We pack the camp. This is made more challenging by the wind, which 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.
-- Doug Burbidge
Addedum:
Wednesday PM:
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.
