One of the most puzzling technical questions about UFOs is why they do not appear to make a sonic boom when they break the sound barrier. A sonic boom is caused when any normal flying object, even a meteor, starts to move faster than the speed of sound. The speed of sound varies with altitude, humidity, temperature and pressure. At sea level under normal conditions the speed of sound is 1,220 kilometres per hour (760mph), but because the earth's atmosphere gets thinner the higher you fly, at 10,000 metres above the ground it is only 1,080 kilometres per hour. Something is therefore said to be breaking the sound barrier or flying at supersonic speed, when it flies above the speed of sound for the prevailing conditions. An aircraft flying at that speed is said to be flying at Mach 1. Saying that a jet fighter is capable of flying at Mach 3 means that it can fly at three times the speed of sound (about 3,240 k /h). With advancing technology aircraft designers are now starting to talk about 'hypersonic' flight speeds which refers to speeds above five times the speed of sound or Mach 5 (about 5,400 k/h).
Sound and air pressure are both transmitted through the atmosphere by air molecules bumping into each other like rows of billiard balls. As a subsonic craft, doing less than the speed of sound, moves through the air it sets up a field of air pressure that informs the air in front of it to get out of the way. This forewarning travels ahead of the aircraft at the speed of sound. But once the craft itself reaches the speed of sound, it catches up with its own air pressure bow wave. This creates a shock wave of sound and pressure shaped like a large sideways cone that moves parallel to the ground with the plane at its apex. The lower part of this conical shock front leaves a swathe of noise and air pressure that moves along the ground behind the aircraft. This sonic boom causes windows to rattle or break and makes a loud disturbing noise.
The legal ramifications of the extensive noise and repeated window damage that would be left in its wake is the major reason that the world's only supersonic passenger aircraft, the Concorde, is generally restricted to flying across the Atlantic on the LondonNew York route. There are no windows beneath to worry about. While over built-up areas, Concorde has to fly subsonic which makes flying on it rather pointless. This sonic boom problem is one reason no modern supersonic replacement has been built for Concorde.
With the enormous growth in modern air travel, any aerospace company that builds a supersonic passenger plane that does not make a sonic boom will probably make buckets of money. It is interesting to speculate as to why this has not yet been done given that UFOs are reported to have been flying around silently at supersonic speeds for at least fifty years.
In an article on UFO propulsion theories, nuclear physicist and UFO researcher Stanton Friedman writes that: "Substantial research, much of it classified, has been done showing that a magneto-aerodynamic (MAD) system would be capable of solving all the problems of high speed flight by controlling lift, drag, heating and sonic boom production all electromagnetically rather than mechanically or chemically. The system would be symmetric, highly manoeuvrable, relatively silent, would often have a surrounding glow, and would be capable of sudden starts and stops." Unfortunately he then tells us that research on MAD propulsion systems is classified because they have some relevance to the flight aerodynamics of ballistic missiles.
In his book Unconventional Flying Objects: A Scientific Analysis the late Paul R. Hill, who spent his working life as a rocket scientist at NASA's Langley Research Centre in the USA, devotes two detailed chapters to an analysis of why UFOs can break the sound barrier without making a sonic boom or overheating.
Hill points out that with regard to sonic booms, in supersonic flight the air ahead of an aircraft does not know that the craft is coming whereas in subsonic flight it does. In other words, once the speed of forewarning the air in front of the plane becomes slower than the actual speed of the aircraft, you have a problem. The solution is simple. If you are flying faster than the speed of sound, you have to transmit the information that you are coming to the air ahead of the craft at a speed that is also faster than the speed of sound. This gives the air time to get out of the way, thus helping prevent a noisy shock wave. How can this achieved?
Hill claims that UFOs radiate a force field a short distance ahead of the craft that is capable of repelling air molecules. This force field travels at the speed of light and is therefore easily able to stay ahead of the craft even at hypersonic speeds. By giving the air sufficient prior warning to get out of the way, no bow shock wave is created no matter how fast the UFO is flying. Hill even points out that rain, small bugs, dust and sand particles would be repelled by this field and would flow around the craft instead of hitting it. The UFO would not even need windscreen wipers he claims.
However that is not the complete solution. The shape and length of a plane affects what sort of shock wave it creates as it breaks the sound barrier. Some long planes make two sonic booms, one from the front and one from the back. This distinctive double bang is well known to those watching NASA's Space Shuttle as it prepares to land after re-entering the Earth's atmosphere. Coupled with this is the problem of aerodynamic drag and the overheating of a craft as a result of beingbuffeted by the atmosphere as it increases speed. The outside surfaces of the Space Shuttle for example "reach a blinding-white heat, of the order of 1,300 degrees centigrade" on re-entering the earth's atmosphere (Hill, p.208). To attempt to counteract these problems, most supersonic aircraft are long and thin with sharp points at the front, yet the average UFO is saucer shaped, which would seem to be a highly unsuitable shape to minimise overheating and aerodynamic drag.
To solve these additional problems Paul Hill produces pages of calculations to show that in addition to putting a repulsive force field facing its direction of travel, UFOs would need to put another repulsive field at the back. To put it simply, any air that meets the UFO in supersonic flight would be repelled sideways from the front, sucked along the sides and then pushed away from the back. This has the amazing result of enabling the UFO to fly with no wind resistance, no turbulence, and no sonic boom. It also gives the UFO's propulsion system a higher level of energy efficiency and helps explain why these craft come in so many unaerodynamic shapes.
The last benefit of UFO airflow-control force fields that Paul Hill discusses is of "aerodynamic heating" (p.208). Hill's calculations suggest that by diverting the atmosphere from the front of the moving craft, allowing it to flow along the sides and then pushing it away from the back, no thermal energy is imparted to the UFO's surface. Not only does this prevent the UFO from heating up, but Hill suspects that the opposite may be the case. He claims that air repelled from the front of the UFO will experience "a big pressure drop" causing it to expand and drop in temperature as it goes along the sides of the craft (p.326). "The temperature gets so low that even with boundary-layer friction the air at the UFO surface is below ambient atmospheric temperature
. Under these circumstances, the UFO is cooled at various flight speeds, not heated. This would be true at any speed for which the UFO can maintain the high field strengths needed." (p.326)
There have been a few UFO close encounters where evidence suggests that the UFO somehow significantly cooled the surrounding area. I recall a case where a witness who had seen strange lights at night while returning home from driving in the country, was unsure whether he had had a close encounter or not. What he did know was that a water bottle that had been in his vehicle was frozen solid when he got home later that night. This was very puzzling because the weather was warm, so what he wondered had frozen the water in the bottle? Paul Hill's calculations about aerodynamic heating and cooling may have provided an answer. "In a surprise fallout it was found by this theory that if a UFO left such an air-control mechanism turned on while hovering low over water, air temperatures near the machine could get cold enough to create ice" (p.327).
If these well informed calculations about UFO aerodynamics are currently available in the public domain from a NASA scientist, it is perhaps not unreasonable to suspect that the United States military has known about the matter for years and has probably had time to conduct the appropriate experiments and test fly various prototypes of their own versions of this technology. If this is the case, one wonders for how much longer air travellers are going to have to endure the tedium, cost and inconvenience of travel by outdated subsonic passenger jets.
Friedman, Stanton T. (1980) UFO Propulsion Theories. The Encyclopedia of UFOs. Ronald D. Story (editor), pp.281-284.
Hill, Paul R. (1995) Unconventional Flying Objects: A Scientific Analysis.
Scott, Andrew. (1990) Acoustics. The Guinness Encyclopedia, p.31
Source: Journal of Alternative Realities - Volume 7, Number 1 1999