Sungroper: WSC 2005 diary

Leeming Senior High School is a specialist science school in Western Australia participating for the first time in 2005. Working with the Sungroper Solar Car Association, the school has used the solar car project as a theme for cross curricular learning and development.

Sunday 18th October 2005: to Darwin

6:45am meet at the airport. 7 degrees outside. 18 students, four laptops, three teachers, two satellite phones and a UHF CB antenna. Qantas handle us smoothly as a group booking. Fly to Darwin. Pick up bags off the carousel: students form a bucket brigade, sorting the teams bags (all marked with "group booking" tags) and ferrying them into a heap. Acqire two 4 wheel drives from Hertz, kindly paid for by a sponsor, McMahon. Step out of the terminal into a wall of Darwn heat: 34 degrees and humid. 4WD's are supposed to have rotating amber lights on top, and tow-balls on the back; but have neither.

Take one 4WD to Thrifty, pick up 22-seater bus. Meet Michigan Solar's team leader and their internet guy at Thrifty. Internet guy says he has a dish cooler than Onno's: 0.9metre dish but it's permanently mounted on the back of a ute, and auto-targets itself onto the satellite upon command. He says his company has built a second one and shipped it to New Orleans.

Students onto bus, then drive to Alatai apartments, in the north-east corner of the heart of Darwin, spitting distance from the Stuart Highway. A week from now we'll be racing down that road.

Team meeting, then the entire group goes to the supermarket for shopping. Supermarket is open: no southern-half-of-Western-Australia stupid inconvenient restrictive shopping hours here. Not that I have issues or anything.

In the evening, down to the Mindil Beach Markets. Food. Torches, firestaffs, poi and juggling balls to muck around with, though I don't play with any actual fire. Flaw in the Buddy System revealed: I am late back to the bus, and everyone has a buddy except me. Bus does not get far before this is realised. Embarrassment.

Return to Alatai. A couple of Nuna team members are in the pool. All of our students join them.

Today: pick up car, take it to Hidden Valley, debug.

Monday 19th: to Hidden Valley

Breakfast. Following yesterday's shopping mission, bags of Stuff have been distributed to each room. Each bag has identical Stuff, but multiple possible breakfasts can be created from the Stuff so provided. I have a cheesy.

8am is the appointed start of our coordinated day: everyone is to congregate at or outside room 116, so that John Beattie et al can outline the plan for the day. The plan for today is to take the only vehicle we have with a towball (i.e. the bus) to the shipping company, Shaw's Darwin Transport, in Palmerston, and pick up the trailer which contains Sungroper. Shaw's also shipped our logistics trailer, but since we only have one towball, it'll have to wait a bit. Shaw's in Perth told us that our gear would already be ready when we reached Darwin.

We get there. Oh, you should have phoned, says the guy. Your trailers are still in the backs of trucks. And it'll take us a while to unload them. After we figure out what trucks they're in, that is.

We go to the shopping centre to burn some time.

Hertz phone us up. Yesterday, they delivered us vehicles without towballs. They're calling to let us know that they're putting another Landcruiser in the shop, so that a towball can be fitted, so that they'll have a vehicle-with-towball to give us. Sweet.

Shaw's phone us up. Our trailers haven't been unloaded yet, but they are calling to let us know they want full payment before they'll give us anything. Just in case, I don't know, the entire WA education department does a runner to avoid paying them. And Shaw's don't take cheques. Or credit cards.

John goes and empties his bank account to get the requisite cash. We bum around a little more until Shaw's let us know that the trailer is available. We pay, and pick up. We drive to Hidden Valley race track, which is in fact not terribly well hidden, mostly because it's on Hidden Valley Road, which is well signposted.

We find Peter D in short order, and he lets us into pit 16. There are half a dozen or so teams on site, including Aurora, MIT, Formosun and Michigan Solar. There's not a lot we can do with the car yet: all our tools are in the logistics trailer, which John is going back to Shaw's to get. So I spend some time chasing the remaining bug in the Sungroper electronics (which is that when you plug a Lillington go-switch-and-speed-knob box into the Lillington motor controller, it works fine, but when you plug our go-switch-and-speed-knob in, it doesn't). Our is niftier, partly because it additionally has a go button, a go light and is integrated with our brakes and telemetry, and partly because it is shiny.

Most of the rest of the team wander around the pits, visiting other teams. A few people stop by our pit, and chat. One of the Aurora people is suggesting that maybe it's time for a new class of solar race car, which is a bit more street-ready: takes two people, etc. Interesting.

We break for lunch. Meat-and-salad sandwiches prepared by some of the students. They are quite proud that they did today's shopping with a target of $200, and wound up spending $200.30.

Back to the racetrack. Andrew has arrived in Darwin and is waiting for us there. He shows me the board he's built to plug into our Extra Sensor board (which really we should call the Voltage Sense board, 'cos that's what it does), to collect wires from all over the car in a tidy way. Nifty.

Some students drive the race course in a Landcruiser, to familiarise themselves with it. Aurora does some laps. As it rushes past us down the straight, we hear the noise of its passage -- it is the sound of air tearing over its shell, with just a hint of motor sound underneath.

Steve Morgan works on the brakes. The brakes have had a mysterious fading problem, and Steve figures it must be the master cylinder. So he changes it for a new one.

I work on finding the speed controller bug. And I make a mistake.

Given that the speed knob box can be detached from the motor controller, you'd expect it to be designed so that when you have no speed knob at all attached, that the controller would interpret this as a request for zero speed. Wouldn't you? And you'd think that when you don't have a go switch connected, that the controller would be so designed as to interpret this as a request for not-go. Yes?

But this is not the case. I power up the car to test some numbers, trying to narrow down the bug. I do it without a go-switch-and-speed-knob connected to the controller. I lean over the side of the car and turn on the main breaker. I turn on the battery strings. I turn on the 12V. I turn on the 24V. And then I turn on the motor controller.

The car lurches, at full power, backwards, trying to leap out of its wheel chock and twist out from under me. I have the presence of mind to turn the motor controller off.

I've scared myself, twisted the wheel chock a bit, and left a 40 cm long burn-out on the floor of our pit, but I've gotten lucky and damaged nothing.

Some investigation later, I find the problem with our speed knob panel: one of the wires in the cable leading to it simply doesn't conduct. No sign of damage at either end; it just doesn't work. Moral: don't use telephone cable for mission-critical applications.

Our day is about done (and this email is too long). We return to the Alatai Apartments. Dinner is spaghetti bolognaise prepared by students in each room. There is some competition between students, visiting each others' rooms to check the relative quality of the fare. In all cases, the quality is good.

John discovers that a nifty way to supervise the distributed students is by giving each room a two-way radio. Much radio chatter ensues.

I drop in and visit my friends at Zone 3 Darwin, just a couple of blocks from where we're staying. I play a couple of games, and manage to rank second in my second game.

Back to the apartments. More radio chatter. Check email. Sleep. Tomorrow, we'll take the car out onto the track.

Tuesday 20th: track testing, track training.

Morning. Breakfast. Weetbix. Check email. Onno, from the WSC website, lets me know that he's putting my email missives up on the web: http://www.wsc.org.au/2005/competition/our.teams/Leeming.Sungroper/index.html

At the appointed 8am gathering time, we have far less students than we did at the same time yesterday -- John knew that they would be full of energy and stay up late the first night or two, and now they have evidently burned through that initial energy burst. We get a couple of radio calls from other rooms, letting us know they'll be a couple of minutes late.

We gather, and the plan is announced. Some people go shopping for food, some people go shopping for electronics, some people go to the track. I, as usual, am with the track group.

I replace the non-conducting wire in the cable leading to our go-switch-and-speed-knob panel. This does not fix the problem. Dag-nabit.

Andrew turns up, and plays around with his voltage-and-alarms board. He wants to glue temperature sensors (the rather technically marvellous LM35's) to the batteries, but there's no suitable glue. So it goes on the shopping list.

