SABLE-1
Southern Alberta Balloon Launch Experiment #1

March 1 / 2006

Tony, a teacher from Hanna, Alberta, contacted me in October of 2005 after finding the BEAR Web Site and that it was a group, also in Alberta, as he wanted to launch a high altitude balloon and do some aerial photography with his students and was looking for help to get started as this was all new to him. Tony also knew little about amateur radio and nothing about APRS needed to track a balloon so James, VE6SRV, was involved and the two of us have been helping Tony get up to speed since last October. Tony had already scheduled and made arrangements for a balloon launch on May 20th, 2006, so there was little time for him to learn and do everything that needed to be done by himself, including studying for and getting an amateur radio license, so James and I offered to lend him an APRS tracker and I also offered to help prepare a digital camera for him. The tracker was assembled from BEAR's GPS receiver and a Pocket Tracker that James had and the camera is a Canon PowerShot S200 Digital IXUS V2 that Tony purchased and needs a way of triggering to take a photo every few minutes.

April 14 / 2006

March was spent trying to resolve an unexpected problem with Tony's camera after it was modified. Read all about My Canon Camera Modification & Trying to Deal with Canon's Famous E18 Lens Error which left Tony with no camera for his balloon flight and no time to try and modify another to take photo's automatically so Tony did what was originally considered which was to simply purchase one of the more expensive cameras which have a built-in timer for this function, like the new Nikon P2 camera he now has.

Tony now also has this bright, colourful, new parachute to use that his grade 8 class girls have been busy sewing for him and .......

this balloon filling adapter that he made. Tony has also been busy
studying for his amateur radio license, which he recently received.

Congratulations Tony, VA6TNY

The APRS Tracker we promised Tony is now finished.......
and Construction of the Tracker Antenna was completed the week before the launch.

May 19 / 2006

Besides James and myself, Curtis, VE6AEW, and Carl, VE6GGG, also accepted Tony's offer of food and lodging and on Friday afternoon made the trip to Hanna to help launch and recover SABLE-1 the next morning. We all made ourselves at home and spent the evening visiting and making last minute preparations.

May 19 / 2006

On Saturday, May 20th, 2006, the SABLE-1 Balloon Mission was launched at 8:09 AM after an 8 minute countdown hold which was extremely good considering all of the instruction & learning that took place, questions being answered and the fact that Tony had his students doing as much as possible. With 40 km/hr winds gusting to 60 km/hr, time was also spent questioning if a launch should even be attempted. But it was felt we had to at least try with the school term ending, this the only chance for some students to participate and with some of us traveling several hundred miles to help. The wind would not affect inflating the balloon with helium as this would be done inside a large wash bay with a nice high door, but we questioned how difficult it may be trying to handle an inflated balloon in the wind and what other problems the wind may cause.

Trying to handle the balloon in the wind was worse then expected and the photo taken by the payload camera of Tony holding the balloon (left) does not even come close to showing how impossible it was to keep the wind from blowing the balloon about and down into the gravelled earth repeatedly. Something had to be done immediately before the balloon was damaged so Tony released the balloon while I held on to the payload to move further away from buildings and closer to where we wanted to launch from with the hope that the balloon would rise and stay out of the gravel. It sounded like a good idea at the time, but with the balloon unrestrained at the end of a long leash the wind was now able to blow it about more wildly and down into the gravel even harder.

The only choice now was to launch immediately from where we were, but the tracker antenna had become tangled up in the payload package support lines so we were forced to watch as the wind blew the balloon into the gravel a few more times first as the antenna was untangled in a state of panic.

The short 30 second delay ended up being a good thing as it almost perfectly synchronized payload camera photos to the launch time and . . . next


The next payload camera photo, 1 min. later at 8:10, shows the balloon has gained some altitude and was taken looking NW and as it passed over corrals on its way towards hills in the west.next


But 10 second's later the battle appeared to be won as the balloon rose to over 100 feet (above) & (right) disappear from view over hills to the west 30 sec's later as everyone watched.

No digipeaters were within 100 miles so James brought and setup a portable one to ensure no one would have a problem receiving APRS transmissions while the balloon was tracked and recovered. But we soon realized that no tracking data had been received since the balloon disappeared from view and we would have to quickly give chase to hopefully regain sight of, follow and see where the balloon ended up. However, as we were leaving we were told that someone had watched from the hill top as the balloon became tangled in trees several miles away and payload camera photos later showed what had happened while the balloon was out of sight and why APRS transmissions had not been received .next


1 min. later, at 8:12, the payload was still travelling quickly, but close enough to the ground now that the dangling antenna would have been bouncing and whipping about as it was dragged across the rough field. This is obviously what damaged the antenna and why further APRS transmissions were not received after this time. next


At 8:14 the payload package was airborne again, but now with the payload camera knocked out of place after several minutes of bouncing across fields for about a mile .next


