jhg:
Firstly, I'm a year 12 student so I don't really need the advice, but thanks anyway. I'm also considering writing up an article on the principles of solar car design, with some stuff on project management in there as well. BHHS results this year were rather poor, so those need to change.
Secondly, re mill drill: I was describing my team's chassis construction method, not wheels. BHHS is probably one of the best equipped schools in the state for solar car, we've got a few drill presses, proper electronics benches, 2 mill drills, and a pair of lathes.

Finally, we got the whole race with the crash on video, plus plenty of pictures. I promise to post them up soon here, along with some pics of my team's cars over the years.
Just for clarification, Killswitch is a front-wheel drive three-wheeler design, using a Carbon Fibre frame with heavily sanded foam side panels (prolly only about 5 mm thick at the most). It's optimised mainly for low weight, not neccesarily structural integrity . We decided that if we can't make it strong and light, it may as well be light and easy to repair: hence the overnight repair job.

We look forward to seeing you at the nationals this year in Melbourne, perhaps we can talk more there?
Cheers.

PWK! Comments I post up are not fully addressed to you but the general public!

PWK! I know BHHS is one of the best equipped schools. I would have guessed it to be the best in the whole Australia. Our school is more of a trade school, so we used most of the equipment from the D&T department. Although we often bothered our science technician which has is his own small press drill. His taught us a lot in 2007 and 2008. But this year we didn't seek his advise as we often don't see eye to eye. Girrawheen SHS doesn't even have 1metre of track, so we are actually drawing on luck and hoping our theory base is sufficient. In two years you learn a lot. After that you don't really need to do testing before because you should know the design principals. (i.e where the guides should be located etc...)Some of the private schools in WA have a full track to play with! We won a total of $750 this year, but i don't know where that's going towards next year. In 2007 we had around $1000 to play with and 2008 an additional $1000. Thats all the finance that we have received. In 2007 we won a panel for best poster from Western Power, so that saved $200 for 2008. This year we didn't spend much. I spent around $40, on new balsa (2 sheets of 1mm thick because our school doesn't have that size) carbon fiber rods, 8 new bearings (at $1.30 each),more loctite glue and contact sheeting for our cars. We bought heaps of foam in 2008 ($150 worth) however at the size of 75mm. This year the cars had to be 100mm, so we simply cut and placed pieces on top. Yes, our bodies are like Killswitch's, thin!

I can't wait to see your images and videos.
I sent Marc and John a 5sec clip of my unfinished design to show them the rolling resistance and to ask if my kitchen bench was really that uneven. I place a 2litre bottle on top of my car and it started to roll on our apparently not even kitchen bench used for cooking! Don't worry. The design isn't that good. It started to roll due to the force and the positioning of the front wheel. Also the gear and motor haven' t been set up (unfinished) - hence less friction!

I might not have time to talk at the nationals because I'm the only team member from my car going! If I can convince the other boys to race my car then, I'll be around talking to as many people as I can. Where was the VIC competition held?

Anyone - Address Please!

HI jhg,

jhg wrote:Some of the private schools in WA have a full track to play with!

At Aquinas we don't have a proper track, we just nail the PVC guides into an outdoor basketball court. It's just a basic oval shape (about 75m in length) It's far from ideal as the surface is quite rough and the extra friction results in different optimum gear ratios.

jhg wrote:We bought heaps of foam in 2008 ($150 worth) however at the size of 75mm.

I can see from the picture that Horizan 3 is made from balsa wood, is it the same for Explora or is that one foam?

jhg wrote:I might not have time to talk at the nationals because I'm the only team member from my car going!

Is Girrawheen going to be racing two cars or just one? and are any other WA schools going apart from those in the top four?

Looking forward to Melbourne...

Redlands, nice to hear from you! At least I know people are paying attention to detail!

Where do I begin!

