Solar racing car numbers

As in all races, solar racing cars are identified by number. Some solar car numbers are simply traditional, like the 8 for Agoria Solar Team from Belgium (above). Others have a specific meaning, as shown in the chart below.

Some numbers are lucky in some way, such as 21 = “Twente-One.” Some are coded references to solar technology, such as 55 = the year that Western Electric began to sell licenses for silicon PV technology. Alternatively, numbers indicate the team’s home base. This can be done by specifying a road, such as the the Interstate 35 or Strade Statali 9 = the Via Aemilia. More commonly, telephone country or area codes are used, such as 40 = Eindhoven, 46 = Sweden, 82 = South Korea, or 828 = western North Carolina. Not shown in the chart is 34 = the vehicle license plate prefix for Istanbul.

Mobile phone picture by Rafael Fernandez

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Results of the ASC 2022 Road Race

Wrapping up the American Solar Challenge, the chart above shows the final official distances. The chart places optional “loops” driven at the end of each stage, even mid-stage loops. At the bottom of each bar is the final placing, with a star marking MOV (Cruiser) cars. The notation “(Tr)” identifies cars that trailered or were deemed to have trailered.

Below is a logarithmic visualisation of the MOV (Cruiser) scoring. The final score (last bar in each group) is the product (visually, the sum, since the chart uses logarithms) of seven factors:

• The distance driven d (in miles)
• The distance driven with penalties d’ (in miles)
• The average number of people p in the car
• The reciprocal of the total external energy usage E (in kWh)
• The practicality score P (out of 100)
• The speed derating T (1/70.86 = 0.014 for AppState)
• In grey, the reciprocal h of 171,780 (the longest distance driven, times 100)

This is equivalent to the way that the scores are broken down officially (since C = d’/1717.8 and D = d×p).

The final score for AppState is 1/4.2 = 0.24, as in the official results. Esteban (Poly Montreal) achieved the highest score through low total external energy usage, but was demoted to third place after missing a turnoff early in the race, which prompted this retrospective modification to regulation 12.11.C:

“Any team leaving the tour route must rejoin the route at the same intersection where they left the route or they will be considered to have trailered from their last completed route step before going off route. Their Load On Trailer Time will be the time that they went off route.”

PrISUm (Iowa State University) was forced to withdraw early on due to electrical issues, so scores 4^th in the MOV (Cruiser) class.

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Challenges in the ASC 2022 Road Race

True to the name, there have been some challenges in the American Solar Challenge now taking place. On the first stage, Esteban (Poly Montreal) missed a turnoff, prompting this modification to regulation 12.11.C:

“Any team leaving the tour route must rejoin the route at the same intersection where they left the route or they will be considered to have trailered from their last completed route step before going off route. Their Load On Trailer Time will be the time that they went off route.”

PrISUm (Iowa State University) was forced to withdraw early on due to electrical issues

“Unfortunately things did no go as planned for PrISUm. Due to safety concerns for both the car and our team, we did not want to drive the car any farther. It is unfortunate that there was an electrical issue, which is hard to quickly and safely fix on race. We are very proud of our team performance at FSGP, compared to the last couple of years. Thank you to everyone for all of your support and following us throughout our journey.”

Canadian team Éclipse (ÉTS) had a major crisis on stage 2:

“On our 2nd loop in the city of Casper, our topshell detached from the vehicle; no injuries. The damage from this incident to the vehicle is not minor, but we worked very hard to get it back on the road! Thank you to all who helped!

Solar panels replaced, topshell corner redone in carbon fiber wet layup, tightened security attachments, lights picked up, stronger canopy, MPPTs repaired and even two flat tires all under 24h our convoy made it to time at stagepoint #2 in Lander, Wyoming just minutes from closing! The vehicle is in shape, today we are driving to Montpellier, Idaho.”

Illini (University of Illinois) had a narrow miss on the same stage:

“Today on our way to Lander, the team and Brizo faced a very near collision. As the convoy was waiting to turn left along the route, a semi lost control and tried to swerve around a pickup in front. The semi crashed a few feet from Brizo and the pickup truck landed mere inches from our chase car. Thankfully the entire team and Brizo were unharmed. However due to lost time, we had to trailer part of the second stage. Tonight we arrived in Lander and are ready for the rest of the American Solar Challenge.”

Official times for the first two stages are summarised in the chart below. The chart places optional “loops” driven at the end of each stage, even mid-stage loops. MIT leads the SOV/Challenger class, followed by Principia and Kentucky. The MOV/Cruiser scoring system is more complex, and only distances are shown here. However, Minnesota does appear to be ahead.

