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Category: 2002
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Launch date/time:

23 Feb 2002 1551 UTC (0951 CST)

Launch site:

Scott Clark farm near Treynor, IA

Payload frequencies:

Primary - 144.390 MHz (national APRS frequency)
Callsign N9XTN-11
Backup  - 147.585 MHz call N9XTN-12
Voice   - 446.30 MHz simplex repeater

Telemetry:

AX.25 APRS-formatted location and telemetry, other raw text

Envelope:

1200g Kaymont balloon

Maximum altitude:

93,232 ft

Payload weights:

5.0 lbs main capsule
5.5 lbs secondary capsule

Helium used:

270 cu ft (approx.)

Flight duration:

2 hours 8 minutes

 

 

Equipment manifest

 

 

Basic Stamp 2p microcontroller
Kantronics KPC-3 v6.0 TNC (modem)
Alinco DJ-190T 2m handheld radio
Garmin GPS-35LVS GPS unit
12" dual-band whip antenna
Custom 7.2V 4000 mAh battery pack

2 - Yaesu VX-1R dual-band mini handheld radios w/12" whip antennas
2 - custom 7.2V 2700 mAh packs
Radio Shack simplex repeater
JVC GR-AX220U VHS-C camcorder
Motorola Oncore M12 GPS
Synergy Systems GPS mini-antenna

The 23rd was a near-perfect day for a launch, considering it was late February.  Temperatures in the early morning were in the high 30s, with 60s expected by afternoon.  Most of the chase teams arrived by 8:30am and we had an opportunity to socialize and take our time with launch preparation.  By 9:20 the winds were starting to pick up a little, so I decided we'd start preparing for the launch a little early.

We had a little trouble during the fill with the wind blowing the balloon about, but it wasn't anything that risked the launch.  After we got everything powered up and tested, we launched into a 10-15mph southerly breeze at 9:51 am.

Within a few minutes of launch, we could see that the balloon was rising at about 1300 ft/min which was a bit faster than the 1100 ft/min expected.  Since that would take us up through the strong jet winds faster, we figured the landing would be a little short of Mt Ayr.  The simplex repeater was OK on the ground, but soon we had difficulty hearing it.  Future flights will have the repeater on a higher power setting.  The backup beacon was set for the same power and we also had difficulty hearing it.  We headed east on US 6 to 59, then south to US 34.  As we got on the east side of Red Oak, the balloon was ascending through 60,000 ft and had slowed down.  We decided to stop near the intersection of US 34 and US 71 to await the burst.

Because of the cloud cover and its position relative to the sun, we were unable to see the balloon this time.   Burst occurred at 1116 CST at an altitude of 93,232 ft.  Based on the burst location, we then projected the landing would be southeast of Sharpsburg, so we then proceeded east on 34 and then south on Hwy 148.

As we headed south on 148, it became apparent that the balloon would land not far east of 148.  By the time we approached the town of Gravity, the balloon was passing 148 about a mile or two south of us and heading east.  We turned east on a main road, then dropped south one mile to a county road.  However, the balloon turned more sharply north than expected and we ended up back towards the main road we had just left.  The landing was just before noon CST in a grassy field about 100 yards away from the road.  Fortunately there were no power lines in sight and only a few short trees it could have tangled with.  Larry N0BKB and Mike N0GGU were chasing from the south and east and joined up shortly after landing.  After recovery, we headed for the Godfathers Pizza in nearby Bedford for some lunch.

The simplex repeater did work through the flight, but the output was too weak to be useful.  The repeater appeared to hear ground stations fairly well, but we could not hear the output well at all.  My home station did not record much traffic either.  Since the antenna setup was the same as for previous flights, I suspect the lower power setting was the problem.  Next flight we'll have high power set for the VX-1Rs.

The backup beacon had powered off near impact, but was working just prior.  The impact shock may have briefly caused the spring contacts on the battery to open.  It was not padded well for this flight, so I'll try a different setup next time.  The backup beacon was not very useful either.  Paul KC0KXR monitored it through 28,000 ft, but after that it was too weak to be useful.  My home station copied it well up to about 40,000 ft, then only intermittently through 90,000 ft.  No packets were decoded on the descent, though some of us did monitor the audio output and the beacon was transmitting.  It too will be set to high power for the next flight.

The primary beacon had mixed success and failure too.  I had inserted some programming to detect balloon burst and to control a still camera to provide pictures at different levels.  This programming worked flawlessly.  However, because I had relocated the beacon's antenna closer to the payload, the RF generated by the beacon interfered with the serial GPS data.  Characters were garbled causing the beacon to report its position, course, and/or speed incorrectly sometimes.  This only affected packets transmitted about 0:16 after each minute.  The reason for this was deduced to be the transmission of the telemetry packet immediately prior to this position packet.  While the telemetry packet is being transmitted, the GPS data for position, course, and speed (the $GPRMC string) is being read in from the GPS.  The garbled characters then were parsed and formatted incorrectly for transmission.  This will be cured by (a) moving the telemetry transmission to a different time in the cycle, and (b) possibly changing the antenna setup for the primary beacon.

The camcorder recorded for about 1 h 45 min, then the battery ran out.  This was enough to record through burst and about 10-15 minutes afterwards.  The B/W viewfinder was not working afterwards, possibly due to high-voltage breakdown. The camcorder itself still functions and will be used on future flights.  The videotape was fine and I'll post some clips and stills at a future date.

Thanks to Paul KC0KXR and Doug KA0O for providing log files.  This made the flight record nearly 100%.  Also thanks to Scott Clark for the use of his farm as a launch site, and to the rest of the NSTAR launch and recovery team.