What is Coefficient of drag: Definition and 18 Discussions

In fluid dynamics, the drag coefficient (commonly denoted as:



{\displaystyle c_{d}}



{\displaystyle c_{x}}



{\displaystyle c_{w}}
) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag equation in which a lower drag coefficient indicates the object will have less aerodynamic or hydrodynamic drag. The drag coefficient is always associated with a particular surface area.The drag coefficient of any object comprises the effects of the two basic contributors to fluid dynamic drag: skin friction and form drag. The drag coefficient of a lifting airfoil or hydrofoil also includes the effects of lift-induced drag. The drag coefficient of a complete structure such as an aircraft also includes the effects of interference drag.

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  1. EelAnes

    How to calculate the drag force?

    Problem How to calculate the drag force of the model helicopter using the given data above? Research Question How does increasing the length of the wing planform of a model paper helicopter affect the time it takes the helicopter to fall to the ground and hence the air resistance? Variables...
  2. EelAnes

    What is the coefficient of drag on a flat surface?

    What is the coefficient of drag on a flat surface? Note: The body is in free fall The object has 2 wings planform (it's a paper helicopter), which is flat The object's wing spin in a circular motion (anti-clockwise) during free fall
  3. T

    Where do I find coefficient values for these 2 formulas? (drag coefficients)

    Hi there, So I asked a question here how I would calculate the air drag and the wheel drag of a train and I got an answer that made me very happy. Unfortunately i don't know where i could find the coefficient values required for the formulas. So i am wondering if someone knows where i can find...
  4. L

    Finding the sum and difference of two drag coefficients

    Homework Statement I have to determine the sum and difference of the two coefficients of drag between two individual items that make a torque AUT. I'm given the diameter of each bottle (6.35 cm), wind velocity (14.3 m/s), the forces of the lift load cells (+0.0741 N, -0.0741 N), and the force...
  5. D

    Finding the Coefficient of Drag for Partial Parachutes

    Hey Guys, I'm on a rocket team at my university and we are attempting to figure out the force of opening acting on some of our parachutes. Typically this is done using the following equations, in particular, the one in the top right corner. This is where our trouble begins. In the Recovery...
  6. RandomDude123

    Fluid Dynamics - Calculating Coefficient of Drag

    How would one calculate the drag on a projectile (in this case a 1cm3 cube) that was launched at 0°. The vertical drop, initial velocity, distance, and time (taken to travel distance) where measured. I want to say that I could compare these experimental drop (bellow hight that projectile was...
  7. Andy24

    Coefficient of Drag on a model rocket

    Hello everyone, I am predicting the altitude of a model rocket based on some testing I did where I found the impulse of a little single stage model rocket motor. I am wondering how to incorporate drag into my calculations to make it more accurate. I know D=Cd*rho*v^2*A and I can definitely find...
  8. T

    Aerodynamics- Coefficient of Drag

    Homework Statement Hello, Let's say I was given a problem where I have to calculate CD I find everything except CD Now, CD = CD0 + K CL2 I know how to calculate K but I don't know what CD0 is. Would that be a given? or do I have to find it myself? If so, how? Then there's another formula for...
  9. Y

    Coefficient of drag and surface smoothness

    So i am working on a program that models the movement of a rocket through different planets. and i sm starting to get teach my self fluid dynamics. As i was reading a presentation by NASA about the forces that act on a rocket they got into shape effects on drag, i noticed from their equation Cd...
  10. 462chevelle

    Coefficient of Drag: Exploring Thrust & Application

    Could someone explain to me the difference in calculating the coefficient of drag with thrust, and without. What causes the difference in application?
  11. D

    Coefficient of drag of a ping pong ball

    Homework Statement This problem is from a homework assignment. The professor says that the the ping-pong ball will go up if the cd = 0 and will go down if the cd is much larger than one. Is this logic correct? I keep thinking about how if an aerodynamic car is pushed by wind, the car...
  12. T

    How to find the coefficient of drag of a car model?

    Can we assume that the coefficient of drag of a car model is constant using one of the values from: http://en.wikipedia.org/wiki/Drag_coefficient The reason I ask this is because the coefficient of drag of a car varies with velocity. So wouldn't it change depending on how fast the car is...
  13. O

    Coefficient of Drag: Low Velocity Ellipsoids

    Hello, I understood that in low velocities the standrad drag equation: F_d=\frac{ρv^2C_dA}{2} Could linearized to something like: F_d=γv I am looking for the drag coefficient(either γ or Cd) for either a prolate or a tri-axial ellipsoid at low velocities (less than 0.5 m/s) in water. I found...
  14. H

    Calculating Coefficient of Drag: Pressure & Friction Drag

    Hi I know what pressure and friction drag are, I am having a hard time trying to find out how can you calculate the coefficient of drag for them? I think i have came across an equation for it: F_{D} = .5*ρ*v^{2}*A*C_{D} where F_{D} is the force of drag, ρ is density, v is velocity, A is the...
  15. K

    Understanding Drag and Coefficient of Drag (Cd) in Aero Engineering

    Hi everyone, I'm completely new to the aero engineering and have a question regarding drag. The lecturer explained it briefly, threw some formulae at us and now I'm confused trying to make sense of it all. So, i have these two formulae relating to drag: 1) D = 0.5(rho)(V^2)(A)(Cd) and...
  16. S

    Coefficient of drag question

    Homework Statement It is said that Lance Armstrong can maintain a average power output of 500 watts for a time trial. The additional power (above that needed to fight gravity) is primarily used to fight aerodynamic drag. On a flat time trial Lance is able to maintain an average speed of about...
  17. B

    Coefficient of drag of an object in water

    I'm working on an idea that has to do with placing wind turbines on lake beds to catch the constant undercurrents (not a wholy original idea, I know). One of the most important factors to take into consideration is the lateral force exerted on the tower by the current--which is identical to the...
  18. H

    Calculating Drag Coefficient for Skydiving Research

    Im doing research on skydiving and I am trying to find out how much drag is created on different jumps. I have different velocities for each of the jumps. D = Cd ((rV^2)/2)A That is the equation I am using. r is air density which I am using 1.2 kg/m^3. V is the velocity. And I've...