InCFD Team smashes Water Rocket World Record

A team from UCT’s Industrial Computational Fluid Dynamics (CFD) Research Group joined the elite club of internationally renowned rocket scientists when they successfully broke the longstanding Class A Water Rocket World Altitude Record by a massive 33%.

The record was formally ratified on in October 2015 after international peer review by the Water Rocket Achievement World Record Association. The previous record of 623m, set in 2007 by US Water Rockets, has had no equal for eight years.

The research group, based at UCT’s Department of Mechanical Engineering, followed a multidisciplinary approach that involved innovative design, lean manufacture and CFD, or computer-based mathematical modelling. All this was done on a shoestring budget and using off-the-shelf materials and standard tooling.
Innovation and tenacity - the key ingredients needed to overcome demanding challenges – resulted in a featherweight record-breaking rocket that is 2.68m tall yet weighs less than 1.5kg (this includes a flight computer, on-board camera, parachute and parachute deployment system). The rocket produced 550kg of thrust, blasting off to 550km/h (would cross a rugby field in 0.75 seconds) in under 0.5 seconds.  In addition to computer based modelling, the team made extensive and creative use of carbon fibre materials, due to their amazing strength.

A tale of trials and tribulation
The project commenced in 2013 when Stuart Swan and Donovan Changfoot took on the challenge as part of their undergraduate final-year project, under the supervision of Professor Arnaud Malan, Department of Science and Technology South African Research Chair in Industry Computational Fluid Dynamics at the Department of Mechanical Engineering.  Donovan focused on building a numerical water rocket simulation model, while Stuart was tasked with designing and building the rocket.

The first ascent
The team launched the first full-scale water rocket, Ascension Ι, in November 2013 to an altitude of approximately 600m. However, the carbon-fibre rocket tube was leaking air severely, which would nullify any world record attempt. To resolve this, Swan and Malan devised a creative and cost-effective sealing solution (for which a patent is currently being applied). As this was clearly revolutionary technology, the team opted to test its efficacy first under laboratory conditions. Malan assigned this task to the then final year mechanical engineering student William Liw Tat Man. The laboratory tests proved that the sealing method was highly successful.

The second attempt
A second world record attempt, which required multiple design refinements, followed. In addition, Liw Tat Man developed and built a significantly improved launch pad - important for the large forces expected. Months of hard work culminated in the attempted launch of Ascension II in December of 2014.
Unfortunately, the rocket failed to lift off and the flight was aborted. The team’s spirit was severely hard hit. After careful study of the failures, Swan’s father Patrick added some key insights. However, two new pressure vessels failed during hydrostatic testing, and morale hit an all-time low.

The last leg
Resolute not to give up, a new phase was started with increased focus and drive. With Swan as lead designer and Malan as project manager and design critic, a number of key innovations followed. These ranged from pressure-vessel manufacture to a radical fail-safe parachute deployment system. After sustained and lengthy efforts in which designs were pulled apart to the smallest detail, and with strict adherence to the Water Rocket Achievement World Record Association rules at every step, Ascension III was born.

The launch
On 26 August 2015, the team headed out to Elandsberg Farms in the Western Cape. Ascension ΙΙΙ was ready for its maiden flight at 9:37am. A small crowd of die-hard supporters held their breath as the countdown began. With a loud roar from the onlookers, the rocket blasted off, accelerating into the blue yonder at a staggering 550 km/h in less than 0.5 seconds. Rapt silence followed as everyone waited for Assentation III to return safely via parachute. Cheers erupted as the bright red parachute gently guided the rocket back to earth. Minutes later the rocket landed safely and flight data was downloaded from the on-board computer.
A height of 835m was recorded - a massive 217m higher than the current record. To secure the world record, a second launch had to be completed within two hours of the first. With 10 minutes to spare the second launch took place and reached an altitude of 825m, setting a new world record of 830m.