It was a short 1/3 mile walk across a pasture from the road where vehicles were left to where SABLE-1 was tangled in the upper most braches of several trees and to where everyone was asking the same question "How are you going to get it down?" The answer was easy as James was close behind me. James was the one who made the long swim and recovered BEAR-2 and probably wouldn't hesitate (too long at least) to climb and recover SABLE-1 from the tree tops.next


at 8:09, just sec's after being launched, the payload camera took the above photo, looking NW, as the wind blew the balloon westward. The balloon had trouble gaining altitude, but everything made it past the south end of the building pictured OK, however it wasn't as lucky with another building further west where the payload package hit and bounced off the SW corner of the roof as it passed by.
  next
From the ground it appeared the balloon may be loosing its fight with the wind and down drafts as it barely clears the first hill.
  next
 

At 8:11, shortly after it disappeared from view, the balloon was travelling quickly and the payload was back down to a few feet from the ground again after being over a 100 ft higher and even though the ground elevation was less now than the hill just cleared, continued to become less, and was 190 ft lower where the balloon became tangled in trees.
  next


At 8:13 the payload was still moving quickly, but it and the antenna were both bouncing along on the ground now as they were dragged across the field.
  next


The final payload camera photo at 8:15 shows the camera has shifted further from another payload encounter with the ground or from simply rolling around freely in the payload container. Being the last photo also indicated that the camera off button was bumped and activated sometime during the next minute which was likely when the payload encountered the trees where it was found.
  next


40 km/hr winds stretched the balloon into various shapes and made it dance about as it as it tugged on the parachute and payload line.

(left) Seeing the payload instantly answered why APRS data had not been received. 95% of the tracker antenna element was missing and only a small stub remained where brass tubing used to splice the element snapped when the antenna was dragged across rough fields.

As expected, James was the one who ended up climbing not just one, but two difficult to climb trees. First one tree to cut the balloon free (upper right) and after figuring out how to get to the chute (right), free the parachute from the branches it had become tangled in (below).


And then a second tree had to be climbed to recover the payload container (below).
.





SABLE-1 travelled about 2.5 miles during it's 7 min. flight making its average speed 21.4 mph which is close to the 40 km (24.8 mph) wind speed reported by the weather office. The balloon would not have been travelling as fast while dragging the payload across fields however, and its speed while air born was likely close to the reported wind speed which may have even been higher than thought.

Even without GPS data, using Google Earth, land features and shadows it was possible to locate quite accurately where, and in which direction, 6 of the 8 payload photos were taken and determine SABLE-1's path, speed, distance travelled and what happened while SABLE-1 was out of view.

If you have Google Earth installed, download SABLE-1.kmz and follow SABLE-1 from where it launched to where it became tangled up in trees and was recovered. If not, get & install it from Google Earth first.

So why did SABLE-1 never get much higher than 100 feet?

My first thought was that down drafts from the strong wind were the reason, but after writing the above and a lot of thought, I'm sure that if winds had been much lighter to permit the free lift to be confirmed outside after everything strung together and tied to the balloon, we would have found that it was much less than the 1 lb we thought it was. Different scales of unknown accuracy were used to weigh individual SABLE components and the weights were totalled, but scale accuracy errors and even small errors due to the rounding off of a number of individual weights all add up quickly.  It would have been better to use a single scale of known accuracy for all measurements, but best is to simply weigh everything making up the balloon's load together, as a single item. And it's difficult to measure balloon lift using a scale and easier to simply add 1 lb, for free lift, to the weight the balloon must carry aloft, subtract the filling device weight, fill a plastic pop bottle with sand or water until it weighs the same as this result and tie the bottle to the filling device while the balloon is filled with helium. When the balloon, filling device and bottle all become neutral buoyant the balloon will contain the correct amount of helium.

Update: Further information regarding free lift has been found.

When precipitation, icing, or terrain turbulence is occurring, sufficient free lift shall be provided to ensure that the balloon will not descend or float. An increase of 100 grams free lift is typically sufficient to compensate for an increase in the weight of the train resulting from light precipitation. Under light or moderate icing conditions, moderate to heavy precipitation, or terrain turbulence induced by high surface winds, an increase in free lift of 200 to 300 grams will usually be sufficient. Under severe icing conditions, an increase of 500 grams or more may be required.

I'm sure 40 km/hr winds would qualify as “high surface winds” and 200 to 300 grams is 7 to 10.5 ounces. This means out balloon only had 5 ounces more free lift then required to over come the effect of the wind if filled with the correct amount of helium to provide 1 lb of free lift and about 5 ounces of free lift is what the balloon appeared to have in the wind so I'm sure we had close to the 1 lb of free lift normally required and that our balloon would have surely overcome the terrain turbulence induced by high surface winds if we had known and provided an additional 200 to 300 grams of free lift.
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