2, it has
an ATmega168 running at 3.3v and a Radiometrix NTX2 434.075Mhz 10mW
Radio Transmitter. To this a Lassen IQ GPS module is attached. The job
of the master flight computer is to provide the main downlink. A
secondary ATmega168 is connected to the master board by i2c, this
board contains a backup morse beacon on 434.225. The secondary board
also has 4 temperature sensors, one onboard, one attached to the GPS,
on attached to the ballast pump and the other external, it also has a
photocell which will be used to detect day and night. The secondary
board also controls the ballast system, the ballast pump is connected
by a relay and the ballast level sensor consists of a IR photodiode
and opamp which is at the top of the tank and an IR LED at the base of
the tank, the ballast attenuates the IR light so by measuring this we
can sense the volume of ballast remaining.

The aim of the flight is to test a concept for ballast tank sensing
and pumping that may be used for the Atlantic Halo trans-atlantic
flights - see more at http://spacenear.us/wiki

More info can be found at:
http://www.pegasushabproject.org.uk/wiki/doku.php/missions:ballasthalo:ballasthalo3

James
http://www.pegasushabproject.org.uk

[Mark Caviezel]

good to hear about this interesting test flight...... are you guys ever going to use those zero pressure balloons?

best

- Mark

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