vazno!

[SkyLord]

I found a very interesting article about usage of folding lines at European Para Academy website. It's only a few days old. Unfortunately it's only in german, but I think it's worth to translate.

Original here:
http://para-academy.eu/deutsch/index.php?option=com_conten(shrinked URL)iew&id=322&Itemid=147

I will try to make a short translation:

- the EN 926-2 in principle allows the usage of folding lines, but only if the collapses can not be executed correctly without folding lines.
- the original purpose of allowing folding lines in EN 926-2 was to enable correct execution of 70% assymetric collapse. By using some diagonal folding lines (for example from right riser to the left part of the wing) you can perform a correct execution of 70% collapse.
- the certification house should in principle test if the maneuveres can be executed without folding lines. In praxis, they often believe the manufaturer and just test with the folding lines.
- todays practice greatly deviates from the original intension of folding lines usage. The folding lines are used to make the collapses softer.
- often, more time is spent on finding the right setup of the folding lines to pass the certification than on actual behaviour of the wing.
- for example, 70% collapse is substantially different with and without folding lines. This leads to certification of some wings that would otherwise not be possible. Open class wings can become CEN D wings and CEN D wings can become CEN C wings.
- to end this confusing situation, a consensus between PMA and certification houses must be reached. At the moment the consensus is not there.
- the European Para Academy has therefore issued some additional conditions to the manufacturers that wish to certificate their wings. If they don't agree to this conditions, they should certificate their wings at another testing house.


Please note again that the above is not my interpretation, but only a (short) translation of the article. Please correct me if you think there is some mistake.

For me as a customer, reading the article, the situation is very serious. I feel I should know what kind of wing I'm buying.


Od PGforum!

http://paraglidingforum.com/viewtopic.php?t=43421

[Pumba]

U pravu si Martine, VRLO vazna tema. Nije bitno da li se neko interesuje za tehnicke detalje glajdera. Ovo bitno utice na svaki SIV sa modernim krilima. Mislim da se danas zahteva od prosecnog pilota mnogo vise razumevanja o ponasanju krila nego sto je to bilo pre. Takodje, mislim da se javlja problem sto ljudi odbijaju da razumu pravo znacenje sertifikacije i procesa testiranja.


Russell Ogden:

The use of collapse lines for the purpose of certification is acceptable IMO. Collapse lines have been used on several wings by several manufacturers over the last few years, I believe it was the Magic 4 (or 5?) that started the trend. We (Ozone) have used them on the Mantra M4, Delta and Rush3. It is openly stated in the manuals that this is the case, with clear advice regarding SIV.

 The aim of the EN test is to asses the behaviour of a wing after a collapse of a specified proportion, it is not necessarily to asses the reaction of the glider after a pull on an A riser (that is just a method used to induce the collapse)....there is a difference.

 In the case of the 75% side collapse, at the moment, the test is to collapse 75% of the leading edge, with a 45deg kink angle, so that 50% of the trailing edge is also deflated, there is a small tolerance either side of this, but if the collapse is of a significantly different proportion then it is not within the requirements of the norm. (eg if the % of the leading edge is too large or too small, or if the kink angle is too large or small). If the glider cannot be collapsed to these dimensions with the use of the A lines alone then collapse lines can be used. I don't see the problem with this.

 SIV is another matter, trim speed collapses and all other manouvres are possible, but we do not recommend full speed collapses with such wings.

 Real life behaviour is not adversly affected, in fact the gliders I have experience with that have been certified with collapse lines are significantly less prone to collapse in the first place and they behave in the same way (as a non collapse line certified wings) when an unprovoked collapse occurs.

 Certification is not suddenly broken and is not out of control, it is the same as it has always been; a standard to ensure wings meet the necessay safety requirements. The guys at Air Turquiose, DHV & European Acadamy etc do a difficult job well, the problem is that many pilots put so much faith into the process without fully understanding what the actual process is or means.

 Cheers
 Russ

[Zligor]

Ja i dalje ne mogu da skuzim chemu sluze ti Collapse lines Zar nije dovoljno kad se krilo jednostavno testira tako da se A gurtne vuku tek nakon izlaska iz oshtrih zaokreta. Hocu reci, kada je krilo u tendenciji da ima sve manji i manji angle of atack Tad se sasvim realno prikazuju sve one deformacije krila iz najgorih uslova za letenje Jedino bi taj sertifikat bio validan

[Pumba]

Collapse lines sluze upravo da se dobije realniji kolaps. Na novim krilima su A kanapi pomereni dosta nazad. Posledica je da kad vuces A gurtne mehanika desavanja kolapsa nije ista. Ako kod takvog krila vuces A gurtne krilo ce prvo da smanji napadni ugao, onda ubrza pa tek onda ode u kolaps. Ovo kolaps cini znatno agresivnijim i vecim. Dodatnim kanapima se postize da se krila testiraju kao sto su se do sada testirala. Jos jedna stvar je to sto je potrebno napraviti tacno propisan kolaps da bi se testiranje u opste obavilo. Ovo nekad nije moguce bez dodatnih linija.

Testiranje sa kolapsom na izlasku iz zaokreta uvodi niz dodatnih parametara koji uticu na kolaps cime testiranje postaje manje pouzdano i ponovljivo.

Nikakva simulacija kolapsa nije 100% realna situacija. Ako nista drugo, kad se kolaps desi u realnoj situaciji krilo leti kolapsirano u turbulentnom vazduhu sto je vrlo razlicito od uslova testiranja ili SIV-a. Ali, od neceg mora da se pocne. Ljudi i dalje teraju po starom i smatraju da sertifikacija govori u potpunosti kome je krilo namenjeno a to nije uvek tako. Vrlo je moguce da EN B krilo bude zahtevnije od EN C krila.

[Zligor]

Sad nesto razmishljam, treba jedan dobar wind tunel za paraglajdere da se napravi, specijalizovan, sa vishe izduvnih grana, sve turbulencije da pravi...dajte paraaaa

[Zligor]

Neshto kao ono zatvoreno skijalishte u Dubaiu bude...
Joj, ne smem vishe ovoliko piva da pijem...
Aj laku noc

[menigeru]

Brabonjce ,ne poznajem te ali te obozavam i 23557885212789055674688x 

[Zligor]

Hehe, evo i tebi jedna poshto sad imam 23557885212789055674688 za razbacivanje