6th July, 2017

SEM 2017 part 2: out of the comfort zone

Saturday, the second last day of SEM 2017, mid-morning. Niamh had just driven the second of our competition runs, setting a new Geec London best of 241 km/kWh to move up to 21st place. Only the best of our four runs would count in the final score, so we could afford to take some risks now. We’d have another chance later that day, and a final one on Sunday.

We had two strategic options. We could continue with the current configuration of the car, learn from the on-car data, and probably squeeze some more performance by fiddling with the gearing and the drive plan. Or switch to the Maxon RE50 motor, which is capable of efficiency over 90% according to the manufacturer. The catch is that this motor is rated for current of 10.8 amps, significantly lower than we need to pull up the hill. But the catch has some wiggle room – what really matters is temperature, not current. If the high-current bursts up the hill are short enough, with enough cooling-off time in between, the motor wouldn’t get dangerously hot.

It’s a particularly expensive motor (it’s Swiss, dontcha know), and certain long-term team members were traumatised ever since frying the first motor in a car park at home. But thanks to the homework on Johnny’s dynamometer and Hugh’s computer simulation, we weren’t relying on gut feelings to make the decision. The simulations suggested the motor would get progressively hotter over 10 laps, but not into the danger zone. It was installed in the car for an on-the-spot dyno test. The motor casing was getting hotter than predicted. Still, even the most pessimistic interpretation suggested the windings would stay (just) below the rated temperature of 125¬įC by the end of the run. It was time to start believing all that analysis. The car went into the queue with the precious 200-watt motor.

Most of the team huddled on a vantage point at the foot of the hill and waited for Laura to come into view on run 3. The car hit the slope flat out about 35 km/h, with a distinctive new high-revving whine. It kept going. At that speed, it didn’t have enough torque to overcome gravity, and the speed dropped, as expected. As speed dropped, the motor delivered more torque and pulled more current. Finally it reached the crest of the hill without smoke or fireworks. We breathed again. The motor would have three minutes to cool off a little before climbing on the next lap and taking another 35-second blast of heat.

Lap after lap was laid down, inside the schedule, until disaster struck on lap 7. There had been an incident involving another car. Laura and the Geec took an undignified ride home to base on the back of a rescue truck. On arrival, Laura and team manager Hugh lodged a formal protest. While they did, we were able to do an unofficial joulemeter reading, and convert it into a km/kWh score that made our eyes water (in a good way).

It seemed the change of motor and gearing could deliver the kind of score we’d hoped for. It had survived the hill, but it had done only 6 climbs in a row. The calculations said it would get hotter lap after lap, and we had yet to find out for sure if it could survive 10. While we digested this, Laura bounded back to the paddock waving a piece of paper and recounting the whole story – a car in front had veered across the track, out of control, at the entrance to the hairpin. Her quick reactions, and SEM safety standards, meant a collision was avoided. Trackside video had captured it all and the race director awarded us another attempt. As a bonus, we had a free pass to skip the starting queue, to ensure we’d actually have time to use our additional attempt. Happy days. Dylan put a job list on the whiteboard and we did our final night’s tweaking. Oiled the chain, checked the bearings, clipped out another few hundred grammes, and retired to the SEM barbeque at the campsite.

And, already, it’s Sunday. When the session opened, we were at the top of the queue to make use of our repeated third run. An official photographer brilliantly captured Laura’s determination at the moment the car was closed around her (below). As the first to roll out, she enjoyed an empty track for a while. It looked like a superb run – laps 2 to 6 were clockwork, between 3:52 and 3:57 (the target is 3:54). Then, incredibly, our luck failed again. Lap 7 took almost 5 minutes. Once again, another car had cut across the Geec (this time under control) and forced Laura into a barrier. The Geec doesn’t have a reverse gear, and your run is over if you get a push; but using some unknown driver-fu, Laura extricated the car and got going again. Because the run was already so tight on schedule, there was no cushion to make up that lost minute. Despite a blazing last lap of 3:12, the run finished an agonising 9 seconds over the limit. Laura hightailed it to the race director’s office, where she was now a familiar face. Sure enough, the other driver was found to have broken the rules. 39:09 was rounded down to 39 minutes and the run was allowed to stand. The score? 274 km/kWh.

The motor had performed as predicted – it was warm, to say the least, but within tolerance and very much alive. 274 was a score we’d be happy to bring home. But that was with a mid-race restart and an energy-burning final sprint. The track was still open and we had one more shot. We rolled the car back into the queue, swapped in a freshly charged battery, put icepacks on the motor, and generally fussed around, trying hard very hard to be calm as Niamh strapped in.

With dozens of prototype teams hoping to put one last score on the board, conditions on track weren’t easy. But this time there were no disasters. Niamh came home  with a respectable 30 seconds to spare. Half the team huddled around the car as the score was checked, to the mild annoyance of ever-patient race officials at the end of their long week. And the Geec delivered – 354 km/kWh! We jumped into 13th place, and stayed there while the last few cars completed their runs.

Four years ago, we started from nothing, and now we’re on the fringes of Europe’s top 10. We’re finding out that a team from Galway can compete with the world’s finest. This is only possible with the support of many people, offices and units in NUI Galway, and our generous sponsors:
Shell E&P Ireland, Galway University Foundation, Blackstone Launchpad, √ČireComposites, CADFEM UK & Ireland, Molex, GE, David Nestor Freight Services, Tool Trays, Enform Plastics, Mathworks, and IPG Automotive.

Aaaand finally – if you’re still reading – thank you! Your support means a lot.

Josefine Kristy Web Developer

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur vestibulum eget justo sit amet varius.

Website: http://www.spikeincor.eu