High Altitude Ballooning: Horus 48 – Flight Report

At 10:08AM CDST, on the 11th of March 2018, Horus 48 was launched from Mt Barker.

This planning for this flight started out as an excuse to use up some helium leftover from the previous two launches, and quickly evolved into a mechanism for testing out some new payloads and launch concepts – the main one being the use of the ‘THOR16‘ data mode, which is considerably more robust to interference than RTTY, at the cost of being about 50% slower.

Horus 48 Payloads

Horus 48 Payloads

As we only had a limited amount of leftover helium available (~1.6m^3), the mass of the payloads had to be kept to an absolute minimum. New foam payload boxes were built with this in mind, with the new THOR16 and RTTY payloads weighing in around 70g each. (Thanks to Peter VK5KX for supplying the antenna wire!)

The week prior to the launch, a ‘test and tune day’ was conducted. An example THOR16 signal was broadcast from Mt Lofty summit, with many stations tuning in and decoding telemetry. The responses from this test were promising, with one station reporting he had much more success with THOR with it’s forward-error-correction, as local LIPD noise would disrupt RTTY decoding resulting in invalid telemetry.

Thanks to the following stations who participated – it was great to see so much interest!


Launch Preparation

The launch was quite light-on with helpers – Mark VK5QI and Will VK5AHV performed the launch activities, with help from David VK5DGR, Drew VK5XFG, Rod VK5ZOT and a few others.

The original intention to use a small 100g balloon went out the window the night before the launch, when it was discovered the specified burst diameter for the 100g balloon was not quite as expected – this would have resulted in a ~3km burst altitude! Instead an old 1000g Hwoyee balloon was used. The larger balloon meant all the gas in the cylinder had to be used up, and even this only resulted in an ascent rate of 2.5m/s (we usually aim for 5m/s).

To counter the low ascent rate, which would have resulted in a 4 hour long flight, and a landing well to the east of Bowhill, one of the Horus cutdown payloads was flown, allowing termination of the flight via a command from the ground. This cutdown payload used a newly developed cutdown device (to be kept under wraps for now!), which is intended to replace the nichrome wire string-cutter device previously used – Experiment #2 for this flight!

All up, the payloads combined only weighed ~300g. The smallest parachute we have in stock was used (a 2ft ‘Rocketman’), and was hung off the side of the balloon train instead of in-line with the payloads as we would usually do. This was to try and reduce the tangling of the parachute with the payload string that had been encountered on the last few flights – Experiment #3!

Launch & Chase


Launch was pretty much textbook – some light winds encountered during filling died down for an easy release into the skies. Will and Mark immediately headed off towards the target landing area, while David VK5DGR and co headed off to Mannum for a bakery stop.

At about 10km altitude the cutdown signal was sent to the payload, with the intent of landing the payload to the south-east of Mannum. The new cutdown device worked first-go – a success for Experiment #2! The payloads then quickly descended to a landing on a property just across the river from Port Mannum.

Will and Mark caught sight of the payloads at about 800m altitude, and were able to watch the payloads descending behind a hill, into an empty field. The parachute was clearly doing its job, and was not tangled up or ensnared in the other payloads – another successful experiment!

A quick discussion with the landowners (and their friendly dogs) and permission to enter the field and retrieve the payloads was granted. A short walk and the payloads were in hand!

Flight Statistics

Everything is more interesting with data – so here is the flight’s vital statistics.

Flight Designation:Horus 48 - THOR16 Test Flight
Launch Date:2018-03-10 23:38 UTC
Landing Date:2018-03-11 01:16 UTC
Flight Duration:1 Hour 37 Minutes
Launch Site:-35.07568, 138.85701
Landing Site:-34.93807, 139.31944
Distance Traveled:44 km
Maximum Altitude:10,187 m
Horus 48 Flight Path

Horus 48 Flight Path

New Telemetry System Performance

Even with a 10.2km maximum altitude, many receiver stations around the state were able to decode both the THOR16 and RTTY telemetry:

RTTY Telemetry Scoreboard
CallsignPackets HeardPercentage of Flight HeardPayload Alt at First RX (metres)Payload Alt at Last RX (metres)
THOR Telemetry Scoreboard
CallsignPackets HeardPercentage of Flight HeardPayload Alt at First RX (metres)Payload Alt at Last RX (metres)

The callsign pie chart shows the combined result of both RTTY and THOR telemetry streams – great to see so many contributors this time!

