Sasol Race Report #8

Here are the final results for the Sasol Solar Challenge in South Africa, after 8 days of racing (click to zoom). The photo is from here (taken on day 8), and the daily “loops” are marked. Only the Challenger class is shown (City U, the only car in the Sustainability class, did 175.5 km). The big news was the penalty of 117.4 km imposed on Nuon when a sick team member dropped their bag in the wrong van. The kilometres subtracted by the penalty are marked with light orange in the chart above. They did not, in the end, affect the outcome of the race.

Nuon has some excellent videos about the race (Dutch with English subtitles) for day 1, day 2, day 3, day 4, day 5, day 6, day 7, and day 8. In addition, I should note that SER came 3rd in a tough race, which probably puts them in the world top 10. Tshwane University of Technology (TUT) have taken over as South African champions. Congratulations! And the high school team Sonke (from St Alban’s College and St Augustine’s LEAP School) also deserves a special commendation, displaying both talent and persistence.

After WSC 2017, several people (including me) attributed Nuon’s large lead (see the chart below) to clever weather strategy. But this race, where all cars have been more or less in the same part of the country, suggests that, as well as having flawless race strategy, Nuon have a car that really is significantly faster than all the others (roughly 7% faster than Tokai in Australia, and 6% faster here). This fact may encourage other WSC teams to stick with a tried-and-true catamaran design (as Canadian teams Poly Montreal and ETS Quebec have done). And Nuon themselves? I cannot see how they can possibly improve on Nuna 9S. Maybe they will try something radically different, just for a change.


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Sasol Race Report #7

Here are the results for the Sasol Solar Challenge in South Africa, as at day 7 out of 8 (click to zoom). The photo is from here (taken on day 6). The big news is the penalty of 117.4 km imposed on Nuon when a sick team member dropped their bag in the wrong van. The kilometres subtracted by the penalty are marked with light orange in the chart above, and move Nuon down to 2nd place. In my view, it reflects poorly on Tokai that they made a formal complaint about this incident, and it reflects poorly on the Sasol Solar Challenge that they imposed such a large penalty.

Nuon has some excellent videos about the race (Dutch with English subtitles) for day 1, day 2, day 3, day 4, day 5, day 6, and day 7.


A Day in the Life of Nuon Solar Team

This blog post is something a little different: it will use the GPS tracker data feed to describe a day in the life of Nuon Solar Team during the Sasol Solar Challenge. Specifically, it will describe Wednesday 26 September, which Nuon’s media team summarised in this 90-second video:

Wednesday 26 September (day 5 of the race) opened in Graaff-Reinet. On the Tuesday, Nuon had fallen 36 km behind Japanese team Tokai, due to electrical problems. The support engineers began work at 4:00 AM to return their car Nuna to tip-top condition. The morning was chilly, but sunny, which allowed some solar recharging of the batteries.

The plan for the day, as outlined in this livestream by media team-member Bianca Koppen, was to drive to the control stop in Jansenville faster than Tokai. At Jansenville there was an optional 65-km “loop” to Klipplaat and back. The plan was to drive this “loop” six times (Tokai was expected to do so only five times) and then continue to the end-of-day stop in Port Elizabeth, arriving there just before 5:00 PM. In line with this plan, Nuna sets off at around 85 km/h, soon overtaking Tokai:

The chart below (click to zoom) shows the progress of the day. The horizontal axis is distance, and the vertical axis of the main chart is the speed of the solar car. Underneath the main chart is an elevation plot. The letter A marks the start for the day.

The letter B marks the control stop at Jansenville, where Nuna initially stops for 30 minutes (as per the regulations; later stops will only be 5 minutes). Nuna then continues to the small town of Klipplaat, where the route simply loops and returns along the same road (see the map). However, the road to Klipplaat is uphill, and from Klipplaat is downhill. As the chart above shows, the shiny new “intelligent cruise control” adjusts the car’s speed to suit, running more slowly while climbing.

Point C on the chart is interesting. A few minutes into the 4th Jansenville–Klipplaat leg (shortly after noon), Nuon’s strategy team decides that the plan isn’t going to work. Either because of the weather, or the state of the car (I don’t know the reason), they decide that they will only drive five loops today, not six. The whole plan for the day is recalculated, so as to still get to Port Elizabeth just before 5:00 PM (but having used less energy). Instead of peaking around 87 km/h, the next two loops only peak around 70 km/h. The strategy team in the mission control (chase) vehicle must have been working furiously on this plan. On the chart, there is a sudden slow-down at 12:05 PM, but the new driving pattern is established just a few minutes after that. A good strategy team is critical to winning a race!

