Sonic boom attenuator

The Sonic Boom Attenuator is a device designed for use with supersonic aircraft wherein a laser beam is shone down the leading edge of a short, rigid, straight, thin wing, heating thus rarefying the air before it passes over and under the wing. In this manner, the compression (which results from the rarefication) occurs more slowly as the relative wind passes through the beam than it otherwise would by impact with the hard surface of the wing. Because of the simplicity of design there are fewer components than have been proposed by other inventions and fewer mechanical devices to fail. Because of the rarefication, there is an overall reduction in drag to the aircraft and an attenuation of sonic boom in supersonic flight.

CROSS REFERENCES TO RELATED APPLICATIONS 
The Sonic Boom Attenuator (hereafter referred to as the Attenuator) can be 
used on any straight, thin, rigid, leading edge of an object moving 
through the atmosphere, but is primarily designed for use on the lifting 
air foils such as commercial supersonic aircraft, stealth aircraft, and 
rigid helicopter rotors. It can also be used on other forward surfaces or 
tail sections of any atmospheric craft, provided design criteria are met. 
(The rounded nose of a conventional fuselage would not be suitable, for 
example.) Additionally, some applications can be found with atmospheric 
reentry vehicles where it is determined to be of benefit in reducing shock 
to the structure or sonic boom. 
BACKGROUND OF THE INVENTION 
The invention relates to the use of an electromagnetic beam, a laser, used 
to interact with air molecules to heat and rarefy them. Physics and 
aerodynamics combine to artificially create a more preferred sonic 
condition over a wing. 
In the preferred application, a laser can be shown down the leading edge of 
a rigid, narrow wing to the tip, heating thus rarefying the air through 
which the wing quickly passes. The air is re-directed--not suddenly as in 
striking the wing under normal conditions but more slowly through the 
width of the beam, leaving thinner (less dense) air to flow over the wing. 
This creates a higher density altitude, resulting in a lower indicated 
airspeed over the wing at any given true airspeed for the airplane as a 
whole. This creates a condition unfavorable for the formation of sonic 
boom. 
This is preferable to other inventions which have been suggested in the 
past. Others do not work the same way and do not solve all the same 
problems, such as a device for ionizing then redirecting ions using their 
positive charge to a second charged device aft on the wing; 
electrophoresis and dielectrophoresis, which use electrostatic attractions 
to again re-direct air flow to a second charged device aft on the wing; 
and an electromagnetic force field to accelerate fluid rearward and push 
it aside. The principles of above inventions have some similarities to 
each other, but they are not like the Attenuator in that they do not 
significantly decrease initial relative wind impact with the hard, 
material leading edge of some structure or device, they do not use heat as 
the primary source of rarefication, and they are not single 
component/single stage devices. They're more mechanically complex, using 
such as multiple electrodes/terminals with different electrical charges or 
intensities, which are therefore more prone to failure. 
SUMMARY OF THE INVENTION 
The Attenuator is a laser beam directed along the leading edge of an 
aircraft wing to the tip. (The laser is housed in the fuselage and is not 
exposed to the wing.) When the aircraft is travelling at high speed, the 
air will heat and rarefy as it passes through the width of the beam, 
compressing more slowly than it normally would and creating (just above 
and below the wing) a higher local density altitude, resulting in a lower 
indicated airspeed over wing surfaces at any given true airspeed for the 
airplane. This produces a condition which is less favorable for the 
formation of sonic boom. There are advantages to the design: it is 
simpler, not as mechanically complex as other designs and therefore not as 
prone to failure; and it is "cleaner," in that the air is completely 
treated and rarefied before it ever touches the wing. (In other 
inventions, the relative wind is not completely rarefied before impact 
with the hard surface of some object, be it wing or protruding electrode.)

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As was stated earlier in this application, simplicity is one of the 
features of the Attenuator. FIG. 1 is an overhead view of a wing (A) with 
a laser beam (B) immediately ahead of it. The beam is shone out of the 
fuselage, down the leading edge of the wing immediately ahead of the 
cruise stagnation point of the wing (such that the relative wind must pass 
through it to reach the leading edge), to a mirror on the wing-tip (C). 
The beam is then reflected back over its original path relative to the 
wing, remaining in the loop to reduce power required for the laser. 
With this beam operating (refer to FIG. 2), and the plane in flight, the 
relative wind will need to pass through the beam (FIG. 3, B) before 
hitting the wing (FIG. 3, A) during which time the air will rarefy. 
Electromagnetic radiation interacts with matter as quanta. A quantum of 
radiation transfers both energy and momentum. When electromagnetic 
radiation is absorbed by an atom, the energy is degraded, raising the 
internal energy of the atom and hence the temperature. This is the source 
of and process for producing the heat in the air passing through the beam 
and is the primary source of rarefication. Of additional interest, 
however, is the radiation pressure exerted on the atoms by the transfer of 
momentum, assisting the process. 
As the rarefied air then passes over the wing, the wing flies through an 
area of artificially-created high density altitude, resulting in a lower 
indicated airspeed over the wing for any given airplane true airspeed. In 
supersonic flight for the aircraft, then, the wing will itself be subsonic 
for any given flight condition, until the speed of the aircraft exceeds 
the ability of the beam to rarefy the air sufficiently before striking the 
wing. 
It should be noted, also, that the Attenuator will not work on just any 
wing. A long, thick, flexible wing would be contraindicated as (1) it 
would require a greater-diameter beam and increase in power required for 
the beam, and (2) the wing flex would not allow a straight laser to remain 
ahead of the stagnation point. Ideally, a short, thin, rigid, straight, 
sharp-edged wing would best suit the design needs of the Attenuator, as 
pictured (FIGS. 1, 2, and 3). As an example for description, and in the 
absence of a wing designed specifically for the Attenuator, the F-104 
Starfighter wing would be one of the more preferable designs.