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羽翼中国 DHV 安全通告:降落伞状失速事故 Parachutal stall accident 1-08-06 On Sunday 23rd July 06 a serious accident occurred to a Swiss paraglider pilot while flying from the Ebenalp in Switzerland. An experienced pilot was surprised by weather developments and flew through a rain shower. Her paraglider (DHV class 1-2) then entered a parachutal stall, which the pilot was not able to recover from using the standard methods (pulling the A-risers or accelerating with the speed bar). The pilot decided to attempt to land on a steep grassy slope while still in the parachutal stall. Shortly before impact (2m above the ground) the canopy entered a full stall, probably due to brake input. On impact the pilot suffered severe spinal injuries, thankfully with no neurological side effects. 6月23日在瑞士发生一起严重事故,一名女士在飞行中遭遇阵雨,伞在淋湿之后进入降落伞状失速使用通常的拉A组和蹬加速均无法恢复;该飞行员决定降落在一个山坡上,在落底前两米发生全速度(估计跟刹车操作有关系),落地撞击导致脊柱受伤,幸好未伤及神经. It is known that some canopies have an increased tendency to enter parachutal stalls when wet. It is also known that there are big differences in the reactions of canopies from different manufacturers – some fly quite normally when wet, as has often been reported by cross country pilots caught in rain showers, whereas others report that minimal rain is sufficient to increase the danger of parachutal stalls on their canopies. Last year a school pilot was injured after crash landing in a parachutal stall, after having only flown for a few minutes in very light rain. In the current accident report from Switzerland, again, the rain fall was described as minimal, and the rescue helpers reported the canopy being dry on their arrival at the scene. 现在已经知道有一些伞在湿了之后很容易进入降落伞状失速;各种品牌的伞在淋湿之后表现迥异,........... Winch tow pilots are particularly sensitised to this problem – a canopy which has become damp merely from lying on wet grass may well demonstrate a higher tendency to enter parachutal stalls. 牵引起飞的飞行员一定要注意的是在潮湿的草地上放了的伞,很容易进入降落伞失速... A pattern indicating which types of canopies are more prone to this problem has not been identified. Occurrences of parachutal stall when wet have been reported throughout all classes. It would appear that older canopies, where the cloth can absorb water more readily may be at higher risk, however, the current accident occurred with a new glider. It is most important that pilots recognise this potential danger source and act accordingly. Should a pilot fly through rain, the area should be left as quickly as possible, the brakes must only be used sparingly, manoeuvres which cause the canopy to fly with a greater angle-of-attack (e.g. Big ears) should be avoided, and should the conditions safely permit it, the glider should be flown accelerated by using the speed bar. If a landing while in a parachutal stall is unavoidable, it is most important that the brakes are not used at all, even though this goes against all normal pilot instincts when approaching the ground. When a canopy flies in a parachutal stall, applying a few centimetres of brake may result in the canopy going into an uncontrollable full stall. Should a parachutal stall occur when flying at sufficient height for a reserve deployment, this should be considered. The advantage here, is that the reserve descent is more stable, and not prone to either stalling or diving as in a parachutal stall descent. The sink velocity of a reserve descent is generally lower than that of a glider in parachutal stall providing the reserve canopy is of the correct size for the pilot. The Swiss pilot reported a sink velocity of -6m/s for her canopy while in parachutal stall. Karl Slezak 参考阅读:滑翔伞伞在雨中的表现 ,来自swing的研究 http://www.swing.de/?main=sicherheit&sub=allg_sicherheitshinweise&lang=en Paragliding in the rain?!
An accident has prompted SWING to carry out extensive test runs and simulations (with the support of the DHV and Dr. Stefan Müller) to identify the cause of deep stall in rain. In general, there are two reasons why a paraglider may go into deep stall in rain: 1. The first risk lies in the fact that the canopy weight increases if a glider is flown in rain for a lengthy period. The centre of gravity and angle of attack then shift, which is why it can result in airflow separation/stall. It is relevant here that if a glider absorbs more water (as older gliders do because they lose their water-repellent coating over time) and is closer to the deep stall limit because of its design and aging, less water absorption and thus weight increase will put the glider into deep stall.
We will contact you immediately if we have any new findings SWING Flugsportgeräte GmbH
Managing Director
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