Happy Solar Car New Year!

The American Solar Challenge is on again in July/August 2021 (hopefully), and the World Solar Challenge in Australia follows in October 2021 (again, Deo volente). As the pictures above from Canadian team Midnight Sun/Waterloo illustrate, chassis/suspension + aerodynamics/electrics = a solar car.

How that equation works out in practice can vary. The World Solar Challenge has now allowed three-wheeled cars again, and Chalmers Solar Team from Sweden is taking advantage of this to build a sleek tadpole three-wheeler called Sköll (render below). Other teams are still frantically designing new cars. The big-name teams hope to reveal completed cars in July. Good luck and Happy New Year to all!

History, geography, and the Western genre

Once Upon a Time in the West, Rio Grande, High Noon. We know the films – and the many books.

The bray of a lazy burro broke the afternoon quiet, and it was comfortingly suggestive of the drowsy farmyard, and the open corrals, and the green alfalfa fields. Her clear sight intensified the purple sage-slope as it rolled before her. Low swells of prairie-like ground sloped up to the west. Dark, lonely cedar-trees, few and far between, stood out strikingly, and at long distances ruins of red rocks. Farther on, up the gradual slope, rose a broken wall, a huge monument, looming dark purple and stretching its solitary, mystic way, a wavering line that faded in the north. Here to the westward was the light and color and beauty. Northward the slope descended to a dim line of canyons from which rose an up-flinging of the earth, not mountainous, but a vast heave of purple uplands, with ribbed and fan-shaped walls, castle-crowned cliffs, and gray escarpments. Over it all crept the lengthening, waning afternoon shadows.” – Zane Grey, Riders of the Purple Sage (1912)

But why are the films and books all set in the United States? Didn’t the very similar continent of Australia have similar stories? Well, up to a point.

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If we want to know why things are the way they are, the answers often lie in history and geography (Jared Diamond makes an especially strong case for geography in his Guns, Germs, and Steel). European settlement in the US began several centuries ago. The Appalachian Mountains (rising to 2,037 m or 6,684 ft) formed a barrier to westward expansion, but hardly in insurmountable one. The eastern US is also blessed with many navigable rivers, especially the Mississippi and tributaries such as the Ohio, Missouri, Platte, and Arkansas. The eastern US is also blessed with good rainfall.

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Western expansion in the US constantly outran organised government. This created a degree of chaos that lasted for a surprisingly long time. The Oklahoma Panhandle, for example, was “No Man’s Land” from 1850 until 1890 – not part of any state or territory. The western part of the Minnesota Territory had the same status between 1858 and 1861. In addition, some of the organised territories in the contiguous US (Arizona and New Mexico) did not become states until 1912.

One tool for dealing with this situation was the resurrection of a thousand-year old English law enforcement strategy: posse comitatus or “power of the county.” Law enforcement was provided by a sheriff, who was authorised to call on armed citizens as needed. Part of the drama of Western stories lies in the sheriff deciding when this was actually needed.

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In contrast to the US, Australia is significantly drier. The Great Dividing Range in the east is somewhat loftier than the Appalachians, with the highest point being Mount Kosciuszko (2,228 m or 7,310 ft). A significant part of the water falling on the west of the range winds up underground in the Great Artesian Basin, a vast bed of porous sandstone holding up to 64,900 cubic kilometres (15,600 cubic miles) of water, capped by an impermeable layer of rock. In places, the basin is 3 km (2 miles) deep. The basin was discovered in 1878, and only after that date did cattle stations or sheep stations in certain parts of the country become feasible, thanks to water from deep bores.

Click map to zoom

Politically, the Australian situation was quite different from the US as well. The entire continent east of 135°E was initially part of the British colony of New South Wales, and by 1829 all of the continent had been claimed. Colonial boundaries shifted several times before Federation in 1901 (and the Northern Territory was transferred to federal control in 1911), but the US situation of unorganised territory was nonexistent.

Law enforcement in Australia was initially military, and early police forces were composed of military personnel. In 1853, Victoria was the first colony to merge law enforcement into one colonial police force. However, law enforcement was never decentralised, as it was in the US.