Latest news had most solar cars arriving at the Montpelier, Idaho checkpoint (including AppState and, I believe, Berkeley):

Follow the remainder of the race with the ASC car tracker (or just the dashboard). You can also check out the official ASC social media at        (click on the icons).

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ASC 2022 Road Race Team Photo

Above is the official American Solar Challenge team photo (slightly cropped). From left to right, the teams are:

• 32. Principia Solar Car Team
• 35. University of Minnesota Solar Vehicle Project ★
• 4. MIT Solar Electric Vehicle Team
• 3. Kentucky
• 55. Esteban (Poly Montreal) ★
• 6. UC Berkeley Solar Vehicle Team (CalSol)
• 22. Illini (University of Illinois)
• 9. PrISUm (Iowa State University) ★
• 828. Appalachian State University (Sunergy) ★
• 101. Éclipse – Véhicule solaire de l’ÉTS

Stars (★) mark cars in the MOV (Cruiser) class.

Follow the race with the ASC car tracker (or just the dashboard). You can also check out the official ASC social media at        (click on the icons).

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ASC 2021: road race, final day

Today sees the end of the American Solar Challenge. Above (click to zoom) are the final SOV standings, in New Mexico flag colours. MIT won, followed by Kentucky and Principia (Principia would have come second, were it not for some fairly stiff penalties given during scrutineering for minor regulation non-compliance).

Teams marked with a dot were forced to trailer at some point, and hence score lower. The optional “loops” driven are marked at the end of each stage (even the La Junta loop, which occurred in the middle of Stage 2). In the MOV class (not shown), Minnesota ran into problems, making App State the winners – their mountain-built car having taken all the passes in its stride.

Note: this chart reflect minor recent updates to the official Stage 2 numbers. The chart posted yesterday is therefore very slightly out of date.

The last day of the race was a short drive from Las Vegas, NM to Santa Fe, NM and back, across the Glorieta Pass through the Sangre de Cristo Mountains (easier than the Raton Pass). Above (click to zoom) is a day in the life of Illini according to the GPS tracker. Elevation data is from the tracker, so the elevation profile is slightly incorrect where the tracker cut out.

The chart above (click to zoom) shows MOV practicality scores. Black stars indicate final ASC placing (App State won the class). PrISUm did not qualify for the road race, but came third at FSGP.

Below (click to zoom) are some memories of the route (photos are from the ASC and the teams).

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ASC 2021: road race, Day 4

Today sees the end of Day 4 and Stage 2 of the American Solar Challenge. Above (click to zoom) are the SOV standings at the end of Day 4, in Colorado flag colours. MIT leads, followed by Principia and Kentucky. Teams in red were forced to trailer at some point, and hence score lower. The optional “loops” driven are marked at the end of each stage (even the La Junta loop, which occurred in the middle of Stage 2). In the MOV class (not shown), Minnesota ran into problems, leaving App State in the lead. There is one short day of racing still to go.

Kentucky at Fort Union National Monument (credit)

Above (click to zoom) is the Gato del Sol VI of Kentucky visiting Fort Union National Monument. Marion Sloan Russell, who travelled the Santa Fe Trail multiple times, was an “army wife” there for some time. In her memoir, Land of Enchantment, she writes about revisiting the site:

“At Fort Union I found crumbling walls and tottering chimneys. Here and there a tottering adobe wall where once a mighty howitzer had stood. Great rooms stood roofless, their whitewashed walls open to the sky. Wild gourd vines grew inside the officers’ quarters. Rabbits scurried before my questing feet. The little guard house alone stood intact, mute witness of the punishment inflicted there. The Stars and Stripes was gone. Among a heap of rubble I found the ruins of the little chapel where I had stood—a demure, little bride in a velvet cape—and heard a preacher say, ‘That which God hath joined together let no man put asunder.’”

Fort Union in 2006 (credit: Scott)

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ASC 2021: what about MOV cars?

I have been asked about covering the Cruiser (MOV) cars this year. As the ASC photo above shows, Minnesota was the first team into La Junta (at 18:23:47 MDT). Cruiser (MOV) scoring is complex, but it’s mostly a complicated nonlinear function of speed. External energy usage, number of people in the car, and penalties also have an effect, but they are minor.

The chart below is an attempt to visualise who is ahead (I may not have gotten it quite right). For each team and day, there is a group of 4 bars. Mathematically, multiply the first two bars (distance with and without penalties) and divide by the third bar (the speed derate, which penalises going less than 35 mph) to give the fourth bar. Visually, just add the first two bars and subtract the third. So App State was well ahead on Day 1 (because they averaged 34.1 mph to Minnesota’s 29.6 mph), but Minnesota is well ahead now (averaging 35.6 mph to App State’s 34.3 mph).

