Warren,
:-)
That's nice. I searched for a similar video. But the 4guys are not so
clever and the wind was rather moderate. At > 4 BFT you have no chance
to bring that kite down by hand. It is important just to pull it down
into the direction where the wind blows, to minimize the forces.
I'm using a deflection roller out of stainless steel which are used by
sailors. These are hold by a big supporting loop:
http://www.drachenshop.de/images/e-1012406_3.jpg Anyway it was a hard
fight in one of the nights, the field completely in darkness and massive
winds becoming stronger and stronger. That was when i've been young...
73, Stefan/DK7FC
Am 27.07.2012 20:31, schrieb Warren Ziegler:
Stefan,
I saw this Youtube video of 4 big guys trying to bring down a kite
like yours:
http://www.youtube.com/watch?v=K7q34sw4XMo
I would love to try this but I live in an area densely covered with
tall trees, and it would be quite a drive to an open area where I
could launch an antenna (children's playground is not a good place for
a HV antenna!)
73 Warren K2ORS
On Thu, Jul 26, 2012 at 4:48 PM, Stefan Schäfer
<[email protected]> wrote:
Hello Warren,
Am 26.07.2012 19:39, schrieb Warren Ziegler:
Stefan,
I imagine that a LF or VLF small vertical is a relatively high-Q
circuit, how do you manage to keep the kite vertical in resonance and
matched while the kite bounces around in the wind?
Most of the time the kite was quite stable, i.e. the angle and so the C did
not change significantly. The antenna current is stable within a 10% limit.
When the wind was poor in some situations, the kite drops to a lower angle.
Then the falling ERP is rather affected by the lower effective height than
by the changing current. The current (say 1A on 8970 Hz) can easyly drop to
400 mA when the angle changes from 80 deg to 40 deg.
One method is to compensate this by turning the variometer from time to time
or you can use a working point of the variometer that uses a slightly to low
L. Then the antenna current does not reduce when the kite falls (in certain
limits of course). This is the case because the little generator that i used
(up to 550 W RF power in the best times) can be seen as something like a
constant power source. So if the kite falls then slightly, the working point
moves to the peak of the resonance curve and the rotation speed is somewhat
lowered. It was funny to observe this effect for many hours on the field :-)
But normally the movement of the wire does not strongly change the antenna
current.
OK?
73, Stefan/DK7FC
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