Solar Freaks

Hello all,

With a lot of teams now beginning to complete their cars and the various state events slowly approaching, most would probably have an idea or two as to how the rules could be changed for in 2011.

If you have any suggestions, please post them here. John or I will bring these up with the national committee to consider over the next few months. Rule changes for 2011's challenge will then be discussed in greater detail at a national committee meeting in November at the nationals.

miseli

Hi Marc

My concept car doesn't meet all the regulations. But I believe that the infringements are very minor. I have a switch or two on my solar array. So this is what I purpose; 8.8 should be editing.

Currently it is
8.8 No devices on the array = All mechanical, electrical or electronic devices including the on/off switch and any devices for changing the panel voltage must be separate from the array support structure and supported by the chassis.

Somewhat edited version
8.8 Acceptable/ Non acceptable devices on the array = All mechanical, electrical or electronic devices including the on/off switch must be separate from the array support structure and supported by the chassis. However any devices for changing the panel voltage may be found on the array but can not influence the measuring of the panel. Students must show a full diagram of there circuitry to be able to use this configuration.

Benefits of this is it will promote and encourage students to experiment with not using a maximizer! Being able to flick a switch to change voltage and current rather than changing gear ratio is easier? Although changing gear ratio is required but at a less extent.

jhg wrote:Hi Marc

My concept car doesn't meet all the regulations. But I believe that the infringements are very minor. I have a switch or two on my solar array. So this is what I purpose; 8.8 should be editing.

Currently it is
8.8 No devices on the array = All mechanical, electrical or electronic devices including the on/off switch and any devices for changing the panel voltage must be separate from the array support structure and supported by the chassis.

Somewhat edited version
8.8 Acceptable/ Non acceptable devices on the array = All mechanical, electrical or electronic devices including the on/off switch must be separate from the array support structure and supported by the chassis. However any devices for changing the panel voltage may be found on the array but can not influence the measuring of the panel. Students must show a full diagram of there circuitry to be able to use this configuration.

Benefits of this is it will promote and encourage students to experiment with not using a maximizer! Being able to flick a switch to change voltage and current rather than changing gear ratio is easier? Although changing gear ratio is required but at a less extent.

I think that any device used for changing the panel voltage on the array would be defined as a switch of some sort.

One can still set up their car to change panel configuration using a switch. It just needs to be on the car instead of the panel. Pretty straight forward really.

Marc

Somewhat edited version
8.8 Acceptable/ Non acceptable devices on the array = All mechanical, electrical or electronic devices including the on/off switch must be separate from the array support structure and supported by the chassis. However any devices for changing the panel voltage may be found on the array but can not influence the measuring of the panel. Students must show a full diagram of there circuitry to be able to use this configuration.

Benefits of this is it will promote and encourage students to experiment with not using a maximizer! Being able to flick a switch to change voltage and current rather than changing gear ratio is easier? Although changing gear ratio is required but at a less extent.

jun, i must agree with the proposed change that u have offered. while competing this was the common practice that we used in order to componsate for varying weather conditions along with as u mentioned changing gear ratios also. (this was obviously before using a maximiser became a common practice). we had a panel set up using switches that would allow us to change between certian variations of series and parallel. the switches were mounted to the panel and at the time were completely within the rules.

yet every year (at nationals) a particular scrutineer (who will not be named) would argue the fact that the switch set up that we had was completely unneccessary. and "all we need do was use a maximiser."
and funnily enough the rules were altered the year after our school won the nationals.

though with the current rules it can be seen that in some light conditions that it can be advantagous to go without using a maximiser though changing gear ratio alone is not enough to be able to change a car panel that is set up (in series) to go without the use of a maximiser in low light conditions.

if the rules were to be altered as u have said (which there is absolutely no chance that it will btw, no offence-cause i think they should be changed) this would allow a much easier method of being able to componsate for the changing between using a maximers or not and changing panel configurations for various light conditions.

though the current rules allow switches to be used for this purpose though not being allowed to be mounted on the panel seems pointless. (other then adding a few grams of weight to the panel that allows less ballest to be carried, or because a switch may cause a very small amount of resistance leading to a lower power reading when tested)

I'd like to see the bulkhead rule removed, just because it annoys me. I'd suggest possibly going back to the drink can rules that were used in 2005 or earlier, since no one who competed then will be competing next year (Excluding people who competed in primary school). I know the bulkhead rule created a lot of confusion amongst some less experienced schools, and even one teacher who's been doing this for years had interpreted it incorrectly.

