NSL-84

Another test flight in the series, NSL-84 launched from Christopher R's house on Saturday, July 11, 2020.

Christopher, preparing for a student flight towards the end of the month, wanted to test out some payload suspension ideas to help reduce spinning. His payload consisted of a circular tub held with four lines from an upper spreader. A swivel was added above on the suspension line. The tub held a LightAPRS tracker, and two cameras -- one looking out and one looking down.

Suspended above this, Paul L. contributed a small black box containing the T-Beam/camera hardware from NSL-83. This TTGO T-Beam 434MHz LoRa tracker ran code to turn-on a camera at a specific altitude or time (SpaceX had planned to launch a rocket from Florida that morning, so perhaps it could be imaged). This added 200g to the flight, but provided an additional tracker and camera.

Suspended above this was Tim W's Femto APRS tracker. This tiny device, under 20g, attached directly to the suspension line.

Above this in the train was a new 1m parachute that Christopher was testing. This was student-constructed out of rip-stop and tulle. The flight was lifted with a 600g cell with H₂ filled to 1500g of neck lift.

Tracker woes

The LightAPRS tracker ran into issues just prior to launch. Additional integration testing should determine if the cameras were generating interference for the GPS receiver. The Femto tracker's signal was received by some HAM radios, but not by the APRS iGates in the region (Tim believes that low battery voltage had dropped the transmit power below 50mW). To add to these tracking issues, HABHUB apparently had some sort of database issue and the Payload Record for the T-Beam was missing. It took several minutes post-launch to add this back into the system to allow for tracking on the website.

Meanwhile, the flight proceeded as expected...

Initially the flight traveled east over Raleigh. It's LoRa signal was being received at Christopher's house via a large Yagi antenna.

Half way up, the flight then returned west over Apex where it was expected to burst. Now underneath the payload's antenna "shadow", Paul had to leave Apex and quickly drive east in order to continue to receive LoRa telemetry.

As the payload approached time for the SpaceX launch, Paul's tracker reported that it had powered-on the Mobius Mini camera. Sadly, SpaceX had scrubbed the launch.

T-Beam telemetry reported burst with "MaxAlt=31496".

All chase teams headed towards the US-401 & Ten-Ten intersection near Lake Wheeler.

Once there, they split into different groups to witness the landing. It should miss Lake Wheeler, but will it land on US-401? Or in a suburban neighborhood?

Also, there was a pine tree farm half way in between...

The crew met up on the side of US-401 and was able to identify the landing spot as being in the middle of a farm of 50' pine trees.

The next morning; after coordinating with the land owner, Christopher and Tim headed out with bow in hand and were able to recover the payload.

Descent rates showed that Christopher's parachute worked great. Paul's black payload box heated up quite a bit in the stratosphere, affecting the outside temperature probe affixed directly to it.

T-Beam landing prediction

Due to the HABHUB database issue, this flight didn't have the large red X displayed automatically on the map, but it did transmit coordinates that could be plugged into a map (Matthew L. did this manually during chase). The map below shows the varying predicted landing calculations as they updated during the 48 minute descent.

Even while the payload was on the other end of the county, the T-Beam still plotted its expected landing location within 1-2km of the actual landing site!

Paul drove to the landing spot computed about 7 minutes before landing.

He and Matthew were unable to spot the flight coming in for landing (it is too small to show up in this image), but the flight's Mobius was just able to image their car.