The vast size and relatively small population of Australia meant that there was plenty for law enforcement to do, of course. Stage coaches and gold miners were robbed, and what Americans call “rustling” also took place. In 1870, a daring theft of around 800 head of cattle took place at Bowen Downs Station in Queensland. Harry Redford and four accomplices overlanded the stock to outback South Australia, where the brands would not be recognised (a distance of about 1,300 km or 800 miles). Employees of Bowen Downs successfully tracked the herd, but Redford was acquitted by a working-class jury who didn’t much mind rich graziers being robbed.

The Western genre tells stories of human drama and resourcefulness on the frontier, and in that it resembles the science fiction genre. But to a large extent the Western genre is also a celebration of the land. To quote one of my favourite contemporary short stories (a Christmas story, actually), from novelist Elisabeth Grace Foley:

A million diamonds glinted in the smooth, untouched white curve of snow in the basin, struck out by the sun that pierced the bright silver-white sky. The bitter wind whisked across it, kicking up little powdery swirls. Cal Rayburn turned up the collar of his sourdough coat with one hand, hunching his shoulders a little so the collar half covered his ears. He squinted at the blinding-bright landscape, and one side of his cold-numbed lips twisted back a little in a half-smile.” – Elisabeth Grace Foley, “The Bird of Dawning

Australians may have lost contact with the land to a greater extent than Americans have, so that the genre of Australian colonial stories has largely faded away. Australia was formed as a collection of colonies with coastal capitals (and with the national capital only 100 km or 60 miles inland). That, together with the dryness of the interior, facilitated a drift to the cities, so that 70% of the population now lives in the 8 capitals.

In contrast, the US has many landlocked states which seem to retain a greater connection to the land. The state flag of Kansas, to pick just one state, seems to tell an entire story, including Indians hunting bison on the Great Plains, a steamboat on one of the navigable rivers, a settler ploughing his field, and a wagon train heading west. There is scope for all kinds of literature and cinema right there (as Laura Ingalls Wilder, Louis L’Amour, Howard Hawks, John Sturges, Clint Eastwood, and many others have shown). Let us hope that people will keep telling those stories.

World Solar Challenge Cruiser scoring

Having participated in some recent discussions about the World Solar Challenge Cruiser Class, I thought I would explore the scoring again. Scoring in the WSC is based on a multiplicative formula (see reg 4.4.7), but as we all learned in high school, multiplying is equivalent to adding logarithms.

By appropriate scaling of logarithms, the chart above breaks down the various components of the multiplicative formula into additive points (black bars are negative numbers).

For example, on this system, in 2019 Eindhoven received a total of 67 points:

  • 100 points for completing all three stages
  • +12 points for an average of 2.6 people in the car
  • −53 points for 71.2 kWH of external energy
  • −0 points for no lateness
  • +8 points for a practicality of 93.1%

Lateness refers to arrival at stage stops after the “soft cutoffs,” which in 2021 will be Sat 15:30 in Tennant Creek, Mon 16:30 in Coober Pedy, and 11:30 Wed in Adelaide (there are also “hard cutoffs” leading to elimination, of 17:00, 17:00, and 14:00 respectively). According to reg 4.4.8, teams are ranked by the number of completed stages, and then by score.

In 2019 Minnesota received a total of 39 points:

  • 86 points for completing only one stage (thus also ranking after all the finishers)
  • +9 points for an average of 2 people in the car
  • −40.5 points for 25.7 kWH of external energy
  • −21 points for 165 minutes of lateness
  • +5.5 points for a practicality of 76.3%

Suppose a larger battery and a longer race had increased Minnesota’s external energy use to 128 kWH (an extra −20 points), but this had removed the lateness factor (an extra +21 points) and allowed achieving all three stages (an extra +14 points). Minnesota would then have been 15 points ahead, for a total of 54. This would have put them neck-and-neck for second place with Sunswift.

This example makes clear how the rules create an incentive for large batteries. It also highlights the difficulty of the second stage from Tennant Creek to Coober Pedy – I wonder if an extension to the “hard cutoff” is possible there?

Technical note: I am multiplying natural logarithms by 12.48 (so that 3020 gives 100), and I have also doubled practicality, and thus the total score (this doesn’t, of course, give practicality any extra weight). Sanity check for Eindhoven: 12.48 × ln(104×2) = 67.

