Izbegavanje usisavanja!

[JuVentus]

Kada krenemo u prelet ili letenje pod oblacima moramo računati na mogućnost usisavanja. Preformirani oblaci - cc i cb - su velika opasnost po pilota koji se nadje ispod ili blizu njih. Usisavanje u oblak nije nešto što se samo nekom drugom dešava već može i vas iznenaditi.

O ovoj temi najbolje će nam reći najiskusniji piloti, a do tada ću vas prosvetliti sa pasosa iz određenih članaka koji se bave ovom temom.

Da počnemo. Nalazimo se na 1000m ispod kumulusa i vrtimo stub. Na par stotina metara ispod baze primećujemo da je dizanje pomahnitalo i da se oblak razvio do besvesti :( Šta sad?

U zavisnosti od vaše lokacije ispod oblaka(dal je ivica ili centar) i jačine usisavanja možete izabrati jednu od sledećih opcija izbegavanja/spuštanja.

Manevar	Curenje	Izvodljivost
Uši (manje od 15% svake strane)	2.1 m/s	*****
Uši + spid	3 m/s	*****
Velike uši(min 30% svake strane)	3.1 m/s	****
Velike uši + spid	4 m/s	****
"B" Line Stall	8.5 m/s	****
Spirala sa spoljašnjim uhom	9 m/s	***
Agresivna spirala	15+ m/s	*
Spirala sa ušima	18 m/s	**

Ako je usisavanje preko 8m/s nekad je bolje izvesti velike uši sa spidom i uputiti se ka ivici oblaka. Ideja je da se što pre odaljite i izadjete iz oblaka a ne borite ispod najjačeg usisavanja.

Nešto više o navedenim manevrima:
(potreban prevod - staviti u odgovor pa ću prebaciti ovde ispod)

Velike uši + spid:
Big Ears (Execution). If you need to come down faster than your normal sink rate without significantly reducing your forward speed, use this technique. Depending on your wing and the size of the ears you make, your new horizontal speed may be faster or slower than without the ears: Increased wing loading trying to overcome the drag from the ears. For related problems, see Big Ears (Problems). Don't do this in anticipation of a rotor, instead gain as much height as possible (see Blown Back) and then Dealing with Turbulence. Now for the method. Looking at your "A" risers, identify the line leading closest to the wing tip. Without letting go of the brakes, pull on both of these lines such that the wing tips will fold under. Don't pull too abruptly as this may induce a Frontal Collapse (Recovery). Hold these line otherwise the wing tips may re-inflate. See Image: Big Ears. You have the option to use your Accelerator (Usage)  (applied after the ears are made) if you fear the effects of an increased angle of atttack, or to gain more speed, but flapping tips may start oscillations at higher speed. Control your direction by weight-shifting in your harness. One can also improve steering control by making the "Ear" bigger (pulling more on the "A" lines) on the side to turn into (keep brakes in hand). To resume normal flight, release the Accelerator (Usage)  if it was applied, then let go of the lines and if the wing does not return to its normal shape within a few seconds, clear one ear at a time by weight-shifting away from the side to be cleared, or by treating it as a Collapse (Asymmetric, Recovery), but be gentle to avoid a Spin (Recovery). This technique will produce a sink rate of about 4 m/s (800 fpm) depending on your wing and how big the ears are.


Spirala sa spoljašnjim uhom
Spiral Dive with 1 Outside Ear (Execution). A small/moderate outside ear is folded and held, then a Spiral Dive (Execution)  is progressivly initiated. Do not let go of the ear before exiting the spiral dive and flying straight. Being able to use the inner brake makes the initiation and exit easier than a Spiral Dive with 2 Ears (Execution). The theory is that the drag caused by the ear diffuses the energy and makes the pilot feel less centrifuged. Note that the pilot's load is supported by a smaller portion of the wing and less lines. Dangers:

    * If you let go of the outer ear during the spiral dive, your wing will turn to face the ground, risking a Locked Spiral Dive (Recovery).
    * Spiral dive is initiated too sharply: Risk of Spin (Recovery).
    * The pilot may push the maneuver too far (G load not high enough to alert him to stop) and produce a Locked Spiral Dive (Recovery).
    * Making the outer ear too big can generate too much drag, combined with inner side braking, can lead to other incidents.


Agresivna spirala
Spiral Dive (Execution). The fastest descent rate can be achieved by performing this technique. See  Video: Spiral dive from the movie "Fly Hard"  and  Video: Sébastien Bourquin makes a spiral dive, a wing-over, and a spin. Just start turning more and more until you feel your body centrifuged (you feel your feet swelling from the blood pressure) and your wing starts facing downward. I don't recommend pushing this until your wing is fully facing downward, leave a 30 degree angle to it. Read up on your wing's DHV test report (see Wing Certification) for this maneuver. You should notice that your variometer is indicating -12 m/s (2200 fpm) when executed properly. This is a very fast descent. Keep your eyes on your glider, the inside wingtip, otherwise looking at the ground or looking at the upper wingtip will result in nausea. If you see your field of vision narrowing and fear blackout (less blood pressure in your head), clench your stomach muscles (or bring your thighs up to your chest) to force blood back up to your head. To resume normal flight, reduce the amount of inside braking gradually to avoid a monster surge.

