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NSTAR 04-A Flight Summary |
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At 29,800 ft during descent, looking southeast. The north end of Lake Panorama is visible in the upper left. |
Our first attempt to launch NSTAR 04-A came on February 22. We joined up at Gretna Middle School about 8am for a 9am launch. Unfortunately, our balloon got away from us before we could tie it off and without enough helium for a second attempt, we had to scrub the launch for the day. See this PG-rated clip for the results.
As we made our way to the launch site for our second attempt, on Saturday, February 28th, I wasn’t sure we’d be successful on this day either. While driving through Treynor, about 4 miles from the launch site, we noticed the flags snapping in about a 15-mph breeze. It is fairly risky trying to launch a balloon in such conditions, as the wind can blow the balloon into surrounding objects or the ground itself while filling or soon thereafter.
To my relief, as we got out of the car at Scott’s, the wind was nearly calm. Scott’s farm is at a lower elevation and with the morning inversion, the higher winds were restricted to a layer off the ground. Treynor itself is on a ridge top and was in the layer of higher winds. We unload the car and start preparing to fill the balloon.
As a result of our first attempt of the year, we obtained some quick-release hose clamps to keep the balloon securely on the fill tube. These worked very well for us and we filled the balloon without incident. Also, we released the lanyards while hanging onto the payloads to reduce the risk of the lanyards fouling. This also worked well and we released the balloon at 1342 UTC.
Soon after launch, when the balloon was still less than a mile away, we got our first SSTV picture. The signal was weak and noisy, barely enough to decode. During the preparation, I decided to put our "questionable" equipment on the SSTV payload. This would help to determine which radio and antenna were bad. The SSTV’s radio was the VX-1R that fell 13 miles back in 2001 – it’ll be retired now. The antenna has some teeth marks from one of our cats and will be taken out of service as well.
The other payloads are working well, including the backup beacon that had been troubling us for quite a few flights. We chase east on US 6 and then north on US 59 to I-80. Our projected landing site was a few miles south of Jefferson IA, so our plan was to wait north of Guthrie Center until the burst and go from there. As we got north of Guthrie Center, we made contact with Larry N0BKB who was waiting at the intersection of 25 and 141. We pulled in behind him and waited on the burst.
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NSTAR 04-A Flight Summary |
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At 29,800 ft during descent, looking southeast. The north end of Lake Panorama is visible in the upper left. |
Above 40,000 ft, the balloon’s ascent rate decreased from about 1000 ft/min to less than 600. Since the winds were light at those altitudes, it didn’t have much of an effect on the landing prediction. However, our 1500g Kaysam balloon gave up earlier than expected, at 1533 UTC and an altitude of 92,913 feet.
Since the actual burst location was near the predicted burst location, we expected the landing to be north and east from the intersection of 25 and 141. We headed closer to the predicted landing site, but it soon became apparent that it was not going to go quite that far. We backtracked to the west and south in an attempt to be close to the landing when it happened. We were within about a half-mile, but I could not see the payload stack against the high overcast. The rest of the Des Moines-based chase team all converged on the same area and some of them reported seeing the payload. Landing occurred at 1606 UTC about 3 miles NE of Bayard IA.
We had a 3/8-mi walk into the field to retrieve the payloads. Fortunately, it was near enough to a fence line that we could walk on the somewhat-frozen snow drifts most of the way there. The payloads landed in some mud but were undamaged. After recovery, the chase team had lunch at a nice pizza place in Guthrie Center before heading home.
The still pictures turned out reasonably well. The ISO 200 film did not allow for a fast enough shutter speed to stop the payload’s rotation and swinging all the time. But several did turn out well. The camcorder video taped to a few minutes after burst, and showed that the payloads may have nearly turned upside down in the post-burst chaos. However, they did stabilize within about 20 seconds or so. The EEPROM log was still using the settings I had for our short 03-F flight, so the detailed logging ran out of memory at about 78,000 ft.
Thanks to a couple of contributors who made donations to help keep NSTAR flying!
Our second launch of the year was at the Central Plains Severe Weather Symposium in Lincoln. Wayne, Doug, and I arrived shortly after 8am to check out the launch area surroundings. Eventually we found a spot south of the auditorium that was well-shielded from the 20-30 mph winds blowing that morning. I gave a 45-minute presentation on NSTAR at 9:30, then started launch preparation about 10:30.
