Interesting Aerodynamic Cars (Mike Vetter's ETV, also Avion)

[aerohead]

I like the car very much! And it IS a race car,so it's been optimized for the race course(s).
It looks very stable.It looks like Australian land trains won't blow it off the road or flip it over,as has happened with some solar cars.
The integration of the windshield into the body is as good as I've seen,and this car,like the Arivett Bros. streamlined dragster,may actually have a lower Cd than 0.14 when in a crosswind.The bulbous nose beats everything in a crosswind,and since we rarely have days without wind,designing for yawed flow is smart engineering.If that's the case.
Since there are no photos in true-length,it's hard to 'see' what's been done.And without X-Ray vision its hard to know the strategy behind why it was done the way it is.
These teams will provide the driver with weather data,having them outrun storms when necessary,take advantage of wind conditions when they avail themselves,and maximize battery management,solar charging,etc..
Winning will take more than just the car.
Changing flat tires can make or break a race.
I'd like to see if the batteries are in those thick wheel fairing sections,attempting to get the C.G.as low as possible.

[Cd]

There is a Flash video of the car showing the Cd dipping below .14 as the car is being tested in a wind tunnel.
I'm still trying to find where I saw it . ( I seem to remember on their main site )

[NeilBlanchard]

The red lines are on the area where I suspect is causing the most drag:





The sides should come to as sharp an edge as the top does, and the curve should be larger radius. The rear wheel track should be narrowed to allow the sides to taper in, and the rear wheel strakes could be narrower.

[kach22i]

That rear shot is a real tease in certain ways. The front wheels are turned, but no photos of the front wheels fairings (when cocked) from other angles are yet posted.

EDIT:
Saw the other thread on this car, fairing mystery solved, see video.

http://www.youtube.com/watch?v=iNZZl...layer_embedded

NOTICE
Go to this thread below for more discussion about this car.

Q:What is this car? A: SolarWorld GT (Cd 0.14 solar car going around the world)

[aerohead]

Originally Posted by NeilBlanchard

The red lines are on the area where I suspect is causing the most drag:





The sides should come to as sharp an edge as the top does, and the curve should be larger radius. The rear wheel track should be narrowed to allow the sides to taper in, and the rear wheel strakes could be narrower.

Looking at the university's earlier cars indicates that these folks are plenty acquainted with how to get low drag.
Without a look under the skin I'm not gonna try 'n guess about the design.
Many of the past solar champions had Cds of 0.13,0.12,and 0.10 (HONDA Dream 2),so there seems to be a specific reason for the 0.14 compromise.
I'm gonna go to Fort Worth to T.C.U. on the 23rd and have a look.
Years ago,the N.American Solar Challenge came through Weatherford College,Texas and all the cars pulled there bodies off to orient into the afternoon sun to charge for the next day's run.
There should be ample time to look at the guts of the car.
One thing to mention.All the cars a few years back ran Bridgestone's Ecopia Solar Race 20" race tire exclusively.These tires are slicks,are very gummy,and have a useful lifespan of only 200-miles before they must be changed.
Having easy-to-get-to wheels,even if they cost extra drag,could provide a competitive edge in competition.Everyone has seen pit-stops at Indianapolis 500 and NASCAR,yes?

[NeilBlanchard]

These are Michelin tires, I think. These panels come off the same way -- there are photos from New Zealand showing this. And I'm sure the basic chassis is tube steel and the shell is fiberglass (or carbon fiber). Some of the videos have brief glimpses of the car and the battery, etc.

I'm glad you will be able to see the car in person -- I hope you can get the side, front, and rear long angle photos that show the true shape.

[aerohead]

Originally Posted by NeilBlanchard

These are Michelin tires, I think. These panels come off the same way -- there are photos from New Zealand showing this. And I'm sure the basic chassis is tube steel and the shell is fiberglass (or carbon fiber). Some of the videos have brief glimpses of the car and the battery, etc.

I'm glad you will be able to see the car in person -- I hope you can get the side, front, and rear long angle photos that show the true shape.

My camera is a non-SLR with only 10X optical zoom,so no telling what I'll be able to pull off.If the cars park close together as they did at Weatherford,I may not get decent shots at all.
I have an old 35mm SLR film camera with interchangeable optics.I'll see if I can resurrect it.I think that film is still available.
I hope Michelin has improved on the old tire.I believe that pit-stops were mandatory at each 200-mile interval to allow for new rubber.
PS,I ran some numbers on the 1993 Honda Dream 2 and am going to do a separate post so everyone will have access to the figures.

[Frank Lee]

Some racers report getting thousands of miles out of those tires, and some report excessive failures. The ones getting good life say the ones that aren't may have chassis issues (like poor geometry resulting in scrub) or they burn out on accel, or lock 'em up on braking, so of course the ones that don't take care of their tires are going to have more problems. Some of it may be dumb poor luck i.e. hitting hazardous to tires potholes and debris. It may be possible that the racers are hugging the shoulder- where more hazards lie- more than regular vehicles due to their speeds and others wanting to pass.

[aerohead]

Originally Posted by Frank Lee

Some racers report getting thousands of miles out of those tires, and some report excessive failures. The ones getting good life say the ones that aren't may have chassis issues (like poor geometry resulting in scrub) or they burn out on accel, or lock 'em up on braking, so of course the ones that don't take care of their tires are going to have more problems. Some of it may be dumb poor luck i.e. hitting hazardous to tires potholes and debris. It may be possible that the racers are hugging the shoulder- where more hazards lie- more than regular vehicles due to their speeds and others wanting to pass.

You'd think that for all the trouble they go to to create and race these things,that they'd have everything dialed in to a knat's --s.

[Frank Lee]

Quality of engineering varies wildly on student projects, from the expertise and involvement of the advisor(s) to the random chemistry of the group of students working on it. I can see subtleties of suspension design "slipping through the cracks".