If you don't remove the bulkheads, I would recommend adding diagrams to the regulations and possibly rewording it a bit.

unussapiens wrote:I'd like to see the bulkhead rule removed, just because it annoys me.

Your not alone on that one! I can't stress how many different ideas at school we had, all sounding right. I think i went for two months thinking it was a space in the car. I don't mind what it is replaced with, but its has to go...

Karo,

Hello all,

Despite the 30% panel weight reduction for no electronics in 2010, most teams across the country have not even considered the option of going without, let alone actually race in that configuration.

If the weight reduction jumped to say 40% or even 50% in 2011, would the story be any different? Comments please.

Marc

Despite the 30% panel weight reduction for no electronics in 2010, most teams across the country have not even considered the option of going without, let alone actually race in that configuration.

If the weight reduction jumped to say 40% or even 50% in 2011, would the story be any different? Comments please.

hi marc,

im sure by now my views have been clear on the topic of running with or without a maximiser. just to be clear i have nothing against teams opting to use a maximiser; though making a car that chooses to run without the use of a maximiser more competitive against one that does needs to be addressed further. sounds reasonable increasing the weight reduction in future years to further tempt teams opting to run without a maximiser more appealing and worth while.

as seen from this year many teams have like u said not even given it a real thought. from my experience i have only seen one car from the nsw comp go without. it is true more work will need to be addressed in concerns of choosing the correct gear ratio for particular light conditions, series/parallel panel set up and or switches but more knowledge concerning the workings of a teams car can be seen to be gained. though the gamble may not always pay off obviously depending on changing light conditions it is one that may seen to be rewarding if the weight reduction could be further increased in the coming years, though saying that there is only so much advantage in terms of 50% and further weight reduction that can be given to teams choosing to go without a maximiser.

viper01

Agree. I'll keep it short and simple!

50% with the current formula wont be possible, 40% might be pushing it also. The engelec panels would be slightly higher than the weight required to be carried? Even the best designed cars may have trouble staying on. I'm sure Marc might disagree. =]
I'm building another car in the next week after exams. I'll try running it without a maximizer at the nationals.

Thanks for the comments guys. Hopefully we'll get some teacher and student feedback on the matter as well.

At the moment the 50% weight reduction is looking likely. It is true that a number of panels will be too heavy for this but that will just be tough luck. Some panels are in fact already too heavy for this year's 30% reduction. A lot of the cars these days are using either Scorpio panels (which will have no problems with the 50% reduction) or Engelec panels (which won't be far off depending on the number of modules used, the power they put out, and the backing that they are attached to).

I doubt that the ballasting formula will be changed in order to make all panels heavier since the committee has been looking at reducing car weights, not increase them. To achieve this weight reduction, the 12W limit that currently stands may be brought down to 10W in 2011.

jhg wrote:Even the best designed cars may have trouble staying on. I'm sure Marc might disagree. =]

Whether I disagree or not probably doesn't really matter. Going off past years, it can certainly be done.

For a number of years up until 2003 the ballasting formula was: Panel weight = (Power - 4) x 220, where panels reading 4W or less would not be required to weigh anything.

As a result, a number of teams therefore made up lightweight panels weighing less than 100g and had them producing a little over 4W. This meant that the racing weights of some of these cars were down at as little as 400g or 500g. Just ask John. 2 of his sons took this approach in their last couple of years of racing.

These cars still managed to stay on while doing 17 something seconds on the old national track (that would be in the 16s on the current track) so you be the judge. The old national track was nowhere near as smooth as the the NSW one and so I can't see why teams would have any more problems this time around.

Marc

Oh and since we're on the topic of possible rule changes for next year, it's also looking like the 2 lap races in the finals will be scrapped for in 2011.

Hi Marc
I like the one lap rule change for all races, I think that will level the field and challenge those who rely on the high powered panels which can be an advantage over two laps at the nationals.
Andrew

So we will have best of 2 laps from quarter finals onwards for this year?

jhg wrote:So we will have best of 2 laps from quarter finals onwards for this year?

Yes, that's correct.

John and I are attempting to get the 2 lap races scrapped for in 2011 since a single ballasting formula just can't make things fair for everyone over the different race lengths. No one on the committee seems to have any real problem with the change and so it looks likely to be brought in for next year.

Marc

jhg wrote:John and I are attempting to get the 2 lap races scrapped for in 2011 since a single ballasting formula just can't make things fair for everyone over the different race lengths. No one on the committee seems to have any real problem with the change and so it looks likely to be brought in for next year.

