Flytec 5030 v2.24 * - Manual (Page 47)

Flytec
5030 GPS
in the next thermal or the climb already achieved in the previous thermals. In order to give
the pilot an indication of the average thermal climb, the grey marked double rim at the
analogue vario displays the average value of the past 10 minutes of climb This value is not
influenced by passing through sinking air.
To fly at an optimized speed, we have to adjust our speed in such a way that the McCready
indicator covers the pointer for the average thermal climb (Picture on the left). Of course
arbitrary deviations from this indication are possible and the decision lies with pilot as to how
these will be assessed. As a rather cautious and conservative pilot, I prefer to fly with the
McCready indicator in a middle position between 0(= best glide) and the shown value for the
average thermal climb.
All the functions described here can be imitated in the simulation mode. The measured
values such as speed, sink or climb, flight direction and also ground speed can be varied by
the user and their effects on the results can be observed on the LCD screen.
5.6 Final Glide Calculation
Here the GPS data and the McCready theory go hand in hand. (Please also read the section
5.5 McCready Theory) Principally it is about reaching a goal as fast as possible (of course it
has to be logged as a waypoint in the list), or rather, to get a signal from the flight instrument
of when the last thermal can be left to arrive at the WP as fast as possible. To be able to
make a decision about this, the distance to this location (goal/waypoint) has to be known.
The distance is calculated with the help of the GPS receiver. Additionally we require the
altitude of the waypoint (is in the WP list) and the present altitude of the pilot. From this
information the required glide ratio over ground (L/D req) that is necessary to reach the goal
can be calculated. All other conditions such as wind and wind direction, flight speed and
polar curve are not considered. The required glide ratio can be shown in the user defined
fields: LID req. Only when the flyable glide ratio (over ground) has to be calculated do the
conditions just mentioned, play a role.
Basically the final glide (final approach) consists of two phases, to be considered separately:
1) Climbing in the last thermal
2) The straightest possible glide path to goal
1) Let's assume that our pilot is circling under a cloud in a very good thermal, which
provides him/her with an average climb of 2 m/sec. While circling he/she will naturally try
to fly with the speed for minimum sink. Besides the polar curve table in the Flytec 5030
GPS's memory, there is a second table calculated S2F (speed to fly), which knows the
associated McCready speed for each average climb (30 sec average) in a thermal. To
this belongs a glide ratio (through the air). If, while circling, the nose of the aircraft turns
again and again in the direction of goal, the wind component and the glide ratio over
ground can also be calculated at that moment.
A zero wind has a wind factor =1; Tail wind >1; and Head wind <1. From the distance to
goal and the glide ratio (over gnd) the Flytec 5030 GPS calculates the altitude which the
pilot will lose on his/her glide path to goal. If we also add the altitude of the goal, (input
for each waypoint) then we obtain the optimum departure altitude.
One's own altitude is known; therefore, the flight instrument can tell by comparison (in
the display Alt. over WP) whether we still have to thermal up to arrive at the fastest, or
whether we are already above the fastest glide path. Of course it depends on the
experience of the pilot whether he/she wants to leave immediately during a positive Alt.
ov.WP indication, or to climb up further and take some reserve altitude. The Flytec 5030
GPS naturally does not know whether in the course of the glide path, lifting or sinking air
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