RSSHEADLINES SKYSPORTS

The problem came out from a wrong pilot maneuver, followed from a wrong correction.

If you carefully watch the video, you will see that after the dive, the pilot starts to turn and push the bar forward. The situation seams quite normal, but it is not, because the vibration of the sail is an indication of the stall that occurs to the wing. In others words, this pilot made a high speed stall during a spiral. 

The fact that the battens ends open is something that make the situation worst but the real problem is the reaction of the pilot.

Instead to pull on the control bar to re-establish the right angle of attack on the wing, this pilot just tries to move outside of the turn his shoulders, leaving the bar too much forward considering the fact that one wing is in stall.

This is the explanation of the first accident.

Then the DHV test pilot, Tim Grabowski (rigid wing World Champion but with not a very big experience on flex wing) tried to simulate the same situation, using as a method to re-establish the normal flight conditions, the same procedure: leaving the speedbar far in front of his shoulder and trying slightly to move his shoulder outside of the turn. What it is crazy, it is the fact that this correction maneuver was suggested to him from the president of DHV!!! 

Manfred made two tests flights, to demonstrate the right correction maneuver and to check if the battens ends could open when in good conditions. He tried several high G maneuvers and he was not able to open the battens ends. Then, after this first flight, he broke the battens ends on purpose, just opening them without pressing the rear part of them on the ground.

On the second flight, during the spiral, some battens ends opened. As you can see in the video, even with the battens ends open, pulling on the control bar the glider starts to fly again in a normal way.

At this point, the question could be this: why a stalled glider could not re-establish the normal flight conditions by itself like we (all pilots) are used to know?

Because during a spiral the acceleration is already quite high. If during this spiral, the inner wing stalls the radius of the spiral became smaller and the vertical speed higher. The acceleration increases and so the load on the wing increases the angle of attack, causing a worst situation. The only way to re-establish the normal flight conditions it is to pull on the control bar.

Alex Ploner asked to Tim Gabrowski if he would perform a similar maneuver in both, a normal flight or during aerobatic. He said: "No, because that is not a correct maneuver"!

Please, let me know if everything is clear.