World Solar Challenge; inmiddels in 2014!

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Konvooi strandt door bosbranden

De World Solar Challenge 2011 is tijdelijk gestrand door bosbranden langs Stuart Highway. 1120 kilometer na de start gisteren in Darwin staan vier teams op een parkeerterrein weer bij elkaar. De Challenge moet wachten tot Stuart Highway weer opengaat. De overige teams zijn eerder langs de route tegengehouden.

Alle teams vertrekken waarschijnlijk dinsdagochtend weer. De nacht wordt doorgebracht op het parkeerterrein van Wauchope Roadhouse in Australië. Het onderlinge tijdsverschil bij aankomst wordt dan weer aangehouden om de strijd eerlijk te laten verlopen Tot de ‘roadblock’ streden Tokai University en Nuon Solar Team een strategisch spel om de eerste plaats. De teams hebben op racedag twee 400 kilometer kunnen racen. Het UMSolar team rijdt op de derde plaats.

Bij de race rijden de zonnewagens met een snelheid van ruim 90 km/h van Darwin naar Adelaide. De derde plek is voor UMSolar van Michigan University op een paar minuten achterstand. Tokia ligt een paar minuten voor op het Nuon Solar Team.

Coureurs
Bruno Moorthamers heeft de eerste etappe gereden na de overnachting
Javier St Jago reed de tweede etappe tot het moment dat zij door de politie het parkeerterrein bij Wauchope werden op gestuurd.

Facts & Figures
Afstand gereden:
390 kilometer

Tussenstand:
1. Tokai University
2. Nuon Solar Team
3. Michigan University

Quotes
‘Wie van ons tweeën de minste fouten maakt, die wint straks de race. Het is bloedspannend’
(Teamcoach Wubbo Ockels)

‘Zo zie je maar, het is pas voorbij als we in Adelaide over de finish rijden. Er gebeuren altijd onverwachte dingen’
(Coureur Javier St Jago)

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Op maandag 17 oktober 2011 10:43 schreef _VoiD_ het volgende:
Ik krijg echt altijd zo'n naar gevoel in m'n mond als weer die verdomde Wubbo Ockels om de hoek komt. Heb namelijk het vermoeden dat die kerel zelf gewoon nagenoeg geen flikker doet maar gewoon aanhaakt bij het succes van de studenten om zelf maar genoeg exposure tijd te krijgen in de media.

Je geeft zelf al aan dat hij een adviserende rol heeft, maar wat houdt dat precies in dan? De studenten weten natuurlijk veel meer over de Nuna dan Wubbo..... Wat is zijn toegevoegde waarde? Adviserende rol klinkt al zo lekker wazig.

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Op maandag 17 oktober 2011 10:45 schreef Clondijk het volgende:
Krijgen de andere teams niet een nadeel omdat zij eerder werden tegengehouden in verband met die bosbranden? Of zouden ze zoiets gelijktrekken?

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Ik bedoel de top vier heeft mogelijk meer tijd gekregen om te rijden op dag 2.

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I did find some smaller and older updates, for instance this one from MIT. This team had the most awful luck before the race when their shipping company misplaced their battery, shipping it off to Singapore. When faced with either spending US$15000 on a charter airplane to maybe deliver the battery in time or building a new one from scratch in less than a day and a half, they chose the latter option. The University of Michigan team kindly donated their spare battery which the MIT electronic engineers then had to disassemble and adapt to Chopper del Sol.

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The Belgian Umicore team has updated its blog (in Dutch). The team has made it to control point Tennant Creek in position eight after the race was suspended, and is spending the night their with many other teams. According to the article their first racing day wasn't a very big success, as they had unspecified electrical problems in the last hour. The article mentions that Taiwan Apollo team can not continue the race because of unspecified unsolvable technical difficulties.

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Op maandag 17 oktober 2011 18:50 schreef Erasmo het volgende:

[..]

Stappenmotortje, arduinotje, paar meter aluschroten en je bent klaar

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Op maandag 17 oktober 2011 20:01 schreef Clondijk het volgende:
Over twente gesproken, ze hebben hun auto dit jaar zo ontworpen dat hij eenvoudiger te repareren zou zijn. @TR08 bedankt voor het delen van de ervaring!!

Als TU/e student gaat zo'n avontuur natuurlijk aan me voorbij helaas. Was er een selectie destijds om deel te nemen trouwens?

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Why is Tokai so good?

