# Solarcars are hot!

On Sunday 16 October, 39 solarcars will set off from Darwin to race the length of the Australia continent. Three thousand kilometres and four or five days later they can relax when they reach the finishing line in Adelaide. The Register’s Special Project Bureau will be there to cover the 2011 World Solar Challenge, for the …

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1. #### Richard French

If you are in Adelaide visit RiAus (Royal Institution Australia) at the Science Exchange, where the solar challenge 'Mission Control' will be hosted. Visit the web site at http://riaus.org.au/programs-and-events/veolia-world-solar-challenge-outreach-program/ for more information and map to find the Science Exchange.

2. #### Australia is longer than that

I won't call the race route the length of Australia, more the height or width.

The length of Australia from east to west is around 4100km.

3. #### Oz

"...we also like the purpose of the event..."

And I expect you like Australian beer as well.

4. #### "a race Observer – who is fed and watered by the team"

As in "...including spiked drinks, so he won't notice they're actually towing the electric vehicle."

[Which would be spectacular anyhow, at 120+kmh.]

1. #### Can we have this in old money please miles per hour.

120 is 74.565

130 - 80.778

140 - 86.992

150 --93.206

Impressed that anyone would be happy to sit in such a rickety contraption at these speeds. Get a litre bike instead...much more fun.

1. #### Why?

This is a race to be held in Australia, with competitors being all engineering teams - both use metric by default.

I often have to do the multiplications myself to get the miles into kms, so nice to see it in metric for a change.

5. #### Why not two wheels?

Presumably there's rules against it. But two wheels would have less rolling resistance and a smaller frontal area. A central "fin" containing the wheels would also let you mount the batteries right down low, keeping it stable. And an electrically-controlled balance weight would keep things nicely vertical under all circumstances except very very low speeds, when retractable wingtip stabilisers (think Harrier jumpjet) would be used.

1. #### Two wheels?

Technically if you only have two wheels, you no longer have a car - you have a bike.

Therefore you wouldn't be competing in the same class.

2. #### @Graham Bartlett

I already find the idea of only three wheels slightly worrying with a 5 square metre horizontal flat surface at >70 mph. I'd worry that a balance weight couldn't compensate fast or strong enough for the gust that a Transit van (or whatever they use down under) will give it while overtaking.

While I think that your idea is perfectly good under controlled circumstances, I wouldn't want to sit in it on a public road with traffic around me...

1. #### aye

fuck the transits, a road train wont move out of the center of the road for you. I'd more worry about the "off road" capability whilst swerving out of the way.

3. A stabilizer requires extra weight, complexity and electricity, all of which come at a premium in these vehicles, I would guess. There may also be regulations against it.

6. #### Not very green

if you have to have two support cars with you at all times!

8. #### @andreas and Michael

But you *would* want to sit in a solar-powered 70mph mobility scooter...? Hmmm.

I reckon if most of the weight's down nice and low, it wouldn't be a problem. Remember you've got all that nice gyroscopic stability from the wheels too. And the energy to slide a balance weight is likely to be fairly small compared to the energy used by the wheels. Hell, the batteries could even be the balance weight, so no need for extra weight in the system apart from an accelerometer and a small motor. Also remember that what you lose in balancing the vehicle, you gain in significant reductions to rolling resistance and frontal area.

Interestingly, the rules don't say anything about the number of wheels required, so a two-wheeler does appear to be a legitimate design. (A unicycle is only prohibited because the regs say that braking has to be appplied to two wheels...)

1. Could be a unicycle in terms of road use with a second toy wheel fitted with a brake somewhere in the corner of the cab to obey the riules (not touching the road)

9. #### British version

would of course be rain powered.

10. #### Speeding?

I didn't realise how fast they were capable of these days... Sounds like some can even get done for speeding in the NT now!

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