SABLE-4

St. Albert Balloon Launch Experiments
May 29th, 2010

Photo from SABLE-4 close to maximum altitude of 110,219 feet.

Tony's choice to use SABLE for his balloon launch experiments worked well as it's still applicable after moving from Southern Alberta to teach at Sir George Simpson Jr. High in St. Albert where SABLE-4 was designed as a school project for a group of grade 7 & 8 students. Teachers Tony Rafaat & Doug Eglinski led 16 students through the planning and development of SABLE-4 starting in October 2009. During the course of the year students learned about the various aspects of high altitude balloon launches and how they are all interconnected. They looked at concepts related to VHF radio theory, GPS, weather, pressure, geography, mathematics, structures and forces, design and our atmosphere. Students worked in a collaborative manner and accomplished a number of tasks prior to the launch. We would like to express our gratitude to the SABLE-4 team members and parents, Principal Pierre Rousseau, the staff of Sir George Simpson, Oxypro Oxygen systems (helium supplier), Chapters Booksellers, the Hunder family and all those who came to help us with the tracking and recovery of SABLE-4. Overall, SABLE-4 was a success and students were exposed to an exciting, innovative and hands on science project. It’s these experiences that kids remember for a lifetime!

A poem written by one of the students was also sent aloft in the payload.

Tony and a student prepare the balloon & fill nozzle and James helps place the balloon on the nozzle.

Doug Eglinski assists Carter with the helium regulator whileTony keeps an eye on the balloon as the helium valve is opened. The balloon with the attached filling nozzle and bottle of water (which weight the same as the payload plus 1 lb.) soon become buoyant.

The payload lands & the lens

clears of fog 62 min's later.

We arrive 36 min's later and

Tony is caught in a final image.

194 images were captured (1/min) during the 3 hr. 14 min. flight, but few showed much detail with it being so overcast.

6 images were captured before the camera entered the clouds and lost sight of the ground at ≈ 3300 ft.

It was a beautiful sunny day as usual as the camera emerged above the clouds 33 minutes later at ≈ 31,000 ft., but most of the images were simply a blanket of white for as far as the camera could see with the cloud bank extending hundreds of miles.

Luckily, 1 image just before the balloon burst showed some cloud detail making it much better then the rest. During decent the balloon remnants, parachute and payload all became very tangled and few images showed much with all the spinning, tumbling and clouds. The high descent rate also only allowed time for 1 blurry image after emerging below the clouds prior to landing. It took a while to recover the payload this time which ended up being good as it took fog on the camera lens 62 min's to dissipate while it lay in the field. We arrived on the scene 36 min's later and one of the last images shows Tony placing the payload in his vehicle after a short 5 minute walk back from the field.

When the payload landed we were in the area, but like BEAR-6 we were unable to receive the tracker signal needed to determine its exact location and organized a grid search listening for the signal. The last received position report was from ≈ 8000 ft. and we knew when to listen for the tracker signal, but as we started the search one of our vehicle trackers was beaconing about the same time which masked the signal and we drove right past where we finally received a position report and found the payload about 80 minutes later.

Examining the antenna (right) revealed why we had trouble receiving the tracker during its descent and after it landed. The active antenna element that should have been ≈ 19.6" long was tied up in a knot along with the parachute and other cords leaving it only ≈ 8" long. More info about this antenna and improvements can be found on the 1/2 wave center-fed antenna page.

Sable-4 landed 61.1 miles (98.3 km) from where it was launched after travelling 83.5 miles (134.4 km) during its 3 hr. 14 min. flight. In addition to photos and tracking data, the student's also have data from 2 temperature sensors (1 internal & 1 external) plus a humidity and pressure sensor to study.

Click on map for a larger image

A SABLE-4.kml file is also available for viewing the flight using Google Earth.

The same camera as used for SABLE-3 was used for this flight and the tracker was a prototype of a new one being developed by RPC Electronics, called RTrak-HAB which was flight tested for the first time on this flight. See my RTrak-HAB Page for more information about this tracker.

This flight provided some interesting data near its maximum altitude that we have yet to fully understand. The rate of rise was about 700 ft/min until ≈ 100,000 ft. and then slowly decreased until about 300 ft/min at 109,114 ft. or ≈ 50 ft every 10 sec's. Around 109,356 ft. this slowed to ≈ 10 ft every 10 sec's and we wondered if we may have a floater and never get our equipment back, but it then rose back up to ≈ 50 ft every 10 sec's by 109,612 ft. At 110,114 ft. it started to decline again and at the maximum altitude of 110,219 ft. it started dropping again, up to 23 ft. every 10 sec's at 110,124 ft., until at 110,075 ft. it started rising again up to 33 ft. every 10 sec's at 110,167 ft. when the balloon burst. The balloon had slowly descended almost 150 ft. and we thought it may have developed a slow leak until it began rising again. We figured there was too little atmosphere above 100,000 ft. to affect a balloon in this manner, but we were obviously wrong unless someone has a better explanation. Regardless, we were very happy to see the balloon finally burst and our equipment return to us.