Specifications
FASTER Planning Software
52
to different lens in order to have the same ground resolution when relative distance to
ground varies.
When along-track, , and across-track overlap, , are introduced and values can
be calculated and the trajectory can be finally determined. The flight trajectory is a sum of
different parts: acquisition stripes, re-alignment turns and the acquisition area entrance
maneuver. Exposure stations (where the image is effectively acquired) constitute the
stripe waypoints while re-alignment turns must be adapted according to .
Re-alignment turns are based on the Standard 45/180 procedure turn which has been
modified in order to connect two consecutive stripes. The original maneuver is designed
to reverse course, passing two times over the same fix point (Figure 45); the turn rate is
fixed at
= 3°/s. The maneuver has three straight legs and two turns, the first one is a
45° turn while the second one is 225°. The 60 s final straight leg allows the pilot to
correct re-align the airplane before entering the acquisition stripe. This is fundamental,
especially when dealing with small aircrafts which are particularly sensitive to
meteorological conditions. The 38 s leg, called the extension leg, can be modified
according to in order to return to a fix which is translated with respect to its original
position; the turning radius =
can be used to express the extension leg length
(supposing the x-axis parallel to the 60 s leg): =
45
and
=
2
.
Figure 45: Standard 45/180 procedure turn [Ref. (29)]