Spirala sa ušima
Spiral Dive with 2 Ears (Execution). Do Big Ears (Execution), then widen the Chest Strap Adjustment  and lean in your harness to start a Spiral Dive (Execution). Patience, it takes a few seconds before it starts, but accelerates afterwards. Descent rates close to 20 m/s (3600 fpm) can be achieved, so be aware of your altitude over ground. During the maneuver, look towards the inside of the turn. A big advantage of this maneuver is that there is almost no G loading on the pilot because of the limited bank angle of the wing and low centrifugal effect, making this maneuver more accessible than an agressive Spiral Dive (Execution)  alone. The maneuver can be done in a very turbulent air mass. To exit, release the ears, then dissipate the rotation energy by straightening up in your harness and doing 2-3 more turns. But this maneuver is hard on the lines and you loose brake input control. No problem with new equipment, but don't do this often. And if your lines are getting old, don't do this.


Jako bi voleo da iskusniji piloti dopune ovu temu sa svojim iskustvom. Ako imate da dodate nešto unutar ovog članka pošaljite mi preko PM-a i ubaciću. Isto tako dodajte u odgovorima vaša iskustva i mišljenja.

Pozz
Djole

Skinuto sa sajta: http://www.expandingknowledge.com/Jerome/PG/Skill/All/J_Tips/English.htm#Cloud_Suck_Theory

[Zligor]

Dobro poznavati sve tehnike spiralnih propadanja i uvrstiti anti-G odelo u obavezan deo pg opreme
Sto se tice velikih usiju sa spidom, tacno je da moze brzo da se pobegne ka ivici oblaka, ali kada je usisavanje prejako, ono je i jako iskanalisano tako da bez obzira na oblik glajdera (zguzvan ili otvoren), "let" moze biti i u rikverc, jednostavno prateci najjacu struju. U tim situacijama neki piloti su se uspeli spasiti samo sa agresivnim spiralama i stegnutim trbusnjacima, dobivsi prosirene vene i strahovite upale misica. Mislim (mozda i gresim) da je spirala sa velikim usima manje efikasna od klasicne duboke spirale jer glajder sa usima ima veci otpor, a G sila ce ostati ista jer je duzina kanapa uvek ista. Sta vise, u uputstvu za moj glajder, a verovatno i sve ostale glajdere stoji da se spirala sa usima niposto ne radi jer tada manje kanapa nosi isti teret pa mogu vrlo lako popucati.
U slucaju kada je usisavanje tako jako (mislim na ogroman kumulonimbus) da u spirali i dalje idemo gore, jedini spas bi bio odseci sve kanape (odbaciti glajder) i imati padobransku rezervu koja za razliku od pg rezerve trpi jake dinamicke udare pri otvaranju, ali i tada je neizvesno da li ce nas oblak ponovo poceti usisavati sa visine od stotinjak metara od zemlje gde bi rezervu trebalo otvoriti (nikako pre jer bi onda mnogo brze dospeli u oblak). Mozda bi bilo dobro kada bi glajderi imali fabricki ugradjenu foru da mogu na neki nacin da se bukvalno odbace usi, odseku, popucaju po savovima i sa sve spoljnim kanapima odbace. Da ostane samo centralni deo glajdera sa kojim bi se razvijale brzine do (ili preko 100km/h) pa sletanje bilo izvodljivo samo u vetar ili u vodu. Onda bi spirala bila mnogo brza pa bi se moglo uteci.

[Zligor]

Kopao sam pola sata po netu dok nisam nasao clanak koji sam trazio. Evo, ko nije citao o usisavanju u cb u Hrvatskoj na takmicenju. Ima mnogo da se cita zato sto je let dugo trajao

http://www.pjkflumen.org/e107_plugins/content/content.php?content.19

A nasao sam i super text uopste o XC letenju, ima mnogo korisnih saveta:

http://www.extreme.org.ba/paraglajding/tehnikaletenja.htm

[sasa]

slazem se sa Darkom sve vezano za spiralu.mislim da je cak u nekim situacijama izvodljivija nego usi.
 imao sam dosta prilika da budem usisavan od strane raznih oblaka,a sreo sam se i sa cb-om ali tada za razliku nisam imao penjanje vec strasan nispon od preko 15m/s.
  najvise sam koristio usi i spid,ali to morate koristiti na vreme.ovaj manevar vise koristi za promenu pozicije nego za borbu protiv penjanja.ALI...       i ova figura je podlozna deformaciji.imao sa strasan frontalac sa usima i onda nos spirala sa usima i velikim opterecenjem.tada mi vise nije problem predstavljalo bekstvo od penjanja vec kako da popravim usi i da usporim spiralu.usi su bile kao zalepljene za konopce,a glajder nije reagovao na blage pokusaje da zakocim i smirim spiralu.posle nekoliko jakih udara otvorilo se uvo sa spoljne strane i onda uspeo da zakocim tom stranom glajder koji je jos uvek imao uvo sa unutrasnje strane.
   ako spiralom bezite od oblaka moj je savet da drzite spiralu dok ne pobegnete od dizanja.
   kada je poceo da me usisava oblak poceo sam da radim spiralu.dok sam radio u oblaku osecao sam veliku dezorjentaciju i mucninu.to je potrajalo nekih 15-20 sekundi.cim sam izasao ispod oblaka resio sam da malo odmorim od opterecenja,pa nastavim i za dve sekunde opet bio gde sam poceo,samo sada vidno iscrpljen.onda ponovo spirala skoro 90 sekundi. radim najstrmiju spiralu i u pocetku propadanje 4m/s pa raste na 6, posle nekog vremena krece 8 i onda naglo raste na 15 pa 20 i tada izlazim.90 sek. 800 m.

[simplyfly]

ccc... znaci jeben taj kumulonimbus   

Ja za sad nisam imao isukustva sa usisavanjem u oblak jos uvek nisam iskoristio nijedan kumulus ali sam plavom termikom izlazio na visinu do 2000 metara na gucevu i moglo je se spiciti u prelet ali nisam poneo ni pasos ni licnu kartu a drina tik ispod mene  !