Looking for an equation related to lifting force of air

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    Air Force Lifting
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Discussion Overview

The discussion revolves around the physics of hot air balloons, specifically focusing on the equations related to lifting force, volume, temperature, and pressure of the air involved in the lifting process. Participants explore the relationship between buoyancy and weight forces in the context of balloon design and operation.

Discussion Character

  • Exploratory, Technical explanation

Main Points Raised

  • One participant inquires about an equation that relates lifting force to the volume of air at a given temperature and pressure.
  • Another participant shares a document that may provide insights into the physics of hot air balloons.
  • A participant suggests a basic model involving buoyancy and weight forces, presenting an equation that equates the total weight of the balloon system to the buoyant force provided by the surrounding air.
  • A later reply acknowledges the similarity of their derived equation to the one mentioned previously, indicating a shared understanding of the concepts involved.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on a specific equation but share related ideas and models regarding the lifting forces in hot air balloons.

Contextual Notes

The discussion does not clarify assumptions regarding the conditions under which the proposed equations are valid, such as the effects of acceleration or variations in air density with temperature and pressure.

Paranemertes
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Hello,

I've been wondering for a while now how hot air balloonists figured out how big their balloons needed to be to lift themselves, the basket,the balloon itself, ect. Is there an equation that would tell me how much lifting force I could get out of x amount of air at x temperature, what volume that would take up, and maybe the pressure?

Thanks!
 
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I didn't read the document, but you can construct a basic model just by knowing two forces: the bouyancy force and the weight force.

(mass_basket+mass_balloon+mass_air_in_balloon)*g = Volume_balloon*g*density_surrounding_air

This equation would be for if the balloon were not accelerating up or down.
 
Yep, that is very similar to what this fine gentleman derived. Thanks!
 

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