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aostling
08-14-2011, 09:41 PM
Every entry always thinks they have the fastest solar-powered car, before the race. My friend Dennis, who directed the solar car entry from Texas A&M when he taught there ten years ago, says "this time it looks like Stanford is right."

Here are photos of the car, taken (perhaps) on a street near Frank Ford's house.

http://news.cnet.com/2300-11386_3-10008946.html?tag=topStories

darryl
08-14-2011, 11:17 PM
That's pretty cool. Seems all the solar cars are stuck using a broad horizontal deck in general to mount the solar cells. Two or three square meters of sunlight would be enough to generate the 1500 watt level they talked about, and that's allowing for 'only' 50 % efficiency. I'd like to see them come up with something other than solar cells to generate the electricity. It's unlikely that the cells they're using are even 25% efficient- couldn't they use say a long parabolic trough, or even a pair of them, with tilting to track the sun, and garner more of the energy of the sun- or also, how about arranging the cells in a corrugated manner and shining the sunlight into the 'pleats'. This would require a special refractive coating on the cells, but could minimize the rejected sun energy as a bonus. Maybe there's another, more efficient way of generating an electron when you 'knock' photons sideways-

i want to see heat into electricity, not just light into electricity. While we're at it, why not heat into axle rotation, operating in parallel with the electric motor, not just electric propulsion.

Ah, you got me going a little bit there-

lazlo
08-14-2011, 11:59 PM
The amount of engineering that goes into these Solar Challenge cars is amazing, and the competition is fierce. We hired the team lead of the University of Kentucky solar car, which did really well at the Indy Brickyard Race.

You'll notice the University of Michigan team is dominant in many of the Solar Challenges, including the World Solar Challenge that Allan posted - they have a massive budget sponsored by Detroit. Over a million dollars/year, and a team of over 100 students (!)

The Indy race coverage, including so closeups of the chassis designs, start at 8:00 in this Discovery Channel article:

http://watch.discoverychannel.ca/#clip472968

Evan
08-15-2011, 01:13 AM
Using concentrators doesn't make it possible to "garner more energy". It just allows you to use many fewer solar cells although much more expensive ones. You are still limited to the max insolation of about 1000 watts per sq metre.

For that reason solar cars will never be practical. They are a good test bed for solar energy systems. Much more interesting that a few panels on the roof of the engineering college.

ikdor
08-15-2011, 05:36 AM
There have been teams using fresnel lenses and tilting panels, but I think the rules have changed to disallow them.
My old university Delft was always using triple junction GaAs solar panels, the last one with an efficiency of 34%. But the rules have also penalised that by allowing less area for GaAs panels.
So everybody is now back to silicon with something like 22% efficiency......
It is a lot cheaper though :D

Igor

Evan
08-15-2011, 06:14 AM
There is a lot to be gained by having the panels aimed at the sun at the right tilt. I wonder if anyone has considered building a car that can drive in any direction via pivoting wheels with perhaps a saucer shaped body? That wouldn't violate the no tilting rule.

ikdor
08-15-2011, 06:53 AM
Aerodynamics are king in this competition, if your vehicle body is tilted front to back air drag will be enormous.

This is an example of the lenses + tilting. We donated the actuation system for this car
http://conceptlicious.solarteam.nl/wp-content/uploads/2011/06/12850_168971664794_816664794_2705273_8283285_n.jpg

Igor

loose nut
08-15-2011, 09:11 AM
When are they going to build a practical car, these are of no use what so ever. The rules should be changed to a vehicle that can seat 5 + some cargo and then start developing new usable cars.

Isn't that what solar car development is suppose to be about.

aostling
08-15-2011, 09:55 AM
Photo #12 shows the sophistication of the steering. All three wheels must be steerable, else they could not fit within the narrow confines of the cowlings. The rear wheel has two modes, dynamic (for turning) and sailing, in which it can put the vehicle in a crabbed posture to face into angled headwinds.

As Evan mentions, solar cannot supply the bulk of the energy needed for a car. The competitions are teaching aids, rather fun I think.

lazlo
08-15-2011, 11:12 AM
When are they going to build a practical car, these are of no use what so ever. The rules should be changed to a vehicle that can seat 5 + some cargo and then start developing new usable cars.

They've tried that, Google had a high efficiency gasoline car competition, but it was boring, and they didn't get many participants.

These Solar Challenges are projects for mechanical engineering students, and a solar car has a great combination of engineering and system integration challenges.

Evan
08-15-2011, 12:17 PM
BTW, this looks like an ideal application for supercaps, if they are allowed. It sure would help with getting up the next hill and keeping the speed up through the shadows.

Abner
08-15-2011, 12:47 PM
LOL!! - loose nut - (I don't think they are going to invite you to the party.) Here they are having millions(!) of dollars of fun and you go and get all practical. :)

mike os
08-15-2011, 12:52 PM
while i appreciate the engineering & design that goes into this stuff I must say I think it a major waste of time energy & resources that could be put to better use designing "the next generation" real world transport rather than reinventing the wheel..... which is all this is.

loose nut
08-15-2011, 05:14 PM
LOL!! - loose nut - (I don't think they are going to invite you to the party.) Here they are having millions(!) of dollars of fun and you go and get all practical. :)

Sorry to be such a downer but in this day and age of the so called "greens" and faced with rapidly dwindling resources, I just think that it is time to start getting something useful from all this experimentation. Redoing the same type of race with basically the same type of cars over and over doesn't do much good. If this is done for training then they need to push the envelope a little more and get something useful out of it.

lazlo
08-15-2011, 05:23 PM
Redoing the same type of race with basically the same type of cars over and over doesn't do much good. If this is done for training then they need to push the envelope a little more and get something useful out of it.

