UFO Recognition – Part 1
By Bill Hamilton (firstname.lastname@example.org)
Another important aspect of aerodynamics is the drag,
or resistance, acting on solid bodies moving through air. The thrust
force developed by either the jet engine or the propellers, for example,
must overcome the drag forces exerted by the air flowing over the airplane.
Streamlining the body can significantly reduce these drag forces. For
bodies that are not fully streamlined, the drag force increases approximately
with the square of the speed as they move rapidly through the air. The
power required, for example, to drive an automobile steadily at medium
or high speeds is primarily absorbed in overcoming air resistance.
Supersonics, an important branch of aerodynamics, concerns
phenomena that arise when the velocity of a solid body exceeds the speed
of sound in the medium, usually air, in which it is traveling. The speed
of sound in the atmosphere varies with humidity, temperature, and pressure.
Because the speed of sound, being thus variable, is a critical factor
in aerodynamic equations, a so-called Mach number, named after the Austrian
physicist and philosopher Ernst Mach, who pioneered the study of ballistics,
represents it. The Mach number is the speed of the projectile or aircraft
with reference to the ambient atmosphere, divided by the speed of sound
in the same medium and under the same conditions. Thus at sea level,
under standard conditions of humidity and temperature, a speed of about
1220 km/h (about 760 mph) represents a Mach number of one, that is,
M-1. The same speed in the stratosphere, because of differences in density,
pressure, and temperature, would correspond to a Mach number of M-1.16.
By designating speeds by Mach number, rather than by kilometers or miles
per hour, a more accurate representation of the actual conditions encountered
in flight can be obtained.
Another factor, long known to rocket designers, is
the direct influence of ambient atmospheric pressures on the efficiency
of the flight of planes in supersonic speed ranges. That is, the closer
the surrounding medium is to a perfect vacuum, the more efficient is
the power plant of the plane. Reducing the area, or cross section, displacing
atmosphere, can also increase the range of the supersonic plane. Increasing
the weight by increasing the length, but at the same time making the
plane more slender and equipping it with a needle nose, are necessary
features of design for planes operating in the supersonic range in the
Generally, UFOs seem to bend the rules when it comes
to aerodynamics. The maneuverability of discs seen in flight is
such that the UFO accelerates so quickly that it seems to overcome any
forces of drag that would retard its movement. Discs have been
seen to make 90-degree turns instantly, and in some rare cases, instantly
reverse their direction of travel. When accelerating to speeds
estimated to be supersonic, no shock wave seems to be generated and
no sonic boom is heard. Some maneuvers accomplished by UFOs would
place extraordinary stress on the airframe if flying like conventional
aircraft. Coming in contact with the surrounding atmosphere at
high rates of acceleration would challenge the structural integrity
of the vehicle, would induce enormous drag and heat the skin of the
craft to glowing temperatures, but perhaps the UFO does not come into
direct contact with the atmosphere, but actually repels the atmospheric
boundary layer surrounding its form. This would account for how
they can move quickly without encountering air resistance and thermal
Structural integrity is a major factor in aircraft
design and construction. No production airplane leaves the ground before
undergoing extensive analysis of how it will fly, the stresses it will
tolerate and its maximum safe capability.
Every airplane is subject to structural stress. Stress
acts on an airplane whether on the ground or in flight. Stress is defined
as a load applied to a unit area of material. Stress produces a deflection
or deformation in the material called strain. Stress is always accompanied
Engineers carefully calculate the stress a particular
part must withstand. Also, the material a part is made from is extremely
important and is selected by designers based on its known properties.
Aluminum alloy is the primary material for the exterior skin on modern
aircraft. This material possesses a good strength to weight ratio, is
easy to form, resists corrosion, and is relatively inexpensive.
Fittings must be made of carefully selected materials
because of their importance of holding the aircraft together under expected
stress and loading. The same holds true for important fasteners such
as bolts and rivets. It is essential that these parts not fail under
stress. It is also essential that these parts not weaken with exposure
to stress and weather elements.
UFOS have been observed that seem to have seamless,
rivetless hulls which could give such a craft high structural integrity.
Corrosion is also a consideration. A fitting made of one metal cannot
be secured to the structure with a bolt or fastener made of another
metal. This situation may result in "dissimilar metal corrosion"
over a period of time and result in a weakening of the assembly to the
extent that the assembly is rendered unsafe.
Types Of Structural Stress
"Shear" stress tends to slide one piece of
material over another. Consider the aircraft fuselage. The aluminum
skin panels are riveted to one another. Shear forces try to make the
rivets fail under flight loads; therefore, selection of rivets with
adequate shear resistance is critical. Bolts and other fasteners are
often loaded in shear, an example being bolts that fasten the wing to
the spar or carry-through structure. Although other forces may also
be present, shear forces try to rip the bolt in two. Generally, shear
strength is less than tensile or compressive strength in a particular
"Bending" is a combination of two forces,
compression and tension. During bending stress, the material on the
inside of the bend is compressed and the outside material is stretched
in tension. An example of this is the G-loading an airplane structure
experiences during maneuvering. During an abrupt pull-up, the airplane's
wing spars, wing skin and fuselage undergo positive loading and the
upper surfaces are subject to compression, while the lower wing skin
experiences tension loads. There are many other areas of the airframe
structure that experience bending forces during normal flight.
An airplane structure in flight is subjected to many
and varying stresses due to the varying loads that may be imposed. The
designer's problem is trying to anticipate the possible stresses that
the structure will have to endure, and to build it sufficiently strong
to withstand these. The problem is complicated by the fact that an airplane
structure must be light as well as strong. The manufacturer states upon
certification that the design meets or exceeds all FAR requirements
for the category of aircraft being produced. However, hard landings,
gust loads caused by extreme turbulence, performing aerobatic maneuvers
in a non-aerobatic airplane, etc,. can affect the airworthiness of one
or more major airframe assemblies to the extent that the airplane is
no longer airworthy. This reiterates the necessity of operating the
aircraft within the limitations outlined by the manufacturer. Every
flight imposes loads and stresses on the aircraft. How carefully it
is flown, therefore, will have an effect on the service life of its
It is the UFO’s ability to withstand or defy the normal
loads and stresses of our conventional aircraft that allows them to
fly in such erratic modes as zigzag flight, instantaneous decelerations,
and instantaneous accelerations. The type of flight pattern makes
a UFO stand out from the aerobatic performances of conventional aircraft.
This is only a small part of a subject that could fill a textbook.
It is by capturing these details of UFO flight dynamics for the record
that adds weight to the evidence that unconventional flying objects
have been cavorting around the earth for decades.
The PAG Network
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