Frontal Area

avsfan733 · 12 Feb 2003, 19:44 (Ref:504763)

how would one go about computing the frontal area of something such as a racecar?

and I mean this in the realistic rather than the theoretical sense

GTV27 · 13 Feb 2003, 03:06 (Ref:505110)

I would presume it would be a matter of getting out your tape measure, taking some measurements and working out the area in square centimetres (or inches).

avsfan733 · 13 Feb 2003, 04:57 (Ref:505147)

wow i feel stupid i should have specified about when u have curves and the like...for example an F1 car is it still the same just a head on view?

GTV27 · 13 Feb 2003, 06:17 (Ref:505164)

as far as I know it is just the same as a head on view - the total displacement does not vary whether you are pushing a flat or a tapered surface, the air has to find a way around regardless (eg I and < have the same frontal area).

The coefficient of drag measures the "efficiency" (not quite the right term?) or the air passing around the object - obviously for this measure a flat surface ( I )will be outperformed by a tapered one( < ) (wish I had a white board - but I think this makes sense

)

Dave Brand · 13 Feb 2003, 10:15 (Ref:505279)

Frontal area is just as you see it in a head on view of the vehicle. The effect of the shape as seen in three dimensions is taken cars of by the drag coefficient (Cd).

GTV27 · 14 Feb 2003, 03:33 (Ref:506080)

Quote:

Originally posted by Dave Brand
Frontal area is just as you see it in a head on view of the vehicle. The effect of the shape as seen in three dimensions is taken cars of by the drag coefficient (Cd).

I wish I had explained it as well as this

MulsanneMike · 14 Feb 2003, 12:28 (Ref:506405)

Don't forget that frontal are is also effected by overall rake angle and wing settings.

**Aysedasi** · 14 Feb 2003, 12:45 (Ref:506428)

Does assessment of frontal area work in the same way for human beings?

Sorry for being ever-so-slightly smutty, must be coz of Valentines Day.....

)

shiny side up! · 14 Feb 2003, 13:33 (Ref:506479)

MMike, you're clearly qualified to talk about this, glad to see you here. Perhaps you can set me straight, I thought that frontal area was independant of the plane of attack for the wings, shape of the body, etc, and the Cd reflects those things... much as GTV27 and Dave Brand explained above... Am I not understanding something correctly?

avsfan733 · 14 Feb 2003, 16:57 (Ref:506657)

see this is what i was told to some extent al though not explained this well and i got confused, what is the formula or whoever it is determined?"

avsfan733 · 14 Feb 2003, 16:58 (Ref:506658)

see this is what i was told to some extent al though not explained this well and i got confused, what is the formula or whoever it is determined?

Dave Brand · 14 Feb 2003, 17:48 (Ref:506725)

Quote:

Originally posted by MulsanneMike
Don't forget that frontal are is also effected by overall rake angle and wing settings.

Only to a very small extent - several degrees of camber change on a wing will only affect its projected frontal area by a few millimetres; the effect on Cd will be more important.

shiny side up! · 14 Feb 2003, 20:52 (Ref:506900)

Oh, I get it now... MMike (and Dave, above) are talking about the fact that if you make a wing angle change, it will effect the frontal it presents slightly. I should think that for a front wing it won't matter much, because the whole car is still behind it, but the rear could probably make some significant changes...

MulsanneMike · 15 Feb 2003, 13:40 (Ref:507566)

Yes, certainly the difference is minimal if you take into account wing angles. But ultimately it will effect the numbers. Most simply use a close guesstimate and stick with it for all their calculations. For closed wheeled prototypes, 1.8-2.0 m^2 is a good ball park number. You'll be within 10% of the actual number and it won't effect your results much.

An example of the slight difference. These are real numbers for a GTP car, won't disclose the actual car:

Frontal projection sans wing: 1.665 m^2
Add wing, very low wing architecture: 1.68 m^2

These numbers come from a CAD drawing, CAD number is very close to the real frontal projection as measured.

shiny side up! · 15 Feb 2003, 20:28 (Ref:507882)

Excellent, thanks for the example MMike!

Garp · 25 Feb 2003, 16:46 (Ref:517312)

Wat is so importand about the actual frontal area. Is there a way to measure the frontal area from the car plus the turbulent area created by the boundarylayer.

Onlooker · 26 Feb 2003, 20:01 (Ref:518603)

I will say straight up that I have no idea if this will work but if you had time to put grid paper on a background place the car in front of it and using some form of light you could project the image of the car,trace around it and count the squares in the area.measure the angles of the front end and you should be pretty close in my opinion.

Dave Brand · 26 Feb 2003, 21:46 (Ref:518722)

Quote:

Originally posted by Garp
Wat is so importand about the actual frontal area.

Drag = frontal area * Cd.

Does that answer your question?

Garp · 4 Mar 2003, 15:57 (Ref:524572)

Sometimes it's easyer to reduce your cd than reduce the frontal area. I think the frontal area of disturbed air around the car is more importand than the car's frontal area.

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