[Kelmark]

Trying to figure out the drag coefficiency and frontal area of my 1978 Kelmark GT (replica Ferrari Dino).

[IamIan]

How accurate are you trying to get?

[Kelmark]

I would like to get as close as possible, but a consensus from some more experienced members would be enough to start doing some math.

[galeson]

Look on the Mayfield Co homepage. They have lots of Ferraris there( but no Dinos)

[Kelmark]

Originally Posted by galeson

Look on the Mayfield Co homepage. They have lots of Ferraris there( but no Dinos)

My guess for drag coefficient .35 looking at other Ferrari's in 1986. Does that sound about right? Still not sure on frontal area 1.82m^2? I am guessing at this point.

[IamIan]

Originally Posted by Kelmark

My guess for drag coefficient .35 looking at other Ferrari's in 1986. Does that sound about right? Still not sure on frontal area 1.82m^2? I am guessing at this point.

Seems like a reasonable guessing point.

Maybe add ~10% to the final combined CdA number just to be conservative.

but that should be good to get started on calculations and such ... you can always roll up your sleeves to get more specific if you want to later.

one basic / easy method to get a basic idea of the frontal / displacement area is to take a string or something and wrap it around the car ... find the largest part ... that is the circumference ... divide my pi... ~3.14 to get diameter ... diameter times diameter times ~0.7854 will give you a ball park frontal area.

( String / 3.14 )^2*0.7854

usually best to avoid protrusions like side mirrors and antenna.

That is an easy way to get in the ball park of your frontal area.

[tomofreno]

One way to estimate frontal area is to take a photo from the front of the vehicle and draw a grid to scale on it. Add up the areas of the squares to estimate the area. Smaller the grid, the more accurate the estimate.

This site gives drag coeff of a number of vehicles. It gives 0.34 for a Ferrari F40. No idea how that compares to your dino.
http://www.madabout-kitcars.com/kitcar/kb.php?aid=327

[Kelmark]

Originally Posted by tomofreno

One way to estimate frontal area is to take a photo from the front of the vehicle and draw a grid to scale on it. Add up the areas of the squares to estimate the area. Smaller the grid, the more accurate the estimate.

This site gives drag coeff of a number of vehicles. It gives 0.34 for a Ferrari F40. No idea how that compares to your dino.
http://www.madabout-kitcars.com/kitcar/kb.php?aid=327

Do I just print an outline of the front view of the car on graph paper figure out the apropriate scaling per square add them all up. If I am understanding you correct, thanks that's a great idea!

[tomofreno]

Do I just print an outline of the front view of the car on graph paper figure out the apropriate scaling per square add them all up.

Yes, that would work. You just need to ensure you have the scale correct. One way is to set something of known length on the car, like a piece of cardboard with large (3" tall) markings on it at say every 2 inches. Another way is to measure between two points on the car (like distance between inner edges of headlights) and use this to determine the scale of the printed photo.

[Kelmark]

Originally Posted by tomofreno

Yes, that would work. You just need to ensure you have the scale correct. One way is to set something of known length on the car, like a piece of cardboard with large (3" tall) markings on it at say every 2 inches. Another way is to measure between two points on the car (like distance between inner edges of headlights) and use this to determine the scale of the printed photo.

My eyes are crossed from counting squares. But what I ended up with was approximately 1,124 squares with a scaling of 1.45" per square. I determined scaling by physically measuring the width 69 ¾” and height 37” of the car as it sits on the floor. (Just the body) That gives me 1,629 sq inches or 135.8 sq ft. That doesn’t sound right? Go figure I messed it up, I wasn’t very good at math better with a wrench! Can you help me out?