ASC 20: Solar cars and the Oregon Trail

Given that the American Solar Challenge is going to be following the Oregon Trail this year, I thought that it would be fun to do a comparison between the “prairie schooners” of two centuries ago and the solar cars of today.

At the time of the “Great Emigration” of 1843, aluminium was known, but could not yet be produced on an industrial scale (that came in 1854, and was initially very expensive). Steel likewise existed, but the Bessemer process for producing it came later (1855). Fibreglass composites came a century later (1936), and carbon fibre later still. Modern electronics could not even have been imagined. The “prairie schooners” were built using a much older technology.


Prairie schooner and solar car – picture credits NPS (left) and Anthony Dekker (right)

ATTRIBUTE PRAIRIE SCHOONER SOLAR CAR
Dimensions (W × L) 1.2 × 3 m (4 × 10 ft) for wagon bed Up to 2 × 5 m (7 × 16 ft) for entire car
Horsepower 4 to 12 hp 1 hp solar power for Challengers (SOV), up to 4 hp mixed solar/grid power for Cruisers (MOV)
Sustained speed 3 km/h (2 mph) 50 to 75 km/h (30 to 45 mph)
Empty weight 600 kg (1300 lb) 150 to 450 kg (350 to 1000 lb)
Load 900 kg (2000 lb) 80 to 320 kg (200 to 700 lb)
Motive power Horses or oxen Solar cells, battery, and electric motor(s)
Body materials Wood, cotton canvas Steel, aluminium, carbon fibre, fibreglass
Tires Iron Rubber, low rolling resistance

Prairie schooner and solar car – picture credits Albert Bierstadt (left) and Anthony Dekker (right)


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ASC 11: Leadership


Nuon Solar Team celebrates their 2017 WSC win (photo: Anthony Dekker)

Ernest Hemingway famously said that “war is fought by human beings.” It’s the same with solar cars – they are built and raced by human beings. Or, as Solar Team Twente likes to say, they are “powered by human energy.

There are many aspects to this human side of solar car racing. I’ve written before about how little things like team clothing contribute to team cohesion. A diversity of skills is important if a team is to succeed. During the race, nutrition is one of the things necessary to keep people working at top efficiency. But today, I want to talk about team leadership.

Engineering leadership is critically important, although surprisingly little is written about it. Tracy Kidder produced a fantastic, almost ethnographic, description of real-world engineering in his 1981 book The Soul of a New Machine, but even that book has the actual leadership happening mostly in the background.

A century earlier, Leo Tolstoy opened his novel Anna Karenina with the words “Happy families are all alike; every unhappy family is unhappy in its own way” (“Все счастливые семьи похожи друг на друга, каждая несчастливая семья несчастлива по-своему”). That is true also for solar car teams. Many things have to be done right if a team is to succeed, but doing one thing badly is enough to stop a team in its tracks.

A team leader must, first of all, motivate team members to do their best – it is no accident that all the solar car team leaders I’ve met have been really nice people. A team leader must make sure that the overall problem of building, racing, and finding sponsorship for a solar car is broken down into manageable pieces, and that the right person is in charge of each piece – this is the essence of engineering.

A solar-car team leader must also have – and promote – a clear vision of the car that the team is going to build. It is possible to have a world-class suspension, a world-class body, world-class solar cells, and world-class everything else, and still fail, because the components were designed under different assumptions, and don’t actually fit together to make a world-class car.

A team leader must keep an eye on the critical path as well. Building a solar car for a race is one of the most challenging kinds of engineering project – one where the delivery date is fixed in stone. What project managers call the critical path is the sequence of activities which, if they take any longer than planned, are guaranteed to delay project completion. Generally, the schedule for building and testing a solar car doesn’t leave much room for that kind of schedule slippage.

One perennial question with solar car team leaders is how long it takes them to realise that there is a problem requiring the team to either (a) change the way it operates or (b) pull out of the competition. Each year, I am reminded by somebody or other of Napoleon’s 1812 invasion of Russia, summarised so well in the famous data visualisation above (by Charles Minard).


Napoleon’s death march (painted by Illarion Pryanishnikov)

Napoleon began his invasion with 422,000 men, and reached Moscow with only 100,000 survivors. This was not enough to do anything, so he turned around and went home again, losing most of his remaining troops to cold and skirmishes in the process. I have often wondered at what point Napoleon realised that his plan was not working the way that it was supposed to. In a similar way, there is always a solar car team that begins a last-minute “death-march,” working until 3:00 AM each night, desperately trying to finish their car. The early hours of the morning are not a good time to be making safety-critical engineering decisions, and teams which leave it so late to panic generally don’t do very well.