More teams continue to arrive at Hidden Valley through the day, including Kormilda, Southern Taiwan and Annersley.

We hook the array up to the car, to push some photons into the battery. Telemetry shows that we're pushing in 0 Amps, which doesn't sound like a good number. We figure that there must be a problem with the current shunts. (In this modern world, it's much easier to measure voltage than current. So when we want to measure a current, we put a very very small resistance in the wire, and measure the voltage drop across it. We call it a "shunt" for historical reasons totally unrelated to the way they work today.) We pull out the centre battery string and poke around at the shunts, and eventually become convinced of their goodness.

We spread our search, and eventually figure out that the trackers (the four magic boxes that optimally accept power from the solar array, and optimally push that power out into our batteries), are seeing the array just fine, and are seeing the batteries just fine, but are failing to push any power from A to B. Between us, we're sure that the trackers worked back in Perth, and between us we're sure that none of us have rearranged any of their configuration switches. It's lunch time, so rather than getting the rest of the team to deliver lunch to us, we elect to return to Alatai and talk about it.

Lunch is toasted cheese sandwiches, also featuring sliced tomato and sliced meat of your choice. A few students burn their first efforts, by turning the frying pan up too hot.

We make some phone calls. Several back to key people in Perth, to check data sheets for us, to fish replacement parts out of Sungroper 1, to generally hedge our bets. And one to Stuart at AERL, the manufacturer, to ask about the problem. We describe the current state of the switches on the trackers. They've each got an OFF switch, which is in the ON position. Oh yes, says Stuart, if the OFF switch is in the ON position, then they're off, and they won't pump any power.

Back to Hidden Valley. As we drive in at about 70km/h, parallel to part of the race track, we get passed by a solar car. In the pit, we flip the OFF switches to the OFF position, and power up again. The car comes up smoothly, and the trackers pump power in just the way that they are supposed to. Applause.

We still have no idea how the OFF switches got to the ON position. An Aurora team member wanders by and suggests it was the switch fairies. Apparently Aurora have had some experiences with switch fairies in the past.

Steve and crew work on aligning the steering. Andrew and I work on bringing the Extra Sensor board up. It resolutely refuses to cooperate. Even though everything on it looks perfect, its little brain gives no sign of life. Luckily, after our earlier experience with the trackers, we've asked our friends in Perth to ship some key Sungroper 1 boards to us, including the original Extra Sensor board. They will arrive tomorrow. We'll drop the known working board in and either trouble-shoot some more, or just write off the new board, and replace it after the race.

This leads Andrew and I to the realisation that there will be a fair amount of work back in Perth getting the original Sungroper back to near-original condition. And I figure it'll be a little while after the race before we have the enthusiasm for that.

We roll the car out, and do some testing. We haven't driven yet on the newly fixed brakes, nor have we seriously driven on the present motor.

I drive first, on the basis that I'm the most technically experienced driver. I do a few low-speed bunny-hops in the pit lane, as a means of testing the brakes. Then it's out on the track for a lap, hotly pursued by a follow car. There are one or two other cars on the track, so we have a student up on on the viewing platform calling some perspective to us, so as we don't get in anyone's way. I take the car for a bit of a flog. The steering is a bit different from Sungroper 1, as it's 3 turns lock-to-lock, as opposed to Sungroper 1's 0.9 turns, but otherwise it's a very similar experience. Leeming Sungroper presently has an identical motor and controller to Sungroper 1, is of very similar geometry, and identical electronics, except for the bits we haven't finished yet.

I return to the pit and pronounce it good. Steve Morgan goes out for a couple of laps, partly to check the car for mechanical soundness, and partly because since he's put so much time into this car, he's damn well going to have a bit of a play.

Then, with sufficient happiness as to the state of the car, we put students in. We have three of our four drivers here, and they each get some laps. We get some idea of the car's present efficiency, too: at 9 Amps (a touch over the amount we can sustainably spend during the race) it goes at about 37 km/h. This is not enough to finish the race without trailering. So we need some efficiency improvements in the days ahead.

Nevertheless, the day is a success: we've got some mechanical and electrical stuff sorted, and we've got some driver practice in. Another team has arrived at the hotel: Apollo Solar, a Japanese team. We return to the Alatai. Dinner is curry (your choice of chicken or beef), and rice, with a piquant smoky flavour caused by the fact that the bottom couple of centimetres worth of the rice is burned black. Radio chatter is quieter this evening.

More tomorrow.

Wednesday 21st: more of the same

No, really. Today is more of the same as we had the previous days. We're still scattered into about three different groups: track work, food shopping, and everything else. "Everything else" includes buying batteries, buying and fitting antennas, getting signage done, setting up computers, and making sure we have all our ducks in a row for scrutineering.

Scrutineering. The next few days will _not_ be more of the same. Thursday and Friday are scrutineering at the Darwin showgrounds. Paul, the chief scrutineer, stops by our pit and goes over the details with us. We've got to show that we meet all of the race's technical requirements (that our car is within the size limits, that our battery is within the weight limits, etc.) and also that we meet all the safety requirements: our drivers must have 10 hours of practice each, our drivers must be able to exit the vehicle unaided in under 30 seconds, our car must have adequate visibility, we must have an emergency cut-off accessible from outside the car, we must have safety vests, traffic cones, a red flag, etc.

There's a random draw later today to determine what car gets what timeslot for scrutineering. We might have only today to prepare, or we might have today, tomorrow, and half of the next day.

More driver training out on the track, more debugging of electronics.

The boards out of Sungroper 1 arrive at lunchtime. We swap bits to narrow down our problems. The problem with the Extra Sensor board is that the chip is dead. This despite us trying two different chips, one of which is known to work.

The problem with the the go-button-and-speed-knob panel is not the dash/connector board. This is something of a confidence booster for me: neither of our hard-to-find bugs is being caused by boards which I printed. OK, some of our previous problems have been my boards, but not _these_ problems.

Tony, a race assistant, comes by our pit and gives us the draw. We are first. There are 22 teams listed, 14 on Thursday and 8 on Friday, and we are stone-cold first.

There's an up-side to that, of course: if we have any problems, we get the maximum possible time to prepare for "re-presentation", at 16:00 on Thursday, and 13:00 onwards on Friday. That means that we'll effectively have three chances to get everything right.

More driver training. Most teams are on-site now, and the track is getting busy. At one point, I count 7 cars out on the track, including us. We have the honour of being passed by some of the fastest cars in the race, including Nuna. (Theoretically, there's no passing allowed out there, for safety reasons. But everybody is cooperative, and when we pull way over to the left on the straights most other teams get the idea and pass us.)

At the end of the day, we put the car back in its trailer (a trickier procedure than it was with Sungroper 1, because with Leeming Sungroper's stub axles, we cannot use a steering yoke), along with all the safety gear, and trailer it back to the Alatai. Since we have to be at the showgrounds at 8am, we don't want to have to stop by Hidden Valley and pick up the car on the way.

And then we go play laser tag. Two friends of mine, Craig and Emma, own and operate the Zone 3 here in Darwin. I and five or so other people arrive late, because we were still at the track, so I get to play in the second and third game. I shoot not quite four times as many people as shoot me in the second, but I don't manage as well in the third, because it's a game called "Vampire", which essentially means "everyone versus Doug". My "team" wins anyway.

Dinner is a barbie, with crisp and crunchy potato salad. Interesting.

Thursday 22nd: scrutineering

Early rise. We're due at the showgrounds at 8am. We have already had one trying-to-remember-everything session yesterday, when we packed the trailer at Hidden Valley; we have another one this morning. Nonetheless, we nearly manage to leave without the laptop which contains vital data. I run back for it.

It turns out that I'm the only one who knows the way to the showgrounds, where scrutineering is.

We pull in to the carpark, full of vehicles covered in WSC Official stickers, but empty of solar car teams.

