Amateur balloons still flying after 30 days

[Dan Bowen]

I went to the UKHAS conference this weekend, and got the details on Leo Bodnar's three tiny superpressure balloons that have been up for more than 30 days, and still flying.  I was highly alarmed when they told me they were at 12km and had circled the globe more than twice!  

http://habitat.habhub.org/mobile-tracker/?latestonly=0&

There's some other flights on the map, but it's clear which ones have wanderd around the planet.

I was less concerned with altitude when I realized the entire payload weighs half that of the smallest type of sparrow (bird), and is about as long as the bird too.  I still highly encouraged him to go above 19.5km for future flights.

I saw the guys payload, and it's an electrical engineering marvel, a single 1cm x 10cm PCB with UHF transmitter, gps, solar cell and tiny lipo battery.  Including the piano wire 3" long antennas, the payload weighs in at 11grams.  That's not a typo, it's eleven, about as much as two US quarters.

 The balloon is made from the full width of the rolls of party balloon film (alumnized nylon or Mylar with PE on one side I think) flat circular, I think about 40" in diameter uninflated.  He heat seals the fill tube it after he fills it indoors. 

His telemetry is strictly amateur radio APRS, automatically changing frequencies for each country it passes over.  That's why there's large dropouts. 

It turns out Carl was right - we should have gone small!

UKHAS.org.uk or #highaltitude for more info.

:-)

Dan

[DE 'Tad' Heckaman III]

How big of a super pressure balloon would be needed to get the balloon to 20km carrying the same payload? 

With the balloon sticking to the northern hemisphere, I wonder if it could be possible to carry a small global GSM modem instead. Two way communications, it'd be reasonably cheap... only concern would be being 'above' the cell towers, which aren't looking for signals coming from above. Perhaps an antenna could be built with lots of gain on the side and minimal gain straight down, so it'd favor towers further down on the horizon. 

Dan

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Tad Heckaman

[Ryan Butcher]

Hi Tad,

At 20km (or 65k feet) you're going to be out of cellular range so you're best bet is sat comm,  but even then you'll need to do your homework.  The Gov limits GPS data over 60k but some hardware will report it anyway.  We generally lost cellular coverage prior to 40k feet with no external or amplified antennas thus the reason for moving to sat comm as primary.  You may be able to pull it off but it would have to be a directional antenna and even then I would have a secondary comm.  

Best of luck

Ryan

[Anthony Stirk]

Forgot I was part of this mailing list :)

One of the great features of Leo's flights is they replay position back log via APRS comments (5 days worth on one of them, 10 on the others) which means even though they can be out of contact for a while we get to know where they have been. This single feature alone has made the flights even more amazing. 

The limitation of altitude is the balloon size and currently Leo is unable to source the film in larger than 90cms wide rolls.

I think Leo is working on a sat based version but we use ublox GPS modules which are good to 50km (See my shop http://ava.upuaut.net/store) and rarely use GSM (never on the picos). 

Cheers,

Anthony M0UPU

Dan