Cecil, !5DXP wrote:
"According to Rohn, a single set of guy wires limits the tower to 40 -
feet maximum height - sorry about that."

Well, it depends on the Model No. and how you will load the tower. It is
best to follow thw manufacturer`s recommendations to the letter.

There is a length that you can stack which will endure without guys in
most cases. Towers usually come in 20-ft. sections. Often one or two
sections is all it is safe to use without guys. Windloading the tower is
expected to withstand, often determines space between guy points.

Wind exerts force on the tower and its appurtences, often expressed in a
sum of pounds per square foot on the area facing the wind.. Resistance
(drag) produces a differential pressure on items in the wind. Force is
proportional to the projected area in the wind, and varies with the
shape and roughness of the item in the wind. Windload on a tower is not
uniform. The wind usually blows harder at higher altitudes. Wind tries
to turn the tower over but until something yields, it is in equilibrium
and the summation of of forces about the base of the tower is zero. The
summation of torques is zero.

Guywires exert force in yje only way they can. They have tension in the
direction of the wire. This may be resolved into vertical and horizontal
components. This prevents movement and increases base loading when the
wind blows.

Pressure on items in the wind (pounds per square feet) is a function of
the square of the wind velocity (miles per jour).

One formula considered useful is named "Ensewiler" which is said to
give:
22.5 psf = 85 MPH
45 psf = 134MPH
60 psf = 155MPH
75 psf = 173MPH

Best regards, Richard Harrison, KB5WZI