World Solar Challenge: about the Cruisers 2

Here is an alternate presentation of the World Solar Challenge Cruiser Class score calculation:


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World Solar Challenge: about the Cruisers

To illustrate the World Solar Challenge Cruiser-class scoring for 2017, here is the calculation for Kogakuin’s 2015 car (above). Disclaimer: this is, of course, my personal interpretation of the regulations.

Notice that Cruisers are not in a race this year – any arrival time during the 11:00 to 14:00 time window on Friday is OK.

Arrival time

Friday 11:35.
Inside window? YES

Energy efficiency

Battery capacity, Q = 14.855 kWh
Number of recharges, n = 1 (at Alice Springs)
External energy use, U = (n + 1) Q = 29.71
Person-km, C = 3022
Energy efficiency, E = C / U = 101.7
Highest energy efficiency, E* = 203.6 (Eindhoven)
Relative energy efficiency, E / E* = 0.4996

Practicality

Practicality P = 51.75
Highest practicality, P* = 84.5 (Eindhoven)
Relative practicality, P / P* = 0.6124

Total Score

Total score, S = 80 E / E* + 20 P / P* = 39.97 + 12.25 = 52.22

This is a massively lower score for Kogakuin than was actually awarded in 2015. This year, the World Solar Challenge Cruiser Class is all about energy-efficiency, carrying passengers, and practicality. Expect to see the four-seat and five-seat Cruisers (like the Polish car below) running with every seat occupied.


Silly Season in the Sky (again)

It’s apparently time for lunatic end-of-the-world prophecies again. The latest relates to a “great red dragon” in the sky (a reference to Revelation 12):

Turns out that this is a double image of Saturn, taken way back in 1983 by the Infrared Astronomical Satellite (IRAS). Saturn was then at RA 13h45m18.2s, DEC -08d13m07s.

It’s a false-colour image (i.e. not red at all), being taken at 100 microns, in the infrared region of the spectrum. But with enough spin, apparently it can be made to sound scary.

In the final version of the infrared sky survey, this artefact was blacked out, since it doesn’t reflect any actual stellar infrared sources (just a planet that moves around). Of course, that removal got the conspiracy-theory nutters going.


World Solar Challenge: route notes

Following on from my route map for the World Solar Challenge – all 3,000 km or 1,900 miles of it – here are some personal route notes (revised from 2015). The graph below (click to zoom) shows approximate altitudes (calculated by overlaying the route on an altitude raster). The highest point on the route (about 730 m) is 20 km north of Alice Springs, although the steepest hill (Hayes Creek Hill, summit 203 m) is about 170 km from Darwin.

Darwin – Start


Solar Team Eindhoven’s Stella starts the race in 2013 (photo: WSC)

The city of Darwin marks the start of the race.

Katherine – 322 km – Control Stop 1


En route to Katherine in 2011 (photo: UC Berkeley Solar Vehicle Team)

The town of Katherine (on the Katherine River) is a gateway to Nitmiluk National Park. It also serves the nearby Royal Australian Air Force base. The average maximum October temperature is 37.7°C.

Daly Waters – 588 km – Control Stop 2


The famous Daly Waters pub

Daly Waters is a small town with a famous pub. The Eindhoven team left a shirt there in 2015.

Dunmarra – 633 km


University of Toronto’s Blue Sky Solar team leaves the Dunmarra control stop in 2013 (photo: Blue Sky Solar)

Dunmarra once served the Overland Telegraph Line. Today it is little more than a roadhouse, motel, and caravan park. In previous races, this was a control stop.

Tennant Creek – 988 km – Control Stop 3


Tennant Creek (photo: Tourism NT)

Tennant Creek (population about 3,500) is a small town serving nearby mines, cattle stations, and tourist attractions.

Karlu Karlu / Devils Marbles Conservation Reserve


Nuon Solar Team’s Nuna7 drives by the Devils Marbles in 2013 (photo: Jorrit Lousberg)

The 1,802 hectare Karlu Karlu / Devils Marbles Conservation Reserve lies along both sides of the Stuart Highway about 100 km south of Tennant Creek. It is home to a variety of reptiles and birds, including the fairy martin (Petrochelidon ariel) and the sand goanna (Varanus gouldii). Race participants, of course, don’t have time to look (unless, by chance, this is where they stop for the night).

Barrow Creek – 1,211 km – Control Stop 4


Barrow Creek Roadhouse and surrounds (photo: Adrian Kitchingman)

Barrow Creek once served the Overland Telegraph Line and nearby graziers, but is now nothing but a roadhouse. The Telegraph Station is preserved as a historical site.

Ti Tree – 1,300 km


Nuon Solar Team’s Nuna6 drives by a fire between Tennant Creek and Alice Springs in 2011 (photo: Hans Peter van Velthoven)

Ti Tree is a small settlement north of Alice Springs. Much of the local area is owned by the Anmatyerre people. In previous races, this was a control stop.

Alice Springs – 1,496 km – Control Stop 5


Alice Springs (photo: Ben Tillman)

Alice Springs is roughly the half-way point of the race.

Kulgera – 1,766 km – Control Stop 6


Sunset near Kulgera (photo: “dannebrog”)

Kulgera is a tiny settlement 20 km from the NT / SA Border. The “pub” is Kulgera’s main feature.

NT / SA Border – 1,786 km


Entering South Australia (photo: Phil Whitehouse)

The sign at the Northern Territory / South Australia border shows Sturt’s Desert Pea (Swainsona formosa), the floral emblem of the state of South Australia.

Coober Pedy – 2,178 km – Control Stop 7


Coober Pedy (photo: “Lodo27”)

The town of Coober Pedy is a major centre for opal mining. Because of the intense desert heat, many residents live underground.

Glendambo – 2,432 km – Control Stop 8


The Belgian team’s Indupol One leaves Glendambo control stop in 2013 (photo: Punch Powertrain Solar Team / Geert Vanden Wijngaert)

Glendambo is another small outback settlement.

Port Augusta – 2,719 km – Control Stop 9


Port Augusta (photo: “Deborah & Kevin”)

At Port Augusta, the highway reaches the Spencer Gulf. From this point, traffic becomes much heavier, which makes life more difficult for the drivers in the race.

Adelaide – Finish


Adelaide makes quite a contrast to that lengthy stretch of desert (photo: “Orderinchaos”)

Adelaide, the “City of Churches,” is the end of the race. The official finish line marks 3,022 km from Darwin.


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.