A planetary conjunction and a Christmas greeting

It’s time for a Christmas blog post, and there’s really only one thing to write about. On 21 December, there will be a great conjunction, in which Jupiter and Saturn will appear very close together in the early evening sky. Look for them near the western horizon, as they get closer and closer over the next two weeks. The diagram below (from fourmilab.ch) shows what the solar system will look like at conjunction. A line from Earth to Jupiter continues on to Saturn, but skims by the Sun (which is why the “kissing planets” are only visible in the early evening). These two giant planets have not appeared so close for several centuries.

The Christmas connection relates to the Magi mentioned in the Bible: “After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east came to Jerusalem and asked, ‘Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him.’” (Matthew 2:1–2, NIV)

One theory as to what the Magi might have seen was a set of similar conjunctions of Jupiter and Saturn in 7 BC (the great astronomer Johannes Kepler was the first to suggest this – and yes, thanks to a calendrical error 500 years later, Jesus was born around 7–4 BC). There were three such conjunctions in 7 BC: in May, in late September, and again in December. Here is a view of the September one, as seen from Ctesiphon in Parthia (from fourmilab.ch again). The planets Jupiter (♃) and Saturn (♄) would have risen just before sunset, and been visible in the evening twilight (and then throughout the night):

The Babylonians and Persians had an elaborate system of seeing omens in the sky. For example: “If Jupiter becomes steady in the morning: enemy kings will be reconciled. … If Jupiter passes Regulus and gets ahead of it, and afterwards Regulus, which it passed and got ahead of, stays with it in its setting, someone will rise, kill the king, and seize the throne.” So a conjunction is the sort of thing that would have gotten the attention of star-gazers in the Parthian Empire (the planet Jupiter was associated with the god Marduk and with kingship). Others have suggested a nova recorded in China in March of 5 BC. Yet others have suggested that a sequence of astronomical events led the star-gazers to search for a newborn king specifically in the frontier province of Judaea:

Countless paintings show the journey of the Magi across the desert (the one above is from James Tissot). If they were sensible, they would likely have travelled along the trade routes via Palmyra and Damascus. “A cold coming we had of it” wrote the poet T.S. Eliot (adapting lines from a 1622 homily by Lancelot Andrewes), “Just the worst time of the year / For a journey, and such a long journey.”

The real danger was Herod, of course. He had murdered his own sons Alexander and Aristobulus in 7 BC (and was to murder a third son, Antipater, in 4 BC). According to Macrobius (Saturnalia Book 2, IV, 11), Caesar Augustus had quipped “Better to be Herod’s swine [Greek hus] than his son [huios],” making a Greek pun referencing Herod’s Jewish religion and its prohibition on pork. Naturally, a man like that would be less than thrilled at the suggestion that another heir to the throne might exist:

When King Herod heard this he was disturbed, and all Jerusalem with him. When he had called together all the people’s chief priests and teachers of the law, he asked them where the Messiah was to be born. ‘In Bethlehem in Judea,’ they replied, ‘for this is what the prophet has written:

“But you, Bethlehem, in the land of Judah,
are by no means least among the rulers of Judah;
for out of you will come a ruler
who will shepherd my people Israel.”’
[a summary of Micah 5:2–5]

Then Herod called the Magi secretly and found out from them the exact time the star had appeared. He sent them to Bethlehem and said, ‘Go and search carefully for the child. As soon as you find him, report to me, so that I too may go and worship him.’” (Matthew 2:3–8, NIV)

This is the kind of trouble you get when you mix star-gazing boffins and international diplomacy (I have been to enough international scientific events to know how that works). The gospel account makes a further confusing reference to the “star” and mentions the famous gifts of “gold, as to a king; myrrh, as to one who was mortal; and incense, as to a God”:

After they had heard the king, they went on their way, and the star they had seen when it rose went ahead of them until it stopped over the place where the child was. When they saw the star, they were overjoyed. On coming to the house, they saw the child with his mother Mary, and they bowed down and worshiped him. Then they opened their treasures and presented him with gifts of gold, frankincense and myrrh. And having been warned in a dream not to go back to Herod, they returned to their country by another route.

