Aussie solar car fastest in world

kym@kymhorsell.com wrote:
[...]

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&cntnt01returnid=15>

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.

--
[Full metal rebuttal:]
Not true.
-- John Stafford <nhoj@droffats.net>, 08 Dec 2010 10:16:59 -0600

 

[Phil Allison]

" Kym is so full of Horseshit - he is funny "

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&cntnt01returnid=15

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).

** 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

 

kym@kymhorsell.com wrote:
[...]

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&c
ntnt01returnid=15>

where Top Gear made a initally 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.

--
[Full metal rebuttal:]
Not true.
-- John Stafford <nhoj@droffats.net>, 08 Dec 2010 10:16:59 -0600

 

[terryc]

Phil Allison wrote:

"terryc"
Phil Allison wrote:

Reckon that is no more air drag than experienced by a racing cyclist on a
velodrome.
It would have to be a lot less.


** Nonsense.

The speeds and input powers are similar.

Means the drag force must be too.

I sure hope your understanding of electrical matters isn't as poor.

 

[Phil Allison]

"terrycunt"

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

It would have to be a lot less.


** Nonsense.

The speeds and input powers are similar.

Means the drag force must be too.

I sure hope your understanding of electrical matters isn't as poor.

** Power = Force x speed.

Most 12 year olds know this.

How old are you ?


..... Phil

 

[SFD]

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:8otuvrF54bU1@mid.individual.net...

"terrycunt"

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

It would have to be a lot less.


** Nonsense.

The speeds and input powers are similar.

Means the drag force must be too.

I sure hope your understanding of electrical matters isn't as poor.


** Power = Force x speed.

Most 12 year olds know this.

How old are you ?


.... Phil

Wot if they ate baked beens the nite b4 then lit a match upon take-off!

 

[fritz]

"David L. Jones" <altzone@gmail.com> wrote in message news:28f567e6-3313-4578-be40-67e41787fa63@y19g2000prb.googlegroups.com...
On Jan 9, 10:43 am, "Phil Allison" <phi...@tpg.com.au> wrote:

**See:

http://bigpondnews.com/articles/Technology/2011/01/07/Aussie_car_brea...

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

Congrats to Irving and the rest of the Sunswift team, awesome effort.
Hopefully I'll be doing a video blog tour of the Sunswift racer at the
end of this month.
If anyone wants me to show any particular area in detail, or ask any
specific questions, then let me know.

For those interested in some details, at 90km/h the aerodynamic drag
accounts for over 70% of the driving power. The rest of the required
power is directly proportional to the mass of the car. The base
chassis weighs only 50kg.
Also, the breaks can stop it from 50km/h in under 10m.
The whole car weights 165kg, including the 25kg battery pack, so the
record attempt car weighed only 140kg.
The wheel motor is over 97% efficient.
The tires are inflated to 90psi and are easy to puncture, so are
usually changed every day.

Dave.
----------------------------------------------------------------------------------------------------------

A couple of specific questions on the Sunswift..
What is the frontal area (A) of the car ?
What is the drag coefficient (Cd) of the car ?
How does the drag area (CdA) compare to a racing bicycle ?

 

David L. Jones <altzone@gmail.com> wrote:
....

79kph on only 1200 watts of DC input is VEEERY efficient.
....
For those interested in some details, at 90km/h the aerodynamic drag
accounts for over 70% of the driving power. The rest of the required

So air resistence is equiv to 840 W. The math then shows the
friction coeff is .05; an effective profile almost 10 times better
than my old electric kart project which was around that for a
bike + rider in race mode.

From the rough calcs before, it certainly seemed air resistance
was very low.

power is directly proportional to the mass of the car. The base
chassis weighs only 50kg.
Also, the breaks can stop it from 50km/h in under 10m.
The whole car weights 165kg, including the 25kg battery pack, so the

Rolling resistence around 360 W. My old formula with race tyres would
have it .05*m*v == .05*(165+80)*55 = 674 W. The tyres used were
apparently 2x better than Michilin "solars".

record attempt car weighed only 140kg.
The wheel motor is over 97% efficient.
The tires are inflated to 90psi and are easy to puncture, so are
usually changed every day.

Thanks for the details.

--
[...] I want you to acknowledge that AGW is only one possible reason
for temperature increase, out of a number of possible reasons.
-- No Pressure <no.pressure.at.all@gmail.com>, 7 Dec 2010 02:31:55 -0800

 

[David L. Jones]

On Jan 9, 10:43 am, "Phil Allison" <phi...@tpg.com.au> wrote:

**See:

http://bigpondnews.com/articles/Technology/2011/01/07/Aussie_car_brea...