So, was the THOR16 telemetry useful? It’s hard to tell with just one launch. From the chase-car, the following observations were noted:

  • The slow speed of THOR16 (one update every ~20 seconds) makes tracking the flight through critical stages like burst and descent difficult. The chase team ended up switching to the cutdown payload telemetry (updates every 5 seconds) to get more frequent position updates.
  • THOR16 was quite robust to mobile fading, however,
  • … fldigi has no automatic frequency correction for THOR16. While the payload’s transmitter didn’t drift very far, it did drift far enough for the performance of the demodulator to drop, resulting in quite a few lost packets until the issue was noticed.

Since the THOR16 payload is so light (only 65 grams) you can expect to see it on more upcoming flights – please continue to send in reports on how it compares to the RTTY payload!

Thanks again to all listeners who decoded data from the flight, including those who went portable to track the payload down to the ground (VK5KX, VK5ZM & VK5GR).

RTTY as received at VK5KX

THOR16 as received at VK5KX

Addendum: HabHub Tracker Issues

Some listeners noted issues with the Tracker where the payload list on the left side of the webpage did not populate. This is a known bug and is currently being worked on. The bug is related to window sizes, so if you re-size your browser window slightly it should re-draw the web-page, and the payload list should appear.

HORUS 48 Balloon Flight: Sunday 10.00am ACDT

As per the previous announcements on the AREG website, there will be a (small) balloon launch occurring this weekend. The current predictions for Sunday have the payloads landing to the south-east of Mannum (hopefully not in the river!).

Currently the prediction for Sunday looks the best in terms of recovery/distance/bakery factor, and also leaves Saturday free for some last-minute preparations! As usual, we’ll aim to launch around 10AM CDST, with the launch being conducted from the Mt Barker High School Oval.

This will be a fairly low-key launch, with a tiny balloon and tiny payloads, but visitors are still welcome! We’ll be on-site from around 9-9:30AM, and should have an ear out on VK5RSB 70cm.

The current prediction (noting this will probably change between now and Sunday!!) has us landing near Palmer just after 11AM – a very short flight! We’re using a 100g Totex balloon, so the expected burst altitude is only 11-12km.

UPDATE: We will now be using a 1000g Hwoyee balloon, but with a minimal amount of helium. Depending on what ascent rate we achieve, we may terminate the flight early for a landing near Mannum, or let it ascend to a potential height of 35km. Either way, the landing area is in the Mannum area.

Telemetry Information

The telemetry frequencies for the flight are as follows:

  • RTTY – ‘HORUS’ – 434.650 MHz  (100 baud, 425 Hz Shift, 7N2)
  • THOR16 – ‘THORUS’ – 434.640 MHz

Both payloads are running 10mW transmit power, and have essentially identical antennas.

DL-FLDIgi Setup for THOR16

As usual, use dl-fldigi to decode telemetry, but in the case of the THOR16 payload, you will have to manually select the operating mode from the drop-down list as follows:

The auto-configure capability for the RTTY payload (‘HORUS’) will work as usual, however you will have to manually select ‘HORUS’ from the payload drop-down list. Auto-configure will not work for the THOR16 payload.

If you have the capability of running two 70cm receivers, please consider running two instances of dl-fldigi to decode both payloads. This may require either multiple PCs, or multiple sound cards. If you can only run a single receiver, please try and alternate between the different telemetry payloads.

We would very much appreciate reports as to your experiences decoding the different telemetry payloads – please e-mail these through to vk5qi@rfhead.net

Tracking for the launch will be available on the HabHub online tracker. We hope to see you as part of the tracking nets!

Images and comments from the chase will be sent via Twitter, using the #horus48 hashtag.

