ASC 2021: 2 days to go

It is now just a few days until the start of scrutineering in the American Solar Challenge (27 July in Topeka, KS). I have updated my teams list with facts and pictures.

There are 13 12 teams still registered for the race. Of these, 5 teams (CalSol 6, Kentucky 3, Illinois State 17, Georgia Tech 49, and App State 828) will be racing veteran cars – although with various improvements. In addition, the Brizo of Illini 22, the Nimbus of MIT 4, and the Cruiser Eliana of PrISUm 9 were completed some weeks or months back. Western Michigan 30, Principia 32, and Kansas 785 have not yet revealed a completed car, which is disconcerting. However, UMNSVP 35 have revealed their beautiful new Cruiser Freya:

Freya from University of Minnesota Solar Vehicle Project (credit)

Along with MIT 4, CalSol 6, and AppState 828, UMNSVP have departed for the racetrack. AppState is doing so with a hot new look:

ROSE from Appalachian State University (credit)

Update: Sadly, Kansas 785 have withdrawn from the race.

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The High School Solar Car Challenge: Day 4

Today we say goodbye to the (High School) Solar Car Challenge held at the Texas Motor Speedway. Here are the official results (dashed lines show the 2019 winners). In spite of rain on Day 1, RAHS Green Energy has done very well indeed. Covenant Christian and Wylie East have both exceeded all Classic scores since 2009, thanks to thinking seriously about aero.

The beautifully engineered catamaran from Iron Lions did not live up to its full potential, because of battery problems on Day 4. However, they still came 3^rd, in spite of only racing for three days. I expect to see this car to do very well in the future.

The three rookie teams (marked with black squares) have done extremely well. If the Classic and Advanced Classic cars were grouped together, Holy Solars would be 3^rd, KCAL would be 7^th, and WASP would be 9^th out of 10.

Let me finish with the official group photo (click to zoom), and what I believe to be the correct car identifications:

Front row: Staten Island (Advanced), RAHS Green Energy (Advanced);
Second row: Plano Green Team (Advanced), Covenant Christian (Advanced), Iron Lions (Advanced);
Third row: LISA Academy (orange shirts, Advanced Classic), Prosper (Advanced Classic), Holy Solars (Classic), Kentucky Solar Cats (Classic), Iron Lions (ESP), Covenant Christian (Advanced Classic);
Fourth row: KCAL (Classic), WASP (Classic), Wylie East (Advanced Classic), MISD Shine Runners (Advanced Classic), Coppell (ESP), NTCA (Classic), Western High School Solar Cats (ESP), Heroes’ Alliance (ESP);
Rear: All Saints (Advanced), Prosper (Cruiser).

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The High School Solar Car Challenge: Day 3

Here are the unofficial lap counts for Days 1 through 3 of the (High School) Solar Car Challenge at the Texas Motor Speedway. The symbols at the top of each bar refer to my car identification chart. Black squares next to names indicate new teams. The Holy Solars (from Kent School, Kent, CT) are doing especially well, but all the new teams have clocked up a respectable lap count.

There are several nail-biting contests going on (for 1^st place in the Advanced Division and the Advanced Classic Division; for 3^rd in the the Advanced Classic Division; for the entire podium in the Classic Division; and for 2^nd in the Electric-Solar Powered Division). Also, I am glad to see Plano Green back on the track after having a bad MPPT.

As an Australian, it is interesting to reflect on the mix of U.S. schools participating in the Solar Car Challenge. Independent Christian schools like Covenant Christian Academy and North Tampa Christian Academy appear to be over-represented, as are non-standard STEM-focused public schools like Raisbeck Aviation High School (RAHS), and public charter schools like LISA Academy North Middle High School. Certainly, whatever RAHS is doing seems to be working!

Let me finish, once again, with an action shot, although this one is from Day 2 (click to zoom):

On the inside, the red-and-white Appalachian Spirit of the Kentucky Solar Cats (Classic Division) leads Black Widow from the MISD Shine Runners (Advanced Classic). Overtaking on the outside, Staten Island’s High Energy #5 (Advanced Division) leads the current Advanced Division leader Invictus from the Iron Lions (SCC race photo).

