Navworld Quarterly Newsletter - The Navigator

Autumnal Equinox 2002 Issue September 23, 2002 0423 UT

    

INSTITUTE OF NAVIGATION (ion.org)

ION GPS Conference 2002 Sept. 24-27 Portland, Oregon

ION National Technical Meeting 2003 Jan. 22-24, Anaheim, California

BAD CORIOLIS

Coriolis is the apparent force acting on a moving body as a result of the rotation of the Earth. It is noticeable in the long term effects such as seen in the erosion of one side of river beds and the wear on railroad tracks around bends. In the Northern Hemisphere, the Coriolis effect causes a deflection to the right thus the river bed erodes more on the right side and the railroad tracks wear more on the right side in the direction of motion of the moving body. The direction of the Coriolis effect is to the left in the Southern Hemisphere.

Recently your editor attended a retirement party and became engaged in a conversation with two of the attendees who recited their belief in the age-old tale that one can identify the hemisphere one is in by observing the direction that water rotates during the flushing of a toilet or emptying of a sink. It was all the more interesting since the conversation became animated with arm waving and finger pointing illustrating the forces at hand when the Coriolis effect was considered. As a former Air Force navigator, your editor always acknowledged Coriolis’ influence when he made celestial observations with a bubble leveled sextant by adjusting the observations made by moving the obtained fix so many nautical miles to the right of the direction of the aircraft travel in the Northern Hemisphere and to the left in the Southern Hemisphere. The magnitude of this displacement correction was obtained from a table in the Air Almanac. He knew that the Coriolis effect was proportional to the sine of the latitude and the speed of the aircraft. As he entered the inertial navigation world, he became familiar with how the Coriolis effect was compensated for in the output of an inertial accelerometer. But clearly the Coriolis effect was too feeble to be sensed in the bathroom. Recently he referred one of my friends who believes that the Coriolis effect can be detected when toilets are flushed and basins drained to the Bad Coriolis web site at http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html.

After his friend’s visit to the site the friend asked, “Where are the analysis and the equations that prove the Coriolis movement can’t be found in the bathroom?” A highly regarded expert aerospace friend of the editor offered the following analytical proof that the Coriolis effect is too feeble to be detected by the flushing or draining of water in the bathroom :


CORIOLIS

One can get into endless arguments about Coriolis.
Simply put, the Coriolis acceleration is always 2*OMEGA(vector)
Cross-Product RDOT(vector). Since RDOT of the water particles in the sink is on the order of maybe 10 cm per second, and OMEGA is a maximum of 15 deg. per hour, or 7.27E-5 radians per second at the most; the Coriolis acceleration due to Earth rotation of the water particles would be at most [2*(7.27E-5)*10 cm per sec-squared]/[980 cm/sec-squared] in G's: or 1.48 micro-G. This is below the needed threshold sensitivity of most Inertial Navigator accelerometers, that being usually 10 micro-g's for moderately accurate INS navigation.

Next time you drain a sink, see if you can get the water to circulate in either eddy direction by starting it swirling by hand.

Voyages of Discovery
May 5 through August 11, 2002
Natural History Museum


The subjects of Captain Cook and the Endeavor and Darwin and the Beagle were stimulating exhibits that entertained many Los Angeles Natural History Museum visitors as they were able to view unique artifacts, beautiful works of art and rare specimens relating to the historic marine voyages by the two notable British discoverers whose sea voyages and discoveries in the 18th and 19th centuries gave us new insights on evolution and geography. Cook used both lunar distances and the chronometer in his celestial navigation. His mapping of the islands and continents of the Pacific were extremely accurate; some of which are used even today.

The Endurance: Shackleton's Legendary Antarctic Expedition
June 9 through September 2, 2002
Natural History Museum

Sir Ernest Shackleton’s memorable and thwarted Antarctic expedition in the Endurance to Antarctica1914-1916 was portrayed at the Natural History Museum in vintage film and haunting photographs capturing the tragic moments of the saga of the Endurance as it survived nine months of frozen immobility in packed ice only to end crushed and sunk. Its crew survived and when conditions improved made its historic boat trip to Elephant Island. Their ultimate safe haven was South Georgia Island 800 miles away. While 22 survivors remained on Elephant Island, Shackleton , Frank Worsley and four others sailed in a lifeboat to South Georgia for help. Worsley’s flawless navigation led to a successful landfall in spite of the perilous seas and rarely visible skies. The remaining survivors were then rescued.

AUTUMNAL EQUINOX

The annual flooding of the Nile in ancient Egypt was announced by the appearance of the dog star Sirius. The floods created havoc for the farmers of the Nile region. One theory holds that the washed away boundaries of the farms were re-established by enterprising surveyors who used the vertices of the Great Pyramids as a reference and the known bearings of the benchmarks of the boundaries of the farms to re-establish the farms’ borders. Four millennia later GPS was tested using an inverted range consisting of pseudolites in El Centro, CA. before the advent of the launched GPS satellites reflecting that perhaps the ancient Egyptians used the first inverted range. More on the autumnal equinox at http://scienceworld.wolfram.com/astronomy/AutumnalEquinox.html.

THEORY OF RELATIVITY

Einstein’s theory of relativity, which has withstood many challenges since its introduction in the last century, now faces a new challenge. Recently a team of Australian scientists led by famous cosmologist Paul Davies has concluded that the speed of light may not be constant. Astronomer John Webb, member of the Davies team, determined that light from a remote quasar may have absorbed atypical photons from interstellar clouds as it traveled 12 billion years to Earth.. The quasar originating light source was presumed to have a slightly different atomic structure than found in humans. The only explanation for the paradox was that either the electron charge or the speed of light (two universal constants) changed. Further studies in black holes led to the conclusion that a change in the electron charge would violate the second law of thermodynamics leaving the only possibility of a inconstant speed of light law. Webb’s quasar observations will require more studies to confirm and validate that the speed of light may be a nonconstant.

