Calculating drag for high mach numbers

[LT72884]

Ok, so i have a high powered rocket i made and it hits about 420 m/s

At low mach numbers, most the drag is due to skin friction, hence why you can solve for the Cd based on the Re and geometry alone (Dr. Gerald M. Gregoreks work shows this)

However, as soon as you hit higher mach numbers, pressure drag is the governing "force"

Meaning that Fd=(roh)(0.5)(A)(Cd)(v^2) is not really applicable anymore

So what is the new equation i should be using?

Thanks

 

[jack action]

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.

Definition​

The drag coefficient is defined as

So the equation is always applicable since, no matter the Mach number, there is always a drag force and a fluid density. The equation is used to define the drag coefficient, NOT to find the drag force.

In addition, at high Mach numbers, you get a wave drag component whose value can be estimated mathematically.

 

[LT72884]

So the equation is always applicable since, no matter the Mach number, there is always a drag force and a fluid density. The equation is used to define the drag coefficient, NOT to find the drag force.

In addition, at high Mach numbers, you get a wave drag component whose value can be estimated mathematically.

Thats what i thought. Though i have been informed differently a few times, and each time they do have a good explanation too.

Im hoping the other user, i think its Russ, will chime in.

I love learning and this is good stuff

 

[marcusl]

Do you hear a sonic boom?

 

[LT72884]

On some yes