Kiwis can fly... rockets

Kiwis can fly… rockets

4am, Launch Day, 21 June, 2023

Alicia Smith wakes with a surge of adrenaline. Excitement! It’s Launch Day – time to go!

Smith, a fourth-year Bachelor of Mechanical Engineering (Aerospace) student at the University of Canterbury, Christchurch, New Zealand, and her team, are far from home. It’s been hot overnight – almost 30oC – and sleep was patchy after a late night checking and re-checking their one precious rocket. Today, after eighteen months of work, they will launch their rocket into the clear blue New Mexico sky, hoping to win a coveted Spaceport America Cup prize. “We aim to win”, says Smith, also Team Leader.

The competition is fierc,e with 5,913 participants from 158 teams representing 24 countries, including 7 from Australia: U. NSW, Monash U., ANU, U. Melbourne, U. Queensland, U. Western Australia, and U. Technology Sydney. This year’s Spaceport America runs from 17 to 22 June, with teams competing in six categories:  

  • Target altitude either 10,000ft. (3,048m) or 30,000ft. (9,144m)
  • Motors either bought (i.e. Commercial off the shelf, COTS) or made (i.e. Student research and development, SRAD).
  • Within SRAD, solid fuel (i.e. Solid Motors) or a mix of solid fuel and liquid oxidiser, called ‘Hybrid/Liquid and other’. COTS is open to any propulsion type.

The UC team will compete in the ‘COTS 30k (i.e. 30,000ft) solid motor’ category, one of 28 teams, all determined to get as close to the target altitude as possible. Points-wise, “going over it is as bad as going under it”, says Smith. Everybody in the COTS category “has to use the same off-the-shelf avionics package”, says the Team’s Faculty advisor, UC Projects Engineer Dr Bill Mohs, which is then made to talk with custom-built avionics.

A brown bird of prey stands on a fence pole
Swamp harrier (Circus approximans). Credit: Oscar Thomas, some rights reserved (CC BY-NC-ND)

Their rocket is called ‘Kahu’, the Māori name for the New Zealand swamp harrier, Circus approximans. The largest of the world’s 16 species of harriers, a kahu flying over a Māori village during a tribal meeting was seen as a good sign.

Building Kahu

Solid rockets have a long history. An energy-dense powder or pellet fuel is packed into a long, capped tube, a match is struck – and, stand well back. Gunpowder powered war rockets were launched by the Chinese, Mongols, Indians and Persians as early as the 13th Century. These are now familiar as fireworks, or with added fins and other technology in military applications, and to give extra boost to space-bound vehicles like NASA’s Space Shuttle.

Solid rockets have a long history.

Sleek and black, the UC rocket is the classic shape – a bright red nosecone on top and four fins at its base. Her carbon fibre-fibreglass composite body is strong, the fibres precisely wound to withstand the stresses of launch and flight, says Smith. “The nosecone, fins and bulkheads are woven sheets of carbon fibre and fibreglass orientated to maximise strength”, she adds. Kahu is 2.9m long and weighs 30kg at lift-off.

The rocket kahu on the launch rail in the desert
Kahu on the Launch Rail, Spaceport America Cup. Credit: University of Canterbury

The Motor

Kahu’s power is delivered by ammonium perchlorate composite propellant, a common solid rocket fuel. Perchlorate (NH4ClO4), a powerful oxidiser, is mixed with a binder and metal powders and cast into grains, then packed into a re-useable aluminium motor tube (i.e. the solid motor), says Smith. The rocket is then designed around it. Once ignited, the perchlorate reacts violently with the metal powder, sending the rocket on its way.

The Flight Computer

Fourth-year Mechatronics student, Henry Eden Mann, designed and built Kahu’s flight computer, enabling precise deployment of radial airbrakes, three metal petals which extend from the rocket, on cue, to prevent overshooting target altitude (9,144m), and of the two parachutes (drogue and main) to slow the landing. Complex and challenging, the process uses “a suite of onboard pressure sensors and accelerometers to figure out where Kahu is, how fast it is going and where it is going to end up” says Eden-Mann. Bear in mind that Kahu’s top speed is Mach 2.1 (2,593.5km/h), more than twice the speed of sound, and there is no steering. Making the rocket go where it should “is a really complex control problem”, says Smith. The custom-designed flight computer, a printed circuit board, took 18 months to complete.


