Connector technology helps student rocketeers reach new heights
02 July 2019
Figure 1. An example of one of the rocket subsystems, with Datamate J-Tek connector attachments
These days, developing problem-solving skills & gaining first-hand experience of how team dynamics play out are increasingly important aspects of getting a university education – helping result in students being far better equipped for the working environment when they graduate.
This article was originally featured in the July 2019 issue of EPDT magazine [read the digital issue]. Sign up to receive your own copy each month.
Project-based engineering competitions are proving to be a really effective way of doing this – and as Jessica Engel, Global Channel Marketing Manager at manufacturer of Hi-Rel & industry standard connectors, board level EMC shielding & associated PCB hardware, Harwin tells us, some such competitions have the students involved aiming for the stars.
Comprised of undergraduates from the University of Waterloo (Ontario, Canada), Waterloo Rocketry is a highly successful team of rocket designers that are looking to keep pushing the performance envelope. Drawing on a broad spectrum of different disciplines (from mechatronics, mechanical engineering, electrical engineering, electronics and chemistry, through to nanotechnology and computing), the team has been competing in the Spaceport America (SA) Cup for the past decade. In this annual competition (which is held in the desert of southern New Mexico), academic teams develop, construct, launch and subsequently recover cutting-edge rockets. There are well over 100 teams participating, from a multitude of nations – with some fervent and longstanding rivalries that have built up over the years.
Waterloo Rocketry have an impressive record of accomplishment behind them, and in recent years they have taken several prizes at the SA Cup. In 2017, their VIDAR III rocket came 1st in the 10,000 feet hybrid contest (where the rockets have a solid fuel source and a liquid oxidizer) and was bestowed with the coveted technical excellence award too. Their UXO rocket helped them to retain the 10,000 feet hybrid title the following year, managing to accurately reach a target height of 13,000 feet.
With 2019’s event rapidly approaching (at time of writing – it takes place in mid-June), final preparations are underway on the team’s latest project – one that is more ambitious than anything they have attempted before. The objective of the new rocket is to reach a staggering height of 30,000 feet (almost 3 times what they have achieved with previous rockets, and around the cruising altitude at which jet airlines fly). So that the 17-foot (5.2m) tall hybrid rocket could attain such heights, the 30-person team had to totally rethink almost every aspect of the design they had employed in their previous rockets.
Figure 2. Two members of the team just prior to testing the rocket engine
As the height is so much greater, the airframe, payload, propulsion and aerodynamics all have to be enhanced considerably. More room is needed for the oxidizer and for fuel storage, as well as for the parachute (which is substantially larger than the size of last year’s one, to ensure safe recovery from such an elevated altitude). All of the rocket’s constituent components must be very compact, in order to save space. They also have to be as lightweight as possible, to give the rocket maximum range with its limited fuel reserves. At the same time, elevated levels of robustness need to be supported, so that they can cope with the stresses that the rocket will be placed under. The rocket engine is expected to deliver far greater power (around 50% more than the previous one), and the time that the engine will be burning for once launch is initiated has also gone up substantially (to approximately 25s), with a longer period at peak intensity.
With this project, the team wanted to be able to network together all of the rocket’s various onboard electrical systems responsible for propelling it and monitoring key parameters while in flight. To do this they would need to have connectors that exhibited enough resilience to survive launch acceleration, while still being quick and easy to assemble, with only minimal tooling (given that much of the assembly work must be done by hand in the desert just prior to launch). The space constraints meant that they needed to move from the large (5mm pitch) barrier blocks used in previous rockets, as these would be too bulky for this new design.
Having looked at different options, via a distributor website they were familiar with, the team’s electrical engineers came to a decision on how best to proceed. Harwin’s 2mm-pitch Datamate J-Tek series was identified as the standout candidate, due to these connectors’ ability to carry both power and data, while also being suitable for withstanding 10G vibrational forces, for periods of 6 hours and extreme temperatures of -55°C, all the way up to +125°C. Made from a Beryllium Copper alloy and employing a proprietary 4-finger single-piece design, the contacts embedded into these connectors can handle exposure to heavy shocks. Each contact also has the capacity to carry up to 3.3A (3A if all contacts are loaded simultaneously), and the new T-Contact versions now available can carry as much as 8.5A.
A total of seven Datamate J-Tek units have now been incorporated directly into the rocket design, linking up six separate onboard electrical subsystems. These are the radio communication subsystem, the sensor suite, the data logging hardware (for diagnostics), a GPS receiver (to assist rocket recovery) and the two valve-driving subsystems.
Figure 3. The rocket engine being tested gives an idea of the stress being placed upon components during launch
“Now that the heights we are looking to get to have increased dramatically, we’ve really had to start thinking a lot smaller when approaching the basic design concept. All the component parts must adhere to the volumetric limitations we have to deal with and not add significantly to the rocket’s overall weight, as this would cause a reduction in range,” explains Aaron Morrison, Project Co-lead at Waterloo Rocketry. “On top of this, they must also be sturdy enough to be able to survive the vibration and acceleration that occurs during the launch.”
“We only get one launch opportunity each year, and all the countless hours of work that all of us have put into the project will be simply wasted if there is a component failure. The fact that the Harwin Datamate J-Tek connectors are small and light, and at the same time very rugged, means that they meet all our required criteria. This will allow us to achieve our targeted altitude – and ensure that there is no risk of any malfunction occurring,” he continues. “Also, as positive attachment is a mandatory stipulation of the competition, the jackscrews on these connectors are a key feature.”
The 2019 edition of the SA Cup will be held between the 18th & 22nd of June, so at time of writing, the team are in the process of finishing off testing and making last minute adjustments ready for the contest. You can see how they got on over at their Facebook page (www.facebook.com/pages/category/Aerospace-Company/WaterlooRocketry) and there are also videos of the rocket engine being tested on their YouTube channel (www.youtube.com/user/uwrocketry).
UPDATE: congratulations to the team, which took home 2nd place in its category (30K Hybrid/Liquid & Other) in the competition, its third consecutive year winning a category award.
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