See “Speed of Light Debate Flashes Again” at http://www.msnbc.com/news/791205.asp

SPACE ELEVATORS

Recently we have seen the space elevator concept revisited in the July 2002 issue “Popular Mechanics” in an article entitled “Elevators to Space” beginning on Page 72. The article is based on current studies by NASA now investigating this concept first introduced in 1960 by Russian engineer Yuri Artsutanov. Artsutanov’s concept was based on the linking of synchronous satellites to the ground with a cable. A synchronous satellite will remain over a fixed point on the equator by matching its speed with the rotating Earth. This is achieved when its centripetal acceleration is equal to its gravitational acceleration (see Geostationary Orbits at http://scienceworld.wolfram.com/physics/GeostationaryOrbit.html). The cable link would be used to mechanically elevate payloads to orbit without relying on rocket power. The geosynchronous orbit altitude is 22,320 miles. One major hurdle to overcome is developing the right cable material. The strongest tensile material currently available according to the Popular Science article is Polybenzbisoxazole (PBO) graphite. It is capable of supporting its own length up to 114 miles but lacks the necessary compressive strength. One implementation scenario of the concept is to anchor the station with its cable to an asteroid whose orbit has been altered to a geostationary Earth orbit of 29,204 miles. NASA foresees the feasibility of space elevators and mass transportation to space to be late in this century. Visit NASA’s site at http://science.nasa.gov/headlines/y2000/ast07sep_1.htm for more on “Audacious and Outrageous Space Elevators.”

Thomas S. Logsdon and Robert C. Africano wrote a paper “Satellites Without Rockets” that investigated the feasibility of using tall structures, long tunnels, or powerful mechanical devices to achieve orbital or escape velocity enhancing performance of rockets or eliminating them entirely. Tom Logsdon later wrote the book Orbital Mechanics Theory and Applications published by John Wiley and Sons, 1998. In Chapter 10 “Space-Age Technologies for the 21st Century” Logsdon expands and elaborates on these concepts.

PORTNEY’S PONDERABLES

Your editor was the luncheon speaker for the Southern California Section of the ION in August held at The Aerospace Corporation. The topic was excerpts from his book Portney’s Ponderables. This talk was originally slated for delivery to the attendees of the ION GPS 2001 conference held in Salt Lake City last September. Unfortunately, your editor was unable to appear as the luncheon speaker owing to the grounding of all flights on September 11, 2001. The speech included excerpts on “Columbus Found Longitude?”, “Peary and Henson at the Pole,” “The Polar Flap,” “The Lady Be Good,” and “The Navigation of Lewis and Clark.” The speech was accompanied by projected graphics and narrative summaries. Excerpts from Portney’s Ponderables appear in the Institute of Navigation Newsletter under the title of “Portney’s Corner” at ion.org.

QUOTATIONS GENERALLY DISCREDITED OR LEFT WANTING

“Everything that can be invented has been invented.” – Head of US Patent Office circa 1880

“GPS can’t work; can’t transmit signals faster than a microsecond.” – Unknown

“The bumble bee can’t fly.” - Popular illustration of the Thirties to show that conclusionary judgments may lead to false conclusions

To the end Dr. Charles Stark Draper believed that the single degree of freedom gyro was the only way to go. – from a paper on the history of the MIT Instrumentation Laboratory by William G. Denhard

“Strapdown inertial will not work because of computational load limitations.” Unknown

“It is impossible to go to the moon.” – Famous 1900’s astronomer

“If you gave me all the money that you invested in brand X gyros, I could make a gyro out of pizza.” – President of brand Y gyros (somewhat prophetic with the emergence of FOG). We‘re waiting for the edible kind.

“You can’t exceed the speed of sound in an aircraft.” – Perception in pre WWII years

“Vertical, Vertical, Who’s Got the Vertical?” – George Gamow’s paper on why inertial wouldn’t work

“We can lick gravity but the paperwork would be monumental.” – Wernher Von Braun. In a paperless society maybe this will happen sooner.

“Enemy rockets can’t hit London; energy per fuel mass ratio of existing sources won’t support it” – WWII British scientific board that overlooked staging

“Doppler can’t work.” – A Government review that overlooked scatter effect

“Inertial Navigation can’t work.” – Vannevar Bush (using a flat Earth analysis)

INVENTOR OF BAR CODE SCANNERS

Your editor’s closest boyhood friend Herbert L. Bernstein died in April 2002 in Escondido, CA of complications of MS a condition that he endured bravely for close to forty years. Herb graduated UCLA with a BS degree in physics and was elected to Phi Beta Kappa in 1957. He married Ruth Behar who predeceased him. Herb went to work for NCR in Hawthorne, CA as a research engineer. He held patents for Micro Image, a high density data storage system, that enabled the optical retrieval of data reduced in size by 1/40,000, in character recognition developing the point of sale bar code scanner system (visit http://www.trident-itw.com/resource-center/content.html for introduction of bar code scanners) and formulated the basic patent for the laser printer. His student years at UCLA were interrupted by the death of his father and the need to support his mother and a short stint in the US Army postponing his graduation for ten years. When Herb's MS condition became too burdensome, he was forced to take extended disability from NCR in the mid seventies. Most of his career at NCR was spent at the Rancho Bernardo, California location. Herb was a member of the American Physical Society and Institute of Radio Engineers. He became an astute stock market investor. In 1991 sixty-one percent of NCR's sales were obtained from products based on his inventions. He was highly regarded by all who knew him. Herb’s kind unassuming manner and intelligence gained him many friends and his inventions helped shape the dynamic and successful growth of commerce in the 20th and 21st centuries.