This sounds like a good idea for the racing - although the two lap races are somewhat exciting, it is evident that the cars with the larger panel wattages appear to have an advantage (case in point us vs Blur)

As regards to the switch idea Jun posted regarding 8.8 I thing this would be a good idea. To be honest there was a certain excitement with the old series/parallel setups and racing back to the pits to gear up/down in changing conditions... Although the introduction of maximisers has changed the competitions structure and there have been faster times posted, it has removed some of the skill required in the pits... just my thoughts

There is currently a discussion about whether all races should be 1 lap including the final series which at present are 2 lap races.

There seems to be a view that a high powered panel offers a significant advantage particularly in 2 lap races.
Where did this idea come from ? It seems to have just materialized with no evidence to support it. In any case, if a competitor believed a high power panel is best why are they not using one. Even if this were the case it will no longer be as relevant in 2011 when the maximum panel power will be limited to 10 watts.

I am not convinced there is any significant advantage in using either a 12 watt or 6 watt panel or in a 1 or 2 lap race format. Why do I think this? Along with others on the National committee, I undertook significant mathematical modeling of cars when considering the new ballasting formula introduced for 2010. The results I obtained from this modeling are shown in table 1 below. Predicted race times are shown for both 6 and 12 watt panels in a 1 and 2 lap race. All modeling was conducted using parameters expected in a well designed and constructed car. (In other words a top car.)

Sun % Race time Seconds: 1 Lap Race Race Time Seconds: 2 Lap Race
6 Watt Panel 12 Watt Panel 6 Watt Panel 12 Watt Panel
100 15.30 15.75 25.60 25.65
50 19.70 19.55 33.45 32.40
20 33.00 32.95 59.95 58.90
TABLE 1
Nothing in it is there! Oh yes I hear you say look, the high powered car has a 1 second advantage in a two lap race at 20% Sun. Maybe it has, but it must be remembered that these results are only based on simulations, the times cannot be considered absolutely accurate + or- 3% would be a reasonable accuracy expectation. In any case how about the 6 watt panel winning at 100% Sun over 2 laps and then winning over 1 lap as well.

These predicted race times are so close it is unreasonable to draw any conclusion other than they look about the same, no panel power or race length has a clear advantage.
In order to obtain the best race time forget panel power and race length, it is critical that you design and build a “good” car. Table 2 below shows predicted race time increase based on a 1 lap race for the car modeled above at full Sun. (Unless otherwise noted.) Various parameters have been changed to give a feel for the effect they have on race time. Remember time difference for a 2 lap race will be even greater.

AREA CHANGE RACE TIME
COSIDERED TO "GOOD " CAR INCREASE Sec.
Aerodynamics Increase air drag by 12.5% 0.25
Increase air drag to = rectangular box body car 1.50
Solar panel Panel characteristics Fill Factor 0.65 1.1
Panel Temperature rises 10 Deg C 0.25
Electronics Bad set point or low efficiency 5% power loss 0.25
Steering No steering 0.25
Build accuracy 4 wheel non steering car axles 3mm off parallel 1.25
Motor selection Use Faulhaber 2224 6V instead of 2232 6V 1.20
Chassis weight Increase chassis weight by 100 gm. 0.25
( for race conducted at 15% Sun 2.5 )
TABLE 2
Frightening isn’t it component choice, bad design or poor build quality makes the choice of 6 watts or 12 watts or 1 or 2 lap races appear insignificant. If several of these are combined the effect can be huge. And these are only some of the things that can influence car performance. My observations of the aerodynamic properties of cars at the National event in Fremantle left me in no doubt that in most cases significant improvements were possible.

CONCLUSION:
With the predicted race times for the same car powered by panels of either 6 or 12 watts and racing for 1 or 2 laps being generally within the expected accuracy of the simulation, and both cars having predicted wins. The actual panel power and race duration cannot be considered significant. Car design and build quality however are crucial. This is where the significant performance variations come from.

I have always thought 2 lap finals were better, mainly because they introduce some additional design issues for competitors who if they wish to succeed at the top end of the competition should be capable of considering. Namely, aerodynamics and car stability. Races of 2 laps duration also increase the excitement and interest level for spectators. Up to date I have not seen any evidence to change my mind.

Sorry all,
My article on 1 and 2 lap races above has the tables all screwed up. Clearly it is not possible to copy from a word file without problems. I will post the tables when I sort out how to do so.

Hello Ian,

To save you from any hassles, I reckon that it'd just be easiest to leave the document as is and load it up as an attachment. Tony seems to have however already beaten you to the punch, as he loaded up your article a day or so ago along with one of his posts in the following thread:

2-lap-races-yei-or-nei-t406.html

Marc