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7

There are plenty of smaller power planes that achieve those numbers; motorgliders. And motorgliders with L/Ds in the high teens and low 20s are pretty efficient cruisers. So the real question is; why aren't all light aircraft made to be like motorgliders? Well, motorgliders have their disadvantages. The long wing span is a problem fitting in on the ...


4

It's an expression of power required to maintain level flight throughout the speed range of the airplane and forms a U shape. The lowest point of the curve, bottom of the U, is the point of minimum power required for level flight and is normally just below maximum L/D speed (flattest glide speed). To go faster moves up the U to the right and requires more ...


2

Let's try to derive something. Assume the x-axis points to the right and the y-axis points up. I'm gonna use the subscripts b and s for bottom and side. The incoming velocity vector is decomposed in two components along the axes, so $v_s=v\sin\theta$. Writing the total drag force as a vector: $\vec D=\begin{bmatrix}-D_s\\D_b\end{bmatrix}=\begin{bmatrix}-C_{...


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