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(OP)
We are designing a large gyroplane and wish to be able to calculate the possible disc loading for large diameter rotors.

Where might we find tabulated data, or formulas for calculating disc loading during autorotation varying the diameter of the rotor?

You will find the governing equations (ie Accurate to within 80%) for disk loading, and the affect of autorotation on disk loading in
Helicopter Performance Stability, and control.
by Prouty

if you have say 25,000 lbs of static thrust, and disc area is 2261.978 sq/ft then your disc loading is:

11.052 lbs/Ft^2

My appologies, I know what your looking for, ill have a post shortly for it.

For approximations, your probably going to get sick and tired of hearing those terms....Approximate values....I can only say get used to it. Engineering is not absolute with anything other than close estimation to anything closer than 2% to 5%.

T/A ::: Disc loading. the :::<-- means "is relative to" normally you will see this in engineering books as an = sign but with one extra line underneath it, so it looks like an equals sign with three lines instead of two.

T = 2Apvh^2
A disc area
p air density
vh = hover velocity squared.

vh = sqrt(w/2p)

now dont panic, this is for a hovering rotor, for calculating say for descent rates, us this equation.

vd = 1/2Vd + sqrt(1/4Vd^2 + (T/2Ap))

Now climb velocities and descent velocities are just interchanged by changing the signs. easy right?

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