Glide Ratio

The Glide Ratio calculator computes the glide ratio based on the change in forward distance and the change in altitude.

INSTRUCTION: Choose units and enter the following:

• (ΔS)  Forward Distance Traveled.
• (ΔH)  Change in Altitude. 

Glide Ratio (ε): The calculator returns the Glide Ratio as a real number.  

The Math / Science

The Glide Ratio is the ratio of distance forward to distance downwards when a glider is flown at a constant speed in still air. The glide ratio varies with air speed, but there is a maximum value which is frequently quoted. Glide ratio usually varies little with vehicle load; a heavier vehicle glides faster, but nearly maintains its glide ratio. 

The following formula is used:

   ε = ΔS / ΔH

 where:

• ε = Glide Ratio
• ΔS = distance of forward travel
• ΔH = altitude change in forward travel

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• Distance to Sea Level Horizon at Altitude: Computes the distance to the horizon from a specified height using a spherical model the mean spherical radius of the Earth
• Force of Drag: Calculates the resisting force of drag on an object flowing through a medium (e.g. air).
• Force of Lift: Computes the lifting force on the surface area of a wing based on the wing surface area, air flow velocity, density of air and a lift coefficient.
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• Velocity Needed for Takeoff: Computes the velocity required to create more lift than the weight of an aircraft or watercraft using a wing (e.g. hydrofoil).
• Glide Ratio: Computes the glide ratio based on the change in forward distance and the change in altitude.
• Wing Surface Area: Computes the wing surface area required to achieve lift, base on a lift coefficient, lift force, wind speed and density of air.
• Velocity of Air over the Wing: Computes the velocity required to achieve a lift, based on lift coefficient, lift force, wing surface area and density of air.
• Air Speed from Pressures: It uses the Bernoulli Equation to estimate air speed based on the total Pressure measured by a pilot tube, total Static local atmospheric pressure and the Density of Air.
• Center of Mass: Computes the vehicle center of mass between two loads (masses).

References

Wikipedia (https://en.wikipedia.org/wiki/Gliding_flight#Glide_ratio)