Project Glide Ratio



Glide Ratio is the primary way to evaluate the performance of a glider.  It measures the distance traveled and the altitude lost.  Usually, this is expressed as a ratio; [some number] to 1.  60 to 1 is the glide ratio of some of the most efficient gliders in the world.  Paper airplanes are much less efficient. 


Glide ratio can also be expressed as angle: tan(a) = h (height loss) divided by d (distance traveled).  Angle a (glide slope or glide angle) can easily be solved with the trigonometric function of tangent. 


Since gliders trade height to maintain forward momentum, and therefore lift, one can look at glide ratio as a measure of lift to drag.  In fact, they are precisely the same mathematically. 



Can the glide ratio be changed by changing the lift to drag ratio?



By adding drag, the glide ratio will be reduced in direct proportion.



Four paper airplanes will be constructed from standard letter size and weight paper.   Care will be taken to make the planes identical in size and performance.  Glide ratio will be determined using a video recording of the paper airplanes flying in front of a geometric grid.  A grid will be created with masking tape or chalk on a wall; or by using existing geometry of bricks, tiles, or similar.  A distance of three meters will be measured and marked for camera frame reference.  The video recording will reveal how much height is lost over the three meter distance.  The glide ratio will be generated. 


One plane will remain unchanged and will serve as the control sample.  The other three planes will have drag added, in a symmetrical way, to the fuselage of the plane near the nose.  Square 2mm tags will be cut and bent outward near the nose of the plane.  The first test plane will have two tags,  the second test plane will have four tags, and the third test plane will have six tags.  Care will be taken to assure that no weight is added or subtracted from the planes.  Only their shapes are affected to increase drag. 


Ten trials will be performed with each of the four planes: the control sample and three test planes. 


The results will be recorded and averages will be generated for each plane.  Both the glide ratio and change in glide ratio compared to the control airplane will be charted.

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