Editing Variometer (section)

==Purpose==

Human beings, unlike birds and other flying animals, are not able directly to sense climb and sink rates.{{citation needed|date=April 2024}}  Before the invention of the variometer, [[sailplane]] pilots found it very hard to [[Gliding|soar]].  Although they could readily detect abrupt ''changes'' in vertical speed ("in the seat of the pants"), their senses did not allow them to distinguish lift from sink, or strong lift from weak lift.  The ''actual'' climb/sink rate could not even be guessed at, unless there was some clear fixed visual reference nearby.  Being near a fixed reference means being near to a hillside, or to the ground.  Except when hill-soaring (exploiting the lift close to the up-wind side of a hill), these are generally very unprofitable positions for glider pilots to be in.  The most useful forms of lift ([[thermal]] and [[Lee waves|wave]] lift) are found at higher altitudes and it is very hard for a pilot to detect or exploit them without the use of a variometer.  After the variometer was invented in 1929 by [[Alexander Lippisch]] and [[Robert Kronfeld]],<ref name=googlebooks>{{cite book|url=https://books.google.com/books?id=x0uLSdn_hFUC&dq=%22invented+the+variometer%22&pg=PA71|title=Dreams of flight|author=Michael H. Bednarek|year=2003|publisher=Texas A&M University Press |isbn=9781585442577|access-date=2009-05-25}}</ref> the sport of [[gliding]] moved into a new realm.

Variometers also became important in foot-launch hang gliding, where the open-to-air pilot hears the wind but needs the variometer to help him or her to detect regions of rising or sinking air. In early hang gliding, variometers were not needed for the short flights or flights close to ridge lift. But the variometer became key as pilots began making longer flights. The first portable variometer for use in hang gliders was the Colver Variometer, introduced in the 1970s by Colver Soaring Instruments,<ref>[http://british-hang-gliding-history.com/magazines/wings/no-48/no-48.pdf Colver Soaring Instruments in British  Hang Gliding History]</ref> which served to extend the sport into cross-country thermal flying.<ref>[http://www.energykitesystems.net/FrankColver/ColverSoaringInstruments.html Frank Colver, Colver Variometer]</ref><ref>[http://paulgazis.com/Humor/Colver.htm The Origin and History of Colver and Roberts Variometers]</ref> In the 1980s, Ball Variometers Inc., founded in 1971 by Richard Harding Ball (1921–2011), produced a wrist variometer powered by a 9-volt battery.<ref>{{cite web|title=Pictures: 1986 Ball wrist Variometer|website=US Hawks Hang Gliding Association|url=http://ushawks.org/forum/viewtopic.php?f=2&t=2657}}</ref><ref>{{cite web|title=Richard Ball|website=Soaring Society of American|date=17 January 2012 |url=https://www.ssa.org/richard-ball/}}</ref>