With the wind blocked by the building, we started filling about 10:45 and didn’t have much trouble with the wind during the fill. About the time we got the payloads tied on, much of the crowd came out to watch our launch. We did a quick check with the Lincoln tower to make sure we were clear, and released the balloon at 1112 CST before an audience of about 100.
A swirl in the wind abruptly carried the balloon towards the west-facing wall of the school, and the bottom payload carrying our backup beacon struck the side and then the roof. Later we determined that this silenced the backup beacon by causing the battery compartment on the radio to open and disconnect the power. We’ll mitigate this next time with some tape. Otherwise, the payload was undamaged.
Soon after launch, we got our first SSTV picture with good clarity, so it appeared we had mostly fixed our earlier problems with slow-scan. We packed our equipment and headed out on our chase by 1120.
It seemed to take forever just to get out of Lincoln. Next time I’ll do a little more research on the fastest way out of town. We went east on Havelock and then south on 84th, seemingly hitting every red light along the way. Finally we got onto Hwy 2 and headed towards Nebraska City. As we were coming up on Syracuse, the capsule reported the balloon had burst at 62,405 ft at 1806 UTC (1206 CST).
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NSTAR 04-B Flight Summary |
We continued on across the Missouri River, occasionally getting SSTV pictures. Some of them had regular dropouts, indicating the payloads were spiraling down as they fell. But the descent rates were reasonable, so we weren’t too concerned with a fouled chute. About the time we got onto I-29 to head south, we got a last report at 2300 ft MSL (1200 ft AGL) south of Fairfax MO. Landing occurred at 1835 UTC (1235 CST) about 4 miles SSE of Fairfax.
It took us about 45 minutes more to get to the landing site. In the meantime, Mike N0GGU had made his way from his QTH near Graham. He called me on my cell phone to report that he was near the payloads and that they were safe. We arrived about 1315 and retrieved the payloads.
The still camera worked well. An improved algorithm to detect bad GPS data prevented any unplanned triggering of the camera, which on past missions had caused "extra" pictures to be taken. The SSTV camera worked better than on previous flights, but still had fairly weak signals. Given that the antenna was just an 8" whip, I suppose that’s to be expected. We may try a J-pole antenna on a future flight.
The video quality was also pretty good. We had a lot of rotation early on, which appeared to be induced by the backup beacon payload striking the school. Within a few minutes, most of that had stabilized. On the way down, the payloads got into a spiral that continued most of the way down. About 10,000 ft the stack stabilized into a nearly-vertical configuration for a few minutes, then began to spiral again a few minutes later. After landing, the wind caught the parachute and dragged the payloads towards a fence line for about 10-20 ft.
Ground photos at the CPSWS web site
Paul Verhage's flight on Sunday the 21st went well too, with the landing 8 miles N of Chillicothe MO.
After a month of delays, NSTAR 04-C finally got off the ground on Memorial Day. We arrived at Scott KC0MTH’s place around 0645. The winds on the ground were calm but the tops of the trees were in motion, indicating the morning inversion was breaking and that we’d better hurry along. We started filling our Kaysam 1000g balloon shortly after 0700 with a full T-tank of helium.
We strung the lanyards and started letting the balloon out to launch position. As the balloon rose, the wind began to catch it and rotated it around. This twisted the lanyards around the load line and was impossible to untangle. We reeled the balloon back down by the load line and still could not sort out the lines, so we cut the lanyards and let the balloon back out by the load line. After a final check of the payloads, we release the balloon just before 0726 CDT (1226 UTC).
When the backup beacon, the bottom payload of the string, was let go, it swung into the nearby shed with a resounding "bang". This was a repeat of our previous flight, where the backup beacon struck the school after release and cause the battery cover on the enclosed HT to open and power off the beacon. This time, we were reassured when the 12:26:04 beacon was transmitted on schedule. The backup beacon continued to function normally the rest of the flight.
The main beacon and the simplex repeater also checked out fine, so we packed our gear and headed off about 10 minutes after launch. Before long, though, the simplex repeater became progressively more difficult to understand even with an S9 signal. This was due to weak batteries in the recorder for the simplex repeater. Well before burst, the voices on the repeater were completely unintelligible.
