Hello all,

I would firstly just like to second Tony that all trolley wheels are the most efficient model solar car setup. Not only does it prevent steering drag around corners, but also the possibilty of increased drag along the straights. Along the straights you say? Well, cars with fixed wheels and axels are often not aligned properly resulting in added drag and slower race times. Tests performed by Ian Gardner in Victoria confirm this.

Here are some 2D and 3D autocad drawing files from the 2008 test car that posted the 15.75 second lap time at last years nationals. They are not 100% identicle to the actual car but are pretty close.




For those of you that do not have access to Autocad, I will upload some screenshots or rendered images in the near future.

I will also include some actual photos shortly.

miseli

OK everyone,

Here are some autocad images of the 2008 test car.







I hope to include some actual photos once I get my hands on a half decent camera with some good resolution.

miseli

We made a similar car last year for the states but it was too unstable. The back wheel/hinge had too much play.

If designed and built properly, the 3 wheel arrangement shouldn't have any problems with stability. Remember, the test car displayed above ran a 15.75 second lap at the 2008 national event and didn't ever look like coming off the track.

The 2005 and 2006 national winning cars were also built according to this arrangement. Over both those years, neither car ever came off the track (state or national) or suffered a crash.

Of course, if you have your guide rollers set too high, then any car will become unstable when cornering. They must be kept as low as possible.

Keeping you panel nice and light will help lower the car's centre of gravity and therefore lower the car's tendency to roll over. The test car used 10 unmodified dicksmith segments which made the panel come to about 300-400g (about half of the required panel weight). A 3 wheel car with a big heavy glass panel may cause a few problems, particularly this year, as panels will need to be elevated by a good 30mm from previous years due to the milk bottle.

miseli

Hello all,

I would just like to let everyone know that I have just loaded up all of the 2008 AIMSCC scrutineering pics that Ian Gardner took last year in Hobart on the Tasmanian website. These include all but one of the cars that competed in the event.

I will also be loading up all scrutineering pics from both 2006 and 2007 over the next week.

miseli

Hello again all,

I would just like to let everyone know that I have recently loaded up a number of video clips from both the 2006 and 2008 National car competitions on youtube. Some of these can be viewed on the Tasmanian website at http://www.tassolarchallenge.org/?page=gallery#videos, but all loaded up so far can be found on youtube by searching "AIMSCC".

I will let everyone know when I have uploaded a new batch.

miseli

Hi,

I was wondering, is it possible to enter the AIMSCC without qualifying through a State competition? Given we have competed at nationals in the past and have a competitive car?

Cheers

That might be a possibility.
South Australian entries were low this year so i think there are available positions left over.
You will need to contact Stanley Woithe as he is the chief decision maker... i think.

Maybe Mark Iseli can shed some light here?

Also, which state are your from?

Hello Redlands,

As Tony mentioned, there may be a possibility. Your chances will vary depending on what state you're from.

How it works is every state and territory to start is reserved 4 entries. There should be 6 state and territory events so that makes 24 cars. If you have been at the nationals before, you will know that it is run as a 32 car knockout comp. Every now and again there are also international entries. The remaining numbers are made up by wildcards from various states. SA and NT have been down in entries for the last few years so to make up numbers, TAS, VIC and NSW have entered 5, 6 or even 7.

If you're in SA, you are pretty much guaranteed entry since I don't think they are holding a state event this year. In Hobart last year we only had 1 SA entry, so any more would definitely be welcome. If you are in SA, contact your state coordinator and let them know you have a car.

If you're in the NT (not quite sure if they have had their state event yet), run it by your state coordinator. You should have a good chance, since the NT has only had 1 or 2 entries in the last few years.

If you're in NSW or QLD and have missed your state event for some reason, run it by your state coordinator. They may choose to send you as a wildcard, although I find that unlikely for NSW since teams that entered the state competition would be given priority. QLD may only have 3 or 4 entries this year, so another entry from there would probably be encouraged.

As for the other states, their events have yet to be run.

If you don't have, or are unable to find, the contact details of your state coordinator, let me know and I'll send you the info.

miseli

Located in Western Australia, our competition is in two weeks.

In that case you'll need to qualify for the Nationals through the Western Australian event.

I think registration officially closed a couple of weeks ago, but if you contact your state coordinator directly you should still be able to enter.

I know the top 4 cars are invited, but what about after that? last year there was 5 WA cars at Nationals.

Since the WA event is run as a knockout event, the top 4 cars come from the semifinals. Any more after that are generally chosen as a wildcard from those cars that lost out in the quarter finals (top 8) if the national event requires it.