Ok, not all the private schools then! Guildford G. have a full track (2lanes). Well that's what I have seen in photos!
Yes you are right to state that Horizon 3 is Balsa. This is my car and i prefer working with it. Although foam is lighter if you shave it down to 5mm after you have hot wired most of it! We add contact sheeting like most schools which adds roughly 10-15grams. Thats why our cars look dodge. Our sanding isn't the best of craftsmanship. Even Horizon 3 has normal sticky tap over it which adds roughly the same amount. Although this composition allows the balsa to break but still retain its shape. For example Winthrop B.C. cars back has a big hole. (they're fixing it up for the nationals) However in our case our balsa will remain there although broken! For what I have heard, it's only the top four schools going. How many students are going from your school. I have seen the list, there's like 28-29 bookings in total, teachers and students. We're sending five students. But what I think your wondering about is that extra Wild Card position! Sorry, I've been asking Thuy and the national coordinators for weeks. Thuy last week told me that we can have a second car enter from Girrawheen because of our state performance and only due to the rule were we not able to get another car in the top four. Like other schools which also had a few cars in the top 8. Thuy had to ask both the national coordinator as well as the Western Powers head scrutineer Fred Adler! I reckon I was in Fred's good books and he knows our school has a good chance of winning. His given us a lot of advise as well as a lot more "bull dust" especially making up his own regulations in the 2009 competition, so he may have favored me in the decision process. Although he could have easily have gave the position to Belridge as they were seeded second!

jhg wrote:Yes you are right to state that Horizon 3 is Balsa. This is my car and i prefer working with it. Although foam is lighter if you shave it down to 5mm after you have hot wired most of it! We add contact sheeting like most schools which adds roughly 10-15grams. Thats why our cars look dodge.

So Explore is made from foam?

and what do you mean your cars look dodge? I thought they were very well presented. Explora looked pretty sharp in that nice green... however nothing can compete with red&black

jhg wrote:How many students are going from your school.

Definitely five at the moment, probably another 3 aswell so that will make 8. We have some younger guys (year 8 and 9) that want to come along.

Nice, if the year 8/9 come along then it will be a good opportunity for them to ask me questions and get a head start in next years competiton.

Yes Explora is made out of foam, so was Burst Limit. What I meant by dodgy was how the contact was placed over the foam. How did you guys get yours so perfectly! Yes, we thought about colour issues. We couldn't chose Red, Yellow, Blue etc because that's what Aquinas, Belridge and Morley use respectively.

So what adjustments have you made with your car. My advise, don't change much to your design. What you need to do is research on your solar panel. This is most probably where your car is letting you down. Explora had the best Wattage to max voltage ratio for our maximizers! Thats why it performed better than all the other cars, along with the 4wheel configuration which is dominating this years competition. All our other cars had a solar panel less favorable to our maximizer. Do you know the your panel readings?

jhg wrote:Yes, we thought about colour issues. We couldn't chose Red, Yellow, Blue etc because that's what Aquinas, Belridge and Morley use respectively.

aha yes that it true. the question is did you like the black lighting bolt?? (I do all the liveries at AC, the last two years I wanted all 3 cars the same but this year decided to go with 3 different designs) I can come up with something for your car if you like!

In terms of the car I don't think much is going to be changed.

Bring a extra panel! We had two dodgy modules last year and then had to use Belridges which was crap!But it was better than nothing! If you can get your hands on 9-10 DSE your car will perform better! With your EasyMax I would used 10 DSE with a gear ratio of 1:6. After that you should be set to go for the two day! However if you can't I'll see what gear ratio I would use, if I had your car! Conitsiotis was suppose to get back to me with the readings, but I'm sure it won't take 5minutes to work it all out on Saturday...

Explora wasn't my car! So I'm not the one to talk to about appearance of the car! I raced Horizon 3. I was quite disappointed how they beat me! Especially because Explora was my design from 2008 which never entered the competition because i never thought it would perform so well. I gave them my proto-type which they manufacture this year!

All I can say is, Explora is going down at the nationals with a new Horizon 3 (or should i say Horizon 4 which will have a casting back wheel). I'm hoping it will perform as good as Marc's demo car. Which made it over the TAS track in less than 25% sunlight when most cars wouldn't!

Horizon 3 is made out of Balsa so unless you cover it I guess that means no livery

jhg wrote:However if you can't I'll see what gear ratio I would use, if I had your car! Conitsiotis was suppose to get back to me with the readings, but I'm sure it won't take 5minutes to work it all out on Saturday...

Yeah I'm sure we'll have plently of time to sort it out

jhg,

Based on the earlier plots, then yes, I would be going for the higher voltage panel if I had two panels to choose from.

If the output power would have been the same for both the parallel and series panel configurations (or higher vs lower current) then the torque plots would be identical apart from the earlier rpm drop-off of the parallel one.

Adding that extra cell to give you a 10 cell dicksmith panel is a good move I feel. Because there are about 4 different types of dicksmith segments, it'd be best if you just measured your panel to find its exact mpp. I will expect it to be at about 13 to 14 volts. The extra cell should also increase your top speed with the gear ratio that you are currently using.

