America's Cup: ETNZ designers leap into the unknown with wind-powered landspeed record
by Hamish Hooper/ETNZ media 27 Feb 2022 06:19 AEDT
27 February 2022
Emirates Team NZ - Wind powered land speed record attempt - February 2022 © Emirates Team New Zealand
In Emirates Team New Zealand’s 30 year history they have designed and built over 20 different race boats but it will come as no surprise that not one of them involved any amount of R&D on tyres.
So obviously this is the main area that is the biggest leap into the unknown for the ETNZ designers that have been working on the team’s attempt at the Wind Powered Land Speed World Record.
The man leading the charge in the area is Mechanical Engineer Tim Meldrum, a mountain biking enthusiast, Tim knows a bit about the value of tyres, traction and turf. He was also one of the key designers behind the legendary Cyclors mechanical system that was so integral to the team’s success winning the America’s Cup back for New Zealand in 2017.
“One of our biggest challenges has been understanding how to get grip on the ground, so to stop the craft slipping sideways, we rely on tires to bite into the salt. So, that's where it differs a lot from a yacht.” He explained. “When you're on water, we just have a foil or a centre board in the water, which resists leeway. We've done as much research as we could possibly do in the time available to figure out what tyres are out there and what may work for us.”
Selecting the right tyres isn’t a matter of popping down to Tony’s Tyre Service and picking a few off the shelf. A few of the Good Year tyres themselves will tell you, ‘For racing purposes Only- Not for highway use’ is the clear label on each one.
As important as the tyres are, they still need to be fitted to something. Like a lot of the hardware through the craft the team has tried to buy a number of existing components off the shelf for budgetary reasons, such as the rear wheels.
However certain components need critical customisation.
“The front wheel is a custom rim that we've designed and made, and it looks really flat on this side, which is due to having a really huge offset. Our main fuselage is kind of acting like a motorbike, in that we have one wheel at the front. It's really important that we have our steering axis centred exactly on the centre of the tire. So in order to get any steering access on the centre line, we have had to make this rim. If we didn't have it like that, we would get a lot of induced torque into the steering from the rolling resistance, and that would just feedback to the pilot, basically he’d be having to fight the whole time.”
Well that’s what the theory tells us, but there is plenty to be learnt once we get the craft out for a test explained Meldrum.
“I don't know which way it's going to go, but we're either going to find that they're too grippy or not grippy enough, straight away. So it's pretty exciting to think, you know, those first days testing what we're learning. We're going to learn so much, so quickly.”