To relate these numbers to the official ranks, multiply by the average number of people in the car, and divide by the scaling factor for the day, which is the largest of all the distance bars for that day. For example, for App State on Day 1, 20,548.5 × 2 / 244.1 = 168.36. I emphasise again that the numbers for today are estimates.

For a simpler view, we can just assess the cars based on average speed. The chart below does this, with the dashed red line indicating the target speed:

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ASC 2021: track race (FSGP) results

We have now come to the end of the FSGP – the track-race portion of the American Solar Challenge. Final lap counts (from here) are shown in the chart below. The chart is in the colours of the Kansas flag, with green bars representing single-occupant vehicles (SOV). White stars mark the teams that have qualified for the coming road race (ad astra per aspera). See also my illustrated list of teams.

To follow the multi-occupant vehicles (MOV), it is really only necessary to look at the brown bars in the chart above. However, the chart below (click to zoom) visualises the actual MOV scores on a logarithmic axis, with six coloured bars being components of the score, and the seventh coloured bar S being the product (i.e. sum of the logarithms) of those components. The six components are:

• d, the total miles driven
• d′, the total miles driven with penalties
• p, the average number of persons in the car (and so the Total Person-Mile Distance in the regulations is D = d × p)
• E, the Total External Energy usage (as in the regulations)
• T, the Target Speed Derate, which penalises cars slower than 30 mph (as in the regulations)
• h, a grey bar (the same for every team) showing the highest driving distance of any MOV entry (and so the Completion Factor in the regulations is C = d′ / h)

This version of the scoring formula, S = d × d′ × p × (1/E) × T × (1/h) is equivalent to the formula S = (D / E) × C × T in the regulations, but makes it clear that the speed of the car essentially appears three times (as d, d′, and T), and hence dominates all the other factors.

The chart below shows how closely the MOV scores reflect the lap counts:

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ASC 2021: Saturday, July 31

We have now had two days of the FSGP – the track-race portion of the American Solar Challenge. Lap counts so far are shown in the chart below. The chart is in the colours of the Kansas flag, with green bars representing single-occupant vehicles (SOV). Stars mark the five teams that have already qualified for the coming road race (see also my illustrated list of teams). The Gato del Sol VI from Kentucky is in the lead, having done even better than I expected.

To follow the multi-occupant vehicles (MOV), it is only necessary to look at the brown bars in the chart above. Technically, the FSGP regulations give the score for MOV cars as S = (D / E) × C × T, where S is the total score, D is the Total Person-Mile Distance, E is the Total External Energy usage of the solar car, C is the Completion Factor, and T is the Target Speed Derate.

The chart above (click to zoom) visualises these MOV scores on a logarithmic axis, with six coloured bars being components of the score, and the seventh coloured bar S being the product (and therefore the sum of the logarithms) of those components. The six components are:

• d, the total miles driven
• d′, the total miles driven with penalties
• p, the average number of persons in the car (and so D = d × p)
• E, the total external energy usage (as in the regulations)
• T, the target speed derate, which penalises cars slower than 30 mph (as in the regulations)
• h, a grey bar (the same for every team) showing the highest driving distance of any MOV entry (and so C = d′ / h)

This version of the formula, S = d × d′ × p × (1/E) × T × (1/h), makes it clear that the speed of the car appears three times, and hence dominates all the other factors. Consequently, we really only need to count laps. Another consequence is that teams in the MOV (Cruiser) class would, in many cases, actually be better off not carrying passengers.

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ASC 2021: Friday morning, July 30

Well, in Topeka, Kansas it is the morning of the FSGP – the track-race portion of the American Solar Challenge. Only 4 out of 12 cars have qualified so far – the veteran Gato del Sol VI from Kentucky; the brand-new Brizo from Illini (the University of Illinois team); the brand-new Cruiser Freya from the University of Minnesota Solar Vehicle Project; and the brand-new Nimbus from MIT. So what does that mean?

Brizo from the University of Illinois (credit)

Well, I’m guessing that it means that two of these cars will win the track race in their respective classes. The road race, which is the main event, is still wide open, though. A bunch of other cars will make it through scrutineering today, put in some solid laps on Saturday and Sunday, and qualify for the road race. Some of those will also be strong contenders. I will keep my teams list (in the previous post) up-to-date on the status of those cars.

However, I anticipate some cars not passing scrutineering, while others hit the track but don’t qualify for the road race. That much is normal at ASC.

Update: four more teams did indeed pass scrutineering during the course of the day – Illinois State, Berkeley (CalSol), Georgia Tech, and NC State. As expected, Brizo from the University of Illinois and Freya from the University of Minnesota are leading the lap counts.

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