Breaking the Amateur Radio Balloon Altitude Record
By Don Ferguson, KD6IRE
The challenges of pursuing and capturing the World Record for ARHAB, "Amateur Radio High Altitude Balloons."
Ron Meadows, K6RPT, has always had a fascination with flight and science. After seeing a PBS special, he became interested in high altitude ballooning and how it could be something he would enjoy doing himself. Ron is the owner of a professional pool and equipment maintenance company. His son, Lee Meadows, works with Ron to maintain a large number of pools in the San Jose, California area.
Ham radio gives Ron access to many technical contacts in the San Jose area and provides support for his balloon activities.
On September 12, 2009 Ron, with support of his son Lee and Ron’s father, Frank, KA6TVU, launched the first of what would become many balloons. This one carried a payload containing a camera, a simplex repeater and an APRS tracking GPS and radio. This project was named CNSP-01, for “California Near Space Project.” It is also the name of Ron’s website and the large team of friends who support him and Lee.
The pictures returned were excellent and fueled the idea to do other similar projects. Here is a link to those first pictures: http://www.californianearspaceproject.com/photos.K6RPT-10.html.
After the success of this launch, Ron decided to repeat the process but add a crossband 2 m x 70 cm amateur repeater and get some more great pictures from Near Space. On March 27, 2010 this second balloon was another success that traveled to 100,442 feet AGL and provided a couple of hours of excellent radio contacts covering central California from Bakersfield to Chico. Again the pictures were beautiful with views from the Pacific Coast to the Sierras.
World Record Attempt
It was at this point that Ron decided to launch a world record altitude attempt. Ron and Lee made several attempts with different sized balloons, both helium and hydrogen, and each of these flights provided additional information on the effect of neck lift (the lift needed to carry the payload) to payload weight. Also, they were able to keep track of the effectiveness of different balloon size and manufacturers from 1500 to 3000 grams.
Other lessons learned are related to the fill process and how to eliminate the effect of the hose weight from the lift measurement. Ron constructed a balanced fill fixture that allows very accurate lift measurements while filling the balloon.
On some early flights radio performance was an issue due to traffic collisions and antenna effectiveness. The antenna was redesigned to a half-wave center-fed dipole and the TNC was reprogrammed to transmit every 31 seconds. The antenna design significantly increased the gain and signal strength and the RF field was measured before each flight. The TNC timing gives much better altitude resolution and eliminates recurring collisions with APRS stations transmitting at regular minute intervals. There is no receiver onboard to see if the frequency is clear before transmitting, so this timing causes each packet to occur at a one second time differential within the minute.
Other considerations include the size and number of batteries and the cold voltage performance of the battery. Ron measures the battery at subzero temperatures to ensure it will last longer than the expected flight and recovery.
Probably the most significant part of the prelaunch process is the calculation of initial fill/lift to successfully carry the payload to maximum altitude before bursting and without stalling at some altitude before bursting. For the October 23, 2011 record-breaking flight, Lee made all the decisions related to fill and led the team during the launch process. Ron and the team supported all his decisions and deserve significant credit for the success and the world record. CNSP-10 reached 136,545 feet, or 25.86 miles, AGL.
I know everyone on the team understands this accomplishment is a total team effort and all of the people involved in past flights have contributed to the team’s success in achieving the ARHAB World Record. This includes all of the people who tracked and recovered earlier flights, specifically the Stratofox Team, to allow reuse of equipment and analysis of failures.
More flights are planned for different experiments so keep track by following the updates on the California Near Space Project web site, http://www.californianearspaceproject.com/.