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NSL-37 & 38

These were our 3rd and 4th flights of the 2015 Global Space Balloon Challenge


On April 25, 2015 we performed a simultaneous launch of two 600g balloons with student payloads. Blessed Sacrament School had been working with Paul on these flights for several months and the Burlington Mini Maker Faire was excited to host the event.

NSL-37  KD4BFP-8 Smallish styrofoam cooler with outrigger.  Payload/chute weight ~950g.  Contained Mobius wide-angle camera, upward pointing 808 #16 lens-D camera, Spot, AP510 APRS transmitter, student projects inside, and a small party balloon and school mascot on the outrigger.  We used ~3500g of lift.

NSL-38  KD4BFP-9 Large styrofoam cooler.  Payload/chute weight ~1100g.  Contained Mobius wide-angle camera, downward pointing 808 #16 lens-B camera, Spot Trace, AP510 APRS transmitter, student projects inside.   We used ~3650g of lift.

Paul acted as consultant throughout the project.  Chris brought his expertise to the event to help with launch and to provide technical assistance to the chase teams.  Student teams managed communications, Mission Control, payload, launch, chase, etc.  The students and teachers chose to go with a Hydrogen (renewable resource) public launch, so they set up a safety perimeter and had dedicated safety officers and procedures.  The adults handled the actual Hydrogen fill.  It drizzled through the entire fill and launch.  Using a cool technique that Tanner picked up from launches at a Boy Scout Jamboree, we set up crisscross guy lines to hold each balloon until the simultaneous release.
    Chris' Launch video      Ascent from NSL-38

Flight visualizations  NSL-37 blue                           NSL-38 yellow

We got lucky measuring the gas fill and both balloons rose at almost the same amounts over the ascent.  They were under 5km apart horizontally, and NSL-37 was only about 1.2km higher when it burst.

Actual flights (again blue and yellow) compared to the projected flight (orange) assuming a 12:00 launch.  The jet stream was dramatically swinging north during the day's forecast, so the small difference in track between projection (orange) and NSL-38 (yellow) could mostly be accounted for by the 12:15 launch.

NSL-38 seen in background from NSL-37 at ~1000 ft         NSL-38 and moon seen near 78,000 ft as NSL-37 burst

NSL-37, although a lighter payload, burst first.    Animated GIF           Downward camera of NSL-38 showing moon at burst

Sadly, the main HD Mobius camera on NSL-38 wasn't activated before launch.  Also, due to all of NC being very overcast (rain), the earth photos are complete white-outs.  The soaking wet payloads and balloons were soon covered in ice as the rain drops froze.
NSL-37 approaching burst             Coming in 'hot' with a tangled parachute     After landing (impact) as landowners arrive

Recoveries of NSL-37 and NSL-38 by the student chase crews.   This flight, we tried the Habhub tracker, this allowed the chase cars to post their positions without needing amateur radio operators aboard.

NSL-37 an early parachute tangle lead to a fast landing.  The smaller payload stayed warmer.

NSL-38  had a larger internal cavity, so there was more room for cold air to rush in, especially during descent.

Rocket and balloon enthusiasts often joke about how their equipment is attracted to trees.  A last moment fouling of the parachute, lead NSL-38 into a stand of woods instead of a nice open field beside a road.

APRS reception plots courtesy of Ray KC4VTX.  These show some of the receiving stations for the telemetry packets during the flight. Although our two transmitters were ~1 Watt, they were easily received far away because of the high altitudes.