RAST in practice |
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There is a principle in science known as falsification, which says that the accuracy of a statement cannot be proven, but only its invalidity.
We were breaking new ground in paraglider design with the RAST system, so this concept saw us encounter curiosity and interest on the one hand, and understandably, on the other hand, scepticism and reservation as well.
Video Examples
Novice pilot Jennifer Lauritzen was flying her Arcus RS Lite on her introduction to mountain flying in Tollhouse, California, she flew into an area of intermittent turbulent air caused by thermals where she experience this frontal collapse. She captured this view using a helmet mounted GoPro Fusion 360 camera.
The Arcus RS pilot was coming in to land in Austria’s Tannheim valley when he experienced an asymmetric collapse shortly before touching down in the intermittently turbulent valley wind.
In this case too, RAST effectively prevents the collapse from spreading further, and the folding line runs practically parallel to the leading edge.
The glider reopens extremely rapidly and there is a flat folding angle, so it doesn’t turn away and there is very little loss of altitude.
Not long after the pilot launched in Annecy, he flew his Arcus RS into an area of very strong turbulence generated by thermals.
The resulting collapse initially starts as a frontal collapse, which spreads from the right side of the wing across to the left and changes into a massive asymmetric collapse on the left side.
It is clearly evident how the front stall is stopped at the partition, even without any pilot input, and the asymmetric collapse is then prevented from extending over into the right half of the wing.
Whilst deformation of the canopy affects approx. 80% of the wing at its leading edge, its trailing edge is not affected until well over into the left half of the wing.
The fact that the canopy does not completely empty behind the RAST system means that it re-opens extremely rapidly and there is little loss in altitude (due also to thermal assist).
Pilot’s comment: “It all happened so quickly that I didn’t have any time to react! “
Jeffrey Griffioen was flying out of a thermal in Greifenburg, Austria when he experienced a front stall on his Arcus RS XL (take-off weight: 121kg, harness: Lightness 2).
RAST stops the symmetrical front stall, thereby preventing it from spreading further into the wing’s rear section.
There is thus no risk of a front rosette and the glider opens extremely quickly, without any significant loss of altitude.
The pilot himself reported that he did not respond to the front stall by braking.
Pilot’s comment: “A front stall on an Arcus RS – a non-event!“
While testing the Nyos RS, the Italian XC-pilot and photographer Gianni De Zaiacomo flew with a tow camera he had built himself (image frequency of 1 sec.). This produced this photo of an asymmetric collapse. The photo shows the image with the most extreme features of the collapse.
It can be seen clearly from the distortion of the right SWING arrow on the bottom surface how the collapsed section of the wing (buffer zone) literally “wraps” around the partition.
Behind the RAST-system, the wing remains stable and filled with air.
Pilot’s comment: “I’m happy to see the effectiveness of RAST in that picture. RAST works very well!”