The ** Drag coefficient**, or short

**(Cw value) describes the flow resistance of a body when a fluid flows around it. A fluid can be about**

*c*_{w}-Value**Water**be, but also

**Air**which, from a physical point of view, also belongs to the fluids. Often there is also the name

**Drag coefficient**for

**. This value is briefly referred to with the symbol Cw. It is a coefficient, that is, a dimensionless measure. At the same time, the flow resistance coefficient corresponds to the pressure loss coefficient of a body flowed through. From the**

*c*_{w}-Value**the force of the flow resistance can be calculated taking into account the speed, the density of the fluid and the area of the body.**

*c*_{w}-Value### following our *c*_{w}-Value Calculator (only for Germany)

*c*

_{w}-Value

### How can you do that *c*_{w}-Value measure up?

*c*

_{w}-Value

Usually the ** c_{w}-Value** in you

**wind Tunnel**determined. The body for which the calculation is to be made stands on a plate that is equipped with force sensors. The wind acts as a fluid. The force in the direction of the flow is then measured. This results in a value, the drag force Fw. Together with this and the already known quantities (

*namely the density of the fluid, air density*) and the frontal area of the object as well as the speed then becomes the

**calculated.**

*c*_{w}-Value**The following formula is used to calculate the drag coefficient: **cw = Fw / qA, = 2 F w /? v² A

**Fw** describes the experimentally determined drag force. **A** is the reference area, **?** describes the density of the object and **v** is the speed of the (undisturbed) flow. The reference surface is usually the face of the object against which the flow occurs. There are exceptions here, for example, in the aerodynamics of aircraft, where the **Wing area for A** is used. It should be noted that the designation Cw (*with W for resistance*) **just** is common in German usage. In the English-speaking world, the value is referred to as cd or cx (drag coefficient).

The value can also be calculated numerically depending on the model shape of the object. This works by integrating the distribution of the coefficient of friction and pressure over the model surface.

### The *c*_{w}-Value in the application

*c*

_{w}-Value

Via the <strong>integrated datalog</strong> the measuring values can be stored on the humimeter RH5 paper moisture meter and additional data can be added. You also have the possibility to use the Autolog function. This function automatically saves measuring values in adjustable time intervals. ** c_{w}-Value** For example, you can say how aerodynamic a vehicle is. The air resistance of a car makes indirect statements about the

**Consumption**of the carriage. Even if the frontal area of a vehicle is rarely specified by the manufacturer, there is still a way to calculate the drag force,

**if you can find out the area**. The drag force is obtained by multiplying the drag coefficient by the reference area A.

**The associated formula is the following: **Fw = Cw * A

Fw as resistance force, Cw as ** c_{w}-Value** and A as the end face of the vehicle.

A modern car has one ** c_{w}-Value **of around 0,3. The lower the

**the more aerodynamic a vehicle is. Compared to this, Formula 1 cars, for example, are not as streamlined as one might think. Classic Formula 1 racing cars have a drag coefficient of around 1,2. That's because these racing cars have their speed**

*c*_{w}-Value**not**achieve that they are particularly aerodynamic, but rather that they are pressed firmly to the ground by their structure and the wind flowing around them. This gives them the opportunity to build up extreme speeds. Especially in curves! But that does not come without a price, because the pressure that is exerted on the vehicle can reach up to a ton at top speeds

**additional weight**act on the car. But it is precisely this weight that ensures that the Formula 1 car

**not**stands out from the track. A commercially available car would become lighter at such high speeds due to its construction and stand out from the road.

Incidentally, motorcycles are judged by theirs ** c_{w}-Value**,

**not**viewed as particularly economical. Even if its sleek shape would speak for it, many other factors play a role here.

### Which statements does the *c*_{w}-Value in cars?

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_{w}-Value

In a car, the fuel consumption depends on the ** c_{w}-Value**. The fuel consumption increases with a higher air resistance. So the smaller the

**is, the less a car consumes. The most streamlined car to date comes from VW and has one**

*c*_{w}-Value

*c*_{w}-Value**of 0,189**. The air resistance, which the

**significantly influenced, results from the frontal area of the vehicle. If a car had a completely flat surface as an inflow surface, then a**

*c*_{w}-Value**of 1,0 result.**

*c*_{w}-ValueBy reducing the area, the ** c_{w}-Value** be reduced and thus ultimately also the gasoline consumption. An aerodynamicist takes care of reducing this area as effectively as possible and keeping it as low as possible

**to reach. At the same time, aerodynamic vehicles also reduce CO2 emissions and are therefore more environmentally friendly. Another way to get the**

*c*_{w}-Value**to influence positively is that**

*c*_{w}-Value**Lowering**of a vehicle. Other accessories, however, such as spoilers on the car,

**erhöhen**the material moisture meter shows you the

**again.**

*c*_{w}-Value**By the way:** tuningblog has other options for **Calculation of various things** on-line. The following gallery provides an overview of other computers.

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