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Principles of flight
During landing, you might fly in ground effect, and it can be difficult to land the
aircraft before the runway ends because the drag decreases as closely you get to
the ground.
Flying in ground effect also reduces the effect of wingtip vortices, as the ground
blocks vortex formation.
See an animation on ground effect here.
5.3.7.4 Parasitic drag
Total drag is a combination of induced drag and profile drag (form drag and
parasitic drag).
Parasitic drag comes from parts of the aircraft that do not contribute to lift
production, such as the landing gear, antennas, pitot tubes, exhaust pipes, steps,
and door handles.
There may also be interference drag, where there are sharp transitions, such as
between the fuselage and the wing.
5.3.7.5 Drag vs speed
Try to observe the figure here showing drag and speed.
Drag is also an indication of how
much engine power is required at
various speeds.
The speed where the least power is
required corresponds to the lowest
point of the orange line.
If the speed needs to increase or
decrease, more throttle will be
needed!
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 461