We chased east on Hwy 92 to Massena for a brief stop, then headed to Bridgewater and south on a main county road. We stopped for a while to wait for the balloon to burst, and were able to see it with the naked eye and binoculars. Because it was 45-50 degrees above the horizon, I got a stiff neck and looked down to relax it. Just a few seconds later, Wayne KE6DZD said "it just burst" – I had missed seeing a burst yet again. Burst occurred at 89,197 ft at 0903 CDT.
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NSTAR 04-C Flight Summary |
We drove south a few miles and began to calculate where the landing would occur. We were a little concerned the payloads may land in Lake Icaria north of Corning, but fortunately the track stayed well to the north. Steve N0ORU called us to say he could see the parachute as it passed over him about 7000 ft. After a couple more stops, we committed ourselves to a county road two miles west of the main road and drove north to meet the balloon. About 1500 ft AGL, we spotted the parachute to our northwest and continued north. At 0937 CDT the payloads landed about 30 ft from the road we were on, and equally close to a set of power lines. Even more convenient, they landed right in front of a gate in the fence.
The payloads landed in some mud and standing water, but were undamaged. We walked in and retrieved the payloads, shut them off, then posed for our usual "trophy photo" of the chase team. Since it was too early to find someplace for lunch, those of use who had to go north or east went back to a gas station to pick up some snacks for the ride home.
The camcorder and still camera worked fine – the pictures were of good quality but did not catch anything too remarkable. The descent spiral noticed on previous flight was not quite as fast this time. There was more payload swinging and rotation on ascent though, which tended to blur several of the still photos.
Our fourth flight of the year took us to Hutchinson, Kansas, for the 2004 Great Plains Super Launch. The first Super Launch was held in 2001 near Manhattan and is an annual event usually held around the Fourth of July weekend. Most of us arrived Thursday evening and attended the symposium on Friday, while the flight itself was on Saturday morning.
Because of the predicted flight profile, our launch site was about 25 miles northeast of Hutchinson, at the McPherson airport. We arrived at the airport around 0730 in anticipation of an 0845 launch time. The surface winds were pretty light on arrival, but began to pick up a little and were around 10 knots by launch time. Our designated balloon filling area was between two rows of aircraft hangars, which gave most some protection from the wind. NSTAR, however, was at the north end of the row and was a little more exposed than the others. This caused us a little difficulty, but we got the balloon filled and tied off, then waited for everyone else to finish filling.
By 0850, everyone was ready to move to our release site, the adjacent aircraft parking apron. The Project Traveler group took the upwind position, planning to release first so as to get video of the others as they launched. I had my handheld radio with me, but I could not find the frequency they were using to broadcast their intentions. The EOSS group was closest to us and had their handheld turned way up, so I told Paul KC0KXR that we would launch as soon as we saw EOSS was in the process of releasing their balloon.
At 09:03:40, we let our balloon go. I was a little surprised at the slower-than-usual ascent but not too concerned at that point. As I looked up, I saw our payloads ascent through a small cumulus cloud perhaps a thousand feet overhead. I thought to myself ‘gee, this will make for some neat video……..had I turned the camcorder on!’. Cursing at that, I then thought ‘well, maybe we’ll get some still photos….but I didn’t open the lens for that camera!’. In the pre-launch excitement, I had left the checklist with the fill equipment and didn’t run through it mentally after we walked to our release position. With a contingent of two, we had our hands full keeping hold of the payloads and balloon – our normal procedure is to have a person reading the checklist and watching the whole thing. But our tracking equipment was working normally, so I figured we get the payloads back OK and do better next time. The SSTV was transmitting but because the camcorder had powered off automatically it only transmitted blank pictures.
Paul KD4STH, from Idaho, rode with me, my wife, and 11-month-old daughter to track his equipment during the flight. The expected landing for NSTAR, and most of the other flights, was about 8 miles southeast of Newton, near Whitewater. Since Paul’s flight was with a larger balloon, we expected his to go higher and farther west, perhaps near I-135 south of Newton. We headed to the south side of Newton and stopped at a Sonic to get some snacks while we waited for the flights to progress.