But enough of Napoleon. Let us listen to some men and women who know how it’s done (translations from Dutch are my own best attempts):

Olivier Berghuis, Solar Team Twente (2017): “As team leader you are the one ultimately responsible for the success of the project. That means that you have to keep a close eye on the progress of the project’s technical, communication, and financial aspects. The mood of the team and the personal development of each team member are also critically important important responsibilities of the team leader.” (“Als teamleider ben je eindverantwoordelijk voor het slagen van het project. Dat betekent dat je de voortgang van het project op technisch, communicatief en financieel gebied in de gaten moet houden. Daarnaast is de sfeer binnen het team en de persoonlijke ontwikkeling van elk teamlid een zeer belangrijke verantwoordelijkheid van de teamleider.”)

Shihaab Punia, University of Michigan (2016): “… build the best possible team and team culture …”


Photo: Jerome Wassenaar

Irene van den Hof, Solar Team Twente (2015): “I think that I am a good listener for my teammates. I try to put a lot of emphasis on that. Everyone is young and inexperienced, and that can sometimes cause problems, but together we are indeed a team, and everyone has to reach the finish line – I make sure of that.” (“Ik denk dat ik heel goed kan luisteren naar mijn teamgenoten. Daar probeer ik ook veel aandacht aan te besteden. Iedereen is jong en onervaren en dat kan voor problemen zorgen, maar samen zijn we wel een team en iedereen moet de eindstreep halen, daar zorg ik ook voor.”)

And it’s worth repeating the excellent insights from Rachel Abril, who was on the Stanford solar car team for four years (“Go fast, but not recklessly fast. Test it. Test it again. Test it more. Use failure as a foundation for success.”):


ASC 4: Testing

It is critically important that solar-car teams clock up test kilometres before the big race. This is partly because of what engineers call the “bathtub curve.” Failures in any piece of technology are common at the start, but then level out to a low constant failure rate during the object’s lifetime (and of course, once the object starts to wear out, failures increase again).

In the business world, short warranties are used to cover that early failure-prone period. In racing, it’s essential to make sure that the car is out of that early period before the race begins. Therefore, the top teams test, test, and test some more!

Here is a montage of recent solar-car testing, which I have already posted to Twitter:


True Stories – a book review


True Stories: And Other Essays by Francis Spufford

I recently finished True Stories: And Other Essays by Francis Spufford – a collection of real gems by a man who can truly write. A selection of essays, book reviews, and other non-fiction works, this book is divided into the thematic sections “Cold,” “Red,” “Sacred,” “Technical,” and “Printed.” The section “Technical,” for example, includes a piece on British engineering, together with a wide-ranging essay on Babbage’s “Difference Engine No. 2,” reconstructed by the Science Museum, London. Babbage never completed this device, of course, and perhaps could not have done so, given the technological limitations of his time. This leads Spufford into a general reflection on counterfactual history, drawing also on the novel The Difference Engine.

The section “Cold” includes several pieces on polar exploration, such as an introduction written for The Worst Journey in the World (a memoir of the 1910–1913 British Antarctic Expedition), and a piece on Ernest Shackleton. I’ve been fascinated by polar exploration since childhood, so I found these particularly interesting.


Grotto in an iceberg, photographed during the 1910–1913 British Antarctic Expedition (image credit)

The section “Red” deals largely with the former Soviet Union. It includes an explanation of Spufford’s fictional documentary book Red Plenty, and the essay “The Soviet Moment,” which is still online at The Guardian: “It was not the revolutionary country people were thinking of, all red flags and fiery speechmaking, pictured through the iconography of Eisenstein movies; not the Stalinesque Soviet Union of mass mobilisation and mass terror and austere totalitarian fervour. This was, all of a sudden, a frowning but managerial kind of a place, a civil and technological kind of a place, all labs and skyscrapers, which was doing the same kind of things as the west but threatened – while the moment lasted – to be doing them better. American colleges worried that they weren’t turning out engineers in the USSR’s amazing numbers. Bouts of anguished soul-searching filled the op-ed pages of European and American newspapers, as columnists asked how a free society could hope to match the steely strategic determination of the prospering, successful Soviet Union. … The loudest and most important lesson of the Soviet experience should always be: don’t ever do this again. Children, don’t try this at home. … Yet we’d better remember to sympathise with the underlying vision that drove this disastrous history, because it is basically our own.

The section “Sacred,” obviously, deals with religion (Spufford is an English Anglican). It includes a critique of Richard Dawkins, a reflection on C. S. Lewis, and a record of travels in Iran. The New Humanist still has online the essay beginning “Allow me to annoy you with the prospect of mutual respect between believers and atheists. … No? No. Because the idea of atheism as an extravagant faith-driven deviation from the null case goes against one of the most cherished elements in the self-image of polemical unbelief: that atheism is somehow scientific, that it is to be adopted as the counterpart in the realm of meaning to the caution and rigour of the scientific method.


