From: greg@bronze.ucs.indiana.edu (Gregory R. TRAVIS)
Newsgroups: rec.aviation
Subject: More Stormscope info
Keywords: ICAO SctormScope Thunder Lightning
Date: 14 Apr 92 20:37:16 GMT
Article-I.D.: bronze.1992Apr14.203716.1190
Organization: Indiana University

I was digging through back issues of the _ICAO Journal_ last night
(looking for the article on GPS that I mentioned) when I ran across
the following article.  Paraphrased WITHOUT permission.

The author is Ken Ostrander "an engineering manager with
3M Aviation Safety Systems in the United States.  Responsible for
product development, he holds 16 U.S. patents"



  "Thunderstorm activity, many researches believe, is a contributing
factor in a signigicant number of aviation accidents."  [duh]

  "For years airborne weather radar has been used for severe weather
avoidance in larger aircraft, but it is difficult to install
the required equipment on many general aviation aircraft.  Radar emits an
active signal from the aircraft which is then reflected from its target
(rain droplets) to identify the location of precipitation and its
relative intensity."

  "Employing these measures and other available meteorlogical data, pilots
have been circumnavigating areas of heaviest precipitation on the bases
of two assumptions:
	(1) that heavy precipitation is an indicator of thunderstorm
	activity and
	(2) that the areas of heaviest precipitation are also the areas of
	the most severe hazards known to accompany tunderstorms.

  "The first clarification that pilots must understand is that meteorologists
define thunderstorms in the _Weather Almanac_ as a storm 'always
accompanied by lightning and thunder'; precipitation may or may not
be present.  If the presence of lightning can be detected, we can be
certain that a thunderstorm, by definition, is present.

  "Pilots also must understand and appreciate that the areas of heaviest
precipitation do not always correlate with the location of lightning
discharges.  ...  Rain showers may or may not present hazards to aircraft
in flight - thunderstorms always do."

	...

  "Electrical engineers first utilized a variety of sensing equipment to
detect cloud-to-ground lightning discharges.  Then, several such sensors
could be used in conjunction with one another and, through the use of
triangulation, provide range and bearing data for each lightning discharge
with excellent accuracy."

  "In the early 1970s, pilots began to emply their automatic direction finders
(ADF) with crossed-loop antennas tuned to a low frequency band to sense
the direction of a lightning threat."

  "Building upon this base of knowledge, Paul Ryan, a private pilot and
inventor from Columbus, Ohio, defined the next challenge as the
development of a thunderstorm avoidance system which would perform two
functions:
	[on board mapping]
	[display thunderstorm activity in all stages of a storm]

  "Ryan learned that the vast majority of all electrical activity from
thunderstorms are cloud-to-ground and intracloud discharges.  While
intercloud (between clouds) activity is possible, cloud-to-ground
and intracloud lightning discharges are most common."

  "After reviewing the data, it became clear that horizontal discharges were
contained primarily within newly forming cumulonimbus clouds which, when
observed, most pilots refer to as "heat lightning."  But, since
these horizontal discharges often are embryonic in development and may not
represent a significant threat to aircraft, a more meaningful
method for identifying thunderstorms is to detect the vertical component
in an electrical discharge.  This would indicate that the cumulonimbus
cloud deck was beginning its vertical development, accompanied by the
additional thunderstorm characteristics hazardous to aircraft.

  "In addition, by monitoring the intra-cloud activity, which is much more
prevalent than cloud-to-ground discharges, pilots could determine wheather a
thunderstorm was in the building or dissipating stage.  With this
added dimension of the weather picture, they could then better determine
an appropriate flight path around the tunderstorm, regardless of its
stage of development or whether it was a frontal system or an isolated cell.

  "The first product of these studies was the Ryan Stormscope Weather Mapping
System, a totally passive electrical signal reception device that was
introduced in the mid-1970s  ... All [models] were developed by the early 1980s
and then acquired by Minnesota Mining and Manufacturing Company (3M)

  "Ryan remained as a consultant and, supported by 3M engineers, development
efforts continued with increased emphasis on improving the technology.
During the first several years, a variety of new models were developed, based
upon the original patents.  But, by the mid-1980s, our expanded engineering
team was undertaking weather radar and Stormscope System correlation
studies and test flying new engineering algorithms, using Gulfstream IV,
Piper Aztec and Beech Baron aircraft.

  "The culmination of these efforts resulted in new engineering algorithms and
electronics which were perfected during 1988.  The newly patented Stormscope
Series II System was approved by the U.S. Federal Aviation Administration
(FAA) for use in 1989.

  "The Series II models featured increased accuracy in both range
and bearing ..."

Source:  ICAO Journal, April 1991, pp. 16-17
-- 
Gregory Reed Travis					D P S I
	
Data Parallel Systems Incorporated	greg@cica.indiana.edu
From: jak@hpbbrd.bbn.hp.com (Juergen Klaiber)
Date: Mon, 6 Apr 1992 05:51:39 GMT
Subject: at Denver  on what else but waiting I can do.
Organization: HP Mechanical Design Division