Flytec 6030 * - Manual (Page 47)

Flytec 6030-GPS
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What else is the Vario used for ? Again an example from common practice:
A pilot crosses a valley at rapid speed. Suddenly he notices a sharp decrease in sink rate
and turns in instinctively. This was a mistake, because the desired climb turns out to be
nothing more than just a zero lift. A short glance at the Netto Vario, which in our case
displayed 1 m/s rising air, would have protected him from losing time and altitude.
The Netto Vario display only makes sense during longer descending glides. While climbing in
a thermal it is better to activate the integrated Vario, which indicates the average climb over a
chosen integration time period.
For the setting Digital Variomode in Basic-Settings „INT/NETT the following time units apply:
Ascent -> Integration time as entered setting,
Netto Sink -> Integration time always on 1 s
9.2.2 TEC Total-Energy-Compensation
What is he meaning behind this expression? Is it valid for sailplanes only, or what can hang
gliders and paragliders do with it? If a cyclist rides up a small hill of a few meters without
pedalling, it is clear to everyone that he gained this difference in altitude out of his own
momentum. This is precisely what TEC explains. The cyclist has converted his kinetic energy
into height. If the rides down the hill again, the same principle happens opposed, he converts
height into speed. His total energy remains constant. This same principle also applies to us
pilots.
It’s always when a significant gain in altitude can be achieved by reduction of excess speed
that the use of TEC makes sense. A hang glider can well gain 20 meters or more in height
when pushing out the steer bar at high speed. It would be a big mistake if this altitude gain
were indicated by the Vario and would even perhaps tempt the pilot to turn in. A good flight
instrument can compensate (suppress) these Vario swings caused by speed changes.
The Vario is only supposed to indicate climb or sink which is due to the surrounding air mass
and not by conversion of speed to altitude. When flying according to Speed to Fly, where
speed adjustments are continuously necessary, the TEC is of real great help. The TEC also
steadies acoustics and Vario tremendously when centring in a thermal.
In Set-Mode “Chapter 3 - The Setting Menus” the penetration effect of TEC can be adjusted.
From experience we recommend values between 60 … 80 %. Complete penetration (100%)
has not proved to be efficient, because even horizontal wind turbulences may influence the
TEC and make the Vario therefore a bit jumpy.
9.3 Speed
9.3.1 True or Indicated Airspeed - TAS or IAS
In general aviation it is customary to measure the airspeed by use of a pitot tube as a dynamic
pressure speed (=IAS) and also to display it as such. The advantage of this method is the fact
that at any altitude level the maximum admissible speed or the stall is marked
(flight safety) at the same position on the scale. Furthermore it is the same for the speed of
best glide for any defined altitude which is on a fixed position on the scale (flight performance).
It is however the disadvantage of this system that the indicated speed is correct only at one
certain altitude (generally at sea level). The higher one climbs, the glider will fly increasingly
faster due to the air getting thinner, without the indication display following this fact. At
approx. 6,500 m the air weighs only half of that at sea level, therefore the air speed will
increase by 1.41 times (as a radix of 2).
The physics could be pictured as follows:
In order to create a certain lift a certain number of air particles need to hit the airfoil. Because
of the fact that at 6,500 m altitude there are now only half as many particles present per
meter, the wing surface has to fly faster, but not twice as fast, because each particle has a
higher striking energy and is then only 41% faster.