Project Horus High altitude balloon project

Horus 6

Did you make a contact via the Horus 6 repeater? If so, please get in touch with me so I can add you to the list of contacts & send you a QSL card!

Technical information:

Launch date 28/8/2010, 1:50pm
Landing date 28/8/2010, 16:40pm
Flight duration ~ 3 hours
Launch site -35.1018, 138.8248
Landing site -34.7027, 140.1211
Flight path Web, KMZ
Distance travelled
126.5 km
Maximum altitude 34,297 m
Average ascent rate 4.5 m/s
Impact speed 5 m/s (18 km/h)
Payload weight 950g
Flight computer Nut 1.1 flight computer
GPS module Falcom FSA03
Radio transmitter Radiometrix NTX2 25mw
Camera eBay spy video camera (provided by VK5ZBR - thanks!)
Telemetry 300 baud RTTY, CRC16 checksum
Tracking Ground stations (distributed listener), 2 chase cars, web based tracker


Horus 6 was the the first flight of Adrian VK5ZSN's simplex parrot 2m repeater - the idea was to test the feasibility of the repeater as a communications platform, as well as inviting the amateur radio community to try and make contacts through the repeater. This launch was great - the repeater proves extremely successful as a comms platform, as well as being popular amongst local amateur radio operators.

This was also the first launch in which we'd switched fully to 300b telemetry, and the first in which we were testing a balloon from a new supplier - we were impressed on both counts.


Launch conditions on the day were ideal - very calm with no rain. Graham VK5GH had kindly offered us his property to launch from - it's a little closer to the freeway than our regular launch site (a definite bonus for us), and is well placed to get into the all the local radio repeaters.

Alan and I inflating as VK5GH supervises

VK5ZBR and VK5FPAU joined us at the launch site to assist - inflation and assembly of the balloon train went smoothly, and we soon had it strung up tethered to Graham's fence, ready to launch.

Tied up and ready to go

This was the longest balloon train we'd put together before - not far off 100m long. The reason for this was to put some distance between my telemetry system (third from the top) and Adrian's repeater - with 1W of TX power, it's likely that if they were close together, the operation of his repeater could have interfered with the telemetry.

Once we'd made radio contact with VK5ZSN and his chase team (who were out chasing and retrieving the BOM balloon launched a few hours earlier) & confirmed they were ready, we cut the payload loose & watched it sail off.


Once launched, the balloon was ascending at just over 4m/s - close to the target of 5m/s. Within 5 minutes of launching we had made out first radio contact via the repeater - from memory, VK5APA in Prospect - we were amazed at how quickly people were able to hear it! Soon afterwards we had a bunch of other ham's pop up - it wasn't long at all before VK5CP in Younghusband along with VK5ZAI in Kingston SE could hear us, and soon after that VK5ZSN was heard.

As the balloon rose and it's radio horizon broadened, we realised we had somewhat of a problem - as the repeater was a parrot repeater and not a talk through repeater, it was very difficult to use it without coming in on top of someone else.

A few requests from Adrian VK5ZSN later, VK5GH and VK5ZBR had established themselves as mission control, and had taken net control - once we'd started working on a system of requesting permission to use the channel & being directed by the controllers, the repeater became quite usable, and we were soon recording contacts hundreds of kilometres away in South Australia and Victoria.

Radio contacts:

Callsign Location
VK5GH Mt Barker
VK5ZBR-Portable Mt Barker
VK5APA Prospect
VK5ZT-Mobile Walkers Flat
VK5FPAU-Mobile Karoonda
VK5KRA Snowtown
VK5CP Younghusband
VK5ZEA Pt. Lincoln
VK5MW Roxby Downs
VK5ZAI Kingston SE
VK5HR Goolwa
VK5BR Pasadena
VK5FMLB Onkaparinga Hills
VK5UDX Salisbury East
VK5KC Blackwood
VK5ZKR Greenwith
VK3MTV Mildura
VK3MIR Emerald
VK3AS Horsham
VK3XPT Forest Hill
VK3KIH Forest Hill
VK3KH Mount Eliza

Click to access the receiever map

Did you make a contact via the Horus 6 repeater? If so, please get in touch with me so I can add you to the list of contacts & send you a QSL card!


Our tracking systems and landing predictions had us well placed to intercept landing - myself and Alan arrived at the landing site a few moments before landing to see the payload coming down, with Adrian's team arriving shortly afterwards.

A long balloon train & clean landing

The payload had neatly set itself down a few hundred meters out in the field - a short walk later and we could see that everything had worked as planned, with no tangling of the balloon train and a clean burst of the balloon.

Roads around the landing site were not ideal - my 2wd sedan was rather out it's depth - I ended bogged right at the landing site after attempting (nearly made it!) to turn around on the very narrow sandy road. Fortunately Adrian and his MAXTRAX saved the day! :D

Not going anywhere in a hurry

A big thanks to everybody who helped make this flight possible, especially VK5GH for letting us launch from his property and acting as mission control with VK5ZBR!