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How to Calculate Lift on a Tethered Blimp

The lift generated by a floating body, such as a tethered balloon, is the result of the buoyant force acting against that body within the fluid. Despite not being in a liquid state, air, as with all gases, is in fact a fluid. Buoyancy and buoyant force were first investigated by Archimedes of Syracuse for an understanding of why objects floated and how it was related to density. The point of force is the sum of the vectors of gravity, the weight of the object, vs. the lift provided by the force of the fluid displaced by the object.

Instructions

- 1
  Review the density of the material with which the blimp or balloon is filled. The density is listed in terms of mass per unit volume.
- 2
  Multiply the density of the material within the balloon by the total volume of the blimp itself. This will give the mass and, as a corollary, the weight of the material within the volume of the balloon.
- 3
  Multiply the same volume by the density of air (1.29 kg per cubic meter).
- 4
  Divide the weight of the blimp by the weight of the same volume of air. The resultant quotient will be a figure between 0 and 1 that determines its buoyancy. As this figure approaches 0, the buoyancy is greater; conversely, if this figure reaches 1, the gravitational force acting against the balloon will be equal to the force acting as lift for the balloon providing buoyancy and it will sink.

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