NSL-50

On Sept 24, 2016, we performed a public launch at the first annual Greensboro Mini Maker Faire. It was a warm, mostly-clear day and thankfully the jet stream was nowhere to be found. Flight projections had the payload traveling back and forth over the city, landing just south of town. Julie, Jimmy, and Chris made the trip from RTP to help with booth, launch, and chase. Matthew and Paul staffed the "Mission Control" booth within the Maker Faire.

For simplicity, the payload was a re-flight of NSL-48 -- The old blue box's 13th flight. It had an AP510 and Spot for redundant tracking, a Geiger counter, two cameras. A mobius camera pointed outward, while the wide-angle Mate808 from NSL-49 was aimed downward. This wide-angle camera was shown to go out of focus in cold temperatures, so the lens was placed inside the payload and a small window was made for it to look through. A cut-down system was added to help with tree recovery. In addition, the arduino from NSL-48 was programmed to listen to the AP510s APRS traffic and comment upon it via APRS. It recorded received data from the AP510 and sported an additional external temperature sensor. We chose a 90cm chute and a 1000g cell as it made for a nice flight plan. The cell was filled to about 2kg of neck lift with H_2.

The fill and launch was unique as we shared the launch space with fire performers. Hydrogen gas and fire eaters! (Yes, they doused their flames during the launch prep.) We had some of the kids in the crowd involved in the countdown and release around 1325EDT.

The flight path stayed very close to the prediction. Visitors to the Maker Faire booth marveled as the payload performed the loops that were predicted earlier in the day.

The chase crew headed out of the Maker Faire, grabbed some lunch, and headed south of town to the landing site.

The payload came to rest in a stretch of trees along a highway. The chase crew located the payload and activated the cut-down system, but sadly the payload box was caught in a tree by its own rigging. The cut-down system severed the parachute string, but this only resulted in disconnecting the parachute, which fell into a branch below the payload. The payload was stuck about 20m up in a mostly rotted, poison ivy covered tree. What to do?

Remember those fire performers at launch? Fire performer Travis (shown at the top of this page) has an affinity for dangerous occupations. He is also an arborist! He came to our rescue, and over the next few days, he was able to scale healthy trees and safely recover the payload. Thank you Travis !!

=== Flight notes from Paul L ===

I am a huge proponent of using a clear payload box with dark colored foam inside. This allows the payload to act like a greenhouse and let-in and trap solar heat. I feel it is also important to fill any open air pockets inside. I figure this limits entry of cold air during descent. The affect of these seemed apparent on this flight. The temperature during descent reached -44C just outside the box, while it was a toasty +33C inside.

I was worried about solar heating on the external TMP36 temp sensor, so I stuck a bit of shiny copper tape on it. It was mounted on the side of the box where it should have had plenty of air flow and limited direct sunlight. The payload spun very slowly above 100,000 feet. I wonder if I can correlate the slight oscillation in temperature at peak with the position of the sun?

The Mate808 camera lens performed better when kept warm inside the payload. I made a little window for it to look out, with plastic wrap. The plastic film, though, did distort the image, especially around the edges. Next time I need to use something like a microscope slide as a window -- Something with less distortion and less affinity to attract dust.

The lens stayed in focus this time in the cold upper troposphere. But the saran wrap and box tape made for a poor window. Especially during periods of glare like when the box inverted at burst.

On this flight, I programmed the Adafruit Feather Arduino to do a few more simple functions. Like NSL-48, it would listen to the APRS data from the AP510 via Bluetooth. But this time, it would also send its own APRS status messages via the same link. I set it to send out a new status message every seven minutes with its battery voltage, ascent rate, and external temperature. Like NSL-48, the device also recorded everything it sent, heard, or did on to a local microSD card. It worked well, except that my math failed when it tried to calculate negative ascent rate. On the way down it kept telling me that is was falling at "Rate=21474836.00ft/sec" which is something like 2% the speed of light (probably an unsigned long in there somewhere).

The arduino recorded hundreds of packets overheard during the flight. I will see what Ray, KC4VTX, can make of the data. Above 90,000 feet it went pretty quite, except for a few select packets from distant locations. These included two repeaters out past Green Bank, WV (336km). One in western MD (390km). AND a packet from an iGate up at Lakewood, NJ (663km) !

The remote tree cut-down got me again. It did what it was supposed to, but that wasn't enough. A branch had stuck through the little harness of string around the box. Should I go back to the NSL-46 system where nichrome wire cuts loose a spool of string that falls to the ground?