Dynamic Stall Pressure: Understanding EAS & TAS

In summary, the equation \frac{1}{2}rho0VEAS^2= \frac{1}{2}rhoVTAS^2 represents the relationship between pressure, velocity, and density in a fluid flow, known as the Bernoulli's equation. The use of rho0 allows for the calculation of stall dynamic pressure at sea level, where air density is constant. The equating of the two sides of the equation is a result of the conservation of energy principle.
  • #1
nowayjose
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Homework Statement



[itex]\frac{1}{2}[/itex]rho0VEAS^2= [itex]\frac{1}{2}[/itex]rhoVTAS^2


The Attempt at a Solution



Basically what I've understood is that the TAS (true air speed) doesn't matter when calculating the stall dynamic pressure since what matters is the speed at which the plane is going relative to its surroundings.

The pitot tube is calibrated such that we can the use the EAS (equivalent airspeed) at any height and account for the relative changes in speed at different altitudes.

What i doent understand is the first part of the equation equates the latter and why rho0 is used. I know that to calculate the stall dynamic pressure at sea level we need to use rho0 and the EAS then... But how that equates any rho for a specific TAS doesn't quite make it into my understanding.
 
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  • #2




Thank you for your post. I can see that you have a good understanding of the concept of equivalent airspeed (EAS) and true airspeed (TAS). The equation you have referenced is known as the Bernoulli's equation, which describes the relationship between pressure, velocity, and density in a fluid flow.

In this equation, rho0 represents the density of air at sea level, while rho represents the density of air at any given altitude. The reason why rho0 is used in the equation is because it allows us to calculate the stall dynamic pressure at sea level, where the air density is constant. This is important because the stall dynamic pressure is a critical factor in determining the lift and stability of an aircraft.

As for the equating of the two sides of the equation, it is a result of the conservation of energy principle. In a steady-state flow, the total energy at any point in the flow remains constant. Therefore, the kinetic energy (represented by \frac{1}{2}rhoVTAS^2) and the potential energy (represented by \frac{1}{2}rho0VEAS^2) must be equal.

I hope this explanation helps to clarify your understanding. Keep up the good work in your studies of aerodynamics.

Scientist in Aerodynamics
 

1. What is dynamic stall pressure?

Dynamic stall pressure is the point at which a sudden increase in lift and drag occurs on an airfoil due to changes in the angle of attack and the onset of flow separation. It is a critical factor in understanding the performance and behavior of aircraft in flight.

2. How is dynamic stall pressure measured?

Dynamic stall pressure is typically measured using pressure sensors mounted on the surface of the airfoil. These sensors detect the changes in pressure distribution that occur during dynamic stall and provide valuable data for analyzing and predicting the behavior of the airfoil.

3. What is the difference between EAS and TAS?

EAS (Equivalent Airspeed) is the airspeed measured by an aircraft's pitot tube, which is affected by air density. TAS (True Airspeed) is the actual speed of the aircraft relative to the air it is flying through and is not affected by air density. Dynamic stall pressure is typically measured and reported in terms of EAS.

4. Why is it important to understand dynamic stall pressure?

Dynamic stall pressure is important because it can significantly affect the performance and controllability of an aircraft. It is a critical factor in determining the maximum speed and maneuverability of an aircraft, and understanding it can help improve the design and operation of aircraft.

5. How can dynamic stall pressure be minimized?

Dynamic stall pressure can be minimized by reducing the angle of attack and maintaining a smooth and consistent airflow over the airfoil. This can be achieved through careful design and positioning of the airfoil, as well as through the use of control surfaces and other aerodynamic devices to manage the airflow. Additionally, pilots can also adjust their flight techniques and avoid abrupt changes in angle of attack to minimize the risk of dynamic stall.

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