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L-R: ORB, NSTAR, KD4STH, and EOSS
ready for launch at the McPherson airport. |
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Flight paths of all GPSL 2004 participants |
While we were driving south on I-135, it was apparent that NSTAR was not rising as fast as the rest. With a 12-lb payload and a full T-tank in our 1000g Kaysam balloon, I had expected an ascent rate of close to 1000 ft/min. However, our rate for the first 20,000 ft was about 800 ft/min, then slowed above that level to about 400 ft/min. This would extend our mission at least another hour longer than expected. Since NSTAR would be the last to burst, we concentrated on where Paul’s flight would end up. We went south on I-135 to Hwy 196, then east towards the expected landing site west of Whitewater. His balloon went up a little farther than expected, to almost 105,000 ft. This also took his track farther west-northwest than expected, so we headed back to the west to chase it.
As Paul’s flight was descending west of Newton in its last few minutes of flight, NSTAR burst at 84,875 ft and 1126 CDT east of Newton. This would put our respective landing sites about 30 miles apart, and would be impossible to get from one to see the other land. Paul KC0KXR was with us for the chase, so we made the decision that I would stay with the Paul STH for the Idaho flight’s recovery, and Paul KXR would take off for the NSTAR site as soon as the Idaho flight was on the ground. We made our way west on US 50 to near Halstead, then north. Paul’s flight landed just barely within our sight about ¼ mile off the road.
After the Idaho flight landed at 1136 CDT, I got out with my Kenwood D7 and a GPS to find our way to the landing site. I continued to monitor 144.34 MHz, but soon noticed that N9XTN-11 had stopped sending data at about 30,000 ft and 1143 CDT on its descent. I surmised that its batteries became exhausted, so I switched to 144.39 MHz to monitor the N9XTN-12 backup beacon. I continued to get posits and helped Paul recover his payloads.
Back at the car, I switched my APRS gear to 144.39 and managed to catch the last 2-3 position reports from the backup beacon before its landing at 1203 CDT. The positions were digipeated through one of the local digipeaters, otherwise I probably would not have heard it. This was a relief, as we now had a good handle on the landing site. Paul KXR contacted me by repeater and said he did not copy any of the backup beacon’s packets, so I directed him to the last known location about 3 miles SE of Potwin.
We made our way to Potwin and found a relatively wooded area as our probably landing site, with poor visibility into the section where we surmised the landing to be. The last report was at about 1400 ft AGL and with a forward speed of 30 mph and about one more minute to go in the flight, I expected the landing to be about a half-mile downwind of the last report. Since that was very near the road bounding the section, that would put the landing near the center of it, well away from the roads. We made two laps around the section, but could not pick up any signals. We knew part of the EOSS Tracking and Recovery (T&R) crew were enroute with better equipment to help us out, so we turned to finding out the landowner. After stopping at a paintball range and getting directions, we found where the landowner lived and made contact.
We asked if we could walk out to conduct a search, but he very generously offered to drive us around the farm in his 4WD truck. Three of us piled into the truck and we headed out. Our first stop was a small lake that had a good chance of containing our payload. It might float for a little while, and with a brightly-colored chute we might at least spot it. But after looking it over we decided it either was not in the lake or was no longer floating. We went north a little bit and then east, looking for a place to walk between a tree line into another field. But with the recent rains the creek between the two was impassable by foot or vehicle. At that point we were near the center of the section and figured that now it would be best to go back to the west towards the last known position to see if it came down short.
As we crested a rise in the field, I could see the parachute lying on the open ground about 200 yds in front of us. I called "tally ho" on my D7 to the T&R crew still hunting for our signals to let them know we had found it. It was a great relief once again to know I could at least take everything home with me even if the flight had not gone all that well.
Examining the payloads, I found that the SSTV and backup beacon radios were off. When I turned them on to test them, both indicated decent battery voltage, so I think they powered off at impact for some reason. All the equipment was intact, so we packed up and headed back to the farmhouse. We gave our profound thanks to the farm’s owner and headed back to Newton for lunch.
With our delayed return, most of the other teams were leaving the restaurant by this time. We had a quick lunch, then took Paul back to the McPherson airport to pick up his car. After that, we headed back home to Bellevue and finally arrived about 2130 after a very long day of ballooning.
