I was wondering if anyone could post some formulas for me.

I had a general aerodynamics class in college years ago, and I've long since forgotten the lift formulas and drag formulas.

I remember there was one that you could calculate the lift a wing will produce given that you know the airspeed, temperature, air density (rho??), lift coefficient, and maybe angle of attack? (Cl may take care of this... like I said, it's been a long time)

I think there was another one where you could calculate the drag given the same parameters.

I remember we had a big table to look at to find rho at different conditions...

If anyone could post these formulas and maybe give me rho for a few different conditions, I'd be really thankful!

My elevation here is about 430 MSL, and if you could give me rho for Standard Atmosphere, 70F, 80, 90, and 100F, I'd really appreciate it!!

Or, if you could steer me to a website that would have the formulas, that would be great too!!

Thanks in advance!!

Brian,

Lift=Cl*1/2*q*V^2*area
Drag=Cd*1/2*V^2*area

Cl is the lift coeff.
q is the density
(Imperial units q=.002378 slugs per qubic foot at sea level, metric units q=1.225 Kg per qubic meter at sea level)
V=velocity
Area=wing area

Example:

If a plane with a wing area of 4 sqft, at 30 fps velocity, at standard density .002378, Cl of 1 then,

Lift=1*1/2*.002378*30^2*4
Lift=1/2*.002378*900*4
Lift=4.28 pounds

To find Cl given Velocity:

CL=Lift/(1/2*q*V^2*area) Lift=Weight and weight/area= wingload so:
Cl=Wingload/(1/2*q*V^2) or
Cl= (2*wingload)/(q*V^2)

same example will say plane weight is five pounds:
Cl= (2*(5/4)/(.002378*30^2)
Cl=2.5/2.14
Cl=1.17

The induced drag= Cl^2/(pi*AR*e) AR=aspect ratio and e=oswald eff factor.

Here is a sight that you can calculated the air density for your conditions:

[link]http://wahiduddin.net/calc/calc_da.htm[/link]

Here a good site for more info:
[link]http://142.26.194.131/aerodynamics1/[/link]

Steve

Steve,

Thanks for the formulas!!!

I remember almost all of that except I'm having a hard time recalling what "e", the Oswald effect factor, is in the Induced drag formula.

I guess Dr. George did OK teaching me in the Gen. Aero class at Parks ; I remember we all would chuckle at the way he would say "slugs" in class .

Thanks for the links too!!! Exactly what I need to look at for a refresher.

I remember very well, Dr. George from Parks! He taught propulsion when I was there, but I think has since retired... [8D]