Spufford visited the Sheikh Lotfollah Mosque in Isfahan, Iran (image credit)

Finally, the section “Printed” includes miscellaneous introductions and book reviews, including an introduction to The Jungle Book, a review of the Mars trilogy, and an obituary of Iain M. Banks. This last section reflects Spufford’s wide-ranging interests in technology, exploration, and imagination. For me, at least, it established a connection of sorts with the author: we read the same things; we are brothers.


The last section of True Stories includes a review of the Mars trilogy by Kim Stanley Robinson

See The New York Times and the New York Journal of Books for other reviews of True Stories. I’m giving it four stars overall, although several of the individual essays deserve five. This book was a delight to read.

* * * *
True Stories: And Other Essays by Francis Spufford: 4 stars


Solar car team composition

The chart above shows 2017 team composition for the Eindhoven and Bochum solar car teams (divided by study major, not team responsibility). Not surprisingly, electrical and mechanical engineering students are the core of both teams (about half in each case) Yet there is also considerable diversity, because the business side of a solar car team requires other skills too. The Bochum team also includes a media unit, which explains the large “other” category (one of the team photographers is a biology student, for example).

The chart was constructed by parsing web pages, which may have introduced errors (also, I guessed a bit with the German words). But the main point stands – solar car teams require a diverse set of skills.


The Bochum car (photo: Anthony Dekker)


The R100 and the R101

An instructive saga in the history of engineering is the story of the British airships R100 and R101. As part of a grand social experiment, the R100 was built by private industry (it was designed by Barnes Wallis), while the R101 was built by the British government (specifically, by the Air Ministry, under Lord Thomson). The R100 worked fine, and made a test flight to Canada in August 1930 (the trip took 78 hours). Here is the R100 over a Toronto building:

The R100 was huge. Here is a size comparison of the R100 (219 m long) and an Airbus A380 (73 m long):

While the government-built R101 used servo motors to control its gigantic rudder, the R100 team had worked out that the rudder could actually be operated quite easily by hand, using a steering wheel and cables. The government-built R101 was beset by poor choices, in fact. It contained overly heavy engines, a steel frame, and too much dead weight overall. After construction, the R101 had to be lengthened by inserting a new 14-metre section in the centre, in order to increase lift. This alteration caused a number of problems. Its design also allowed the internal hydrogen-filled gasbags to chafe against the frame, there were serious problems with the outer covering, and several “innovative” design ideas were never properly tested.

There was enormous political pressure for the R101 to fly before it was ready to do so. On the evening of 4 October 1930, it departed for India with a crowd of VIPs on board. It never arrived, crashing in bad weather over France, and bursting into flames. The disaster led to the R100 also being grounded, and the British government abandoned any thoughts of flying airships (as the rest of the world was to do after the Hindenburg disaster).

There are all kinds of lessons to be drawn from the saga of the R100 and the R101. One of them is that optimism is not a viable strategy for safety-critical engineering. Another is that engineers test things. As Kipling says, “They do not preach that their God will rouse them a little before the nuts work loose.” A third is that risky designs and fixed deadlines simply do not mix.


A History of Science in 12 Books

Here are twelve influential books covering the history of science and mathematics. All of them have changed the world in some way:


1: Euclid’s Elements (c. 300 BC). Possibly the most influential mathematics book ever written, and used as a textbook for more than 2,000 years.


2: De rerum natura by Lucretius (c. 50 BC). An Epicurean, atomistic view of the universe, expressed as a lengthy poem.


3: The Vienna Dioscurides (c. 510 AD). Based on earlier Greek works, this illustrated guide to botany continued to have an influence for centuries after it was written.


4: De humani corporis fabrica by Andreas Vesalius (1543). The first modern anatomy book.


5: Galileo’s Dialogue Concerning the Two Chief World Systems (1632). The brilliant sales pitch for the idea that the Earth goes around the Sun.


6: Audubon’s The Birds of America (1827–1838). A classic work of ornithology.


7: Darwin’s On the Origin of Species (1859). The book which started the evolutionary ball rolling.


8: Beilstein’s Handbook of Organic Chemistry (1881). Still (revised, in digital form) the definitive reference work in organic chemistry.


9: Relativity: The Special and the General Theory by Albert Einstein (1916). An explanation of relativity by the man himself.


10: Éléments de mathématique by “Nicolas Bourbaki” (1935 onwards). A reworking of mathematics which gave us words like “injective.”


11: Algorithms + Data Structures = Programs by Niklaus Wirth (1976). One of the early influential books on structured programming.


12: Introduction to VLSI Systems by Carver Mead and Lynn Conway (1980). The book which revolutionised silicon chip design.

That’s four books of biology, four of other science, two of mathematics, and two of modern IT. I welcome any suggestions for other books I should have included.