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BEAR 3 Post-Flight Forensic Analysis
The Parachute: It worked absolutely perfect. We could not have asked for anything more. The colors were easy to spot from the chase plane and easy to see from the ground by the recovery team. It sustained NO damage after the flight and it will fly again.
The Payload Line: Everything worked very well except for the wooden stabilizer ring which cracked upon launch. But, it is easy and inexpensive to replace. Most of the miscellaneous flight hardware can be reused again.
The Hobo Data Logger: The Hobo worked extremely well and resulted in very useful data about the internal versus external temperature of capsule 4 (the particulate sampler package), the relative humidity of the upper atmosphere, the location of atmospheric boundary layers, confirmed the time of the balloon burst and most importantly, confirmed a voltage spike at 30, 000 ft. in altitude when the sampling pumps automatically turned on. We are continuing to analyze the data set and will post new information as it comes available. Click here to go to the Hobo Data page which features a larger graphic shot of the data.
Capsule 1: The APRS (144.39 set at 800mW) beacon worked flawlessly from launch through June 2. Even after it was brought back into Fairbanks, it was still beaconing at Neal's house until he cut the main power wire. I am truly impressed the beacon continued to operate so long with the eight "AA" lithium battery pack. I suspect the beacon went to a lower power setting after the battery pack voltage dropped below 9V. Still - it had continued to beacon so that the recovery crew could pick up its signal. Seven days after launch, on June 2, I removed the micro-transmitter from the capsule and tested it. It seems undamaged. I connected it to a 12v battery and it was transmitting at the correct 800mW. I confirmed the remaining voltage in the original "AA" battery pack and it was 6.8V. At that voltage, it should be beaconing at approximately 400mW. The gps for this capsule continued to register and re-register (ad nausea) the position coordinates until it was recovered and moved on June 1. Almost 2,600 very redundant coordinate points were saved. After recovery, I checked the batteries on the gps and almost 90% of battery life remained. The gps captured a total of 3,843 points. When recovered, this transmitter/gps system was hung-up in the tree (see recovery page) so that the gps antenna was still pointing up and receiving satellite data. An interesting side-bar, Bob WL7GK picked up the capsule 1 beacon on his Kenwood D700 radio from Nome Creek, a recreational park about 80 miles north of Fairbanks. Not bad for about 400mW of power. Good ears Bob !
Recommendations: 1) I would like to see a low-power cut-off switch for both transmitters/gps capsules to prevent the possibility of a brown-out, destroying either the radio or micro-transmitter which would turn the completely power off when it is less than 6V. The brown-out problem actually occurred in second first bear flight, when low power damaged the FA8000 on-board amplifier. This particular type of micro-transmitter seems to have a very sensitive (and somewhat problematic) amplifier and I'd prefer to just turn it off after the power drops significantly. 2) Add a small piezoelectric sound beeper or 440Mhz cw beacon to the package using a 9V lithium battery, either of which would make noise and / or beacon for several weeks. 3) I noticed the flexible antenna system worked well, but the pin connector was loose and the construction technique needs to be better. 4) An exterior mounted on/off switch together with a small led light needs to be wired to the transmitter. 5) A second exterior mounted switch and power source needs to be wired to the gps so the capsule can be sealed up beforehand and power simply switched on to operate the gps acquisition system. 6) We need to experiment and fully understand more about the different interval setting on the micro-transmitters.
Capsule 2: The (144.70 set at 300mW) beacon worked flawlessly from launch through touchdown. It was not beaconing during the recovery period. When I received the capsule from the recovery crew, I noticed the DJ-S11 radio was not working - the batteries were dead. The TinyTrak LED was still functioning because it was attached to a separate lithium 9V battery for power. Without an active radio though, it was not sending any information. Upon touchdown, the DJ-S11 radio antenna hit the ground and become almost fully closed, but not broken. According to the onboard gps, only 19 redundant coordinates were recorded. Even though the gps is using its own independent power source, it's as if the gps turned itself off and stopped acquiring data. After recovery, I checked the gps batteries and almost 90% of battery life remained. GPS total pointed captured by this unit amounted to 1,680. When recovered, this transmitter/gps system was lying on the ground with the gps antenna pointed sideways so it was not receiving satellite data. We need to modify the capsule construction so that the metal foil covering the capsule structure does not extend all the way to the gps cradle. That modification would mean a gps looking sideways could, in theory, still receive a limited amount of satellite info.
