Aussie solar car fastest in world

**See:

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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

Reply to
Phil Allison
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Sure is. The rolling resistance must be very low - high pressure tyres and minimal suspension.

velodrome.

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

Reply to
fritz

"fritz"

** 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

Reply to
Phil Allison

"Phil Allison"

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** Oops - the new record is 88 kph.

... Phil

Reply to
Phil Allison

It would have to be a lot less. This is why any serious human powered vehicle speed attempt is undertaken by a bicycle(usually recumbent) with fairings front and back if not a complete shell.

Reply to
terryc

** Nonsense.

The speeds and input powers are similar.

Means the drag force must be too.

... Phil

Reply to
Phil Allison

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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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Reply to
kym

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

Reply to
Phil Allison

...

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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Reply to
kym

" Kym is full of Horseshit "

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

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

Reply to
Phil Allison

Phil Allison wrote: ...

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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Reply to
kym

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

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

And backs mine up entirely.

At SPEED - the AIR drag is always way dominant.

** Wot absolute BOLLOCKS !!

You are totally BESOTTED with your stupid, wrong math.

...... Phil

Reply to
Phil Allison

Phil Allison wrote: [...]

--
[Read before writing:]
>On a bike with rider in tuck position air resistance with no wind
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Reply to
kym

" 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, d*****ad.

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

Reply to
Phil Allison

Phil Allison wrote: [...]

--
[Read before writing:]
>On a bike with rider in tuck position air resistance with no wind
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Reply to
kym

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

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

And backs mine up entirely.

At SPEED - the AIR drag is always way dominant.

** Wot absolute BOLLOCKS !!

You are totally BESOTTED with your stupid, wrong math.

DICKHEAD !!!!!!!!!!

...... Phil

Reply to
Phil Allison

snip>

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

Reply to
T.T.

** Like 211 kph !!

** 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

Reply to
Phil Allison

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 ) 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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Reply to
kym

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

Reply to
T.T.

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