Project Horus High altitude balloon project

Horus 26

Technical information:

Launch date 26/5/12, 22:04 UTC
Landing date 27/5/12, 02:16 UTC
Flight duration 4 hours, 12 minutes
Launch site -34.1747, 142.1385
Landing site -33.1853, 143.1752
Flight path
Distance traveled
145.9 km
Average speed 34.7 km/h
Maximum speed 120 km/h
Maximum altitude 35,470 m
Average ascent rate 2.9 m/s
Impact speed 4.9 m/s
Flight computer MicroNut Flight Computer
Additional payloads Osiris Cutdown Payload, APRS payload, FM cross band repeater
Primary radio TX
Radiometrix NTX2 25mW (RTTY)
Telemetry 300 baud RTTY, CRC16 checksum
Tracking Ground stations (distributed listener), 2 chase cars, web based tracker

Note: this launch was particularly difficult to coordinate because of the limited number of team members available and more intense time pressure than usual.

As a result, we didn't end up with a great deal of photos or video - if you were there & happened to capture some footage of the day, please do not hesitate to get in touch!


Horus 26 was the first of two launches at the 2012 WIA AGM held in sunny Mildura.

Expected radio footprint at apogee.

Thanks to the good folks over at the Sunraysia Radio Group, preparations had been made for a launch carrying a FM voice repeater to altitude.

It was an early start for the team, with everybody out of bed and plans for the day underway by 6am. With 9 payloads between two balloons, we had our work cut out for us!

The ascent profile for the balloon was intended to be quite slow to give the repeater the maximum amount of time at altitude & hence a good opportunity for amateurs to work the system. Given the slow ascent, we sent a chase car off in advance to ensure recovery would be as simple as possible.

Horus 26 & Horus 27 in flight

As well as attracting significant public interest, the airborne repeater provided a communications platform for the team in an otherwise difficult area.

Once the balloon had burst, the cutdown system was used to separate any balloon remnants from the payloads to ensure a smooth descent. The Horus 26 primary chase team (VK5ZM & co) were able to quickly retrieve the payloads once they had landed in a farmers field - an excellent result overall!

A big thanks goes out to everybody who helped make this launch possible - especially the Sunraysia Radio Group and Mildura Workingman's Club for sponsoring the launch.