Things almost didn’t go to plan. It was raining on Test Day in May, 2023; Kahus’s only launch before the competition – at the New Zealand Rocketry Association’s range, 25km north of Hamilton. Heavy rain rolled in. Cold, wet and miserable. Their narrow launch window, authorised by the CAA (Civil Aviation Authority), was approaching fast, the day looking grim – when the rain stopped, the clouds parted, and a rainbow appeared. Scrambling, they launched the rocket, and the flight (almost) went off without a hitch, bar the main chute opening at 6000m, not 460m, as planned. “There were a couple of failures, and if they had happened in a different order, we would have had to dig the rocket out of the ground”, says Smith. Nothing beats testing your rocket in the air.

Launch day, 22 June

It’s now 5am, at Spaceport America, two hours from the Trinity Site on the White Sands Missile Range, the home of the Manhattan Project which, in 1945, heralded the birth of the atomic age. “It was surreal being that close to history”, says Smith.

It was surreal being that close to history.

Alicia Smith

Forget breakfast, UC have a rocket to launch. Jeans and heavy footwear protect against boot-piercing inch-long thorns, scorpions and venomous rattlesnakes. Add broad-brimmed hats, long-sleeved shirts and plenty of water – today’s expected to be 40oC in the shade and 10% humidity – the team shoulders the rocket and heads out to the launch site. Spaceport America is within the Journados de Meurtos (‘Dead Man’s Journey’) Desert Basin. Named by 16th century Spanish conquistadores, this high altitude (1400m above sea level) desert is not to be trifled with.

Since their arrival on the 17th, the Team’s readiness has been heavily scrutinised at multiple technical judging sessions and flight safety reviews. Testing started 6 months earlier with points accumulated for progress and technical reports. But Launch Day finally here, and the long-awaited countdown is hours away.

The 90-minute journey is made to the Vertical Launch Area (VLA), watching the sunrise over the New Mexican desert. Finally, out onto the VLA, to the flyers meeting, and the final flight safety review.


Precious Kahu is handed over to Spaceport America support crew and placed on the launch rail. The Kiwis have come 11,850km, and, once their only rocket has left the pad, that’s it. One launch. “You get one single shot” says, Smith.

This was the toughest part – the Team is no longer in control of their rocket. Back in New Zealand “you’re tense right up until that moment when you press the button. It either works or it doesn’t” says James Graham, 3rd-year Mechanical Engineering (Aerospace) student and logistics leader for the project. Now someone else has Kahu.

It either works or it doesn’t.

James Graham

3…2…1. Pause. Smoke curls … blossoms, then flames explode from Kahu’s base as she streaks into the desert sky.

On her own, she rises many times faster and higher than her namesake. The two onboard GPS trackers show her reaching the right altitude, but how close was she? Good enough to win? Fifty percent of points are allocated to flight performance but until they access the on-board data, there is no way of knowing. 


The next job is recovery.

Four team members hold two pieces of kahu aloft
Finding Kahu after her flight at the Spaceport America Cup. Credit: University of Canterbury

Cramming into their van and racing into the desert, the Team track her. By road most of the way, on-foot in 40oC heat for the last kilometre; she is found nestled near a large cactus. In good condition, slightly battered, but intact. Back through the heat to the van, altitude is read – their target was 9,144m – Kahu was just 7m out! Just two and a half times her length.  

Exhausted but jubilant, they head back to base. Celebrations will come later – it’s been a long day.

Alicia and her UC Aerospace team came first in the COTS 30k category, and were third overall, out of 158 teams from around the world, many much larger and better funded.  

The Future

Alicia Smith has a job lined up with RocketLab in Auckland and James Graham will complete his final year in 2024, including the defence of the UC Aerospace Team’s title at next year’s Spaceport America.

The whole team is aiming for the stars. New Zealand’s first astronaut may be amongst them.   

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