Doug says:
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.
