How Do You Convert CFM to Thrust?

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To convert CFM to thrust, the formula involves several steps, starting with calculating mass flow rate using density and volumetric flow rate. The thrust can be derived from Newton’s Second Law, where thrust equals mass flow rate multiplied by velocity. Velocity is determined by dividing volumetric flow rate by the area, which is calculated using the radius of the propeller blade squared. The user specifically seeks clarification on calculating the area, particularly the term r^2, which refers to the square of the radius of the propeller. Understanding these calculations is essential for converting 2750 CFM to thrust effectively.
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Hey guys! I'm new to the forums here and was after some help for something that I am currently working on. I need help converting cfm to thrust, i have found the formula though i can't get my head around it.

Here it is:

CFM = Cubic Feet per Minute = Volumetric Flow Rate

Mass Flow Rate = (Density) x (Volumetric Flow Rate)

Newton’s Second Law of Motion: Force = (Mass) x (Acceleration), or F = ma

F = ma = (Mass Flow Rate) x (Velocity), given a constant flow velocity
(i.e., constant propeller speed and pitch angle).

Velocity = (Volumetric Flow Rate) / (Area), where Area = (Pi) x (r^2), the
length of a propeller blade is a good approximation for the radius, r.

Thrust = (Density) x (CFM^2) / ((Pi) x (r^2))


The amount of cfm i need to convert is 2750cfm. Any pointers?

Cheers, Addz.
 
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Ummm... to be a bit more specific I'm having trouble with this segment:

Area = (Pi) x (r^2)

What is r^2?

Although most likely dead simple for you guys, it isn't for me so don't kill me lol! (I'm really new to all of this so thanks)

Cheers, Addz.
 

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