Schwarzes Tuch = problematisch?

[camaro67]

AW: Schwarzes Tuch = problematisch?

Hallo zusammen,
ich habe gehört dass diese Tabelle von Porcher nicht mehr aktuell sei. Sie stamme aus 1990. Zur Zeit haben sich die Tücher bei weitem besser entwickelt. Weis jemand was darüber? Und gibt eis eigintlich eine aktuelle Tabelle der UV-Verblassungswerte verschiedener Farben.

Ps, Welche Erfahrungen habt ihr mit schwarz, blau, weiss und grau? Verblassen diese schneller als andere? Oder welche verblassen am schnellsten?

Greetings, Joe

[Niki]

AW: Schwarzes Tuch = problematisch?

Meines wissens nach verblassen neon Farben angeblich besonderst schnell.

Auch denke ich das umso leuchtender die Farben am Anfang sind umso eher fällt es auf das sie verblassen, also denke ich das es bei schwarz/ grau nicht so sonderlich auffällt, wirklich merken wie extrem die Farben dann doch verblassen tut mans ja eh nur im vergleich mit neuem Material ( zb. beim tausch von Zellen)

__________________________________________________ _______________________
"
Poynter Parachute Manual p. 364 Sun Damage

The ultraviolet rays of the sun will damage nylon and will ruin a parachute in short time. The angle of the sun's rays, the position of the material in relation to the sun, the time of the year and the time of day, screening factors of glass, etc. all determine the extent of the damage. Glass absorbs some of the ultraviolet rays, but it does not screen them out entirely. Fluorescent lights work on nylon only half as fast when in close proximity, which is bad enough. Incandescent lights are relatively safe.

Type I Fabric, Percent Breaking Strength in Ibs. lost
-----------------------------------------------------------
Outdoors, summer sun: Outdoors, summer sun, behind glass:
--------------------- -----------------------------------
one week 52% one week 40%
two weeks 71% two weeks 61%
three weeks 94% three weeks 85%

As demonstrated in the above chart, the sun's rays deteriorate the nylon quite rapidly and glass slows the process but little. The parachute's exposure to the sun must be kept to a minimum. Tests indicate that once nylon is exposed to the sun, the damage is done; it will not regain its strength if then stored out of the sun. Some new nylon yarns have been developed which resist damage by ultraviolet rays and they do not deteriorate quite as rapidly. The thinner the material, the quicker the damage; thick materials screen the sun from the inner fibers.

Some late 1957 and early 1958 Pioneer manufactured Navy 26' conical canopies have been known to come apart like tissue paper; there were 200 to 300 in the batch. Prior to 1958, a titanium dioxide delustrant was used to treat nylon fibers to make them dull. It was soon discovered that when exposed to light, this chemical treatment accelerated fiber deterioration. MIL-C-7020 was rewritten to specify only bright, untreated nylon for canopies. See the 1962 report released by the National Research Council of Canada (No. C-98-935).

It is interesting to note that many sport parachutists pack outside in the sun and that if we assume that their canopies are exposed 15 minutes each time, then after 280 jumps, the assembly has been in the sun an equivalent of seven 10-hour days which is probably enough to lower the strength 50% and this does not count the two minutes per jump when the entire parachute is exposed.

Dyed fabric, such as international orange, deteriorates faster than the natural (white).

The damage is identified by a yellowish color when viewed in daylight and a white fouroescence when viewed by ultraviolet light. Dyed components are usually excessively faded.

[...]

Webbing is also damaged by the sun. Parachutes Australia tested some faded Type XIII and it Broke a just 2000lbs. When webbing is faded, it is probably UV damaged.
Wills Wing expects their paragliding canopies to last about 300 flight hours to a maximum of 400 hours of sunlight exposure.
"
__________________________________________________ __________________________________


XIII Gurte haben neu mindestens 7000 lbs.

Das ist aus dem Poynter The Parachute Manual. Volume 2 4. Auflage ( 1991)
Ist zwar schon ewig alt aber vielleicht interessiertes doch wen. Würde mich auch mal interessieren wie sich das Aktuelle material verhält.

Mit den Leinen zerreis test Maschinen die jedes check Center hat muesste man so was ja testen können...


Ah das ist mir grade noch eingefallen, passt auch etwa zum thema http://www.gleitschirm-magazin.com/p...RM_06_2006.pdf

Hab nochn bissle was gefunden (zitate von dropzone.com)

" its the other way around:

darker colors block more uv than lighter colors.

sincerely,

daniel preston
atair <><>

Daniel Preston <><>
atairaerodynamics.com (sport)
atairaerospace.com (military)
"

"There was a great presentation at the last PIA symposium about these issues (heat, light, water, etc affecting canopy fabric.) It was given by Jeff Quill, as I recall.

Basically he said the UV damage is based on free radical activity. And since fluorescent-colored fabrics already contain free radicals, the degradation process is accelerated in the presence of UV exposure.

We've seen in the field that fluorescent fabrics seem to degrade more quickly. It was cool to hear a technical reason for it.
[John Lyman]
"

" fluorescent dye colors fade quicker, however this has nothing to do with damage to the fiber and structural integrity.

i.e. whites contain a brightener, a fluorescent dye usually made from a class of chemicals called courmarins. they absorb a small percentage of the light falling on them and re-radiate light in another spectrum. this action tapers off over time and is independent of any light degradation of the fibers.

dark color dyes protect the fibers from uv damage better than light colors, however in the context of skydiving canopies. get what ever color ytou fancy, and have fun. effects of the color are minimal.

sincerely,

dan<><>
atair

Daniel Preston <><>
atairaerodynamics.com (sport)
atairaerospace.com (military)
"

"I don't know anything about the scientific end of all this, but I have a friend how conducted a real world test. He took several samples of canopy fabric of the same type, the only difference was the color. He made sure of the age, type and kind of fabric. The samples were placed in the desert sun in an unshaded place for 2 weeks then retrieved for a pull test to test the integrity of the samples. to my suprise the black fabric held up the best. I am not sure why. The person who did the test is very educated in gear and a master rigger. Just my 2 cents

"

[Hägo]

AW: Schwarzes Tuch = problematisch?

Servus !

die erwähnte Liste der Firma Porcher über die Farb- und UV-Beständigkeit deren Tücher stammt nicht von einer unabhängigen Stelle sondern vom Tuchhersteller selbst ! Diese Information möge also keiner gar so ernst nehmen, denn kein Hersteller redet schlecht über seine Produkte !
Meine persönliche Erfahrung ist : Alle helleren Orange/Rot/Gelbtöne bleichen deutlich schneller aus als dunklere gedämpfte Farben, wie etwa Dunkelblau/Dunkelrot/Dunkelgrün. Inwieweit das Ausbleichen Rückschlüsse auf die Porosität zuläßt weiß ich nicht - aber für einen stark ausgebleichten Schirm gibts halt am Gebrauchtmarkt kaum mehr Geld, selbst wenn die Tuchwerte noch gut wären. Die wenigsten denken aber beim Neukauf daran - sondern schick muß er halt aussehen - tut er auch solange er neue ist ...

Hägo