John goes inside. Our registration is right now at 8am, but our scrutineering doesn't start 'til 8:30. We use the opportunity to roll out the car onto the dusty grass and apply a few final touches that will help get us through scrutineering, such as a dozen or so "Danger High Voltage" stickers at strategic points over the car.

We bang on the roll-a-door, but they won't let us in yet: we're a few minutes early. We stand around for a while. Then the door goes up, and we go in.

While we are getting the car scrutineered, so too our drivers are getting scrutineered. They present their drivers' licenses, to prove they are actually legally allowed to drive, and they get weighed. All drivers are ballasted to 80kg, so the more you weigh, the less ballast you have to carry. There's a spirit of fairness about the weigh-in: nobody (so far as I know) sticks lead weights in their shoes or anything, but drinking water is considered entirely fair, so people drink water before weigh-in. A lot of water. Really a lot. And then weigh in. And then run for the bathroom.

First station is a doddle for us: stickering. They stick a couple of big "World Solar Challenge 2005!" stickers on the sides of our solar car. It's not a doddle for everyone, incidentally: lots of cars have neglected the rule which says "thou shalt leave room for our damn big stickers", and have a cross-section like a needle, so the stickering team have a challenge to cut down the stickers and squeeze them on the cars. Our car is the first one the stickering guy has ever done, so he takes two tries to get the first sticker right. Good car to learn on.

Next station is an odd one: weighing. The race rules don't lay down any requirements about the weight of the car. The scales are not very accurate because you can't load all the wheels of the car onto the scales at once. And for us, the scales are not wide enough to fit both our front wheels at once. So we weigh the car one wheel at a time.

313kg. That's not including driver and ballast, but including 70kg of battery.

Next: driver eye-line and egress. The race rules require that the driver's eyeballs be at least 700mm above the road, in order to ensure that the driver has a good view. The scrutineer puts black glasses (really black: spraypainted) with a white line painted at eye height on our driver. Then he turns on a laser level on a tripod, and shines it into the car's cockpit. Well, he points it in the direction of the car's cockpit anyway; it actually hits the side of the car, well below the cockpit. So we pass that one.

Egress is a little trickier: each of our drivers have to prove that they can get out of the vehicle by themselves within 15 seconds. (That's right: not 30 seconds, 15.) "Proof" in this case consists of standing up in the driver's seat, as actually leaping out over the solar array could be an expensive excercise in many cars. Three drivers pass first try. One of our drivers just barely goes overtime, but takes a second try and passes fine.

I duck out to get something from the cars, and get accosted by safety scrutineers who are looking over our support vehicles. Who's your team's Safety Officer? Um, well, actually he's on a plane on his way here, so 'til he gets here, it's me, I guess. OK, so first on the checklist: big sign for the follow vehicle saying "solar car ahead": have you got one? Um, no -- it's at the printers; supposed to be ready today. OK, signs for each vehicle showing that they are part of the Leeming team? No, sorry, at the printers. How about signs announcing your UHF channel? Uh. At the printers.

But we do have the safety vests, the traffic cones, the red flag to wave at traffic when we're emergency stopped, the fire extinguisher, the first aid kit. So that's all good. We can come back and re-present when we get the signs all up, and we'll only have to bring the support vehicles for that, not the solar car.

Next is "on-road", which is administered by NT Roads. They look over the car. We demonstrate the indicators, brake lights and horn, and they walk around carefully looking at things like the master brake cylinder. We've done this same thing in Perth just a week or two before, so it's not too hard. John Beattie has a nice chat to them about the WA licencing people. We pass, and move on.

Electrical. We've already got the array off the car, so Prof John can take a good look. Who's your team's electrical officer? Um, it's me, I guess. We discuss the way our circuit breakers work, and exactly what connects to what, and pros and cons of various means of electrically isolating power point trackers. When we conclude, the only point we're bad on is that we haven't got a sign on the side showing people where our emergency cut-off is accessible from outside the vehicle. It's supposed to be a blue triangle with a lightning bolt on it. Well, I say, tell me how big the triangle is supposed to be, and I'll draw it with this blue pen and ruler I've got in my pocket. Um, says Prof John, and both our eyes alight on a stack of blue triangular stickers on his table. Oh, well, I'll have one of those, then. Done.

Battery weigh-in. This is the last stop, and by far the longest. Our batteries get weighed, a laborious enough process in itself, and then they get wrapped in string. And wrapped, and wrapped, and wrapped. They drill holes in the base boards our batteries sit in, all the better to thread the string around and about, to generally make it hard for us to unthread the string and cheat, by, e.g., cutting out dud cells and replacing them with good ones, or substituting the whole battery pack for a more charged one, etc. One of the team comments that it's all a bit silly really, and that it's really more symbolic in nature, and the battery scrutineering team more or less agree.

We hand our folder chock full of solar minutiae back to the scrutineers, put the car back in the trailer, and go for lunch.

Afternoon back at the track. Couple of laps, tweak something, couple of laps, most of the afternoon. John's gotten word that the new motor controller from Tritium in Queensland has arrived, so he goes down to pick it up from the post office, and drops it down to us at the track.

We need something like a 10% to 20% improvement to have a chance of completing the race on solar power, over the whole car. Aerodynamics (which we can't improve at all, now), rolling resistance, motor efficiency, the whole lot. But I've been suspecting for a while that our present controller is pretty stupid, and that stupidity may be degrading its efficiency. So I've been wanting to get a look at this new controller, and if it looks nice, try it out. That's risky at this late stage, so it depends how good it is.

How good is it?

It arrives well packed in carboard, and when we unwrap that, it's in a flight case: you know, the shiny aluminium case with foam inside cut to the exact shape of the thing it's carrying. Inside the case, the controller is Gold. Literally -- that's the name of the controller: a Tritium Gold, and that's it's colour too -- anodized aluminium. It has a note accompanying it explaining that the manual is for the last released version, version 4, whereas this is a prototype version 5. So it's the newest and shiniest Tritium controller in the race. And possibly the shiniest controller in the race, full stop.

I read the manual: basically the way you set it up is that you show it your motor, and it figures it all out. It does forward and reverse, it does regenerative braking, automatically or on demand, it lets you tweak every parameter you can conceive of and some you can't, it'll run your whole car if you ask it. In form and moving how express and admirable! In action how like an angel! In apprehension, how like a god!

And tomorrow, we get to try it out.

Friday 23rd: Tritium

Tritium have loaned us a controller, but have suggested that we should use it only as a spare. In the morning, we phone Dave at Tritium to run past him the concept of us swapping in the Tritium controller now. He gives us a few tips. There are two sets of wires going to the motor: power and data. The data cable has an 8-pin circular DIN-esque connector, to fit the Lillington controller. The Tritium has an 8-pin DIN to go to the motor's data cables, but Dave lets me know tha the pin-outs will be different.

I hatch a plan to build a short adapter cable. That'll involve me getting one connector for the Tritium end (and Tritium have thoughtfully included two in the case), and one for the Lillington end. First, out to the pits to check exactly what the Lillington end is: looks like a DIN-8. Then out to Jaycar to buy the bits, then back to Alatai to receive the email from Dave containing the pinout of the Lillington connector, then back to the track to make up the adaptor cable.

And the connector doesn't fit. The Tritium end is fine (of course), but the Lillington end doesn't fit.

Back to Jaycar, this time with the controller. There are two other teams there when I arrive. The connector looks like a "MIC" connector, which I'm not really familiar with, but's it's fairly academic anyway, as Jaycar top out at 5-pin MIC connectors.

Back to the track, and back to the drawing board. Intead, I build a double-ended cable: the Tritium plug hanging off the side next to the Lilligton plug. Ick. We jack the back wheel off the ground and plug the plug back into the Lillington controller to make sure it still works after I've bowdlerised it; it does.

Unplug the Lillington controller from the car, which involves unbolting the 120V input cables from the controller box. AUAGH!

Of course, the controller has dirty great capacitors in it, and although I've disconnected the motor from power, it's still got some stored up in it; more than enough to bite me. I would probably have figured this out a bit quicker, but when I work hard for many days running, I get a bit fatigued, and I can feel my intelligence and presence of mind slowly dribbling out my ears.

I remove the remaining power from the controller with a wrench and a big fat spark. Probably not good for the controller, but right now I want a bit of revenge on it.

Now, set up the Tritium controller. Plug it into power. See the display light up and the LEDs flash. Plug it into the data coming back from the motor and run it magic PhasorSense configuration, which probably should be renamed "You Just Sit Back And Relax While I Configure Absolutely Everything; All You Have To Do Is Spin The Drive Wheel A Bit". It flashes its lights to indicate that it now understands our motor. Plug the power lines in, including the external Hall sensor module. Hall sensors are nifty transistor-like devices that sense a magnetic field. We've got three Hall sensors buried in the motor (that's what the data coming back from the motor's data connector is: signals from the Hall sensors), and Tritium give us another two to stick outside, around two of the power wires. Now, turn the speed knob on the Tritium's driver control.

It works. It does everything it's supposed to do. It goes forwards, it goes backwards, it does regenerative braking. The creaking groaning noise our motor used to make at low revs is gone. It goes faster. You have better control over the speed. And it stops really nicely on the regen brake.

Right now, the Tritium controller is just sitting loose on top of the Lillington. We remove the Lillington, and unscrew everything from the Tritium in preparation for installing it in its final location.

Of course, before I touch the screws for the 120V, I check it with a multimeter to see if it's safe to touch. Well, of course it is. The Right Thing for the controller to do when powered down is to remove any excess voltage stored in its capacitors, down to say 3V or so. So that's what the Tritium does.

Its final location is upside-down underneath a pair of metal rails -- its a little longer than the Lillington, so it won't fit in the old spot. We reconnect various bits to it, put John in the driver's seat, and push him out into the pit lane.

We've made two serious mistakes, but we havenb't realised it yet.

John turns the speed knob.

Nothing happens.

Dave let us know that since this is a prototype controller, it's possible for the controller code to fail to boot from a cold start, and that the cure is to flick the reset switch. It sort of reminds me of Reason, in Snow Crash.

So we pop the array off and flick the reset switch.

Still nothing.

We roll back into the pit. Take the top off, look at it properly. Find one of our mistakes: we've failed to reconnect the external Hall sensors. The supplement to the manaul adresses this. Quite clearly. And repeatedly. Never power up the controller without the external Hall sensors attached, it says. Damage to the controller will result, it says. Assign someone to always check that they are connected before powering up, it says.

Well, we didn't. We put ourselves in a pressure situation, then it all seemed like it was going well, and we reconnected everything except this one piece.

We put the controller through its paces.

Nothing.

Three different teams, on hearing that we've had a Tritium controller coming, have offered help with installing it. Many teams are at scrutineering today, but one of them is on site: Aurora. I walk down to their pit, and we ask for help. Tom comes and helps. He plugs a laptop into the controller, and shows us how the PC interface works. I've seen it in the documentation but haven't tried to play with it. It's got parameters out the wazoo.

Using the laptop to talk to the Tritium proves that the Tritium's brain is happy and undamaged. But it doesn't directly solve our problem.

We phone Dave at Tritium. We 'fess up to having powered the controller up without the Hall sensors.

The conversation goes on. Initially Dave thinks that we must indeed have blown up the controller, but as we talk more, he becomes less and less convinced -- the nature of the fault we are seeing does not match his expectation of the sort of thing we should be seeing.

We finish the conversation without a conclusion. We continue troubleshooting by ourselves back in the pit. Perhaps there's a problem with my ugly double-ended cable. We check it out, and indeed a wire has come loose: when we flipped the controller upside-down and fixed it into its final location, we must have tugged a little on this cable, and one of my solder joints must have been weak.

While we're doig this, Dave calls back. He's thinking that it's something to do with the Hall sensors in the motor, which are connected to the very connector we're messing with right now. Oh yes, I say. Dave explains how to check the Hall sensors in the motor from the connector end, by hand-turning the motor slowly, and using a multimeter.

We do so, and find that one Hall line is behaving differently from the others -- it's shorted to ground. But only when it's plugged into the controller.

What's changed?

Well, now the controller is upside-down.

Hm.

We flip it the right way up. The Hall line isn't shorted any more. We power it up. It works.

So we made two mistakes, and there was another built in to the controller: we failed to connect the external Hall sensors, which would normally destroy the controller, but we had a fault in our data connector, and the controller had another fault on that same connector. And those faults prevented the controller from spinning the wheel, which prevented it from destroying itself. So we dodged a bullet.

We track test, but it's too windy to get any idea of the efficiency of the new controller.

In the evening, we go to Parliament House. Speech by Claire Martin, the Chief Minister; and Chris Selwood, the WSC event director. We track down Tom and thank him. He tells us that in his opinion, Tritium controllers are the best in the world, and I'm far from disagreeing with him. My opinion of the controller has only gone up. We haven't had a chance to compare its efficiency to the Lilligton controller, and now we won't until we get back to Perth; but on any given issue it does the Right Thing -- you can figure out how its going to behave by figuring out what you want it to do, and pretty much always that's what it does. The only exception is the external Hall sensors -- they're an accident waiting to happen. Nevertheless, it's an accident we've dodged, and we're very happy.

Tomorrow: track testing. We have to run a qualifying lap to get our spot on the starting grid, and have to pass brake and steering tests administered by NT Roads.

Saturday 24th: roll

Our morning starts relatively early: our array does not at present fit on the car, because of the extra bump caused by the new controller, which, while lighter, is a little longer than the old. We cut a chunk of divinycell foam out of the underside of the array, and the car fits together.

Word circulates around the track that UNSW have crashed their car in road-testing. Their double-wishbone front suspension is very low-profile, which means it contains very large forces: several tons. One wishbone has separated away from the carbon fibre it was bonded to, causing the wheel to switch from vertical to horizontal. They have damaged the front of the car. This is a double blow for UNSW: last race they rolled their trailer with solar car inside, on the way to Darwin, totalling the car.

We're required to be on-track by 8am, so that Peter, the WSC safety officer, can brief each team. He starts at pit 1 and works up. He reaches us and gives us the briefing.

Cars are going out in pairs, separated by half a lap, so they don't get in each other's way. I suggest to Peter that he pair us up with the most famous team in the race: HelioDet. HelioDet, led by Detlef, the famous Suitcase Guy (so called because he brings his car to the race in a couple of large suitcases), is about the same speed as us, so that way neither of us will slow anybody else down.

We await our turn on the track. The whole team is here at the track, and many of them are watching as various cars rush past. Some of them are watching as MIT come out of the hairpin on the far side of the track, go into the next corner, and flip. A gasp rises from the crowd. I run up onto the pit roof for a better look. Later, I am kicking myself for not simply leaping the safety barrier onto the track, running across the track, leaping the next barrier, running across the drag strip, leaping, running, leaping, running, out to the far side of the track to check on the driver. A big-budget car like MIT's will be running lithium cells, and if a short develops, say between the batteries and the conductive carbon-fibre hull of the car, the batteries could have a "thermal event", which is a technical euphemism for "get really hot, catch fire, spit burning metal".

But this does not happen. The car rests on its roll bar. A camera crew who were in the middle of the track run over and check on the driver. Then, I assume, they capture some footage which will be on the TV news tonight.

Some petrol cars leap onto the track and run around to the MIT car. They get the driver out, and bring him back to the pits. He's OK. A short time later, he is taken to the hospital for a check-over.

There is some mucking around with the car going on out there; from back at the pits we can't tell what. But we find out soon enough: they've changed the failed wheel, and remarkably, the car is driven back to the pits under its own power, without its array. All applaud as it rolls past, a damaged wheel resting on the front of the car.

