I have been reading car magazinge for like 20 years. But recently, I realized that I dont understand 2 terms I see in print every so often.
The first is generally used in describing the weight of sports cars: “unsprung weight” How does this differ from weight?
The second is “NACA ducts” or “NACA-style ducts” (I think I spelled that right). These are a type of air inlet, and I can visually recognize these, but I am unsure waht NACA stands for, and what makes this style of duct so important.
Unsprung weight is, oddly enough, the weight that’s not sitting on springs; wheels, tires, axles, that sort of thing. Less unsprung weight has less inertia, so the tires stay on the road better when you go over bumps. Too much unsprung weight and the tires will leave the ground when you hit a bump, which isn’t good for handling.
NACA is the National Advisory Committee for Aeronautics. NACA ducts are shaped such that they act aerodynamically like a flat surface, so the opening doesn’t cause any additional drag. Here’s a page about that explains it better.
Unsprung weight = that portion of the car not supported by the suspension: tires, wheels, brakes, some suspension bits, and in the case of a RWD car with a live axle, the axle itself.
NACA is an abbreviation for, among other things, National Advisory Committee for Aeronautics. Presumably they had a hand in the original design somewhere way back. Sorry, that’s the best I could find with a quick search (I’ve also heard this term before and never knew what it meant).