# 7.1.6: Performances in gliding


In all generality, a glider is an aircraft with no thrust. In stationary linear motion in vertical plane, the equations are as follows:

$D = mg \sin \gamma,$

$L = mg \cos \gamma,$

and dividing:

$\tan \gamma_d = \dfrac{D}{L} = \dfrac{C_D}{C_L} = \dfrac{1}{E(\alpha)},$

Figure 7.3: Aircraft forces in a horizontal loop.

where $$\gamma_d$$ is the descent path angle $$(\gamma_d = -\gamma)$$. As in stationary linear-horizontal flight, in order to increase the velocity of a glider it is necessary to reduce the angle of attack. Moreover, the minimum gliding path angle will be obtained flying with the maximum aerodynamic efficiency. The descent velocity of a glider $$(V_d)$$ can be defined as the loss of altitude with time, that is:

$V_d = V\sin \gamma_d \cong V \gamma_d.$

7.1.6: Performances in gliding is shared under a CC BY-SA 3.0 license and was authored, remixed, and/or curated by Manuel Soler Arnedo via source content that was edited to conform to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.