The main payload used a Li-ion battery pack that worked for six hours on the bench, but failed after 3 hours in flight. It was one of the first Li-ion packs I had built and tested, but it may not have been fully charged for the flight. With only at 3400 mAh capacity, it probably does not have enough reserve capacity to be suitable for the main payload. A new battery pack will be built and tested for the 04-F flight.
Pictures to be posted later.
This flight was scheduled to support the University of Nebraska-Omaha Aerospace Education Workshop with a BalloonSat flight. NSTAR provided two tracking payloads, one of which included a still camera, while the workshop participants provided six BalloonSat experiments that we attached.
The weather forecasts for the week leading up to the flight date promised cool weather but otherwise good conditions. However, the forecasts suddenly changed the day before to include a substantial chance of showers through Saturday morning. We all woke up at 0500 on Saturday to the sound of falling rain. After conferring with Dr. Larson at UNO, we decided to have another phone conference at 1000 to discuss the weather.
By 10am the radar showed a lot of rain in the area, but a hole was opening over the launch site that looked like it might last a while. We decided at that point to go ahead with a 1230 launch since the winds were light, the chase plane was ready, and both NSTAR and UNO would have more difficulty delaying to Sunday. On our 30-min drive to the launch site we encountered a few bands of heavier showers, so I started to despair that we would get the balloon off the ground.
We arrived at the launch site about 1130 and the rain had subsided to a very light drizzle. We found a quiet place next to the school to set up our equipment for filling the balloon. As we began to fill the balloon around 1215, the rain became a little heavier. Soon the surface of the balloon was saturated and a mix of talc and water began to run down the sides of the balloon and onto the balloon neck as we were tying it off. We made sure to keep positive control of the balloon at all times, and when we taped off the balloon we added a zip tie over the tape to help keep it in place. As we were finishing up the balloon train we could see and hear the UNO chase plane orbiting the launch site. With the assistance of a couple of the workshop participants, we got the balloon airborne into the overcast and rain at 1243 CDT.
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NSTAR 04-E Flight Summary |
After launch, we headed to our first stop, a gas station in Massena (just off the right center of the map below). Our prediction had the landing a few miles north or northeast of Massena for a 0730 launch, but after we got to the gas station it became apparent the balloon would not go that far. The balloon burst at 93,953 ft just after 1400 CDT.
As we headed back toward the Atlantic area, we made contact with Paul KC0KXR who was in the chase plane. We now expected the landing to be to the north or northwest of Atlantic. We made our way through town and to the northwest edge as the balloon was descending through 10,000 ft and turning back to the west. Our initial plan was to turn east on a county road, but we passed it by mistake. As we went north to the next intersection, I decided the balloon was still making good progress to the west, so instead of turning east we turned back to the south and pulled off the road.
Finally we spotted the payloads passing almost directly over our vehicles at about 2000 ft AGL. There was some swinging back and forth during the descent, but otherwise it was stable. We watched the payload drift down into a safe area over some soybean and cornfields, landing at 1442 CDT about 500 yards off the road. We were able to walk most of the way on a grass vehicle path, but the last 150 yards was through 10-ft tall corn. Paul in the chase plane helped guide us to the landing position, as we could not see the parachute until we were within about 20 ft of it.
All the payloads were recovered intact and the experiments were pretty successful.
In the last few days leading up to this launch, the weather forecasts indicated a good chance for very light surface winds for the entire morning of the launch day. So on Friday the 1st, we decided to delay the launch time from the usual 0730 to about 0930.
Another concern in the last few days before launch was our track forecast. They were uncomfortably close to Creston IA and two lakes northeast of there. However, the Friday forecast indicated we could fill the balloon more to shorten the track and use a 1200g balloon to lower our burst altitude, moving the landing site a more comfortable 6-8 miles west of Creston.
We arrived about 0830 on Saturday morning with a lot of frost on the ground, which melted soon after our arrival. Just a hint of cloud cover well to the northwest was the only obstruction in the sky. As I powered on the payloads, it was apparent the VX-2R used for the backup APRS beacon had a dead battery. With no charger handy and no time anyway, I decided to remove the simplex repeater setup and use its VX-1R for the backup beacon instead. The remainder of the checkout proceeded normally.
