[GCARC] TEST balloon launch planned for Saturday July 20 - 11 AM

[Jon Pearce]

The long-awaited tank of pure helium (not that 80% party balloon gas) has arrived at the clubhouse so we can finally begin actual tests of the radio-carrying balloons. Working with the Woodruff Middle School we will have the materials for enough balloons for many flights over the next year, most of which we hope will circumnavigate the globe and give us an opportunity to test various balloon and radio configurations and see how they perform.

Saturday's test will not be one of those configurations; instead it will be using low-cost balloon, radio and other materials that will hopefully allow us to view the first few hours of its flight. Instead of the $175 SBS balloon that's expected to survive over long periods of time in the upper atmosphere we'll be using a large $5 party balloon that we expect will burst at some point as it reaches thinner air. Instead of the $45 ZachTech Radio with multiple solar cells we'll be using an $11 Taquito WSPR transmitter built from a Raspberry Pi Pico with an add-on board containing the GPS and transmitter module. We'll also be using a battery instead of solar cells, again to save on cost.

The battery should last for about 18 hours, allowing the balloon to move eastward over the Atlantic; however we don't expect it to reach Europe or Africa before it runs down. We should be able to track the transmitter using WSPRnet and several other online sources, and also possibly live RF WSPR transmissions on 20 meters, monitoring its location and battery voltage until its eventual demise. There are many potential points of failure including the balloon itself, storms, battery failure and some mechanical or electrical failure of the radio that we may be able to assess from this flight. If all goes well we hope to launch the "flight" version of the balloon on Saturday August 3, weather and other factors permitting.

The "test" version of the transmitter is currently on the air sitting on a table at the Clubhouse with a W2MMD callsign and is connected to a hamstick on the Skunkworks tower.  It can be viewed on the WSPRnet<https://www.wsprnet.org/drupal/wsprnet/spots> website as well at the Sondehub<https://amateur.sondehub.org/#!mt=Mapnik&mz=8&qm=12h&mc=39.73254,-75.20966&f=W2MMD/3> site that's specifically designed for balloon tracking. Those are the primary sites that we'll be monitoring during this balloon's short flight and for the "flight" version of the balloons thereafter. It's currently running on a battery for battery life testing so it may not be on the air at various points as the battery runs down. We'll be swapping out the battery tomorrow afternoon so it should be back on the air at some point thereafter.

Our plan on Saturday is to connect the transmitter, battery and antenna to the balloon and tether it to be sure that it's transmitting properly. Once we assess the wind direction and make a final launch decision based on wind speed (less than 10 mph) we'll release the tether and hopefully watch it ascend into the air moving eastward. We plan for that to happen around 11 AM although unforeseen issues may change that time. Once launched we'll be aggressively monitoring for the next 18 hours or until the battery finally runs down (these types of balloons are never recovered). This process will take over the main table of the clubhouse so other clubhouse activities that morning will need to relocate until we get the balloon system assembled.

So if you're interested come on out to the Clubhouse on Saturday and see how everything works out. Hopefully you'll view the beginning of some really interesting experimentation over the next year or so.

73 de Jon WB2MNF