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

Congrats to Irving and the rest of the Sunswift team, awesome effort.
Hopefully I'll be doing a video blog tour of the Sunswift racer at the
end of this month.
If anyone wants me to show any particular area in detail, or ask any
specific questions, then let me know.

For those interested in some details, at 90km/h the aerodynamic drag
accounts for over 70% of the driving power. The rest of the required
power is directly proportional to the mass of the car. The base
chassis weighs only 50kg.
Also, the breaks can stop it from 50km/h in under 10m.
The whole car weights 165kg, including the 25kg battery pack, so the
record attempt car weighed only 140kg.
The wheel motor is over 97% efficient.
The tires are inflated to 90psi and are easy to puncture, so are
usually changed every day.

Dave.

 

[David L. Jones]

On Jan 9, 1:04 pm, "Phil Allison" <phi...@tpg.com.au> wrote:

k...@kymhorsell.com



To overcome rolling resistance of a 1 tonne car 1 metre on normal tyres
on a road takes about 100 J.

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

To get it to 80 kph therefore takes around 2.2 kW.

** 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

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.

 

[Phil Allison]

"David L. Jones"

Here is the actual theoretical graph


** WTF does " actual theoretical " mean ??

It simply cannot be both things.


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.

** Rolling resistance is linear - in theory only.

Odds are it diminishes at high speeds since the tyres are subject to large G
forces thereby reducing contact area and hence loss of energy by deformation
PLUS that solar array looks like a wing and so it must have some lift.


...... Phil

 

[Phil Allison]

"David L. Jones"


For those interested in some details, at 90km/h the aerodynamic drag
accounts for over 70% of the driving power.


** Thanks for that confirmation of my original opinions.

The heretics here are seriously looney.


BTW

The actual drag force on the solar car from all sources at the record speed
( 88kph) amounts to no more than 5kg.

1200/24.4/9.8 = 5



..... Phil

 

[David L. Jones]

On Jan 10, 12:11 pm, "Phil Allison" <phi...@tpg.com.au> wrote:

"David L. Jones"

Here is the actual theoretical graph

**  WTF does " actual theoretical " mean ??

    It simply cannot be both things.

Of course, my bad.
I meant that this is the theoretical power requirement graph from the
actual Sunswift car used.

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.

** Rolling resistance is linear  -  in theory only.

Odds are it diminishes at high speeds since the tyres are subject to large G
forces thereby reducing contact area and hence loss of energy by deformation
PLUS  that solar array looks like a wing and so it must have some lift.

All the various external surfaces are aerofoil wings, mainly to reduce
drag and tail vortexes et.al. No lift figures are mentioned.
The graph is the theoretical power required to drive the car based on
total rolling resistance and aerodynamic drag figures. Presumably they
are using known measured test data for both of these, and it kind of
implies that in the document I have.
It is stated they have measured these parameters and use them in a
real-time simulator model to enable optimisation of the cars energy
consumption vs performance etc.

From the documentation it sounds like the rolling resistance is not
insignificant and is split into two components, tires and "bearings
etc".
In a formula provided, the tire rolling resistance and the wheels
bearing resistance are both included.
The tire rolling resistance term is: mass * gravity * rolling
coefficient
The bearing resistance term is: Number of Wheels * bearing coefficient
* velocity

Dave.

 

terryc <newsninespam-spam@woa.com.au> wrote:

Phil Allison wrote:
Reckon that is no more air drag than experienced by a racing cyclist on a
velodrome.
It would have to be a lot less.
[...]

Suspicion seems to be confirmed.

The actual data indicates the streamlining was almost 10x better than a
race bike. No wonder the total power was comparable to just the rolling
resistance of other electric cars.

--
[Specific learning difficulties:]

2.2 kW.
On a bike with rider in tuck position air resistance with no wind
is something like .4 * v^3 Watts [...] 4.3 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.
And that is not a linear function of speed.
-- "[NPD?] Phil Allison" <phil_a@tpg.com.au>, 9 Jan 2011 13:28 +1100

 

[Clifford Heath]

On 01/10/11 13:05, David L. Jones wrote:

On Jan 10, 12:11 pm, "Phil Allison"<phi...@tpg.com.au> wrote:
Odds are it diminishes at high speeds since the tyres are subject to large G
forces thereby reducing contact area and hence loss of energy by deformation

I doubt that has much effect actually, especially with the very high tyre
pressures used on this kind of vehicle.

PLUS that solar array looks like a wing and so it must have some lift.
All the various external surfaces are aerofoil wings, mainly to reduce
drag and tail vortexes et.al. No lift figures are mentioned.

