Flytec 6020 * - Manual (Page 32)

Operating Manual Flytec 6020
2.7.4 Glide ratio ( = L/D ratio)
By definition, the glide ratio is calculated by taking the horizontal distance traveled and
dividing it by the height which was lost. If instead of the horizontal speed is taken the
speed through the air, the error is 2% at glide ratio 5 and just only 0,5% at glide ratio 10.
This small inaccuracy is insignificant and may be disregarded
Within the user defined display fields the glide ratio may also be selected.
Hereby the following facts are applicable:
Glide ratio through the air:
L/DAir = TAS/Sink True Air Speed divided by Sink rate
Glide ratio over Ground :
L/D Ground = GS/Sink Speed over Ground divided by Sink rate
Required Glide ratio over Ground from momentary position for reaching selected WP:
L/D Req = Distance to the WP / Height difference to WP
Required Glide ratio over Ground from momentary position for reaching the goal.
example for explanation of glide ratio (L/D) values:
Best glide 8
Act. distance to WP 5.45 km
Best glide –
exit point 931m
over the goal
act. height
956m
681m
Alt a BG
275m
2km
L/D req 5.7
This field indicates the required glide ratio over ground to the goal crossing several waypoints.
This user field is only displayed if a Route is active. This way it can be decided, whether
one
should be flying directly to goal while crossing several waypoints, or whether one must gain
height in between within a Thermal. The calculation does not take into account if there is
a waypoint in between with higher altitude than the direct line from current altitude position
to the goal.
2.7.5 Safety altitude over the path of best Glide – Diff.BGWayp and Diff.BGGoal
In order to evaluate if one has sufficient safety altitude, these two user fields display the
difference between current altitude and the altitude which is necessary to reach the goal with
the speed of best glide. The best glide includes the momentary flight conditions.
Up-wash and down-wash, as well as head- or tail wind are also taken into account. However,
this calculation does not consider that on the path to the active waypoint other climb- or sink
zones can be incorporated, or that the wind values accounted for in the computing can be
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