A number of other cars do their qualifying laps, and then MIT's vehicle trailer goes out onto the track. They retrieve their array.

Peter gives us the word: we are clear to move into the pit lane. Matt, a student driver, is in the car; the back of the driver canopy has a P plate affixed to it. Right behind us is HelioDet. We wait at the head of the pit lane for the previous cars to finish and turn onto the drag strip, and then we are cleared to go. HelioDet will be held until we're halfway around.

We complete our warm-up lap. The purpose of this lap is simply to get you to the start line: the entrance from the pit lane is just past the start line, so you have to do nine tenths of a lap to get there. A side effect is that you get to hit the start line running.

Matt runs past our pit; our team are lined up on the pit side of the barrier, cheering. I cross the track to the drag strip. Matt completes his lap. He goes to the turn at the end of the straight, and turns in to the drag strip. John talks him through a lane change test, which involves driving the car through a curve made of witch's hats (translation for Americans: traffic cones) at 35 km/h. We actually do it at 33, but the road testing people don't seem too concerned. Then he continues a little further down to the brake test. This also is supposed to be done at 35; this time we hit it at about 37 according to the radar gun. Matt starts to press the brakes when directed, but he has to press them further than usual, because Steve has backed off the front brake pads. So he effectively starts braking well after the line. But it's OK, because he finishes braking well before the end line.

We've passed. And I haven't hyperventilated once.

After all the other cars, MIT get a second chance. They qualify. Faster than us. Considerably faster than us. They run the qualifying lap without their array on, and they fair hoon around the track. All cheer as their driver passes through the straight; as he completes his timing lap, he punches his fist to the sky. I stop by to see if they need any help; they don't, but we do loan them a 240V soldering iron and 240V extension cable. Their array has a bad case of road rash, but they are testing it, and some of the strings are still working.

In the afternoon, we attend the briefing, we pack the car, we return to Alatai, and we do logistic preparation. Tomorrow, we race.

Nothing can now stop us from reaching our objective: the starting line.

Sunday 25th: flat

The alarm is set for 5am, because the WSC requires us to be on the starting grid by 6am. We load cars in the dark. We trailer the kilometre or so from the Alatai to our marshalling point. We're late, but we're still nearer to the front of the crowd of arriving teams than we are to the back. MIT give us our soldering iron back. They've put tape over dead cells on their array, with little messages like "You should see the other guy's car!", and "Our driver is from Harvard."

The start line is at a different spot this year: it's on the paved area in front of parliament. We queue, and get directed to a spot in the parliament house car park. In the shade. The sun is barely over the horizon, but it's easy to see that our bay will be shaded by a largish nearby building (the Supreme Court?) for quite some time. We are somewhat annoyed by this; it is our present belief that our batteries are not quite full, and we were hoping to top off in the hour or so that we are required to sit doing nothing.

A few interested people wander by and ask questions. We wonder how many more people the race start would attract if it were an hour or two later in the day.

Channel 10 stop by and interview me briefly.

Our observer, Sidd, arrives. We stand around. We field a few questions.

Our support vehicles arrive. Our lead and follow vehicles are required for the start, but they are marshalled in a separate carpark, to join us a few metres after we start the race. They bring me some Chux; I clean the array.

The race starts. Cars are brought up to the square in front of parliament at one minute intervals. Chris Selwood, the event coordinator, says a few words about each one, the flag drops, and the car is away. We are 19th off the grid.

We were required to turn up to the grid with our driver and one other person (which is me). There doesn't seem to be any guidance as to when that additional person is supposed to separate from his car -- other cars seem to be coming to the line alone, their additional person having somehow spirited themselves away to a support vehicle, but I stick to my car like glue, walking within a pace of it. We are marshalled into the centre of the square, Chris says some words about us, the flag drops, and we're away. The path from here to the road is guarded by barricades, and there is a substantial crowd behind them. We proceed at a walking pace to the road, whereupon I run for the follow vehicle. We merge up, and proceed down Mitchell Street, and turn right onto to Daly Street, which is the name for this stretch of the Stuart Highway. This is a bit odd: we've missed out the first block or two of the Stuart Highway, meaning that the race will run almost, but not quite, its full length.

The first two or three traffic lights are held at flashing amber for us, with police directing us through. After that, though, we're in general traffic, and we have to stop at lights. Several times we get separated across intersections, and the lead vehicle has to wait for the light to change before we can catch up.

Telemetry range is shocking; we are only getting telemetry when we are nosed right up behind the solar car at a red light.

The first checkpoint is Katherine, 318km away. The listed close time for the checkpoint is 4pm, so we must be there by then. That's an average speed of 43km/h, and we figure that with traffic lights and driver changes and so on, we'll need to cruise at something like 48km/h. With our new battery pack, larger than the one in Sungroper 1, we figure we can make it.

We cruise out of town. We are passed by several Greenfleet vehicles. (Greenfleet is a demonstration class, held over nearly the same route as the solar race, and at the same time.) Some distance along, we pass the French team, Jules Verne.

We continue to cruise. We're pulling an unsustainably large current, but a bit of maths suggests that the battery pack, rated at about 40 Amp-hours, should last.

We driver-change; we driver-change. With the third driver in the vehicle, we lose radio communication with the driver. It turns out to be a flat battery. This also turns out to be the reason that the telemetry range is so bad: the telemetry receiver's 9V battery is at about 6V.

The car is going slower and slower. We find a place to pull over, give the driver a new radio, and continue driving.

We ask the driver to turn up his speed a little; he replies that the throttle is already at 100%. We've just recently replaced the battery on the telemetry receiver, and we spot the out of place number: our 120V battery pack is sitting at about 90V.

We get the convoy off the road. We leap out and pop the array off, and look at the batteries. It is as the telemetry suggests: they are empty. We do some tests to find out if perhaps one third of our battery pack is simply not connected; this is not the case. We've taken about 18Ah out of our 40Ah pack, and it's simply empty.

We don't know why. We thought it was nearly fully charged before the start of the race. We know we had it fully charged a few days ago, because we got a substantial thermal rise out of it: we kept charging it off the sun after it was full, and it got to about 60 degrees Celcius. But these cells shouldn't get damaged until at least 80 degrees.

We continue solaring at a much lower pace, putting as much current out into the motor as we are getting in off the sun, slowing down for uphills and clouds, speeding up for downhills or sunny skies. We get passed again by Jules Verne.

There is much discussion via radio. Eventually, we decide to continue solaring to Hayes Creek Roadhouse, just a couple of kilometres short of the much-feared Hayes Creek Hill, and trailer from there to the Katherine check point, just before its closing time. We do so. Team Heliodet solar past the roadhouse five minutes after we leave.

We reach the Katherine checkpoint a few minutes after four. The checkpoint's closing time has been extended by an hour, because of the cloudy skies; so we discover that we actually made it with 50 minutes to spare.

We are permitted to keep solaring until 5:20pm today, because we did not cross the start line until 8:20am. But after being held at the checkpoint for the mandatory half hour "media stop" (presumably some of the front-runners see media at these stops, but we never do), we'd only get another 40 minutes of solaring, in marginal light, so we elect to simply leave the array on the side of the trailer, facing the cloudy sunset.

At dusk, we adjourn to the budget cabin accommodation.

Now that we have trailered, we are out of the lead pack of the race, who will complete the whole course on solar, and into the trailer pack. Our objective now is to complete as many kilometres as possible under solar power.

Monday 26th: Katherine to Elliott

Andrew is leaving us today, returning to Darwin. That means he also gets to do dawn array patrol. We're allowed to start charging at dawn, so Andrew and some others drive 4km or so from the caravan park to the checkpoint, roll the solar car out of its trailer, and put the array on its mounts on the side of trailer, facing the rising sun.

I rise a little later, and we travel out to join the car.