When they had gone, an angel of the Lord appeared to Joseph in a dream. ‘Get up,’ he said, ‘take the child and his mother and escape to Egypt. Stay there until I tell you, for Herod is going to search for the child to kill him.’” (Matthew 2:9–13, NIV)

This “Flight into Egypt” has been a common subject of Christian art. The painting above, by Adam Elsheimer (1609), includes a beautifully painted Milky Way.

Egypt, of course, was a logical destination. We know first-century Alexandria primarily as the scientific and mathematical centre of the world of that time, but it also had a thriving Jewish community, with hundreds of thousands of Jews living in the city, and hundreds of thousands more in the rest of Egypt. The Hellenistic Jewish philosopher Philo was still a boy at this time, as was the Greek scientist Heron, but the Musaeum was fully active. Eventually, Alexandria was also to become one of the most important Christian cities, and the statement “gold, as to a king; myrrh, as to one who was mortal; and incense, as to a God” was from Alexandria. An active Coptic Church is still there (though suffering hardship).

But troubled as the world of 2020 may be, let me wish all my readers a Merry Christmas, and a better 2021!

Solar racing teams: the US and Dutch models

Stanford at the finish of the World Solar Challenge in 2015

Everybody knows that I’m a big solar racing fan. Today I wanted to talk about solar car team models, comparing what I call the “US model” (although most other countries also use it) with what I call the “Dutch model” (also used by the Belgian team). In the “US model,” students work part-time on a solar car team, and new members are added each year. As an example of this, I will look at the Stanford Solar Car Project, and specifically at one team member: Rachel Abril, who is forever famous for her May 2014 TEDx talk.

Rachel Abril did a 4-year Bachelor degree in Mechanical Engineering (the blue blocks in the chart below show Stanford’s academic years) followed by a Masters degree. The hashed region on the chart shows her extensive involvement with the Stanford Solar Car Project, first as a junior Mechanical Team and Aerodynamics Team member, and later as Suspension Lead and Aerodynamics Lead. She did not, I believe, attend the 2013 World Solar Challenge, but she did attend the 2015 and 2017 races (Stanford was improving during this period, but so were the other top-twelve teams!).

Rachel Abril’s story highlights one great advantage of the “US model,” namely that long-serving team members develop enormous experience in the design, construction, and racing of solar cars. They can take the lessons of one race, and apply them to the next one (and Rachel’s TEDx talk mentions some lessons that Stanford learned).

There are a number of disadvantages to the “US model,” however. New recruits often have limited knowledge of relevant physics (especially in the US, where high school graduates are educationally about a year behind their European or Australian counterparts). What work can new recruits be given that is both interesting to them and useful to the team? How can they be properly integrated into the team, and feel that they are genuinely part of the group? How can the team stop new recruits from feeling “cheesed-off” and dropping out? Answering these questions well is the key to success for US teams. One of the answers lies in running internal training courses for new recruits (there is also the IEF Solar Car Conference), but teams do not always include “Education Lead” or “New Member Coordinator” as one of the key team roles.

Another disadvantage of the “US model” is that the mix of people with varying lengths of experience creates a power structure. It can be difficult for a new recruit to disagree with someone that has been on the team for many years (even if, objectively, the new recruit is right). This can be a trap.

A final difficulty with the “US model” lies in balancing solar car construction, academic study, and personal life. Conventional wisdom is that you can hope for at most two out of three. Privately, team alumni sometimes suggest that one out of three might be more realistic. I don’t know what support mechanisms might help with this.

Solar Team Twente at the finish of the World Solar Challenge in 2019

In contrast, in the “Dutch model,” a smaller group of people gives up a little over a year of their life to work full-time on a solar car. This is quite a sacrifice. The Belgian team’s recruitment page explains the return on investment for the year like this (my translation):

  1. A project filled with experiences that you won’t find in your regular studies;
  2. Discovering a genuine engineering project and its various phases: concept, design, production,
    and test;
  3. Connecting and collaborating with the largest companies in relevant industries;
  4. A close-knit group and a racing adventure never to be forgotten;
  5. The experience of a lifetime and so much more!

