In an ATEC structure the outside walls of the pipe would be approximately
18.5m in diameter and 9,150m tall. This forms what aerodynamic engineers would
call an infinite cylinder with a drag coefficient of approximately 0.2. In
addition to this the glass cloth, which forms the outer walls of the pipe,
would be coated with a thin layer of aluminum.
Due to the difference in height between ground level and the top of the
pipe, which is 9,150m tall, there would be an electric potential of 1.5 x 106
volts. This charge would serve a very useful purpose in preventing a boundary
layer from forming around the cylinder, which means that the drag coefficient
will be much lower – as low, perhaps, as .02. This means that the ATEC cylinder
would not feel the wind pressure impinging on the surface of the pipe. This technology was developed in the early 1990s by
the air force. It did not, however, prove practical for several reasons; primarily, an aircraft has so many sharp surfaces
and joints that it was never possible to sustain a high voltage charge on a structure such as an aircraft.
On the contrary, an ATEC heat pipe would be round, and its full length would
not suffer the discharge problems encountered in a structure such as an
aircraft. It should also be noted that an ATEC heat pipe has a spherical dome
at its top, which of course would also be an equal potential surface. In
addition, an ATEC heat pipe will be a lighter-than-air structure due to the
buoyancy of the ammonia gas with which it is filled. We have calculated this
buoyancy to be approximately 3 x 10 kg5. It is essential to an ATEC
heat pipe design that it will sustain itself without the use of guy cables or
any ground based support. We have calculated that guy cables would weigh as
much as the buoyancy factor and that further they would prove hazardous to
aircraft.
In order for the heat pipe to not feel pressure on the down wind side, it
is necessary to avoid turbulence due to separation of the flow in this area.
This can be accomplished by avoiding the formation of a boundary layer. Here is
where the electrostatic charge comes in. What occurs in an electrostatically
charged structure is that electrons are discharged into the layer of air that
lies immediately adjacent to the boundary of the heat pipe. This means that the
boundary layer of air and the solid boundary of the heat pipe of similarly
charged, and the boundary layer of air, would be repelled by the heat pipe. In
essence, the electrostatic charge acts quite similar to that of an oil film on
mechanical surfaces. It serves to facilitate the sliding of one surface over
the other without creating excessive friction.
