Aussie solar car fastest in world

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**See:

http://bigpondnews.com/articles/Technology/2011/01/07/Aussie_car_breaks_a_world_speed_record_561319.html

79kph on only 1200 watts of DC input is VEEERY efficient.

Reckon that is no more air drag than experienced by a racing cyclist on a
velodrome.




....  Phil








Re: Aussie solar car fastest in world

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http://bigpondnews.com/articles/Technology/2011/01/07/Aussie_car_breaks_a_world_speed_record_561319.html
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Sure is.
The rolling resistance must be very low - high pressure tyres and minimal
suspension.

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velodrome.

Probably significantly less, the frontal area looks far smaller than a cyclist.


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Re: Aussie solar car fastest in world

"fritz"

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** Huh ??

You looking at the same pic as me??

I see two front wheels with fairings, a large pod at the back with the
driver in it and a dirty great solar panel shaped like an aerofoil.

The trick is in the "streamlining" -  a streamlined cyclist can go much
faster than a normal one.


....  Phil



Re: Aussie solar car fastest in world
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http://bigpondnews.com/articles/Technology/2011/01/07/Aussie_car_breaks_a_world_speed_record_561319.html
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suspension.
...

To overcome rolling resistance of a 1 tonne car 1 metre on normal tyres
on a road takes about 100 J.  To get it to 80 kph therefore takes around 2.2 kW.

Using BMX tyres as per many solar cars is not quite a factor of 2 better --
so 1.1 kW.

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Re: Aussie solar car fastest in world

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**  Even if true -  it has got nothing to do with the car in question or
when travelling at speed.


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** Absolutely nuts.

The drag experienced by the solar car or a cyclist is almost entirely due to
AIR resistance.

And that is not a linear function of speed.


....  Phil







Re: Aussie solar car fastest in world
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...

It's not a bad rule of thumb as it turns out. Rolling resistance
can go higher than indicated as the tyres heat up.

Rolling resistance for a bike with average tyres is sometimes taken as around
    .1 * m * v Watts.

Good racing tyres or "solars" might reduce the ".1" to ".05" or so.

So for m = 1000 kg, v = 22 m/s (80 kph) still gives 2.2 kW.
Very much in line with my original rule of thumb.

On a bike with rider in tuck position air resistance with no wind
is something like .4 * v^3 Watts. If possible to get to 80 kph
that would be 4.3 kW.

So a "car" going at 80 kph on 1200 W seems to not only out-perform
a good race bike but also seems to be meeting almost no air resistance
as per one comment.

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Ain't going to happen because there is no raw 'uncorrupted' data.

Re: Aussie solar car fastest in world

" Kym is full of Horseshit "

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** For Christ's sake  -   go learn some basic physics, dickhead.

The drag experienced by the solar car or a cyclist is almost entirely due to
AIR resistance.

And that is not a linear function of speed.


....  Phil









Re: Aussie solar car fastest in world
...
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I get it -- you can't read or understand anything that people write.

In the part you carfully clipped I showed the air resistance
at least for a bicyle is normally much greater than rolling resistance
and is a function of velocity cubed.

The rule of thumb in bike racing is the 2 are equal at around 20 kph.

A few years back a couple mates and I put a 10 kW electric motor in a
go-kart. It managed to do 1 km in around 17 sec. Luckily, we all survived.
Most of the go-kart didn't.

In any case, the report shows the car is "pretty good" with total power
comparable with just expected rolling resistance.

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If there was no warming or cooling trend, then the chance of 2007
being tied with 1998 [130 year record!] would be quite high.
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Re: Aussie solar car fastest in world

" Kym is full of Horeshit and a raving NUT CASE "



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** Contradicts your previous claims now carefully snipped out of sight.

  And  backs mine up entirely.

  At SPEED  -   the AIR drag is always way dominant.


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** Wot absolute  BOLLOCKS  !!

 You are totally BESOTTED with your stupid,  wrong math.