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The High School Solar Car Challenge: Day 2

Here are the unofficial lap counts for Days 1 and 2 of the (High School) Solar Car Challenge at the Texas Motor Speedway. The symbols at the top of each bar refer to my car identification chart. Catamaran cars (stars) are doing well. Black squares next to names indicate new teams (the Holy Solars in particular are doing very well). All Saints and Coppell, who had problems on Monday, have started to put some laps on the board. Plano Green, unfortunately, had a bad MPPT.

Doing an analysis on the lap counts (just for today) reveals a surprising fact. For the six most aerodynamic cars (marked in blue on the chart below), performance decreases as the car gets heavier (although the correlation is extremely weak). This is just as we would expect, because of rolling resistance. However, for seven less aerodynamic cars in the Advanced Classic and Classic Divisions (marked in brown on the chart below), weight has essentially no effect. That is, the effect of weight is swamped by other aspects of car construction.

I also wonder why we have Classic and Advanced Classic divisions. Cars in these two divisions, starting from the top, go AC, AC, C, C, AC, C, C, AC, AC/C. There is a difference between the two groups (Advanced Classic: median 102 laps, mean 125; Classic: median 100 laps, mean 102.8), but this difference is not statistically significant.

Let me finish, once again, with an action shot (click to zoom):

On the inside, The Blurr from the Heroes’ Alliance (Electric-Solar Powered Div) leads the colourful Miss Fifinella of the Women’s Air Service Patrol or WASP (Classic Div), with KCAL’s Deus Volt (also Classic) at the rear. On the outside, the blue-nosed Cougar Pride from Covenant Christian Academy (Advanced Div) is overtaking, followed by Black Widow from the MISD Shine Runners, in the Advanced Classic Division (SCC race photo).

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The High School Solar Car Challenge: Day 1

Here are the unofficial lap counts for Day 1 of the (High School) Solar Car Challenge at the Texas Motor Speedway. The symbols at the top of each bar refer to my car identification chart. Catamaran cars (stars) are doing well, as is the symmetric streamlined car (dot) from Staten Island. Black squares next to names indicate new teams. The Holy Solars (from Kent School, Kent, CT) are doing especially well, having built a very good-looking car.

Covenant Christian Academy’s pair of almost-identical cars are about as aerodynamic as a “table-top” solar car (dagger symbol at top of bar) can be. Their Advanced Division car, Cougar Pride, is 90 kg lighter than its Cougar Spirit partner (mostly a reduction in battery weight), with more efficient solar panels, and a hub motor (which is why it has one rear wheel instead of two). I expect Covenant Christian Academy to do very well in both divisions that they’ve entered. Nevertheless, the results so far do show the aerodynamic superiority of the catamaran design.

 
Two views of the Advanced Classic Division car Cougar Spirit from Covenant Christian Academy, Colleyville, TX (SCC scrutineering photos). It has since acquired an orange nose, to distinguish it from its blue-nosed three-wheeled Advanced Division partner.

In general, I’ve been very impressed by the dedication and skill of both the experienced and the new teams. Several of these high school teams would put university students to shame. Let me finish with an action shot (click to zoom):

Staten Island’s High Energy #5 (Advanced Div) leads North Tampa Christian Academy’s The Solar Stroller (Classic Div) which is being overtaken by the colourful Miss Fifinella of the Women’s Air Service Patrol (WASP, Classic Div). Also overtaking is the orange-nosed Cougar Spirit from Covenant Christian Academy (Advanced Classic), with KCAL’s Deus Volt (Classic) at the rear (SCC race photo).

And another one:

Wylie East’s blue East Beast–Xtreme (Advanced Classic) overtakes KCAL’s Deus Volt (Classic), which is followed by the red-and-white Appalachian Spirit of the Kentucky Solar Cats, in the same division (SCC race photo).

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The High School Solar Car Challenge: car chart

As I have already said, this year I am covering the (High School) Solar Car Challenge, as well as the upcoming university competitions. The high school event (hosted by Texas Intruments) is currently taking place at the Texas Motor Speedway on July 15–22 (with Covid protocols in place). Actual racing starts on July 19.

For the benefit of those following the race from home, here is a chart of all the cars (click to zoom). The chart has been updated, and two errors corrected.

Other useful resources are:

• Official social media:    and    (click on the icons).
• Official website.
• Official YouTube page (event will be live-streamed here, probably at this link).
• Wide-angle live camera at the track (looking south).
• Motorsport weather forecast.
• Sky cover forecast.
• My list of teams (with explanation of the divisions).