Last year, Winthrop Baptist College was chosen as a wildcard because they were the fastest qualifier from the first day but had some track issues and didn't make the finals of the actual event. Aquinas College which came fourth, but declined their invitation, was replaced with Albany SHS.

Another issue that some teams sometimes face is the traveling and accommodation costs involved with competing at the nationals. Since financial assistance is only given to the top few cars, some schools sometimes have to decline an invitation.

My advice to you is that you must finish in your event's top 8. If you haven't made the top 4, then let your state coordinator know that you are willing to compete at the nationals and it might be possible for you to be given a wildcard.
I guess I would be speaking on behalf of the national committee in saying that we'd rather spread the entries more evenly across states and have 5 or 6 entries from WA rather than 7 from NSW or Victoria.

miseli

Ok thanks

I saw your test car earlier in the thread.. very nice But how do you think it would run on the WA track? It's a bit different to the AIMSCC one.

Well, from the photos that I have seen from the WA track, it seems like your overpass is very similar to the one we have on the Tasmanian track. That is, rather short and steep and not like the new national track which is nice and gradual.

As a result, a problem that fast cars here in Tasmania sometimes face in good sunlight is getting airborne on the overpass and having the guides dislodge from the track. This happens to 4 wheeled cars and not just those with 3 wheels. Since we have a 100m track, we finish on top of the hill so this isn't too much of an issue.

As for stability, the test car and the last few cars that I built to win the nationals with in 2005 and 2006 (3 wheels), never rolled over when cornering. A badly aligned track may cause a car to jump and dislodge it's guides, but that will happen to a car regardless of the number of wheels.

Winthrop BC built a car similar to the above test car for last year's WA event and were having some problems with staying on the track from going too fast (I think it was the overpass), but I am not quite sure what the exact issue was there.

Anyway, you shouldn't have to worry anymore since I have heard that Western Power have (were suppose to have) constructed a brand new track (exactly the same as the current national one) for this year's WA event. If a good job has been done with the track, well built cars should no longer have any problems.

miseli

yeah - the old wa track was horrible - any car that was half decent had no chance staying on the track. there were badly alingned joints everywhere and the floor of the track was also pretty horrible. Having the track 1m off the ground didn't help either for those cars who came off

Still, apparently we are using the nationals track (or prehaps an older version) or so my intel suggests, so that should clear up some of these problems.

Also Miseli, you said the 15.75s lap was done in 117% sun. How do you convert this sun% value into a lux value? is that possible?

Redlands,

The sunlight meters that are used to measure sunlight percentage at events are made up of ordinary solar cells and measure their short circuit current output with an ammeter or multimeter. You can easily make your own.
These work on the principle that the cells produce half the current at 50% sunlight, 25% current at 25% sunlight, etc.

Last year at the nationals we used Ian Gardner's meter, which consisted of a couple of dicksmith cells in parallel and taped off to produce 1amp at 100% sunlight. This made reading the multimeter easy since, for example, 63% sunlight would read 630mA. Of course you don't even have to do this. Any cell will do, you just have to include a calibration factor if you want it on a 0% to 100% scale.

The problem with these meters is what do you call 100% sunlight? They are all relative. Unless they are somehow calibrated to a standard, some meters may show sunlight percentage being at 90% while others 110% at the same time. Since most scrutineering light boxes are fairly similar to one another across the different states (or are supposed to be), most light meters are calibrated using these I think.

If you plan on doing some testing, set up your own meter and make sure you base your tests off that. Then when it comes down to racing, use that same meter to help you decide on gears, motors, etc.
Just go out at midday on a sunny day in summer, measure the current and call that 100%. If you want to get a nice figure like 100mA or 1000mA for 100% you‘ll probably need to tape over some of the cell/s.

Because these solar cell meters and Lux meters do not measure exactly the same thing, there isn’t really a single conversion factor between the two. I’m not sure, but something may be able to be approximated. I don’t know. Maybe someone else here might be able to help you out?

Since model solar cars run off solar cells and the light energy that they convert, a meter using solar cells to measure sunlight intensity is a lot more suitable here.

My advice to you is to make up your own. It could be as simple as a single solar cell hooked up to a multimeter.

miseli

Hmm ok thanks for that I'll look into it.

Just out of interest, what do you think the lux would have been for that 15.75s lap?

Not sure. All I can say is that the lap was run during a sunny patch at last year's nationals. During the course of the lap, the light meter averaged 108%. This could have been from straight sun or maybe the clouds around at the time reflected and concentrated the light to higher levels than normal.

All I can suggest is if you have a Lux meter, take a Lux reading at midday in the full sun. This should give you some idea.