Let’s do some numbers based on Day 3 results. Tokai departed Wauchopa at 08:00 and reached Kulgera - 667 km down south - at 16:02, having stopped twice at the 30-minute control stops along the road. So – with 7:02 hours driving – they averaged at 95 kph.

Nuna 6 departed at 08:08 and arrived at 16:37 – thus having averaged 89 kph. This 6 kph difference with Tokai leads to a gap of about 30 minutes between the two cars.

Since this race is about energy, let’s do some energy calculations. I will take this site as example – you can calculate power consumption based on weight and aeroshape.
A typical solar weighs in at 230 kg (150 kg + 80 kg driver) and has a CdA (a measure for aero drag) of 0.09.

Fill this in on that site and look at the resulting tables: 89 kph leads to a consumption of 1315 W. Nuna drove for a total of 7:30 hours, so total energy consumed on this 667 km stretch is 1315 x 7.5 = 9.9 kWh.

As a reference, Nuna used the equivalent energy of 10 dishwashers to travel over 600 km at normal commuting speed.

Tokai’s 95 kph with the standard specs lead to a consumption of about 1550W and since they drove for 7 hours, their consumption amounts to 1550 x 7 = 10.9 kWh.

In other words, to create a gap of 30 minutes to Nuna, Tokai had to consume 1 kWh of energy more than Nuna 6, or 10% more energy.

Obviously, energy flows into the car via the solar panel, but where does it go to? First of all, there are losses from solar panel to electric motor, like in the motor controller and other electronic equipment required for operating the solar car.
Secondly, the aerodynamic shape requires energy – the shape of the car is important but also surface smoothness.
Thirdly, there is rolling resistance, related to the type of tire and the weight of the car pushing on those tires. Less weight decreases rolling resistance.

So, let’s see how good Tokai needs to be to be able to spend 10% more energy create that 30-minute gap.

Keep in mind that 1% of energy consumption is about 12W, similar to a small lightbulb.

A 10 kg lighter car leads to 1.5 % less energy consumption.

5 % improvement in aerodynamics lead to 2 % less energy consumption. 5% is the difference between a clean car nose, and one which has flies on it, or other irregularities. So the car needs to be as smooth as possible at all times. Small things have great impact.

If your panel is able to give a mere 2% more solar power, the car has 2% more energy to spend.

If you are able to make your electronics between panel and motor just 1% more efficient, there is a direct relation and you’ll have 1% more energy to spend.

Let’s talk a bit about the battery. A typical solar car battery can hold 5kWh energy. Solar cars take into account what energy the sun delivers and what they can take out of the battery. Battery energy level is called State of Charge (SOC), and you may finish a Race Day with a certain percentage of SOC. Suppose you have 2 similar cars – if one drives faster on a race day, he will have covered more distance but will have less Battery SOC.

Now suppose Tokai has taken more out of its battery SOC than Nuna, when rolling into Kulgera. Let’s say that number is 3.5% of the total Energy Consumption, which comes down to 0.35 kWh. On a battery with 5 kWh capacity that’s 7% SOC less than Nuna, which is really not that much.

In short, for Tokai to gain 30 minutes on Nuna, they need to have taken 7% more out of their battery, have a car that weighs just 10 kg less, have an aero that is just 5% better (which could already be achieved with keeping the car smooth and clean), a panel that can power 2 small lightbulbs more and a little more efficient electronic system.
That totals the 10% of energy that Tokai got to spend to increase their lead by 30 minutes.

Is Tokai that mystical energy powerhouse that people claim it to be?

No. It’s all in the small numbers as described above. A little bit better here, and a little bit better there can already lead to fantastic results.

Tokai’s technology is not lightyears ahead but just a few lightbulbs in every area.

Tokai is not magic, not supernatural, not sent from the future and they don’t overpower their competitors with special technology.
They are just a very good team with great attention to detail. And that’s how you win races.

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Op dinsdag 18 oktober 2011 21:45 schreef Velocitas het volgende:
Goed artikel over de race en de leider vd race hier:
http://www.solarwebsite.nl/2011/10/how-good-is-tokai-really/

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cpheineman Says:
oktober 18th, 2011 at %H:%M
Hi,

Good article! But remember that tokai buys a solar array, buys batteries and more and let it put together. For example nuon makes the most of the car by itself, which has the consequence that its never that good as bought. But you do get a lot of experience and learn a lot from it. That is the most important goal of the race.