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The High School Solar Car Challenge: some physics

This year I am covering the (High School) Solar Car Challenge, as well as the upcoming university competitions. The high school event will take place at the Texas Motor Speedway on July 15–22 (with Covid protocols in place), and will be live-streamed via the event’s YouTube channel. Today I want to say something about high school solar cars in comparison to world-class cars.

 
Left: Cougar Spirit from Covenant Christian Academy is a high school car in the Advanced Classic Division / Right: Nuna11 is a world-class car from Delft University of Technology in the Netherlands (picture by @lightatwork)

The two main drag forces operating on cars are rolling resistance and aerodynamic drag. The former is indicated in the chart below by red lines. It is a function of the product of the rolling resistance C_rr of the tyres times the mass M of the car in kilograms.

The aerodynamic drag is indicated in the chart below by blue lines. It is a function of the product of the drag coefficient C_d of the body shape, the frontal area A of the car in square metres, and the square of the velocity.

The chart at the bottom of the page expresses the same information in terms of the power (in watts) required to overcome drag at various speeds.

At the world-class level, where special low-rolling-resistance tyres are available and cars glide through the air like a hot knife through butter (low values of C_rr M and C_d A), the aerodynamic drag is much greater than the rolling resistance at race speeds, and shaving a few percent off the C_d A value becomes critical to winning. At high school level, with cars that students can afford and racing speeds from 15 to 50 km/h (10 to 30 mph), aerodynamic drag and rolling resistance are roughly similar, and reducing the weight of the car becomes especially important. Some of the high school classes do not permit hub motors, and for those cars, reducing drive train losses is also critical.

A few high school cars in the Advanced Division are both under 200 kg and quite aerodynamic this year (e.g. Invictus from the Iron Lions and Lumidos from Oregon Solar Car Team), so it will be very interesting to see how they perform.

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The High School Solar Car Challenge: the favourites

As I have already said, this year I am covering the (High School) Solar Car Challenge, as well as the upcoming university competitions. The high school event will take place at the Texas Motor Speedway on July 15–22 (with Covid protocols in place). Actual racing begins on July 19. The race will be live-streamed via the event’s YouTube channel, or check out    and    (click on the icons).

I previously posted a list of high school teams for this year and some useful resources. But who are the favourites? Here is a chart of the number of laps which teams clocked up last race (if they indeed raced), organised by division. Some of these teams are returning in the same car, while other teams are coming back with an even better car, which means that it’s kind of hard to pick winners. We’ll have to see how the race unfolds!

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ASC 2021: 2 weeks to go

It is now two weeks until the start of scrutineering in the American Solar Challenge (27 July in Topeka, KS). I have updated my teams list with facts and pictures.

There are 13 teams still registered for the race. Of these, 5 teams (CalSol 6, Kentucky 3, Illinois State 17, Georgia Tech 49, and App State 828) will be racing veteran cars – although with various improvements. In addition, the Brizo of Illini 22, the Nimbus of MIT 4, and the Cruiser Eliana of PrISUm 9 were completed some weeks or months back. That leaves 5 teams. Of those, North Carolina 99 is continuing their experiment of gutting a commercial ICE vehicle and turning it into a solar-powered Cruiser:

SPX from North Carolina (credit)

The Cruiser Freya I of UMNSVP 35 is looking good, although still missing its vinyl wrap:

Freya I from University of Minnesota Solar Vehicle Project (credit)

Also, Principia 32 is making progress on their Ra XI, and Western Michigan 30 and Kansas 785 are also still busy with construction. Good luck, one and all!

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The High School Solar Car Challenge: Calendar

As I have already said, this year I am covering the (High School) Solar Car Challenge, as well as the upcoming university competitions in the US, Europe, and Morocco.

The high school event will take place at the Texas Motor Speedway on July 15–22 (with Covid protocols in place). The calendar below shows the schedule. Other useful resources are:

• Official social media:    and    (click on the icons).
• Official website.
• Official YouTube page (event will be live-streamed here).
• Wide-angle live camera at the track.
• Motorsport weather forecast.
• Sky cover forecast.
• My list of teams (with explanation of the divisions).

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