I have seen these 2 terms all the time in car magazine, and I never quite understood what they meant.
“Unsprung Weight”. generally used in reference to sport cars or lightweight cars. How does this tern differ from ‘Weight’, and why do I generally see this term under the conditions I described?
“NCCA (Air) Ducts”. Visually, I know what this sort of duct looks like, but I dont know what ‘NCAA’ (I think that is the abbrievation) stands for, or why this style of duct is popular, and what are it’s advantages over other ducts systems?
That is the weight of the components of the car that aren’t dampened by the suspension. Examples would be wheels, tires, brakes. The amount of unspung weight will affect the ride and handling. Thus, it follows that a modification of the unsprung weight can change the designed handling characteristics of the car and therefore may require modifications to the suspension.
NACA ducts were originally used on airplanes (Here’s a better picture. I think that they were first used on the P-51 Mustang.) They’re a fairly aerodynamic way to duct outside air into the car.
So if I am understanding you, the ‘sprung’ (is this a term too?) weight consists of all the items that are riding on top of the shock absorber (which is actually the bulk of the car). The unsrung weight consist of everthing not riding on the shock absorbers - as you said, wheels, tires, brakes. would the axles be part of that as well? what about the driveshaft (it’s connected to the axel, but at the same time it is connected to the motor, which i’m guessing is part of the ‘sprung’ weight
As for NACA ducts (thanks for the spelling) - yup those are exactly what I was talking about. I guess I am looking for a better answer though. how does it draw in more air, or why is it more aerodynamic? are there other named duct systems? is naca still considered advanced or are there better ducts that can be used? if they are still considered very effienct, why do we not see them in the majority of cases, rather than merely often?
The rear end of a rear wheel drive vehicle is part of the unsprung weight, and the driveline would be where the transition between the sprung and unsprung weight occurs. Transition parts also include the upper and lower control arms, trailing arms, shocks and other parts that connect between the two. NASCAR crew chiefs discovered about 20 years ago that adjusting the angle of certain transition parts that they can move weight between the sprung and unsprung weight of the race cars. It is called adjusting the track bar.
NACA ducts work by creating a low pressure hole in the wind. The air rushing by an airplane or race car is packed together creating high pressure. Simple physics says high pressure air will flow into areas of low pressure. And the length of tubing connecting to the duct is used to control how much air flow through the duct, the longer the hose, the lower the pressure. If you look in the back of a NASCAR stock car built for a short track race, there will be 2 or even 3 NACA ducts in each side window and the hoses be as long as possible. The faster the cars go on each track means the car can use shorter hoses. If you were to look on the underside of 80’s Indy cars, the bottoms look like a large NACA duct, beside suckin in air they also helped hold the cars to the track. They were outlawed as a safety measure, both the IRL and CART require the cars have flat bottoms now.
Wow. interesting. I’m understand what the sprung and unsprung weight is. How does ‘adjusting the track bar’ help in racing? Or general driving for that matter?
This is definately closer to what I was looking for. Thank you.
Is it the shape of the NACA duct that causes the low pressure? Wouldn’t any hole in the skin of an airplane/car cause the same thing? How do NACA ducts differ from ‘scoop’ style ducts?
What does NACA stand for?
Is these style of ducts where used on IRL/CART cars in the 80’s and they help hold the car down to the track, how exactly is that dangerous? If anything, it sounds even more safe.
