NSL-86

This experimental night flight flew the early morning of Aug 7, 2020 from Paul L's home in Apex.

Items in test were:

• settings on a low lux camera

• stabilization method where the payload was firmly attached to the balloon neck

How stable would the flight video be if we attached the payload directly to the balloon with a rod?

With no string to spin and un-spin, would video be any better by relying upon the stability of the balloon itself?

The morning of August 7 gave a partly cloudy night with bright moon and planets and also the expected launch of a SpaceX Starlink flight up the east coast. The winds were expected to be very light, although there were also thunderstorms at ether end of the state that might be interesting to video.

The payload box from NSL-82 held a RunCam Night Eagle 2 Pro and a Mobius Mini camera, both set for low light conditions. It would be tracked by an AP510 (APRS) and TTGO T-Beam (915Mhz LoRa). The payload, chute, and rod totaled 550g and was lifted by 1500g-neck-lift of H2.

The carbon fiber rod, zip-tied to the thickest part of the balloon neck, prevented payload spinning (yaw). This rod then inserted into a keyed holder atop the payload box. It was secured in place there by a series of interlocking loops of string and a piece of PVA string (similar example). Additionally, 16m spool of dental floss on the payload deck also connected the parachute. The thought was that if the payload landed atop a tall tree, a rain shower would melt the PVA and the box would then lower to the ground. The strong floss might allow for the rod/parachute to then be pulled down.

Inflation, activation, and launch went off without issue.

As the flight ascended, it should cross Wake County and then turn around and head back west to burst.

But as the flight reached that turn-around point, winds became turbulent, tossing the payload around. Although secured against yaw, only the pressure of the balloon at the neck prevented the payload from pitching up. The wind shear cartwheeled the payload over the balloon. Then the balloon's neck bent and allowed the payload to pitch-up and slam into the side of the thin latex cell. The first thing to hit was the low-light camera, which snagged a small hole in the balloon. The snag also shut down the camera.

Chasing 16km below, Paul received a 'burst' message from the payload. The payload was descending very slowly. He reported that he had never seen this before, but it had to be due to a slow gas leak. Instead of heading back west, the balloon continued easterly. Would it float out into the Atlantic?

On board, the Mobius camera recorded the moon and pitch black surroundings of the countryside. It also captured the sound of the hissing gas leaving the cell. After several minutes of increasing descent rate, the hole in the cell finally tore open into a large gash, the parachute took over then to slow descent. Sadly the payload was most of the way down when the SpaceX flight launched at 1:12am.

Around 1:30am, the payload landed. Paul gathered GPS details and decided to go get some sleep and tackle recovery on the weekend. This would give him time to locate the land owner and get permission. Rain was coming, so maybe the PVA string would melt.

Early Saturday morning, he headed back out to the landing site and safely met up with the friendly and helpful landowner. A quick hike through muddy fields soon brought them to the landing area. This site had been clear-cut about a decade earlier, but now held 5m tall trees, bushes, and mostly brambles. After some bushwhacking and blood letting, Paul was able to grab the payload. The stick, chute, and entire balloon lay only 3m up. The payload had released as intended and was in a bush just off the ground.

Unusual descent rate was due to a slow leak and eventual shredding of the balloon.