Highly unlikely they've designed-in any lift. You can't get lift without
drag. In fact the main figure of merit for sailplanes is L/D ratio,
because that tells you how much of your drag is actually producing lift.
It also happens to give you your sink angle.

Clifford Heath.

 

[Phil Allison]

"Clifford Heath"
"Phil Allison"

Odds are it diminishes at high speeds since the tyres are subject to
large G
forces thereby reducing contact area and hence loss of energy by
deformation

I doubt that has much effect actually, especially with the very high tyre
pressures used on this kind of vehicle.

** Really ??

90 psi is only 6 atmospheres.

88 kph results in about 250Gs on the surface of the tyres.

A = V squared / radius

G = A / 9.8

PLUS that solar array looks like a wing and so it must have some lift.
All the various external surfaces are aerofoil wings, mainly to reduce
drag and tail vortexes et.al. No lift figures are mentioned.

Highly unlikely they've designed-in any lift. You can't get lift without
drag.

** Not unlikely at all.

Even a small amount of lift would reduce rolling resistance as much as
removing the batteries did.


... Phil

 

[Phil Allison]

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

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

It would have to be a lot less.

Suspicion seems to be confirmed.

** Not one tiny bit is has !!!!!!!!!!!!!

Power = Force x speed

FUCK OFF to HELL

YOU LYING PILE OF INSANE SHIT !!!



.... Phil

 

[fritz]

"Phil Allison" <phil_a@tpg.com.au> wrote in message news:8ovo90FkcU1@mid.individual.net...

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


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

It would have to be a lot less.

Suspicion seems to be confirmed.


** Not one tiny bit is has !!!!!!!!!!!!!

Power = Force x speed

What is the relevance of that equation ?

The topic is air drag. Otherwise known as frontal area (A) times drag coefficient (Cd)
Specifically, the air drag of the Sunswift vs. a racing cyclist.
Preliminary investigation indicates that the Sunswift does have a much lower Cd, although I await
further data to confirm that the Sunswift has less total air drag (CdA) than a racing cyclist.

 

[Clifford Heath]

On 01/10/11 17:41, Phil Allison wrote:

"Clifford Heath"
"Phil Allison"
Odds are it diminishes at high speeds since the tyres are subject to
large G
forces thereby reducing contact area and hence loss of energy by
deformation
I doubt that has much effect actually, especially with the very high tyre
pressures used on this kind of vehicle.
** Really ??
90 psi is only 6 atmospheres.
88 kph results in about 250Gs on the surface of the tyres.

From another post, the record attempt car weighed 140Kg.

The Michelin solar car competition tyres have a rolling resistance
coefficient of around 0.0025 - meaning the actual resistance force is
about 3.4N. To carry 140Kg across the three wheels at 88KPH requires
about 80 watts.

Assuming equal loading on the wheels of about 450N, at 90PSI, the
contact patch is about 7.5cm^2.

Estimating the total mass of each tyre at 250g, the diameter at about
60cm, and the width of the contact patch at 1cm, the mass of the tyre
in the contact patch is about 7.5 grams. At 250Gs, that's less than
20N - less than 5% of the 450N.

So you're proposing that the rotational speed at 88KPH can save about
4 watts. Big deal.

Michelin tyre data from <http://en.wikipedia.org/wiki/Rolling_resistance>.

Highly unlikely they've designed-in any lift. You can't get lift without
drag.
** Not unlikely at all.
Even a small amount of lift would reduce rolling resistance as much as
removing the batteries did.

It would increase the aerodynamic drag by much more, especially considering
that the aerodynamic drag is costing (1200-80) watts, or 93% of the energy
budget.

Clifford Heath.

 

[Phil Allison]

"Clifford Heath"

To carry 140Kg across the three wheels at 88KPH requires
about 80 watts.

** The graph posted by DL Jones shows rolling resistance consumes about 350
watts.

http://www.eevblog.com/images/projects/SunSwiftDragGraph.png

Very little energy is lost in ( presumably) ball bearings - else they would
become very hot.

Highly unlikely they've designed-in any lift. You can't get lift without
drag.

** Not unlikely at all.

Even a small amount of lift would reduce rolling resistance as much as
removing the batteries did.

It would increase the aerodynamic drag by much more, especially
considering
that the aerodynamic drag is costing (1200-80) watts, or 93% of the energy
budget.

** Wrong.

Aerodynamic drag is more like 70 % of the budget - as shown in the graph.

Any aerofoil section has drag, whether is produces lift or not. A simple
flat bottom, curved top aerofoil ( as appears in the pics) has lift even
with zero attack angle and so no additional drag.



...... Phil