Strategy: we can't start solaring before 8am, so our only choice 'til then is to charge. But from 8am onwards, we have options. We've got enough in the battery pack from this morning's and yesterday evening's charge to solar for maybe 4 hours at maybe 35 km/h, we have 7 hours to get to Dunmurra checkpoint, and it's 358 km away. Clearly, we have to spend some of this distance trailering at 110 km/h. So of our 7 hours, which 4 should we spend solaring? The correct answer, for those of you who are following along at home, is approximately the middle 4 hours of the day, when the sun is most directly overhead, and we will get maximum possible output from our array.

So at 8am, we set out trailering.

Or not. We don't have our act together, so we actually start trailering at 8:35. We go forward 140km to a bay marked on the official route notes, set down, and solar at about 36 km/h.

We driver-change a couple of times, then trailer forward to Dunmurra. At the checkpoint, there's a board showing who went through this checkpoint when: Nuna was in the lead, with Michigan hot behind. We also get a new observer: Wendy. We hold for our compulsory half hour, then trailer onwards. We set down and solar some more, but the battery goes flat before we reach the pull-over that we were aiming for. We spend some frustrating time crawling along, ever slower, then give up, pull off the side of the road, and load. We trailer forward to Elliott, which is our camp site. We get there at 5:18pm, which puts us into penalty time: for every minute from 5:00pm to 5:10pm, we must start one minute later tomorrow; for every minute beyond 5:10pm, we must start two minutes later tomorrow. So our 5:18pm finish translates into 8:00 + 0:10 + 0:08 x 2 = 8:26am.

We're camping in the Elliott caravan park. When I get there after our dusk charge, camp is already set up. We eat: barbecued marinated beef and chicken with mashed potato, peas and corn, in a big circle of camp chairs under a ghost gum. I mention to the circle at large that some of the chirping sounds we can hear are sonar pings, as bats whirl and swoop to the campground's lights, snapping bugs out of the air. One student immediately retreats to her tent.

We discuss strategy for the following day, and sleep.

Tuesday 27th: skid

I look out of my tent five minutes before dawn, and I can still see the Sungroper trailer in camp. We hustle over to the other side of the road, where we'll get a clear shot at the dawn, roll out, and hang the array. Breakfast gets brought over to me. I get back to camp, shower, pack. We load Sungroper, and trailer to Tennant Creek.

We do our half-hour at the checkpoint, change observers (welcome, Don!), fuel the lead vehicle, then solar out.

About 20km out of Tennant Creek, the tensioner holding the drive chain in place fatigues and breaks. The chain fouls the back wheel, locking it -- two teeth break off the drive wheel sprocket and the car paints a 15 metre skid mark on the road. Support pull a U-turn, and come back. We leap out of follow and push the car off the road; thankfully the chain has come loose and the car rolls smoothly off.

We get the array off, and spot the broken part. Our mechanical team put the chain back on, but without the tensioner it'll fall off again as soon as we hit a bump; and there are several bumps between us and where the road surface begins. The mech team decide to improvise a tensioner using some stainless steel wire - now all we have to do is find where we've put the roll of wire. The support bus with the rest of the team in it arrives, and while the mech team hunt through their various boxes we radio up to the bus to see if they've got anything that will do the job required. No coat-hangers; no random bits of steel are found. The observer has a paper clip; not strong enough.

The assistant clerk stops by on his way up the course; he's just closed the checkpoint behind us. He and our former observer, Wendy, spectate.

Eventually the wire is found right where it's supposed to be: in the tool kit. "Have a girl's look!" says John, meaning that guys fail to spot things right under their noses, but girls will find it every time. The new tensioner is improvised, we jump back into cars, and solar on.

We complete 79 solar kilometres for the day, and trailer forward. The support bus checks out Barrow Creek, but declares it unsuitable, so we stop at a picnic/camp area featuring a water tank, an outhouse, and nothing else. Tents are pitched, the circle of chairs set up, and a camp fire assembled. Steve cooks using camp ovens. The generator is started, providing some lighting, which attracts approximately 1.3 billion flying insects, and power to battery chargers for our constellation of electronica.

After eating, we turn out the lights and appreciate the stars. We spot two satellites. One student cracks open a glow stick, paints himself in glowing phosphor, and dances in the dark.

Wednesday 28th: cloud

We pack the camp. The wind does not help: it tends to blow the tents onto the barbed wire fence. We roll the car into the trailer, and trailer towards Alice Springs. We set down and solar. Today's solaring is made more challenging by the presence of cloud: there is maybe 80% cloud cover. On the other hand, we do have a strong tail wind. We solar along, drawing power out of the pack to get through the cloud. Then the temperature alarm goes off. We pull over and try to figure out why the motor is so hot. We look, but nothing seems out of place. We solar on a little, and the alarm goes off again. We take the array off again, but still everything seems unchanged from yesterday. Eventually, we figure it out: we've moving at about 35 km/h, and the tail wind is about 35 km/h. This means that our cooling fan, blowing air over the motor, is inadequate by itself, and we need extra airflow to keep the motor cool. We improvise a shroud with polycarb and gaffer tape, to focus the airflow from the fan. This time, the temperature stays around 55 degrees.

We solar on through patchy sun to Alice Springs. We successfully solar through town, through four traffic lights, through the Heavitree Gap, and in to the checkpoint. Then, out of the 30 minutes we are required to stop at the checkpoint, I spend 40 of them trying to figure out why telemetry has been down for the past two hours. It turns out that two of the three cigarette lighters in the Landcruiser have blown fuses, as has one of the cigarette lighter double adapters, plus the 9V battery I'm using to run the telemetry receiver in the absence of 12V is now flat, plus Pyustration has crashed. I'm leaning more and more towards thinking that 12V is a fundamentally bad way to pipe power around - if I were scratch-designing a production car, I'd be tempted to go 110V or 240V, and invert that down to lower voltages where necessary.

We solar out of the checkpoint and take the right turn that continues us down the Stuart Highway, but soon decide that in the absence of sun, we're only going to be able to go a trivial distance. We call it a wrap, our new observer (hi, Peter!) spraypaints the road, and we bring the trailer around.

And then of course the sun comes out. But our decision is still valid: cloud cover is still about 80%, and any given patch of sun doesn't last long. So we return to camp, a caravan park not far from the checkpoint. It's only 4pm, so we set the array up to get some sun. 107 solar kilometres for the day, despite the cloud.

The Mac Donnell Ranges caravan park is very nice. Several students climb one of the large hills behind the caravan park; these presumably are the Mac Donnell Range. Word comes that Nuna have won the race, beating their previous record and averaging 103 km/h, despite having to obey all speed limit signs. In the evening, there is a live performance by a local singer; our cameraman gets up and plays wobble-board on one song. We all cheer him on.

Thursday 29th: to Cadney

Again I am not on dawn array duty; again this is a Good Thing. Several students and a couple of teachers climb the hill again. We trailer out of the caravan park about 40 minutes after the official 8am start time. We set down a couple of hundred kilometres further down the track, and solar. We have a tail wind again, and patchy cloud again, but today the clouds are much smaller, and are whipping past us at much faster than our 32 km/h road speed: we are being overtaken by the clouds.

We solar past a Telstra repeater station. These small huts occur every couple of hundred kilometres along the highway; each is a smallish hut with two big masts of solar panels outside. The panels power the optic fibre repeaters, which listen for a weak pulse coming in on one optic fibre, amplify it, and push the message along -- light driving light through an underground network crossing the continent.

As we pull in to a bay beside the road for a driver change, the temperature alarm goes off -- again the motor is overheating. We elect to trailer for a little while so that the motor can cool down. While trailering, the mech team in the lead vehicle design some additional cooling cowling for the motor. We set down at Kulgara roadhouse, pop the top, gaffer-tape some cardboard in strategic spots around the fan and motor, and solar on. We solar across the Northern Territory / South Australia border. Our doco team have lined up a bunch of tourists at the border monument to cheer us on as we pass.

