Glider
Glidersun-powered heavier-than-air aircraft.
They can be divided into two broad categories, true gliderssailplanes.
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2 Sailplanes 3 Other meanings 4 See also 5 External links |
True gliders
True glidersdesigneddescent only (relative tolocal air flow).
The first heavier-than-air aircraftbe flown, Sir George Cayley's Coachman Carrier (1853), wastrue glider.
Other examples weremilitary gliders used insecond world warsupport paratroop operations. These craft were used forsingle flight only. The troops landing by glider were referredas airlanding as opposedparatroops. A typical cargo plane could carry 810 soldiers, but that same plane could towglider20 menit. Furthermoreglider could be released at some distance fromactual target, makingmore difficult forenemyguess their intentions. Larger gliders were also usedland heavy equipment like anti-tank gunsjeeps, which wasmajor improvement inpower available tootherwise lightly-armed paratroop forces.
The Orbiter vehicles or "space shuttles, which glide to earth atendeach spaceflight,also true gliders.
Sailplanes
image:Sailplane landing discus.jpg
Sailplanesspecifically intended forsportgliding. Their design enables themuse energy fromatmosphere"soar";can climb as well as descend. For more about soaring, please seegliding article.
To enable themsoar, sailplanesdesignedminimise drag. They have very smooth, narrow fuselagesvery long, narrow wings withhigh aspect ratio. New materials such as carbon fiber plasticcomputer-aided design have increased performance. While early gliders have had glide ratios below 201,latest open-class competition models can exceed ratios601maintain this efficiency overwide rangeair-speeds. [The ratio60:1 means thatsmooth airsailplane can horizontally travel 60km while losing 1000maltitude]. In modern gliding competitions,winner ispilot who isfastest completingtask set forday. To adaptglider tothermalslift available attime,competition rules sometimes allow gliderscarry jettisonable water ballast. Heavier planes haveslight disadvantage climbingrising air, butextra wing load shiftsglider's performance curve into higher velocities, so thatplane can achievesame glide ratio athigher velocity. While thisan advantagestrong conditions whengliders spend only little time climbingthermals,pilot can jettisonwater ballast beforebecomesdisadvantage whenthermal conditions weaken inevening.
Much more thanother typesaviation, glider pilots userely on an instrument calledvariometer, which measuresclimb or sink rate ofplane. Electronic variometers code their reading into an acoustic signalvariable amplitudefrequency, so thatcan be used without drawingpilot's attention away from watchingairspace andweather. Onlygliders,special variometer system called 'total energy compensation' is used. In this setting,variometer does not measurepure climb/sink rate, which changes dramatically whenplane's speed changes becausekinetic/potential energy conversion. Ideally,only measures true gain/lossglider energy duevertical airflows. Total energy compensationvariometers can be achieved mechanically without microprocessor electronics has been usedgliders fromearly days.
The most common methodlaunching glidersbehindpowered aircraft, although other methodsalso used (see gliding).
Motor gliders
Some sailplanes ("self-launching motor gliders")equippedmotors, usually retractable intofuselage, powerful enoughallowgliderslaunch independently. Others ("self-sustaining motor gliders")equippedmotors just powerful enoughallowgliderclimb slowly under its own power after an assisted takeoff. Some people argue that an engine makesaircraft safer, becausepilot can avoid storms,can goan airstripland. An opposing viewthat motor glidersagainstspirit ofsport, and, more importantly, thatsometimes give pilotsfalse senseinvulnerability. In glidingin single-engine flyinggeneral, itimportant neverbe outgliding range ofsafe landing site.Other meanings
In Conway's GameLifeglider iscertain small structure that moves indefinitely indirection.See also
External links
- General:
- Sailplane Directory - An enthusiast's web-site that lists manufacturersmodelssailplanes, pastpresent.
- Sailplane Directory - An enthusiast's web-site that lists manufacturersmodelssailplanes, pastpresent.
- Web-sites ofmajor modern sailplane manufacturers:
