You are right. It is gone. This is I think because when I joined I didn't upgrade to become a paying member. This is the article I put there:
No link HAAM.
If it is gone look in your PMs for the reason.
Some Secrets of the fans
A fan creates an air stream when it is operating. This air stream is made up of lower pressure at the front and higher pressure at the back. This air stream is the output of the fan. In other words, the output of the fan made up of lower pressure output at the front and higher pressure output at the back.
Highest natural air, atmospheric, pressure is 14.7 psi or 1.00kg/sq centimetre. So theoretically lower pressure output can not become less than -14.7 psi or -1.00kg/sq centimetre but higher pressure output always is more than 14.7 psi or 1.00kg/sq centimetre. We can put this in a formula. If the fan can generate a pressure of 0.25kg/sq centimetre the output at the front will become – 0.25kg/sq cm and the output at the back will become 1.00kg/sq cm + 0.25kg/sq cm
Theoretically a fan can be made to generate a pressure higher than 1.00kg/sq cm or 14.7 psi but this fan can not generate an output at the front lower than -1.00kg/sq cm or -14.7 psi. This is because air weight or atmospheric pressure at the front of the fan, when it is not operating, is 1.00kg/sq cm or 14.7 psi. So it is impossible for the fan to create a lower pressure output less than -1.00kg/sq cm or -14.7 psi
A fan operates with an external input. An electric fan operates with an external electric input. Not all the external input converted to the thrust of the fan to generate both outputs at the front and at the back. Only the mechanical efficiency, input efficiency, of the fan converted to a thrust to generate both outputs. Some external inputs wasted as heat because of the friction of the fan. The rest of the input is the efficiency of the fan and converted to a thrust. Lets call the efficiency of the fan as 'input efficiency'.
So how this input efficiency used to operate the fan? It is used to spin the fan and when the fan spins it creates an air stream, which is made up of lower pressure output at the front and higher pressure output at the back. But how does the fan generate this air stream? The fan throws out or pumps out air between its blades backward, which creates high pressure output air stream at the back. In other words, all input efficiency used as a thrust by the fan to spin to pump out or throw out air between its blades backward.
But the question is this: if all input efficiency goes to generate a thrust to spin the fan to pump out air between its blades backward to generate the air stream at the back, how is the front air stream generated? The answer is easy; when the fan pumps out air between its blades, it creates lower atmospheric pressure between blades. This lower atmospheric pressure between blades is lower than the external natural atmospheric pressure. So natural atmospheric pressure at the front and at the back tries to enter between blades to bring back atmospheric equilibrium between blades.
However the fan creates a pressure at the back higher than the atmospheric pressure. So the atmospheric pressure at the back can not do any thing. But the fan doesn't do any pressure changes at the front. So the atmospheric pressure at the front rushes into the space between blades to bring back atmospheric pressure equilibrium. This act causes the air stream output at the front