Hamnet Experimental BACAR-9 Balloon Chase 2021-10-30

By Russell Dixon - Paver



Susan Prinsloo invited us to join her helicopter support of Hamnet in supporting their chase vehicles for the launch, tracking and recovery of an experimental balloon. Hamnet is a division of SA Radio League, which represents radio amateurs in South Africa. Hamnet provide emergency communication services in addition to communications for sporting events where other communication service coverage is not pervasive.

In order to provide these services, training and testing activities are on-going. They also work closely with the Search and Rescue Services. The various payloads provide telemetry to enable tracking, cameras to record events and devices to collect data to investigate weather, radio propagation and various other experimental payloads. Having supported aviation events for Susan in the past, she was happy to try the first helicopter chase and recovery of the balloon, descent parachute and the various experimental payloads it was carrying.

Telemetry links back to ground are limited, so recovery of the payloads for the data they have collected, as well as equipment value and for re-use are important. Chase vehicles are, of course, restricted to roads in the main and often landing sites are rather inaccessible, or owners are reluctant to grant access for recovery. Communication to various organisations along the expected balloon track had been done for two weeks prior to the launch date.



Weather predictions had been spot on for Saturday, with heavy rain overnight, clearing after 04:00. Early arrival at Brakpan for the first leg to the balloon launch site at Secunda saw no wind, clear sky with light cloud still on the Eastern horizon.


Brakpan Clubhouse was very quiet as the sun rose.


The moon was well into its rise for the day before sunrise, with the windsock still asleep. Humidity was still very high, after the heavy overnight rain, so the R44 Raven canopy needed some wiping down to provide enough visibility for the takeoff, even though it had been in the hangar during the night.

After Susan diligently worked through all the preflight inspections and checks, she lifted off and hovered for a short time while the rest of the condensation cleared from the canopy in the sun. Neil Gerber, call sign ZS6CKC, from Hamnet, was with us in the helicopter for tracking support. The short low-level run to Secunda was into the early morning sun in high humidity conditions, so conditions were not good for photography.


Susan concentrating as we head for Secunda launch site. The countryside was very wet with a few isolated low clouds and ground fog in places.


We circled the launch-site, which was a model airfield and then came in to land on the grass at the end of the short-tarred runway. Fire services were on hand as part of the contingency plans.


The R44 needed a top-up in preparation for tracking the balloon and some tall guys, like Harold, were on hand to lift the jerry cans, so the siphon, which Susan had on board would work. The last of the fuel in the jerry cans was decanted via a funnel.


Final balloon and payload preparations were under way as the R44 was topped up. The latex balloon requires handling with rubber gloves as the skin oils can cause the latex to deteriorate, leading to premature balloon failure.




Last of the R44 top-up with the balloon almost ready for launch in the background and Johan Meyer, call sign ZS6DMX's chase-vehicle, which also carried the fuel to fill up the R44 later in the mission. One of the firemen on duty came for a selfie with the helicopter, so we recorded the event for him. He did not want to be named. After some welcome coffee and a short briefing, the balloon was launched at 07:18, climbing very rapidly and we were soon on our way tracking it.


Johan in his chase vehicle tracking the balloon.

The tracking of the balloon did not work well early on and we landed so Neil and Johan could work on it and also so that Susan could load the expected track into the Skydemon app on her iPad, which provides early warnings of obstacles like towers, bridges and power lines and the recommended safe height for crossing. All eyes on board were backing this up as well! GPS position comes direct from satellites, so there is no reliance on internet coverage. With the track loaded and the telemetry working, we took a more direct track to balloon position as provided by Neil. The balloon travelled very fast but we were able to catch up fairly quickly due to a tailwind.

Between Ermelo and Breyten the balloon slowed down and we circled. We were not sure if the altitude and speed had reduced because of atmospheric conditions or if the balloon had burst and the payload was descending under the parachute. We landed briefly to conserve fuel and wait for the chase vehicles. A call from the chase-vehicles confirmed that the chute had deployed and they were North of our position and that the chute was descending. With a last-known position for the payload loaded, we set out to search and recover it, only around 2 nm away. We had a few visual red-herrings, one turned out to be a feed bag and a flattened stop sign also drew our attention.



Summarised from the Flight Controller Report (kindly supplied by Cor Rademeyer, call sign ZS6CM) here is some interesting data:
Maximum ground speed: 148 km/h @ 10 878 m altitude - ascending
Maximum ground speed: 127 km/h @ 12858 m altitude - descending
Maximum altitude: 19539 m @ ground speed of 5.3 km/h
Flight time to balloon burst: 42 minutes
Overall flight time: 1 hour 03 minutes
Initial descent rate (after balloon burst): 55.9 m/s (201.2 km/h)
Final descent rate (under parachute): 8 m/s (28.8 km/h)


A YouTube video of the BACAR9 High Altitude Balloon Flight



Feed-bag false alarm


The last-known position turned out to be accurate and Susan spotted it quickly and with her game capture experience, helping make the positive visual sighting.






Parachute and payloads landing site and some of the payload "packages". Note the use of lengths of tape measure as some of the antennas!




Neil shows what is left of the balloon on landing and Susan and Neil moved to higher ground to establish communications with the chase-vehicles as there was a dead-spot where the payload landed.


Susan and Neil wrap the payloads in the parachute for safe transport in the helicopter.




Neil looking relieved to have the payloads recovered and then moving them to the chase vehicles when we landed to refuel - being airborne for around 2 hours needed both main and aux tanks to be filled for the flight back to Secunda and back onward to Brakpan.




Susan needed a record picture and Harold and Leon Lessing, call sign ZS6LMG. assisting Susan with the heavy lifting to refuel the R44.


Leon doing the "hold-up" to fill the aux tank, while Susan monitored the fuel gauges to see when it was close to full.


On the way back to Secunda, Susan demonstrated the increased turbulence when flying over dark (turf) ploughed lands.


Before we got to Secunda, we circled a dam with Flamingoes and Egyptian Geese.






The approach to the dam at Secunda, where Hamnet had established a Joint Operations Centre, with many of their members camping for the weekend and a prepared area for landing, complete with "mobile windsock" and reception committee, which Susan skillfully approached sideways to avoid trees and overflying buildings and parked boats.




The Hamnet trailer base station and Johan, our intrepid chase-vehicle driver and mobile "fuel bowser".

After a debrief at the dam at Secunda, after the chase vehicles had returned and among the parked catamaran yachts, each interested group gave a brief report of their payload performance and lessons learned for future flights. A welcome boerie roll and some cold drinks refuelled us too.

By this time, the clouds had started closing in and the wind was coming up, so we started up and headed back for Brakpan. On the way East, we had about a 20 knot tailwind, so progress was swift, but it was a different story heading back West. As the temperature was up, the ride was quite bumpy and at one stage, we were climbing quickly on thermals with power reduced.

A runway inspection on arrival at Brakpan completed a most interesting and different aspect of aviation, combined with the skills of radio amateurs practicing their hobby and ability to provide communication services, especially when "normal" communications are marginal or out of commission. One of the applications of balloon-borne payloads is radio repeater stations, when communications are hampered due to terrain or other obstacles. Helicopter chase and recovery looks like it is the way to go for this type of application.

Pilots Post thanks Susan for inviting us to join this first (and very successful) helicopter chase and recovery of an experimental balloon mission and to the Hamnet and ARCC members who made us welcome among them.



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