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Transatlantic Balloon Flight, December 2-5, 2012

CNSP-18   K6RPT-12


California Near Space Project

Launch of CNSP-18 Transcontinental / Transatlantic Balloon Flight

By Don Ferguson AI6RE

It was a rainy weekend in San Jose but all indications were that the weather would clear in the afternoon on Sunday, December 2nd, 2012. Almost 1 year ago, on December 11th, 2011, a latex balloon, CNSP-11, was launched from San Jose, California, and traveled across the United States, the Atlantic Ocean, Portugal and Spain. The balloon burst at 115k’ above the Mediterranean Sea and fell into the sea of the coast of Algeria.

By 2:30pm Sunday, 12/2/2012, the weather did clear and the Sun showed brightly through the clouds. The California Near Space Project team was ready to launch a second transcontinental balloon flight, CNSP-18.  All the usual people, Ron (K6RPT), Lee, Frank (KA6TVU), Don (AI6RE), Jonathon (AE6HO), Michael (K6MFW), Bob (KG6TBY), gathered at Cherry Ave. and Almaden Expy.

The plan was to launch a 1600 gram Hwoyee latex balloon about 5pm on another attempt to float across the U.S.A to the East Coast and beyond.  Everything progressed as planned and at 5:28pm PST on 12/2/12 local time, 12/3/12 01:28 UTC, CNSP-18 set off on its way across America. The APRS Radio callsign of this balloon was K6RPT-12. The balloon is tracked on the web at and those interested were watching from every part of the globe, in real time.

When we fill the balloon with Hydrogen we must be very concise for a total payload lift to provide enough total ascent to attain about 102,000’ and not so much to cause it to pass through 115,000’ feet. From experience we have learned that at this time of the year there is a constant flow of the atmosphere to the East at above 100 MPH.  This is way above the normal Jet Stream that airplanes use between 30,000’ and 40,000’.

When launched, the balloon ascent rate was about 350’/minute and that was right at our target so that assured us of an accurate fill. Now came the hard part. Everything we could control was over and K6RPT-12 on APRS was on its own with the whole world watching.

This balloon payload was a little different than the package on last year’s balloon. One piece of data transmitted over the APRS system is “Current Battery Voltage” and we noticed that the battery voltage would decrease at night to below 4 volts and this could cause the payload to stop transmitting good data. This year the package carried a heater module, designed by Jonathan, that was controlled by a photocell and came on at sunset to provide added warmth inside the package. This package had its own battery and appeared to be working as expected. The reported battery voltage was much more stable and did not drop below 3.9VDC for 99% of the flight. 

This added weight had to be compensated for with more hydrogen in the balloon. Everything has an effect and the fill of the balloon is the critical part of the process, Lee Meadows does all of the calculations and generates the mission plan for each flight. His father, Ron Meadows, is the overall project director and makes the final decision on each flight.

Back to the flight of K6RPT-12. Everything progressed normally and the balloon leveled off at 103k’ altitude. It traveled overnight to a sunrise above Nebraska. As the sun came up so did the balloon’s altitude which rose to 111k’ and speed in excess of 210mph headed ENE at 75*. The balloon continued in daylight and left the U.S at the most Eastern point of Maine. The balloon was visually spotted at the Univ. of Maine, by Rick Eason – AA1PJ, as it faded into the night sky illuminated by the sun at 111k’.

Daylight takes a very heavy toll on the balloon as it is flying above 90% of the atmosphere and has very little protection form the harsh UV rays of the sun. While the warmth of the sun is a benefit to the payload radio and batteries it’s UV rays will also be the force that will cause the balloon to burst and end this flight. CNSP-18 continued east into the sunset just South of Nova Scotia at 180 mph, still headed for France.

At 3:54 UTC on 12-5-12, 26 ½ hours after launch, the balloon passed out of radio range of the APRS gateway 390 miles behind it in Newfoundland.  It had changed course to the Southeast and slowed to 135 mph. Now we wait to see if anyone ever hears from the balloon again.

After about 8 hours of sleep we arose to see if there is any sign of the balloon. Still nothing received. As in the past we rely on the hams in Europe to retune to the USA APRS frequency from their normal monitor frequency. So hopefully this was the case today.  Many have sent emails and messages to friends in Europe to please listen for our little balloon crossing such a large ocean.

After 22 hours of loss of signal it was starting to look like our balloon may not make it or had gone in a direction where no APRS repeaters could receive the small signal. There were as many ideas being sent to the web site as there were people listening for it to succeed.

At 03:40 UTC on 12-5-2012, 23 hours 44 minutes after Loss of signal in North America, the signal was received by Union de Radioaficionados de Granada, ED7ZAE, a station in Granada, Spain that showed the balloon approaching the coast of Morocco. Suddenly all the cell phones started ringing and the computer screens came alive and there it was K6RPT-12 moving at 72 mph heading ENE toward Morocco, 200 miles ahead.

At 06:37 UTC on 12-5-2012 the balloon passed over the coast of Morocco just 10 miles South of the town of Kenitra at a balloon altitude of 114,400 feet, traveling at 50 mph still heading East. K6RPT-12 would continue for another 140 miles and Burst at 118,262 feet and then fall heading South-east for another 15 miles, and the last radio signal was received at 09:22:31 UTC on 12/5/2012. The last signals were relayed by EA7FQB, Salvador Perez Lanzas, Estepona, MALAGA, on the Mediterranean coast of Spain.

I have searched for a contact in this part of Morocco but have not found any amateur radio people in this part of Morocco. For now the package is sitting at about 2500’ on the ground waiting to be found someday.

The final numbers on this balloon flight 55 hours, 54 minutes, 6092.5 Great Circle miles, 118,262’ altitude, highest speed 232 MPH.


CNSP-18 (K6RPT-12) has been recovered in Morocco!



Launch Video By Michael Wright, K6MFW of CNSP