# How to calculate or design glide ratio? [duplicate]

Was interesting to watch the explanation about glider here, especially about the glide ratio. Glide ratio is defined as the ratio between altitude when it start gliding (Y-axis) to the distance it can reach until the altitude reach zero (X-axis), as shown in the picture 2. Gliding is a descending, opposite of climbing, which is ascending. All airplanes are designed to be able to glide to anticipate the worst case when the engine is failure.

There are many discussions how to calculate an airplane when ascending, explains the relation of wing area, wing ratio, airplane load, initial speed (velocity), and the power it requires to meet the ascending rate. Then my question is, how do I bind such that information when calculating the glide ratio/distance?

Edit: I believe the weight of the airplane contributing the glide distance (ratio) it can reach. Just consider two identical airplanes (say it Cessna 172), one is fully loaded and another one is not loaded at all (except the pilot, of course). They fly at the same speed and turned off the engine at the same time.

Also consider two airplanes (also Cessna 172) with exactly same weight and load, but fly at different speed and then turned off the engine at the same time.

From both above illustrations, we know their momentums are different. Is not the momentum contributing to the glide distance (ratio)?

• I believe the link suggested duplicate is different. If we just consider the LIFT and the DRAG ratio only, it will not be the answer. In my limited knowledge, there will be the initial velocity (Vo), the initial when an engine is off or when we start jump from a heigh if it is pure glider. Beside, I believe total weight also affecting the gliding ratio. A heavy weight however absolutely different from than light weight. We may check it from force components. So, we have to look back the answer rather than to take the answer in the provided link. So I think, better reopen this post. Commented Sep 11, 2019 at 12:09