How is that any different than the MIT mechanical engineering class where they build sumo robots, or robots that climb ropes?

Making incremental enhancements to existing products is not a good educational exercise. You have plenty of time to do mindless work when you enter the real world :p

Gravy
08-15-2011, 09:06 PM
Not to mention that this kind of commercially impractical, extreme experimentation is exactly what discovers new technologies.

If we only put money into improving proven salable designs, we'd all be using incredibly refined buggy whips while riding in our new 2013 Conestogas.

Gravy
08-15-2011, 09:28 PM
Sorry to be such a downer but in this day and age of the so called "greens" and faced with rapidly dwindling resources, I just think that it is time to start getting something useful from all this experimentation. Redoing the same type of race with basically the same type of cars over and over doesn't do much good. If this is done for training then they need to push the envelope a little more and get something useful out of it.

That really is a downer. The "greens" have been warning of "rapidly dwindling resources" since at least the 60's. Now people are blaming them for the problems that they have been trying to warn about.

aostling
08-15-2011, 10:46 PM
There are almost 200 golf courses in Phoenix and surrounding communities, and all the golfers use carts. I wonder if these golf carts could be powered exclusively by solar, charging their batteries while on the course and also when sitting unused at the clubhouse.

They might do this already for all I know I don't play golf.

loose nut
08-16-2011, 02:33 PM
Not to mention that this kind of commercially impractical, extreme experimentation is exactly what discovers new technologies.

If we only put money into improving proven salable designs, we'd all be using incredibly refined buggy whips while riding in our new 2013 Conestogas.

20 years ago these experimental cars where just about the same. Maybe some better electrics and more efficient panels now but they still seat one and have no useful practical tech. in them. They need to focus on a more useful type of vehicle and advance from there.

Evan
08-16-2011, 03:07 PM
The end product isn't the main point. It is a team design exercise for would be engineers. It also requires the students to actually build what they design and that is the most valuable part of the exercise. They not only learn to work together but they also learn how to design something that is buildable within the contraints they are permitted. It's all about teaching engineering, not about making better solar electric vehicles. Trying to make it better than those before introduces a competitive aspect which is a strong motivator.

mike os
08-16-2011, 05:59 PM
only problem is they are reinventing the wheel, not making anything "new" or "challenging"...this project is only about hype and advertising not engineering or even research.

We know we can make solar "cars" ... for want of a better term, perhaps toys is a better one as they have no real world use whatsoever...., and we know they can be reasonably quick, but unless there is a significant advance made somewhere ( in PV or motor design) it is old news.

Now someone developing a significantly better solar system making the car 3x faster or able to take 2 plus luggage, that would be both a sucessful research project and news

lazlo
08-16-2011, 06:16 PM
only problem is they are reinventing the wheel, not making anything "new" or "challenging"...this project is only about hype and advertising not engineering or even research.

I can assure you that is not the case. Each generation of solar challenge vehicle has considerably better performance than the last, and if you watch the video I linked, the (international) competition is fierce.

These solar cars are marvels of mechanical/electrical/control design. Everything is instrumented like a Formula 1 race car.

I think your opinion may be biased by an "anti-greenie" slant, but these races are not about saving the environment. Like the various solar aircraft challenges (the Gossamer Albatross's historic solar-powered flight across the English Channel, for example), it's about building a very sophisticated integrated system, within the budget constraints of a typical university.

Solar Powered Aircraft
http://www.pvresources.com/en/helios.php

Evan
08-16-2011, 07:47 PM
only problem is they are reinventing the wheel, not making anything "new" or "challenging"..

Absolutely. It's the only way to provide a yardstick of how well they did compared to others. Doing original research is for later.

mike os
08-17-2011, 04:04 AM
now gossamar albatross was a new and creative project, pushing the boundaries of what was thought possible, ditto solar impulse and centurion

no green issues with these cars, they are nothing of the sort, toys & no different to a uni deciding to build a nascar contender...

ikdor
08-17-2011, 04:36 AM
only problem is they are reinventing the wheel, not making anything "new" or "challenging"...this project is only about hype and advertising not engineering or even research.

We know we can make solar "cars" ... for want of a better term, perhaps toys is a better one as they have no real world use whatsoever...., and we know they can be reasonably quick, but unless there is a significant advance made somewhere ( in PV or motor design) it is old news.

Now someone developing a significantly better solar system making the car 3x faster or able to take 2 plus luggage, that would be both a sucessful research project and news

As Evan pointed out these competitions are designed to make better engineering students. Instead of just doing some calculations they have to do real systems engineering and design for manufacturing. And even though there is not much research performed in these projects, a tremendous amount of engineering goes into them.
I only have personal experience with formula SAE projects, but the larger teams there have 50 people spending months on (over)engineering every single component. By just looking at the end product, it's impossible to understand the amount of engineering that goes into them.

Your suggestion of making a solar car that seats 2+luggage is no research whatsoever, just engineering. It's also not news, as there has been such a class running alongside the fast cars in the world solar challenge in Australia for years.

The problem is that it isn't as sexy. So the news doesn't care and the students all want to work on the fast cars.

Regarding 24/7 access to university machine shops;
Note that for instance in Delft University, the machine shop for such student projects is owned by the student teams themselves so they have 24/7 access. A necessity as things always break at the last moment. The students themselves are responsible for safety and take it serious.

For your entertainment:
http://dutracing.nl/?lang=en
http://www.nuonsolarteam.nl/?lang=en

Igor