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# The '''configuration''' of the glider. The glide ratio is almost always the highest in the clean configuration, i.e. with nothing sticking out or deployed. Lowered undercarriage, extended brakes and spoilers, deployed and windmilling propellers, opened or lost canopies, attached ropes are things that will reduce the glide ratio. Generally speaking, having the flaps set to other angles than neutral is not good for the glide ratio, but this very much depends on other factors.
# The way the glider is flown. For a fixed glider mass (which is generally the case with the exception of jettisoning water), the glide ratio is a function of indicated airspeed, giving rise to the polar which is the immediate next topic. Moreover, if the glider is not flown straight (with sideslip), or flown otherwise than normal (e.g. stalled, inverted), the glide ratio can decrease drastically.
== Lift and Drag Coefficients ==
In aerodynamics, the lift coefficient (\( C_L \)) and drag coefficient (\( C_D \)) are defined as follows:
\[ C_L = \frac{L}{\frac{1}{2} \rho V^2 S} \]
\[ C_D = \frac{D}{\frac{1}{2} \rho V^2 S} \]
Where:
* \(\rho\) is the '''true density''' of air.
* \(V\) is the '''true airspeed''' of the aeroplane.
* \(S\) is the area of the wing (projected onto the ground), a fixed value for a given glider.
* \( \frac{1}{2} \rho V^2 \) is collectively known as the '''dynamic pressure''', or dynamic head.
