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rocket science

Posted: Fri, Jun 29 2007, 05:21 AM
by Chris
I guess kite flying is rocket science... :shock:

Re: rocket science

Posted: Fri, Jun 29 2007, 06:11 AM
by Mike
Fig. 14 Stability angles of 180° lead to an aerodynamically unstable system


Connect two matches by two strings (Fig. 14 upper left). The left match could now symbolize one of the handles and the right match could stand for the corresponding vertical spreader spar of the kite. If the kite rises (Fig. 14 upper right) matches and strings still form a parallelogram. The angle of attack is therefore not dependent on the altitude of the kite.

If, as shown in Fig. 14 middle left, the kite has rolled on its back () and the handles did not roll (), according to Eq. (12) a stability angle between kite and handles builds up (). If now the kite rises (Fig. 14 middle right) the angle of attack is decreased, thus the lift is increased and therefore the kite rises even more. No stable equilibrium is possible. The pilot persistently has to actively control the kite to stabilize it at a certain altitude. This aerodynamical instability is one of the main reasons, why it is much more difficult to fly a REVOLUTION® on its back than in its normal flying position.

If the kite has rolled one (or more) full turn(s) (), the stability angle becomes a multiple of too (Fig. 14 lower left) leading to a stable configuration. Even though the lines are crossed the kite rises parallel to the handles with a constant angle of attack (Fig. 14 lower right). Neglecting the friction of the lines the handling qualities are identical to the unrolled case.

His analysis neglects the shape of the kite. But if what he says is true, if I setup the kite upside down (bottom lines attached to the to of the kite), I should be able to fly the kite upside down easily. Next time I'm out I'm gonna try it.
His analysis also suggests that smaller handles would have less effect and would be easier. Perhaps smaller handles would make practicing upside down flying easier. It would definitely reduce the chance of over-controlling.