A few kilometres further, on a long slow uphill, the temperature alarm goes off again. This section of the road is elevated above the plain, presumably for resistance to flooding, so there's just barely room to pull off. We put a student out the back of our convoy with the red flag, and largely stay in our vehicles 'til the temperature alarm shuts up. Then we solar a couple more k to a rest stop and charge for half an hour. The support bus catches up -- they've been slowed down by a blown tyre. We trailer to Cadney roadhouse. 98 solar kilometres for the day.

We arrive at the Cadney checkpoint at 5:02pm, so we'll serve our 30 minute stopover from 8:02am to 8:32am tomorrow.

Steve floats the idea of fitting a 19-tooth sprocket to the motor, in place of the 15-tooth we've got there now. We've got no more big hills to climb, so I can't argue against it. He jacks up the back wheel and pops the chain off. Then he discovers that the back wheel doesn't roll freely: the rear brake is dragging. It was too small an amount to notice with the car jacked and the chain on, and too small to notice when rolling the car forward and back by hand. Steve adjusts the brake. With the chain back on, there's a funny noise coming from the motor. Steve finds a bolt rubbing very slightly against the motor fan cowling. He spaces it off. Better, but still a funny noise. He opens the motor, and finds a bad bearing.

Then it's a long slow disassemble of the motor into an ever increasing number of pieces, in fading light, in the gravel carpark of a truck stop in the middle of nowhere. Steve puts the new bearing in, but on reassembly discovers that he has one piece left over. There is a word for this phenomenon in Liff, I am sure.

We elect to put the piece back into the motor in the morning.

The evening is cold, and for the first time our team jackets come in handy. Dinner is chicken satay sticks plus vegie and mash, in our circle of chairs. The circle is getting slightly bigger as the days go by: we now have three sets of parents of students following us more or less closely as we journey: travelling off to do touristy things by themselves, and occasionally rejoining camp to see how their progeny are doing.

Friday 30th: litany

Around dawn, Steve reassembles the motor. But it still doesn't roll smoothly: the other bearing is stuffed, too. The first replacement bearing came out of our spare motor (the motor from the original Sungroper), but the spare has only one bearing this size, so we order new bearings from Coober Pedy, 150km south. The parents of one of the team members are in Coober Pedy, and they run the bearings up to us. An hour or two later, the parts arrive, and Steve fits them; but the motor is still not smooth: the drive shaft is bent.

How long has it been like this? We don't know. Possibly when the chain came off and locked the back wheel, the motor was put under undue strain, and the bearings toasted and the shaft bent then. Or possibly the motor was like this when it was delivered.

We push the car from where we're working on it back to the control stop, with only half the rear suspension connected because of the work we're doing. We serve our half hour, and push back. When we get there, and pop the array off, we discover that the half of the rear suspension we were using has not coped with the extra load, and is damaged.

In an attempt to get a working motor, we put the bearings back in the original Sungroper motor, solder on an additional plug so that we can connect it to the Tritium Gold Controller of Extreme Shinyness, fit a temperature sensor, and bolt it into the car.

When we test-run it, a nasty mechanical noise comes out of it, and we don't know why.

We pack, and trailer to Coober Pedy.

We roll out in the carpark of an underground backpacker's. Literally underground, of course, as this is the Coober Pedy style: a lot of housing and accommodation is simply tunnelled into the ground. This gives a nearly constant 27 degrees C all year round.

But not so in the carpark, blasted by wind which deposits a patina of red dust on everything, including the array. We clean the array with the last of our rain water. After we finish, it's still dirty, but it doesn't matter: if I push the whole power of the array into the batteries, two thirds of the battery pack heats up, one third dangerously so. So I turn on just one of the four array strings, to feed the batteries quarter power.

As we trailered to Coober Pedy, we had the back wheel hooked up to the remaining half of its suspension. When we roll out, we discover that this too has failed under the doubled load.

We acquire a crowd, several of whom are quite helpful.

John notices that we don't have any dash displays, despite 12V being turned on. We've not getting any telemetry either. I poke around with the multimeter, and discover that the 5V regulator, which is supposed to take 12V and cut it down to size for our 5V electronics, is not working. I replace it with one salvaged from another piece of gear. Now 5V works, but still almost none of the electronics that depends upon it is working. Andrew's +4 Voltage Sense Board of Rapid Prototyping is working, but nothing else. I swap in the master board chip from the original Sungroper, and now I get telemetry, but all the numbers are zero: every microcontroller chip in the car that takes that 5V and feeds data back to the master board has been zapped, presumably by the same thing that destroyed the 5V regulator.

(Note for geeks: I'm using a 7805 for 5V, instead of the TEM-1211 DC-to-DC converter used in Sungroper 1. This is because the TEM-1211 is now very rare and hard to buy, and no pin-for-pin replacement is available. A search on Google within Australia for TEM-1211 turns up exactly one hit: the Sungroper website. This means we do not have the isolation that the TEM-1211 would have provided. But I still have no idea how the boards got zapped.)

Steve fixes the rear suspension by removing it, and bolting the arms that used to go to it directly to the frame of the car. To provide some smoothness of ride, he decreases the pressure in the rear tyre.

John, Steve, and the audience look at the problem with the original Sungroper motor, and decide that it is a problem with the keyway. This is a slot in the shaft: when the sprocket slides on, it is this keyway that forces the sprocket to turn in time with the shaft. But it is loose, which will cause rapidly destructive wear. Options are discussed, and a solution involving glue is decided upon.

John takes the car for a short drive in the carpark to test the new non-suspension. Three metres in, the chain tensioner breaks again, and the chain falls off.

So one motor has a bent shaft, the other has a dodgy keyway, the tensioner is broken, the rear suspension is non-existent, the batteries won't charge, the array is red with dust, the electronics are all toast.

But the Tritium controller still works.

We go for pizza; John lays down the conservative strategy he intends to use: trailer to a few k short of the finish, set down, and solar across the line.

Saturday 1st: 40 degrees in 10 minutes

There is no dawn underground. But we are no longer in a hurry to get going early. We do not bother setting out the array for dawn charge.

We trailer forward to the next checkpoint, Glendambo. While we serve our half hour, we are not allowed to work on the car, but Steve has already removed the chain tensioner from the car so that he can fix it with more steel wire. As we roll out for the checkpoint, we drag the chain in the dust.

Steve is very keen to get some more solar kilometres. I chat to a blue shirt at the checkpoint, and it seems that the road ahead will be flat, straight, with broad shoulders and little traffic for another 80km. We are unlikely to get better road for testing.

But we have not yet driven this car with this motor for more than three metres, and with the complete absence of telemetry, I am uneasy. We resolve to drive for five minutes, stop and measure the motor temperature with the pyrometer, drive for five, stop and measure, drive, measure, drive, measure, wash, rinse, repeat.

So we solar out from the checkpoint. Five minutes out or so, as we are looking for a good piece of shoulder to pull over onto, we reach a cattle grid. With our rear non-suspension, the grid is rough, and immediately after it, the driver hears a nasty clunk. He pulls over.

We push him off the road. The lead vehicle loops back to join us. Steve looks under the car for the source of the clunk, and I crawl under with the pyrometer (a nifty thermometer device) to measure the motor.

Temperatures on the bits of the motor I can reach range from 70 to 79 degrees C. That's more than 40 degrees rise since the checkpoint, in less than 10 minutes, and if it's that hot at the surface, you can bet that it's hotter on the inside.

We trailer.

We reach Port Augusta. It was our intention to skip this checkpoint, as we are allowed to skip one over the course of the race. We intended to merely stop in, tell them that we're skipping, so they don't have to hold it open just for us, and continue; but due to logistical complexities we wind up taking 30 minutes there anyway.

Onno phones me to see how we're doing, what the car is capable of, and generally if there's any way he can help us.

