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Power Blast 2-4 weird stuff happening in "glide" mode


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#1 Bmwbob

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Posted 05 March 2013 - 04:13 AM

The kite seems to be flying OK in most flight modes.
BUT, (NO! Jennifer Lopez notwithstanding, I do NOT like big butts!) if I take it up to the top and release all tension on the bottom lines, it will begin to glide.
For about 3 seconds, then it will either point the leading edge straight down and do a kamikaze landing, or flip on its back and spin like a top until the earth interrupts its gymnastic routine.
During these anomalies, no amount of control inputs have any effect on what the kite is doing.
I THINK the spinning and flipping may be happening because of the wind speed suddenly decreasing to zero, which happens too often at my most convenient flying sites. I have yet to get to the beach and some consistent wind.
Can anyone confirm these characteristics as normal zero wind operation for the PB, or can you suggest something to adjust on the kite to lessen its tendency to lose its mind when the wind drops off?
Since the lines are totally slack at the inception of the events, I can't imagine that line trim settings have anything to do with it.
Ideas?
Bob

#2 kwmf

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Posted 05 March 2013 - 05:56 AM

Without tension on all 4 lines, the kite is at the mercy of the wind, air and aerodynamic ...

 

I'm assuming you have the leading edge pointing up in your example, in which case, both experiences are possible.

 

In the first case you've let the training edge go slack, the kite surge forward and overshot the top of the window or the sail flattened out so much that it presented the leading edge only to the wind. In both cases the wind sees only the leading edge and you have only aerodynamic lift hoding it up ... when airflow over the wing drops sufficiently it will stall, the weight of the leading edge is now overcome by gravity and it's going to aim for mother earth.

 

In the second case, there was enough wind that aerodynamic lift raised the nose sufficiently that the rate of climb effected a back flip. At that point the wing is pointing away from the wind and it's basically like a plane trying to fly backwards .... not going to work out so well.

 

Both cases are something you would want to avoid anyway, so don't let the tension on the lines goe slack ;)

 

What is it that you're trying to achieve by removing line tension?



#3 Bmwbob

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Posted 05 March 2013 - 06:07 AM

The Rev tutorials all describe this sudden release of tension on the bottom lines (sometimes described as a sudden "thumbs back" move) as the means by which you release power from the kite. They describe what SHOULD take place after you do this. Ie; the kite should enter a "glide" mode and head back downwind until the lines re-tension and you get control back. So far, the glide doesn't continue long enough before the kite literally falls out of the sky, in one of two modes as previously described. I had laid this off to not having enough wind to drive the kite back downwind. I know that ANY airfoil needs the air to flow over its surfaces to produce lift, whether that airspeed comes from wind blowing over a static or slowly moving surface, or the airfoil moves through the air. See what happens when I start trying to make sense out of something? :-) Bob

#4 kwmf

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Posted 05 March 2013 - 06:32 AM

I think you are thinking of the glide away which is done leading edge down - http://www.learnkite...ht-wind-flying/

 

Even gliding away to do ground recovery, you still maintain tension on the line or you will lose control of the kite. The ground recovery works in zero wind or low wind ... if there is too much wind you simply hold a hover and advance down the field to where you need to be.

 

In low/zero wind, advancing too slowly means you don't gain as much ground as you could since the kite sinks more than glides away from you. Advancing too fast means you sink too fast as well, but for a different reason (speed control).

 

In both cases, the kite is turned leading edge towards the ground and tension is applied to the bottom lines to set the glide angle.

 

The only other glide I know of for the Blast and Power Blast series is when running horizontally and that involve pulling the whole top wing back and letting the bottom out to flatten the sail out and turn it into a wing relative to the airflow.



#5 Bmwbob

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Posted 05 March 2013 - 07:14 AM

OK. I'll try playing around with the line tension whle in glide the next time out. Thanks! Bob

#6 Kitelife

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Posted 05 March 2013 - 07:39 AM

Bob, I've heard of a unique trait in both the Speed and Power Series (all sharing a similar leading edge airfoil) wherein you fly the kite overhead and pull the top lines like for a 3D catch, only with the Power/Speed kites, the kite goes into a strange glide and will often bank through it, eventually returning downwind on it's own.

 

It's not an exact science and kind of and odd "trick", but it did come to mind reading your description.

 

Playing around is what it's all about. :)


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#7 Bmwbob

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Posted 05 March 2013 - 07:48 AM

OK. I must have misinterpreted the " thumbs back" move as meaning to release the tension on the back lines, when in fact, it meant to "pop" the front lines. I'll add that to my list of things to try. Thanks, John! Bob

#8 REVflyer

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Posted 05 March 2013 - 12:18 PM

if you took the lines off entirely and threw the kite (correctly!),... it should glide out, rotate upside down and finish pointing with the leading edge parallel to the ground (inverted)

 

The "catch" part of 3-D flying doesn't come back to you (as John described) downwind, in fact I have found it impossible!  It makes a horse-shaped flight path and winds up facing back upwind with the leading edge inverted.  Play with it and see how far it travels without any more input that that first move.  It's all about positioning your catch "yank" properly.

 

You can throw the speed series kites though,.... that thick leading edge won't bend and it pierces right thru the wind like a javelin.  There's a lot of mass, so you should not be practicing over a concrete sea-wall or a big parking lot's asphalt surface.

 

Glide is about recovering your flying field, either upright/inverted or laying out sideways, with practice you can throw half axels and still walk forward.  Bigger kites require bigger movements (flailing) so don't be shy, yank & spank your way to success.



#9 Bmwbob

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Posted 06 March 2013 - 06:44 AM

I'll admit that I don't have enough experience with the Revs yet to fully comprehend what you are saying here. My interest is, when static flying, to be able to move back downwind to the ground stake to put the kite down and rest. When in the buggy, I want to be able to keep the kite airborne during lulls, or at least move it out far enough downwind from me to put it down in a more desirable landing area. I just viewed the DVD that comes with the Revs, and in it, Joe Hadzicki (I think) is flying a PB 2-4. He demonstrates the "float" mode, and his kite nicely cruises back downwind. It is Skill 19 in the basic training section. I watched it several times. He takes the kite up to the top, pulls the handles down below waist level (appearing to be pulling on the top lines to initiate the glide), and the lines appear to remain totally slack until the kite gets far enough downwind to re-tension the lines. It looks like the kite must be capable of stable flight with NO control inputs. I have yet to see that happen, but then, I have been contending with wind conditions that vary from overpowering to zero very suddenly, so it probably isn't fair to expect much under those conditions. Bob

#10 Bmwbob

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Posted 06 March 2013 - 08:40 AM

Correction: the kite Joe is flying is a Blast, not a PB 2-4. They look pretty similar to my untrained eye. Bob




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