It is true that a lot of the cars had their panels' mpp at only 11 or 12 volts last year. This should still be OK, but they may have performed that ever so slightly bit better with a higher voltage configuration. Having the mpp at 13V or 14V instead might make a small difference. Who knows exactly.

Remember that the earlier plots show the differences between almost two extremes in panel configuration (doubling or halving voltage). Since changing from 11V to say 13V is somewhat less, the differences will also be much smaller.

Whether it will be superior or not to your other panel remains to be seen. If the sun looks like its going to be around, choosing the panel with the best FF may be more effective.

The main reason why Belridge and Morley performed so well in low sun conditions last year may have been because of how they had set up their gearing. When the sun came out however, this was no longer optimal and both cars were hitting their top speeds too early on and started entering into the high end power drop-off region.

As for cars and wildcards, I will keep you updated. I will be sorting out and allocating numbers to cars over the next couple of weeks. If there is still a spot or two open, I will let you know. WA looks like having 5 official entries.
Depending on the number of international entries, I have suggested to the national commitee's chairman that we leave a few on-the-day wildcard positions open. If there are then more cars than available positions on the day, a series of race-offs will then determine who they are given to. This was done in Hobart last year.

miseli

Thanks Marc
No, I don't agree with you. I heard every comment they made about their gear ratio. I was listen to Fred telling the students what ratio to use. Cheating but oh well! You can't really stop it. There were schools getting help from teacher adjusting their maximizers. I will send you a private email, suggesting what I know about this performance in low sun conditions. I shouldn't be saying much because it could just give us the edge in winning! Who knows what the conditions will be in Melbourne on race day!

However all my knowledge will be available in an article I plan to write after the Nationals. I still have to test theories before I can state my crazy opinions!

Hi All,

jhg wrote:Conitsiotis was suppose to get back to me with the readings,

Sorry about the late response, I'm sorry but i dont have any great specs. I think we use cells that I haven't seen any other schools using at either nationals/state levels over the past three years. Our Panel outputs roughly 6.1W, with a higher voltage and lower current. I will however endevour so get back with the full specs sometime in the near future.

With regards to what we are flying the cars over in we have come by a kind of padded suitcase for the car and are looking at custom building one for the panels.

Were going to make boxes out of foam(the 75mm that we have so much of) and carry it on the plane. I don't trust the airport workers! As we will have a few boxes, they might get suspicious that we're planning a terrorist attack our something. I'm sure they're going to stop us and check each box if not for explosives, drugs. lol!

I just need the max voltage!

jhg,

Looking back on the semi final video footage between Boxhill and Belridge you may be correct to some degree. The difference between the two was less than what I remembered.

The fact however is that both Belridge and Morley did lack top speed slightly. Whether this was because of a slightly out gear ratio, electronics setting, less efficient aerodynamics or something else, we will never know exactly.

miseli

miseli

I also had a look at the race, it was really close. I'm worried that Killswitch is going to upset our cars at the nationals! Exactly, we will never know! But we can guess!The timing for the clips are out right? Two laps in 30seconds, that means the time is 15second each lap. So the timing is off? (record is in the very low 16sec mark) although the 2008 demo record a 15... in 108%! Comment video/ youtube wiz's

jhg,

The timing is correct. The first lap is close to 95m. The second 86m. The cars enter the second lap at pretty much top speed and so the second lap obviously takes a lot less time. The cars can reach speeds of around 8m/s or so, so that'll be the second lap done in a bit over 10 seconds. With a 16 second 1st lap, times around the 26 or 27 second mark should be possible. I wish I would have got a 2 lap time of the demo car.
If you have looked at the results spreadsheet from last year then you will find that NFG posted the fastest 2 lap time of about 28 seconds. It's a pity the timer doesn't have intermediate time splits so that the exact times for the first lap could also be known.

John is actually making up a new timer for our track which will show intermediate times too. Once he has it completed it might very well be used at the national event as well. He was also thinking about timing the cars over a short distance and displaying their final velocities.

miseli

the syndalsp south team did well and i was in the team!

Yes, congratulations nader.

It's a remarkable achievement for a primary school to beat the older students from some of the much more fancied High schools and Colleges. Well done.

I have seen some photos of both Syndal South cars and I think you have done a good job with them. In fact, I will load up the scrutineering pics that I have.

miseli