73 de Mark VK5QI

Next AREG Meeting: March 23rd – Introducing FT8 Mode


The next meeting of the Amateur Radio Experimenters Group will be held  1 week later than usual this month, on Friday March 23rd. The date has been delayed as the SA State Election is being held on the 17th and the hall is being setup as a polling booth the night before (our usual meeting night).

The presentation for the evening will be “Introducing FT8 Mode, what is all the hype about?” by Grant VK5GR.

Grant has closely followed the development of FT8 since it’s inception and was an early user of it in DXpedition environments during his activation of Niue last year.

Areas to be covered will include:

  • a brief description of the FT8 protocol
  • the basic hardware and software requirements to get on air
  • how to get that little bit more out of FT8 – add on packages like JTAlert
  • a look at FT8 operating practices
  • how to chase rare DX using FT8 – a practical tips guide
  • a discussion about the new Expedition mode that has been developed

Currently a live demonstration is also being planned. Grant will be available for questions after the presentation during supper.

The meeting  will be held at the Fulham Community Centre (previously known as the ReedBeds) with parking accessed from Phelps Court, Fulham. The venue will be open from 7.45pm with the meeting starting at 8.00pm. Following the technical presentation there will also be the usual club business meeting.

Visitors are always welcome! So come along and meet the Amateur Radio Experimenters Group!

REMINDER: Horus 48 Telemetry Test from Mt Lofty TOMORROW

THOR Receiver Tune & Test Day – Sunday 4th March ~10:30AM CDST

To help stations adapt to the new THOR16 signal, this coming Sunday there will be the opportunity for stations in the Adelaide metropolitan area to set up dl-fldigi as per the linked guide below and have a go receiving a higher-power version of the THOR16 signal. This will be broadcast from Mt Lofty Summit by Mark VK5QI. Mark will be on the VK5RSB 70cm repeater (439.900 -5MHz / 91.5Hz CTCSS) as ‘technical support’, to help assist setting up the software. The signal should be easily receivable from the Adelaide Metro area and some surrounds.

Look for the test signal on 434.640MHz

DL-FLDIgi Setup for THOR16

As usual, use dl-fldigi to decode telemetry, but in the case of the THOR16 payload, you will have to manually select the operating mode from the drop-down list as follows:


AREG IRLP Node 6214 Off Air

The following news comes from Ben VK5BB, the custodian of the 6214 IRLP node that is connected to the VK5RSB 70cm repeater

Due to a failure of IRLP node 6214’s computer hardware,
it is off line until further notice!


I took on the management of the IRLP node 6214 sometime around 2012. Prior to this it was managed by Adrian VK5ZSN. Under his management it was all OK until the HDD died.

I volunteered to take on the project and rebuilt the computer using an IDE to SATA adapter and a solid state HDD. A bit of jiggling but it worked and to date has been very reliable with minimum of hands on support to keep it on air. 

Current Status:

I am not sure what is going on but it appears that the computer that manages the IRLP node 6214 is having severe problems. It seems that the computer is unstable and keeps shutting itself down and rebooting. The machine running the system is now over 10 years old, which is a contributing factor.

Right now, the ultimate fate of the IRLP node is undecided. The club members have been asked if they wish to see the service continued. That discussion is ongoing. If the service is to continue, it could be some time before it is restored as new hardware will likely need to be obtained.

If you would like to see it rebuilt and placed back on the air, why not consider becoming a member of AREG and showing your support for the project? Details of how to join are available on our membership page .

AREG News now available via EMAIL

The Amateur Radio Experimenters Group is pleased to announce that we have a new news outlet. All amateurs can now be kept informed via email of AREGs activities including:

  • High Altitude Balloon Launches
  • Meeting Nights and Topics
  • Club events such as field days and contests

and much much more….

For general information about the mailing list or to subscribe, please visit:


If you ever want to unsubscribe or change your options (eg, switch to or from digest mode, change your password, etc.), visit your Subscription Management page.

This new service is a one way information service and only official announcements from AREG will be available. Traffic is typically only 3-4 messages a month.

We hope you find this new way of keeping non members up to date with the activities of the Amateur Radio Experimenters Group helpful. (Members already have an active mailing list that they can can send and receive through. Announce list bulletins are already relayed to the members only list too).