......  Phil




Re: Aussie solar car fastest in world
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Re: Aussie solar car fastest in world

" Kym is so utterly wrong he is entertaining "


"To overcome rolling resistance of a 1 tonne car 1 metre on normal tyres
on a road takes about 100 J.  To get it to 80 kph therefore takes around 2.2
kW."

 ** For Christ's sake  -   go learn some basic physics, dickhead.

The drag experienced by the solar car or a cyclist is almost entirely due to
AIR resistance.


BTW

On what planet does a solar race like the one in question weigh 1000 kg  ?

Jupiter ??

What planet is Kym from ???

Pluto ??



....  Phil




Re: Aussie solar car fastest in world
[...]

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Re: Aussie solar car fastest in world

" Kym is full of Horeshit and a raving NUT CASE "


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** Contradicts your previous claims now carefully snipped out of sight.

 And backs mine up entirely.

 At SPEED  -   the AIR drag is always way dominant.


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** Wot absolute  BOLLOCKS  !!

 You are totally BESOTTED with your stupid,  wrong math.

 DICKHEAD  !!!!!!!!!!



......  Phil






Re: Aussie solar car fastest in world

snip>
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Fast car.
Is there a mixup between seconds and minutes, or kilometres and metres, or a
missing decimal point or something?



Re: Aussie solar car fastest in world

"T.T."

The Plutonian wrote:

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** Like 211 kph  !!

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** The fastest class of Go Karts are the "Superkarts".

Fitted with a 95hp engine and being fully faired means they can reach over
250 kph.




.....  Phil





Re: Aussie solar car fastest in world

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I came to mock and I left better informed and astounded.
Thanks.



Re: Aussie solar car fastest in world
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It was pretty informal measuring, and we maybe were scared +/- a
couple seconds (10%) on the total time, but it's around there.
An avg of around 200 kph although it felt like Mach 1+.

You no doubt know electric motors have good torque at low revs
so you tend to get off the start line really well but then (at
least in our case) quickly hit a wall.

I have some notes as well as twisted metal out in the garage.
I looked at them before poor ol' NPD Phil got involved :). It's
definitely 17 and not 27. Some other numbers show the accel
maxed around 1G -- 0 to 60 kph in well under 2 sec -- levelling off
well before 10 sec into the best km. Snapped a few bolts that day.

As I said before, it was pretty scary even for bystanders. And that's on
a good day when the motor wasn't making loud noises and trying to screw
the 1/2 the vehicle up into a ball from the inside.

If you look around on youtube there is one neat vid from
a few years back with some mech eng academic in cal who built
what looks like a 50s classic  racecar (something like
<
http://housebroad.com/SpeedClassic/Blue_race-car.jpg)
with an electric motor I think much less than the 10 kW Lynch (100V/100A)
we were using and he was using it to blow away motorheads at trafficlights.

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Re: Aussie solar car fastest in world
[...]

While my little project was a few years back, I noticed this:

<http://www.lmcltd.net/index.php?mact=News,cntnt01,detail,0&cntnt01articleid=2&cntnt01returnid15%

where Top Gear made a 48v (!!) 4.8 kW Lynch motor-based quadcycle
beat a Mustang upto 100 mi/hr (for those what forget -- that's 166 kph).

Yea. There's a lot you can do if you don't give a damn how well
the batteries work after the first 20 seconds. :)

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Not true.
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Re: Aussie solar car fastest in world
" Kym is so full of Horseshit  - he is funny "


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<http://www.lmcltd.net/index.php?mact=News,cntnt01,detail,0&cntnt01articleid=2&cntnt01returnid15%
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** Read the article  -  sunshine.

 The 4.8 kW motor was removed and replaced with one capable of 120kW short
term.

 That's equal to 160 hp.

 And the mad, pommy wankers even blew that up.




.... Phil







Re: Aussie solar car fastest in world
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Here is the actual theoretical graph for the Sunswift car:
http://www.eevblog.com/images/projects/SunSwiftDragGraph.png
The rolling resistance and aerodynamic drag are equal at 60km/h
Drag is not a linear function of speed as you said. Rolling resistance
is linear.

Dave.

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