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Icaro Laminar 13 MRX: Difference between revisions
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→Tuck avoidance: Discussing the U2 diagram
(→Tuck avoidance: Discussing the U2 diagram) |
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# In exactly this pilot position (relative to the wing), the system - consisting of wing and pilot - continues to rotate. The angle of attack is continuously reduced. In the diagram, the hang glider moves from the right to the left on the blue curve. | # In exactly this pilot position (relative to the wing), the system - consisting of wing and pilot - continues to rotate. The angle of attack is continuously reduced. In the diagram, the hang glider moves from the right to the left on the blue curve. | ||
# At point 3, the blue curve intersects CM=0 at alpha=25°. The area under the (negative) moment curve (between point 2 and 3) is a measure of the strength of the rotational excitation. | # At point 3, the blue curve intersects CM=0 at alpha=25°. The area under the (negative) moment curve (between point 2 and 3) is a measure of the strength of the rotational excitation. | ||
# | # For α<25° (to the left of point 3) the moment is now positive. The deceleration of the rotation has started. | ||
# α<sub>0</sub> is reached at point 4. From then on, the lift becomes negative, which results in a reversal of the control effect (see Figure 2). | # α<sub>0</sub> is reached at point 4. From then on, the lift becomes negative, which results in a reversal of the control effect (see Figure 2). | ||
# '''Up to this point the hangstrap is tight!''' | # '''Up to this point the hangstrap is tight!''' | ||
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[[File:MomentDiagram Sensor en.jpg|left|thumb|800px|Sensor Video: Defining the individual phases in the moment diagram]] | [[File:MomentDiagram Sensor en.jpg|left|thumb|800px|Sensor Video: Defining the individual phases in the moment diagram]] | ||
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The initiation of the tucks or near-tucks in the other videos can also be subdivided into the 4 phases. The individual phases are just more or less pronounced. | |||
In the U2 video (whip stall), the initial state of the tuck initiation is at a significantly higher angle of attack compared to the Sensor due to its flight attitude (nose high) at the onset of the stall (point 1). | |||
In addition, the pilot pulls-in more, which results in a very negative moment (point 2). The diagram of the U2 clearly shows that phase 1 is much more dominant compared to the Sensor. The area under the moment curve is huge due to both the range of the angle of attack and the more negative moment (max. pulled-in). | |||
The opposite is true for phase 2. As the pilot remains in a fully pulled-in position (green curve), the zero-crossing of the moment curve (point 3) shifts to the left to a smaller angle of attack. The area under the (positive) moment curve is therefore noticeably smaller compared to the Sensor and the decelerating effect is thus significantly reduced. No deceleration of the pitch-down rotation (as with the Sensor) can be seen in the video. | |||
But even then, the U2 would not have tucked if the pilot had stayed in front. Either he pushed-out reflexively after point 4 or, like the Sensor pilot, he was ‘pushed backwards’ by the glider due to his inertia (despite the reduced rotational deceleration compared to the Sensor). | |||
[[File:MomentDiagram U2 en.jpg|left|thumb|800px|U2 Video: Defining the individual phases in the moment diagram]] | [[File:MomentDiagram U2 en.jpg|left|thumb|800px|U2 Video: Defining the individual phases in the moment diagram]] | ||