Flytec – Flytec 4030 * User Manual
Page 21
Flytec
The relevant descent value can be read from the polars for any flying speed (horizontal speed)
and the relevant glide ratio can be calculated. E = - V
H
/ V
VE
.
A straight line from the point of origin at any point on the polar represents (optically distorted
by the choice of scale) the angle of inclination of the flight path at the particular speed.
From this, it can be deduced that the originating straight line which just touches the polar (tan-
gent) has the flattest level of inclination and thus results in the best glide ratio. In the example:
V
H
= 35 km/h = 9.72 m/s and V
VE
= -1.1 m/s. (The craft flies furthest at the flying speed with
the best glide ratio.)
The polar shown in the example is only valid if the air is completely still. The changes for air
agitated horizontally and vertically will be discussed later.
The lowest descent speed can be determined with a horizontal tangent to the polar. In the
example: V
H
= 30 km/h = 8.33 m/s and V
VE
= -0.97 m/s.
Working out the polars
Since manufacturers’ figures are generally over-optimistic, it is recommended that you work
out the polars yourself. The polars are flown with the same equipment and the same instru-
ments which will be used in subsequent flights. Instrument measurement errors can be neu-
tralized in this way as they will also be present during normal flying later on. The polar worked
out is thus a relative polar which is only correct for the instruments used and their displays, the
absolute values of which may, however, be faulty. In order to achieve the same conditions, the
airspeed indicator in particular should always be mounted in the same manner.
The airspeed
indicator should be calibrated as accurately as possible (e.g. with the help of the GPS receiver)
to ensure that the flight instrument data is as precise as possible. Cf. OPTION mode of the air-
speed indicator: SPEED correction.
For the purpose of information, it should be mentioned at this point that the speed V
FM
indi-
cated by the airspeed indicator does not represent the horizontal speed VH but is composed
of V
H
and V
E
.
Operating Instructions FLYTEC 4030
20
-8.33 m/s
E
=
= 8.59
-0.97 m /s
͌
V
VE
V
GM
V
H
V
H =
V
GM
2 -
V
VE
2
-9.72 m/s
E
MAX =
= 8.84
-1.10 m /s