We reach Angle Vale, the end of timing, at 7:06pm. Normally, that would give us enough 2-for-1 penalty minutes to make us start the next day around noon, but since the only solar cars behind us on the course have also trailered, I think the race officials don't particularly mind about timing. Word comes that the race officials would like us to cross the line somewhere around 11am, give or take; we'll see what we can do.

John has had some difficulty finding accommodation that can take such a large number of people. Possibly this has something to do with the speedway a few k short of the end of timing, and the gajillion parked cars outside it, overflowed onto the sides of the road for over a kilometre.

But there's a caravan park just after the end of timing, and they rent us a building that looks like it used to be a scout hall. So we still need to set out all our bed rolls and such, but we don't need tents.

Now that we are returned to mobile connectivity, students scatter around the gravel lot out front of the hall, each finding a quiet corner to make phone calls. Some phones have flat batteries, and so their owners are tethered to power points inside the hall.

Dinner is piece meal: toast with egg, beans, barbecued potato, frozen curry barbecue-reheated.

Many people ask me if I am OK; I explain that I am just tired. Based on the number of enquiries, either I am substantially more tired than usual, or tonight's camp spot is better lit the last five.

Students horse around, give each other wedgies, throw a football, and invent a game involving a rubber ball and a row of thongs. (Note for foreigners: thongs are a form of footwear.)

We resolve that tomorrow we will trailer back to the end of timing, trailer forward to Torrens Parade Ground, a kilometre or so short of the finish line, and solar in from there.

Sunday 2nd October: finish

We have a slow start to the morning. About half an hour from our planned departure time, we get word that the WSC people would like us earlier, so as not to interfere with the big finish for the World Solar Cycle Challenge, held concurrently with WSC, but over a different course. We roll.

There is some back-and-forth over the radio as to where various things are, who has moved John’s jacket, etc. I realise that I’ve forgotten the pyrometer.

We reach the parade ground. It is disorganised. The logistics area is full of solar cycles, with no room for our vehicles. There is no WSC follow vehicle for the solar car, so we bring our own up. Then the WSC follow vehicle appears (albeit with no stickers, signage or rotating amber lights), so we have to put ours away again. Our solar car has to come up to the location of the bus with no follow at all, 100m along the road and through a traffic light; this is a contravention of our license.

I go in the follow vehicle; everybody else (apart from our solar driver) goes in the bus. We start solaring in, through city traffic, with traffic lights every 160 metres. There is no radio comms between the WSC follow and the bus, so I relay messages via my radio. The rest our crew keep the radio channel fairly quiet from their end so that I can talk our driver in. The lanes are narrower here in the city, and the traffic much more intense, but she manages well.

Just short of Victoria Square, the convoy splits: the bus and follow go into the slip lane at the left of the square, and Sungroper is waved forward and held just short of the finish line. We all leap out and rush across to the line. As I run, I can hear Onno on the wireless mike, working the crowd up to give us applause. Sungroper crosses the line; all cheer. I crawl under the car and check the motor: only 40 or 50 degrees. We gather around the tail of the car for a few minutes for a photo opportunity. Leeming High’s principal is here, and she comes over and shakes the hands of team members. Parents of several students are here too, as are a couple of additional teachers.

A student says, "How good is Sungroper!", to general approval; this phrase will be repeated at random intervals by random students over the remainder of the trip.

I ask a couple of WSC officials what we are supposed to do with our car; we are directed to a scrutineering area off to the right. Chris Selwood comes over, shakes my hand, checks our battery seals and tags, cuts them off, and gives them to us as souvenirs.

We sign the car: John wipes the worst of the dust out of part of the tail, and we all take turns with a sharpie pen.

Again I look for an official to tell us where we’re supposed to take our car next, but by the time I find one, the solar cycles are arriving, and cycles plus crowd have us hemmed in.

The cycle challenge involves partly pedal power, partly solar power, over a 1331 km course. The fastest average just under 40 km/h. Most are tricycles.

After they arrive, but before they do their presentations, we sneak our car out by moving a bunch of WSC fencing out of the way. We roll it into a vacant bay in one of the display tents. We hang out at the finish line long enough to cheer the French team, Jules Verne, as they come in, then take the bus back to the parade ground.

On the way back, we do our one junk food stop of the trip: lunch at a 1950s themed HJ’s.

We return to the hall. A small crew goes to the coin-op laundry at the caravan park to wash the team shirts and other clothing for this evening. Around 4pm, another small crew goes to pick up Sungroper from Victoria Square.

In the evening is the closing ceremony at the State Theatre. In the lobby before we go in, and in the theatre before the event starts, we play the shirt trading game. Team members return to the group, displaying their trophies. One or two people get yellow observer shirts; about four get Nuna shirts. I contemplate the design of an ideal market for shirt trades, but decide that the problem is NP-complete. (This is a special mathematician’s word which approximately means "hard".)

The closing ceremony is a closing ceremony; you know how they go. The last thing is the presentation of the first place trophy, which goes, of course, to Nuna. Nuna do a nice thing: they are wearing their shirt trades, so there are eleven different teams represented on stage, including Leeming Sungroper.

The post-awards drinkies thing this year is not a private function organised by WSC; it’s just a designated pub. This is an issue for under-18 teams. We ask, and are let in, with all our under-18s wearing wrist tags; but other teams such as Kormilda and Annersley simply don’t show.

I have a nice chat with Peter S, the course safety officer. Some of the ways he and I have been thinking to enhance safety turn out to be very similar.

We go to a kebab place up the road for food; the two guys behind the counter turn out a large number of kebabs for us in a very short time. Then we go back to the pub.

Sidd, our first observer, is there; a bunch of our students are on the dance floor, and I tell Sidd he should join them. Sidd tries to persuade me to dance too; bizarrely, he succeeds.

Eventually, John calls time, and at midnight we are back on the bus back to camp.

Monday October 3rd: home

I wake; the sky outside the scout hall window is overcast. I suspect I’ll be noticing the weather for quite some time to come.

We breakfast and pack. We also have to get rid of unused food, but luckily there are some circus people next door, who will see our surplus go to good use.

We peel the signage off our rental vehicles. Some are magnetic stickers, which are easy: lift 'em off and slap 'em on the inside of the Sungroper trailer. Some, like the stripy metallic hazard tape around the "Warning: Solar Car Ahead" sign are a right bastard; luckily, we have plenty of student labour to apply to the problem.

We cram everything into the Sungroper trailer and the support trailer, and set off to the city for lunch. We’ve packed the radios, which turns out to be a mistake: it’s _much_ harder to coordinate three vehicles without them. Most of us go for food, while the vehicle I’m in goes to pick up a student’s bag. He left it in Coober Pedy, and we got the backpacker’s to put it on a bus to Adelaide for us. But it’s a public holiday today in Adelaide, so we get the run-around. Eventually, we pick the bag up from the bus company’s suburban depot, and return to the city centre.

John and Rodd take the trailers to the shipping company. The rest of us wander around for a while, then rendezvous at the appointed time at the Torrens parade ground. Raedthuys are there, getting their car into a suitable state for shipping. I have a nice chat with their strategist.

We drive to the airport and return the rental vehicles. According to the sign on the side of the terminal building, today we’ll be flying Qanta. The team swells as we meet up with various parents, teachers, etc. We check in. (Tip for aspiring terrorists: you don’t need to present photo ID if you’re with a group booking.)

We take off in the late afternoon, and chase the sunset into the west. The sun finally vanishes during our descent into Perth, but it is not so much the sun setting from us, as us setting from it: we descend towards the Earth, and the horizon moves up and obscures the sun.

As the captain gives his "welcome to Perth" message, he congratulates the Leeming High team on their achievement. All cheer.

I go to Peter’s place for a debriefing. Craig is in town for this week only, and since Peter and Craig are the two originators of the Sungroper project, it’s too good an opportunity to miss.

Then home.

Sleep.

Finished.