Road car aerodynamics

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akbar21881
akbar21881
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Joined: Sat Jun 28, 2003 9:49 pm
Location: bristol,uk

Road car aerodynamics

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In the road car, what are the aerodynamic consideration during the design process?

As far as I understand, the aerodynamic consideration scope covers the drag( form drag, wheel drag, friction drag), airflow effect ( noise, flutter, force on body panel, water/dirt deposition) and engine cooling. Are there any other factors that need consideration?

In formula 1, do you think the mass properties( eg cg position) interact very much with the aero properties? This is because in aircraft design, the movement of aero ctr in relation with mass c.g is very important in extablishing the stability and manouvrebility of the aircraft. is this applies to F1 car? does this apply to road car as well?

RH1300S
RH1300S
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Joined: Mon Jun 06, 2005 2:29 pm

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I think you have probably got the key things covered. I would add venitlation into the brief and you are pretty close to done.

AFIK, in F1 (any race car design), the position of the centre of downforce (not sure if this has a proper term) is utterly critical to getting a good balance and I'm pretty sure they aim to match it to the CofG (between the axles).

I'm not so sure whether this relationship is as important in three dimensions (height as well) as it might be on an air-craft.

akbar21881
akbar21881
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Joined: Sat Jun 28, 2003 9:49 pm
Location: bristol,uk

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Thanks RH1300S.

Which ventilation do you mean? Is it the intake for air-con and cabin air outlet?

Do you also have suggestion for reading materials( sites/books)?

Cheers...

West
West
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Joined: Tue Jan 06, 2004 11:42 pm
Location: San Diego, CA

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RH1300S wrote:I think you have probably got the key things covered. I would add venitlation into the brief and you are pretty close to done.

AFIK, in F1 (any race car design), the position of the centre of downforce (not sure if this has a proper term) is utterly critical to getting a good balance and I'm pretty sure they aim to match it to the CofG (between the axles).

I'm not so sure whether this relationship is as important in three dimensions (height as well) as it might be on an air-craft.
I think it's called center of pressure.
Bring back wider rear wings, V10s, and tobacco advertisements

akbar21881
akbar21881
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Joined: Sat Jun 28, 2003 9:49 pm
Location: bristol,uk

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Yeah its called centre of pressure.

When people talk about car dynamics, the common issues are the suspension geometry, roll centre placement etc..

Where is ideal placement of centre of pressure in relation with the centre of mass? In aircraft, it is essential to ensure the aero centre is well-contained within the margin of movement of mass centre. if the aero centre fall outside of this movement margin of mass centre, if i'm not mistaken the manoeuvre( landing, take off) will be diverge( eg during landing, the approach angle can't be maintained and will flip the aircraft).

In automotive, surely this effect is present as well. Lets say, under braking, mass centre will move forward.To ensure that this manoeuvre is sustainable, where does aero centre should be? behind it? or in front of it? surely there is an optimum position of aero centre so that braking and subsequently turning can be done without interfering with the desired inertia or roll or yaw properties as been set up in the suspension setting? is there a software out there that can simulate both aerodynamics and mass properties simulatenaously?

How does F1 designer carry out their aerodynamic design? Is it by designing from front to rear? As I can imagine it probably would start with the nose cone, then moving to the trailing edge of front wing, then around the suspension arm, then the splitter then the barge board and so forth. I assume the properties of the desired airflow at the rear of the car is determine by how the flow upstream of that component is managed.Is this being considered is road car? is it worth doing it at all?

manchild
manchild
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Joined: Fri Jun 03, 2005 9:54 am

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akbar21881 wrote:...How does F1 designer carry out their aerodynamic design? Is it by designing from front to rear? As I can imagine it probably would start with the nose cone, then moving to the trailing edge of front wing, then around the suspension arm, then the splitter then the barge board and so forth....
I don’t think they start with nose cone. I think they start with basic dimensions of chassis imposed by FIA and than develop whole aero over mechanical/structural elements of the car.

RH1300S
RH1300S
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Joined: Mon Jun 06, 2005 2:29 pm

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akbar21881 wrote:Thanks RH1300S.

Which ventilation do you mean? Is it the intake for air-con and cabin air outlet?

Do you also have suggestion for reading materials( sites/books)?

Cheers...
I meant passenger compartment ventilation, obviously you need to get air in, but also out and presumably try and take air from somewhere not too dusty or hot. Also, what happens to the aero when the sun-roof and windows are open, all should be considered as that is how a car will be used. So, you wouldn't just focus on vehicle performance (as you suggest) comfort and noise would be part of the program.

Try this book - Aerodynamics of Road Vehicles by Wolf-Heinrich Hucho

http://www.amazon.co.uk/exec/obidos/ASI ... 30-7205544