Suddenly there was a beeping noise from my chase vehicle. The power inverter used to run the laptop was whining about an undervolt condition. I unplugged it and went to start the car to charge up the car's battery. The relay clunked, but that was it. Our host Scott KC0MTH came to the rescue with his truck and a set of jumper cables, and the car was running again. I made a mental note to keep the car running during our various stops, and borrowed his jumper cables for the morning just in case.
Soon after we got the car started, the laptop went to standby. Since I'd unplugged the inverter, the laptop went to its internal battery for power, and the old laptop battery is only good for about 15 minutes of life. The screen won't turn back on for some reason after going to standby, so the only cure is to reboot. With a 450 MHz Celeron running XP, this takes a while. After booting, a new problem cropped up. The USB/serial converter was still connected to an operating GPS unit. XP detected this as a serial mouse and the cursor was uncontrollable. Another reboot and 5-minute wait.
Finally the chase equipment was back to normal and the launch could proceed. Fortunately for us the surface winds had remained very light so there was no risk to our 1200g Kaymont balloon. We got the balloon launched at 0953 CDT.
Everything was running normally after launch, and we packed up to start the chase. We headed east on Hwy 92 to Massena and then south on Hwy 148. I remembered an east-west blacktop county road from one of our previous chases passing near the tiny towns of Mt Etna and Carl. We turned east on this road and stopped to wait on the balloon burst. With the clear sky overhead, it wasn't difficult at all to spot the balloon with the naked eye. However, being nearly overhead made it hard to keep looking at for long periods. I had looked down to rest my neck when Wayne announced it had appeared to burst - he said it looked like it had split in two. Soon the telemetry confirmed the burst at 84,305 ft and 1114 CDT.
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NSTAR 04-F Flight Summary (above) and detailed map of landing area (below) |
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We continued east with our chase to a couple miles north of Creston. I was becoming more and more concerned with landing in the lakes northeast of Creston. The lakes are 3-4 miles long and about a half-mile wide and our capsules were heading towards them along their long dimension. Certainly nothing we can do now but wait. As the descent continued, it started to look like we'd land short of the lakes which was a bit of a relief.
Soon we could hear Larry N0BKB on our chase frequency. We managed to avoid a construction area by taking a shorter gravel road over a longer paved one. As the balloon descend through 5000 ft, we were just 2-3 miles away. The balloon was to the south of the road we were driving on, but was moving back to the north.
Tally ho! Wayne and Paul had spotted the balloon, but it took me a few seconds longer. I got my video camera out and started shooting the terminal descent. The payload was swinging and spiraling in a fashion that made it difficult to tell just how it was moving. At first it looked like it would land on the road, then it drifted north again. Uh oh, we have power lines on the north side of the road. The payload made one fortunate swing north again and cleared the lines. It dropped between the road and the cornfield in some grass at 1148 CDT, with the chute draped just over the fence under the power lines.
Since we could reach everything from the road right-of-way, we didn't have to see about finding the owner. We were parked somewhat precariously on the side of the road, and within a few minutes a couple of larger trucks had come by already. A few hundred yards up the road there was a small cemetery with 10-15 cars parked there. However, the people weren't dressed as for a funeral. Soon a couple of them came to see why we had stopped there. They had seen us pick up the parachute and had thought maybe it had been there a while. We explained that it had landed just minutes before and that we saw it come down. We also showed them our chase equipment and explained the hobby. They were impressed that we could launch the equipment to such a high altitude, chase it, and be there right when it landed. I handed them some NSTAR cards and we packed up and headed to Creston for lunch.
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At 83,750ft looking northeast. Des Moines is in
the right center of the image. |
The new lithium-ion 6400 mAh pack performed quite well. It has at least a 10-hour capacity and we had used barely 3. Our new Concord EyeQ 4060 digital camera also worked well on its first voyage. The only less-than-perfect aspect was that the camera had switched to standby during the pre-launch delay - when it came out of standby the JPEG quality setting had reset from "high" to "medium". However, 151 pictures were taken during the flight, every time the Basic Stamp had commanded it. Quality was equal or better than the Canon Elph used on previous flights. A modification to the control circuit will be added to keep the camera from going to standby during the pre-launch phase. The camcorder had run for the entire flight from launch to landing. In fact, it was still running as I put it back into the car.
