נלקח מאתר EN September 2009
אותי זה הפתיע
לידיעתכם
אדרי
I think it is time to clear up few issues regarding Rescue Comparing we were involved in March 30 and April 1 this year. There have been several discussing between parties which we weren’t included in and there have been written about the comparing to make pilots more
.
1. We were mandated by Swiss federation SHV/FSVL to compare several rescues on the market today.
2. Background of the comparing was noise about bad behaviour of lightweight rescues. The federation decided to compare these rescues. It wasn’t re-certification it was a comparing between same kinds of rescues.
3. Alain Zoller from Air Turquoise SA sent invitation to the manufacturers, importers and magazines to take part of this comparing. (A kind of comparing of rescue was done in Italy years ago with interesting results). We received 41 rescues with 18 different manufacturers, normal- and light rescues. 4 of manufacturer wanted to compare their prototypes (total 6 proto rescues). Only 9 of the manufacturers agreed to publish the results, this means 22 rescues (out of 41) were published.
4. We decided to follow strictly the EN standard (EN 12491):
a) Weather information; wind speed, temperature, pressure, humidity. With this information the corrected payload was calculated from the declared maximum payload and atmospheric condition using formula after ICAO standard atmosphere.
b) Opening time – less than 5 seconds – using 20 kg weak link
c) Stability – Oscillations shall be reducing. During comparing we scored the stability 1-5 where 5 very stabile. This scoring system is not in the EN standard and it’s not used in certification.
d) Sink rate – less than 5.5 m/s, measured average of 30 m (minimum 100 m descent).
5. Villeneuve is a perfect place to test; we don’t have thermal wind or seabreeze. We choice the days for comparing with same calm weather condition. We tested during two days in same condition means the rescues were tested in same way. We were 4 pilots to share the openings. Every pilot flew above the lake, dropped the rescue, released main-paraglider and waited until they “hit” the lake.
Beforehand we had built 4 complete systems; harness, extra rescue, releasing system, rescue-handles (floatable), 30 m rope with a ball, 20 kg weak link, dry-suite, hoods, gloves, shoes, helmet, earplugs and waterballast for adjusting the weight in flight. The rescues were marked with a number and maximum weight. Only Randi Eriksen knowing which rescue it was and she did the calculation of the correct payload before pilots took off. All openings were recorded on the High definition
. With
of video
we could analyze easily the opening time and sink rate in milliseconds accuracy.
6. Swiss federation decided, because of security reason, to publish whole list with the aim to inform pilots about the results. It was a “storm” of angry manufacturers that threatening Swiss federation and Air Turquoise SA, they told us we are destroying the rescue market (?). Don’t pilots have the right to know what kind of product they have? The story ended with a shortened list of the comparing results on the Swiss federation web page.
Facts:
Some manufacturers and test laboratories are not agreed on how we are testing, but the fact is; we compared the rescues in same way and in same condition, the best rescues had sink rate 4.48 m/s and the worst had 8.62 m/s. The difference is 4.14 m/s!!! If other test laboratories are testing in different way than us; they will maybe not find same results, but the same differences. We can not say a rescue is dangerous with sink rate of 8.62 m/s, but with a combination of instability it could have bad effect at impact.
We found also different result of same rescue than the certification. For example we certified Globe 120 from Dudek in October 2007. We had two openings with same sink rate (5.33 m/s and 5.35 m/s) in following days. During comparison in March this year we got sink rate 5.86 m/s. Without to be 100% sure, reason of the difference could be the airmass was warmer than the lake than during certification.
Conclusion.
During this comparing in Villeneuve we discovered differences in results between test laboratories, because we are not testing in the same way. It is now time to do same test procedure for EN standard.
We don’t know why we have to defend the way this comparing was done, we only followed strictly EN standard. Opening time, stability and sink rate is in same importance. If rescue is unstable of course the sink rate will increase, but during certification we also discover unstable rescue but still sink rate ok.
It is possible to reproduce the tests for rescues, if you take care when testing in same condition (weather). If we testing same rescue for example during winter and summer we will probably not have exact same result because we are not testing in “limited” room. The temperature differences of the lake and the air-mass above it will have an effect of the results.
We should maybe work on +/- 5% tolerance on the sink rate because of the temperature differences (lake, ground, air). This tolerance should be discussed in the working group.There are still open issues to be discovering for the rescue itself and rescue system; we are far away from knowing all of them. Air Turquoise SA have more than ten years of experience of EN testing (rescues) and with 142 openings the last 3 years we are still discover new things which need attention. We for this moment believe EN standard is good enough for using in certification.
Every one of us thinks we will never use the rescue, but if it should happen we hope we will get no damage in landing (or less damage as possible).
A sink rate of 5.5 m/s is like jumping down 1.6 m and sink rate of 7 m/s is like jumping down 2.5 m.
Randi Eriksen (for Air Turquoise SA)
