NSL-46

This was a public launch held at the Burlington Mini Maker Faire on April 23rd, 2016. Chris G., Paul L. and Paul T., along with assorted kids, set up our booth at the faire. Flight videos and hardware were shown. Projection screens showed flight predictions and images. During the flight, these were replaced with live tracking of the flight and chase crew.

The payload for this flight was Paul Thompson's "Eagle 1" from NSL-44. It was reloaded with its AP510 and Tk102 for tracking. An MD80 camera was mounted looking down. A Mobius camera was mounted looking out. New to this flight was a GMC-320+ Geiger Muller Counter Data Logger, which was mounted at the top of the payload with its muller tube unobstructed. A 36" chute was added with a shroud-separating funnel, to test damping of the sway/spin seen on typical HAB flights. A 600g cell was used with ~2500g of neck lift via hydrogen. Also attached to the payload was a device that would drop about 13m of string out the bottom in the event of a tree landing. In the past, the addition of this device ensured that the payload would land in an open field. :)

Flight projections earlier in the day showed that a typical 30Km flight (2000g neck lift) would land the payload very close to RDU airport. It was decided to sacrifice altitude for safety, so an additional 500g of lift was added. This would bring the payload down further to the northwest - the center of RTP.

Around noon, the crew headed out to the mall parking lot to prep for launch.

Some of the event visitors were in attendance as the launch procedure was explained. A safety perimeter was set up and fill of the hydrogen balloon proceeded. The ground winds gusted, at times, over 10kts so the fill team had to fend off the balloon.

and views from the balloon's downward and outward facing cameras

Four views of the mall as the balloon ascended

The weather was perfect for a flight. Lots of puffy clouds to fly between.

Chris led the chase as the Pauls held down the booth at the Maker Faire. Although much of the balloon stayed attached after burst, it kept free of the parachute, which brought the payload down in the desired landing ellipse in RTP.

The payload drifted southerly towards an open yard in a residential neighborhood. At the last moment, of course, the payload shot back to the north side of the street and landed on an overhanging branch of a tree. Knowing that we had a device that would drop a string, the tree gods settled it directly over 12,000 volt power lines!

This landing gave the team pause. Our previously successful tree recovery techniques wouldn't work here due to the power lines. We checked with the power company, but they could only get involved if the payload was actually on the lines. The local fire department was willing to shoot our payload with a water cannon, but understandably they couldn't get their ladders near the power lines. The following day, the Pauls resorted to a balloon trick that we have tried unsuccessfully in the past. They were able to fly a 1m balloon on a pair of strings, far above the power lines. The breezes cooperated and, from their positions far across the street, they were able to grapple onto the payload and pull it free.

The increased ascent rate due to the over-fill is above 6m/s. The parachute behaved during descent. The payload was well insulated and took advantage of solar heating to keep the electronics/batteries warm.

The Geiger counter recorded data to expectation, including peaking twice around 20Km (50-60K feet) as the payload passes the Pfotzer Maximum in the tropopause.

This flight looked remarkably similar to the NSL-23 Burlington flight two years prior. Similar conditions and the same Mobius camera led to very similar images.

At the time of writing this, the videos were still being reviewed to determine the affect of the funnel on the shroud lines.

The string dropping device was tested after recovery, but the on-board batteries had already died in the intervening day. We really need to find someone with a quadcopter that can haul up grappling hooks for us in recovery cases like this.