One of the problems with the camcorder and still camera is its orientation during descent. Both point horizontally on ascent, but are tipped up about 30 degrees on descent. This seems to be due to the balloon pulling on the parachute and tilting the stack out of the vertical. Funny how consistent it's been lately - I don't think it's been oriented with the cameras "down" very much. I hope to install a timer cutaway for our 2005 flights.
Video of the landing from my chase vehicle (2.3 Mbyte Windows Media)
Our seventh flight of 2004 was on a typical November morning - clear and calm with temperatures in the low 20s. Most of us arrived at about 0730 and began setting up. Shortly after 8 we started filling the balloon and checking out the payloads. Everything proceeded normally and we released the balloon at 0829 CST.
After release, I went to my APRS laptop to check out the early ascent data. Immediately it was apparent something was wrong - the balloon's position showed no direction, speed, or altitude information. This is typical for a poor or non-existent GPS fix. I immediately switched to our backup beacon to get an idea of the ascent rate and to verify its operation - we had good data from it and a nominal ascent rate. The simplex repeater checked out OK and we prepared to leave the launch site.
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NSTAR 04-G Flight Summary |
Once we were on the road, I switched back to the main beacon and saw that it was once again reporting good altitude/course/speed information. The GPS fix quality was poorer than usual, but usable. At the time, I speculated that the GPS antenna had slipped out of position within the payload and was no longer pointing vertically.
We continued on the chase, heading for Massena, IA and our usual mid-chase gas station stop. The simplex repeater continued to work well, with stations near Des Moines, Omaha, Topeka, and Kansas City checking in. However, the main payload's GPS showed signs of having poor fixes, and finally at about 70,000 ft became too unreliable to use. We switched to the backup payload for tracking the remainder of the flight.
After we stopped in Massena, chase team members could spot the balloon without much difficulty owing to the clear skies and a favorable orientation relative to the sun. Nearing burst, the balloon was only three miles or so to our west, but 14 miles up. Burst occurred at 0951 CST and 90,273 ft.
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Video stills from last few seconds of NSTAR 04-G's flight |
Soon after burst, one of the team member said he could see the payloads and parachute even though they were still above 60,000 ft. I was skeptical, since the highest altitude we had ever been able to see a parachute was at less than half that altitude. But sure enough, with a little help I could see them too. Using binoculars I could see a large chunk of balloon along with the payloads - I think this is why we could see it so well. We watched the parachute for a while longer, then left the gas station to head north.
Based on the burst location, I expected the landing to happen about 3 miles north of Massena. We went about two miles north and pulled off the road to watch more of the descent. Below 20,000 ft the payload began drifting north and then northwest. It passed almost directly overhead, then landed in a field about a half-mile to our west at 1027 CST. Someone headed south on the highway had seen the payload and stopped to ask us if we were tracking it.
It appeared the landing was closer to the road one mile west than to the road we were on, so we drove around the section and onto a minimum-maintenance road. Fortunately it had dried some from the recent rains and was in good shape. We hopped the fence and headed towards the landing site - the parachute and payloads could be seen in the open field.
Upon inspecting the payloads, the GPS in the main payload was in its proper location. The other payloads were undamaged, but there was quite a bit of fouling by the balloon shards on the load lines.
The videotape ran from launch to landing and was one of the better tapes we have collected to date. The video camera landed face-first into the ground and provided a neat clip. On the way down, the balloon remnants could be seen hanging freely below the payloads, so the fouling may have occurred in the last few minutes of flight. I've theorized that the digital camera may have interfered with the GPS-18 - this will be tested over the winter hiatus. Because the GPS did not function correctly, not all the scheduled pictures were taken. Even so, over 90 were taken and yielded some good ones. It appears that the way to get good balloon pictures is to take lots of them, and the digital camera allows this without the expense of more cameras and film processing. The humidity sensor appears to be stuck on 75% and may be broken - I was not as careful as I should have been with a last-minute wiring job.
Follow-up: It appears the digital camera desenses the GPS-18 by 10-15 dB - this is enough to cause the GPS to lose its position fix if the geometry or number of satellites is unfavorable. There is a similar but lesser effect on the GPS-35. I will switch back to the GPS-35 and increase the physical separation until a permanent solution is found (probably involving some method of shielding the camera).
Payload landing (2.3 Mb Windows Media)