Essentially, the year on the solar car team functions as an unpaid internship (speaking as someone who has helped arrange engineering internships in the past, I can’t think of an internship where you would learn more). One positive feature of industry internships is normally industry networking; this is also worked into the Dutch/Belgian solar car experience (as #3 on that list indicates). Of course, the need to set up those industry connections is one more reason to have a really professional sponsorship team.

As an example of the “Dutch model,” I will focus specifically on the 2018–19 “edition” of Solar Team Twente. Behind this team sits a part-time organisation (mostly of alumni) which handles recruitment and provides technical advice. This organisation began recruiting in February 2018, and a new team was announced on 9 June 2018. All these people were complete solar car novices, of course. The new team began work at the start of the 2018–19 academic year (with the aerodynamic and management subteams starting a little earlier). In the chart below, coloured blocks show academic years, and the hashed region shows the typical duration of full-time team involvement:

One of the first activities of the novice Twente team was to race the previous car, Red Shift, at the European Solar Challenge (iESC) on 21–23 September 2018. Team alumni raced the even older Red One, so that this was not only a training activity for the novice team, but an opportunity for knowledge transfer from alumni. Building on their iESC experience, the novice team then began designing and building their new car, RED E. The new car was revealed on 21 June 2019. After a test race on 17–18 August, the car was shipped to Australia on 30 August (a tragic crash due to wind gusts put RED E out of the race, but it was in the lead when that happened).

Engineering education in the Netherlands is traditionally a 5-year Ingenieur degree. Because of EU regulations, this is nowadays packaged as a 3-year Bachelor degree plus a 2-year Masters, but local students generally take the full package (because of the superior Dutch high school system, the 3-year Bachelor degree reaches at least the same standard as the 4-year US equivalent). As a result, the novice Twente team would have had substantially more formal education under their belts than new solar car recruits in the US. Dutch engineering schools also benefit from a close connection to industry, which drives a practical focus. The Eindhoven University of Technology, for example, is traditionally a feeder school for Philips, DAF Trucks, and other engineering companies in the Eindhoven area.

Of course, not every university teaches every skill needed for solar car design and construction. Dutch engineering schools typically teach agile project management, for example, but this does not seem to be the case in Belgium. The Belgian team therefore arranged industry training on the subject from their sponsor Delaware Consulting. Dutch teams also often benefit from industry-based “team building” activities (this video shows such an activity for Top Dutch). Practice races (including the European Solar Challenge) compensate for the fact that team members have never attended the World Solar Challenge before.

Because of team-building, educational initiatives, and good knowledge management, the “Dutch model” consistently produces top solar cars (Vattenfall/Delft has won the World Solar Challenge repeatedly, the Belgians won in 2019, Twente was on the podium in 2013 and 2015, Top Dutch came 4th in their first race, and Eindhoven has won the Cruiser Class every time). While the “Dutch model” relies partly on specific features of engineering education in the Netherlands and Belgium, I think there are several Dutch/Belgian practices that teams in other countries can learn from.

Nuon (now Vattenfall) at the finish of the World Solar Challenge in 2017

I should finish with a note on Vattenfall (Delft) Solar Team, which runs a variation of the “Dutch model.” Vattenfall (Delft) alternates what I call “big build” teams with “small build” teams. The “big build” teams design and construct new cars for the World Solar Challenge, while the “small build” teams modify existing cars for other events. For example, Nuna9 was a “big build” for the 2017 World Solar Challenge, while Nuna9S was a “small build” modification of the same car for the 2018 South African race (it included a clever radar system). Likewise, Nuna Phoenix was the same car modified again for the 2020 American Solar Challenge (that event was sadly cancelled, but Nuna Phoenix did set a world record). As part of providing a return on investment for the “small build” teams, Vattenfall (Delft) is careful to give these modified cars their own identity.

Solar Buggy aftermovie!

Credit (click image to zoom)

Hochschule Bochum is famous for their Cruiser-class solar vehicles. But they also have a solar buggy team   ). In 2019, they attempted a world record for crossing the Simpson Desert. Things did not go entirely according to plan, thanks to unusually high temperatures and strong winds, but they certainly produced a fantastic, innovative vehicle.

A few days ago, they released a spectacular 100-minute aftermovie of their world record attempt (see the 3-minute teaser and the full aftermovie). Well worth a look!