Recommendations: 1) Although I see some advantages in a radio antenna that self-collapses upn ground impact, I'd like to see the same flexible antenna system used on capsule 1 also used on capsule 2. Unfortunately, modification for the DJ-S11 radio is not easy but can be done. 2) I would like to see a low-power cut-off switch for both transmitters/gps capsules to prevent the possibility of a brown-out, destroying either the radio or micro-transmitter. I'm less concerned with a brown-out for the 300mW radio / TinyTrak transmitter system. One advantage of leaving it on is the fact it should continue to beacon for a week or so and could guide the recovery crew in. 3) Add a small piezoelectric sound beeper or 440Mhz cw beacon to the package using a 9V lithium battery which would make noise for several weeks. 4) An exterior mounted on/off switch together with a small led need to be wired to the transmitter. 5) A second exterior mounted switch and power source needs to be wired to the gps so the capsule can be sealed up beforehand and power simply switched on to operate the gps acquisition system.
Capsule 3: The camera platform. A lot of interesting problems occurred in here. Although I tested and retested the cameras and battery supplies to make sure everything would work correctly, it seems every camera had problems: The 7.1 Megapixel still camera was independently powered and tied to an independently powered 555 timing circuit. It failed to operate correctly. As a result, the camera turned itself off after a few minutes for some unknown reason. In my pre-flight testing, the camera operated flawlessly for 5 hours, capturing hi-rez pictures every 15 seconds. It did this flawlessly for 4 test sessions. The reason for failure is a mystery but I suspect something bumped the on / off switch located at the top of the camera after a few minutes. Most likely cause is the chemical heater pack inserted just prior to launch. The low-rez downward looking camera captured almost 2 gigabytes of nothing. Examining the camera after the payload was recovered, I noted the "mode" switch had moved from the "movie' selection to 1/2 way between "movie" and "still" selection. I'm reasonably sure these problems can be rectified with additional hot-glue or designing a small bumper over the camera so nothing can change the settings. Camera three was the Sony DSC 7.1 Megapixel camera set to movie mode. It worked well but only captured 1.7 gigs of movie on the 4 gig memory card. Ah…another mystery here. Not sure why it didn't capture the 5 hours of movie it had done so in the 3 past test sessions. I'm not sure we'll ever know the reason for this problem. In every case in the camera system, problems occurred because something physically bumped or changed the camera setting. This should be easy to fix.
Recommendations: 1) Each camera cradle needs to have a top "protection" block so nothing can inadvertantly change any of the settings. 2) Adding another inexpensive digital camera would increase the possibility of picture capture BUT something better would be the addition of a canon powershot anti-shake camera. Using the "open source" CHDscript programming language, the canon powershot can be "programmed" to take a series of single shot, still sequence or movies at a user defined time sequence. 3) Either the camera platform needs to be the last item on the line and/or a swivel system or gimbel mount needs to be created to reduce the rotating. If you've seen the movie, its obvious this needs correction.
Capsule 4: The volcanic ash particulate sampling capsule. Generally speaking, the equipment worked well. Two problems and several mysteries occurred which we are still contemplating. The filter and our high altitude sample for the squirrel cage filter system has disappeared. When, where?? Will we ever find out? The Hobo data logger worked very well but we ran out of memory. Partly to blame was the rush of getting everything together at a moments notice when the upper winds suddenly died. By collecting the voltage of the pump electrical system, the data logger noted a voltage increase, confirming the ash collection system kicked on at 30,000 feet and the pumps were running. Analysis of the data shows us we have several mysteries to solve; surging on the pumps, RF interference and very weird altitude / temperature fluctuations. As mentioned, the memory card filled up with too much data and so we don't have all the data on the way down but enough to know everything worked as anticipated. One high altitude sample was recovered and is currently in the hands of Javier Fochesatto, Research Associate Professor of Atmospheric Sciences, Geophysical Institute, University of Alaska Fairbanks who will report back his findings.
Recommendations: 1) A second set of eyes should confirm the settings on the data logger. 2) Use of a capacitor or zeener diode with smooth out the electrical voltage captured by the Hobo. 3) We need to understand why we lost the pump filter and fix it.