Point D on the chart marks the last stop in Jansenville, around 2:10 PM:

Race regulation 6.1 requires that a driver can operate the car for at most 2 hours. Given the distance to Port Elizabeth, Nuna stops briefly for a driver change at around 3:45 PM, shortly after this photograph was taken (point E on the chart):

And just before 5:00 PM, Nuna indeed reaches Port Elizabeth. After some more repair work, taking advantage of the energy saved during today’s run, and as the result of teamwork and skill, the plan to drive one more loop than Tokai succeeds the next day.

Of course, much more goes on during a typical day than this story suggests. People are feed and housed. Sick team-members are looked after. Media reports are produced. Nuna, go, go, go!


Sasol Race Report #6

Here are the results for the Sasol Solar Challenge in South Africa, as at day 6 out of 8 (click to zoom). Only the Challenger class is shown. The optional daily “loops” are marked, the black spots indicate time penalties, and the photo is from here (taken by Tokai on day 4). I have calculated average speeds for the cars (hopefully correctly), and the short dashed lines show distances travelled in the 2016 event (which was a faster race, because the cars had larger solar panels).

On Wednesday, Nuon tried to do one more loop than Tokai, but decided halfway through the day that they couldn’t manage it, and slowed down again. On Thursday, they did manage it, and are now 22.7 km ahead of Tokai.

Despite some troubles on Wednesday (a strong wind gust ripped the array off the car, requiring some repairs), the Swiss team (Solar Energy Racers) is hanging on to 3rd place.

Nuon has some excellent videos about the race (Dutch with English subtitles) for day 1, day 2, day 3, day 4, day 5, and day 6. See also the online tracker and my teams list and information page, which includes links to team social media.


Sasol Race Report #5

Here are the results for the Sasol Solar Challenge in South Africa, as at day 5 out of 8. Only the Challenger class is shown. The optional daily “loops” are marked, the black spot indicates a time penalty, and the photo is from here (taken on day 4). I have calculated average speeds for the cars (hopefully adjusting correctly for time spent in control stops and loop stops).

Tokai still holds the lead, Central University of Technology have finally gotten their car to pass scrutineering, and three cars are in a battle for 3rd place.

Nuon has some excellent videos about the race (Dutch with English subtitles) for day 1, day 2, day 3, day 4, and day 5. See also the online tracker and my teams list and information page, which includes links to team social media.


Sasol Race Report #4

Here are the results for the Sasol Solar Challenge in South Africa, as at day 4 out of 8. Only the Challenger class is shown (not the car from Hong Kong, which is driving non-competitively). The daily “loops” are marked, and the photo is from here. See also the online tracker and my teams list and information page, which includes links to team social media.

Nuon had some minor technical problems today, allowing Tokai to take the lead. Nuon has some excellent videos about the race (Dutch with English subtitles) for day 1, day 2, day 3, and day 4.

I’m beginning to doubt that Central University of Technology (CUT) or Cape Peninsula University of Technology (CPUT) will ever get their cars working; but they clearly have not yet given up. In hindsight, universities offered the chance to start new teams should have been approached much earlier. However, Tshwane University of Technology (TUT) has done a fantastic repair job after the storm damage on day 1. I hope that they will be able to make it to Australia next year.

Weather forecasts for the rest of the race route are:


Sasol Race Report #3

Here are the results for the Sasol Solar Challenge in South Africa, as at day 3 out of 8. The big storm at the end of day 1 is marked. Only the Challenger class is shown (not the car from Hong Kong, which is driving non-competitively). Black spots mark time penalties, and the photo is from here. See also my teams list and information page, which includes links to team social media.

In the Sasol Solar Challenge, teams drive a fixed route each day, with the option of detouring around a “loop” 0, 1, 2, 3, … times. These “loops” are highlighted in the chart above. For example, on day 1, Nuon and Tokai both drove the fixed route as well as driving the 76.1 km loop five times (however, these “loops” actually happen somewhere in the middle of the day’s route, not at the end).

These “loops” mean that strategy essentially becomes a version of the difficult knapsack problem. Teams must maximise the sum of the lengths of the chosen loops, subject to time and energy constraints. This is further complicated by the uncertainty of future energy input (will it be cloudy in 4 days time?) and the psychological cat-and-mouse between the leaders (something which Nuon generally excels at). It will be interesting to see how Nuon and Tokai play the strategy game over the next 5 days.

Nuon has excellent videos about the race (Dutch with English subtitles) for day 1, day 2, and day 3.

Update: NWU apparently had battery problems. CPUT is still hoping to fix their car so that they can get it off the trailer and onto the road. Days 4 and 7 will see some shorter loops, so some distance might open up between Nuon and Tokai then. Weather forecasts for the race route are:

  • Tuesday Sept 25 – Windy
  • Wednesday Sept 26 – Sunny
  • Thursday Sept 27 – Sunny
  • Friday Sept 28 – Rain
  • Saturday Sept 29 – Mostly cloudy