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Edwin Akopian Christopher Davis Sarah Hurley Amy Ngai Ian Sylvester

Spherical Balloon Drag Force Calculations. Edwin Akopian Christopher Davis Sarah Hurley Amy Ngai Ian Sylvester. The Helionauts Objective. OBJECTIVE Establish theoretical drag force on the three foot diameter spherical balloon to be used in the LTA vehicle. The Helionauts Assumptions.

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Edwin Akopian Christopher Davis Sarah Hurley Amy Ngai Ian Sylvester

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  1. Spherical Balloon Drag Force Calculations Edwin AkopianChristopher DavisSarah HurleyAmy NgaiIan Sylvester

  2. The HelionautsObjective OBJECTIVE Establish theoretical drag force on the three foot diameter spherical balloon to be used in the LTA vehicle.

  3. The HelionautsAssumptions ASSUMPTIONS • Balloon is a perfect sphere • Mylar material is a smooth surface • Balloon is at standard atmospheric pressure • Temperature of balloon to be 60°F

  4. The HelionautsEquations of Interest EQUATIONS Munson, Bruce R., Donald F. Young, and Theodore H. Okiishi. Fundamentals of Fluid Mechanics. New York: John Wiley & Sons, Incorporated, 2005.

  5. Team HelionautsCalculating Reynolds Number DETERMINE REYNOLDS NUMBER Physical Properties of Air at 60°F Calculate Reynolds Number

  6. Team HelionautsDrag Coefficient Relationship For Re≤1 For Re>1 The associated drag coefficient is found graphically (Munson p. 526). Graph can be fit approximately using MS Excel.

  7. Team HelionautsRe>1 Drag Coefficient

  8. Team HelionautsDrag Force Relationship DRAG FORCE f(Re) can be determined from the appropriate function domain.

  9. Team HelionautsDrag Coefficient Function Domains DOMAIN f(Re)

  10. Team HelionautsOperational Domain LTA Velocity Domain Assuming LTA will travel between 0.5 mph and 5 mph (0.733 ft/s and 7.33 ft/s) the velocity domain is consistent.

  11. Team HelionautsOperational Drag Force

  12. Team HelionautsTemperature Variance What if temperature reaches 90°F? Physical Properties Change in Domain New operative range (12,658<Re<126,580) falls within same function domain. Drag Value will vary slightly but relationship still holds true.

  13. Team HelionautsReferences REFERENCE Munson, Bruce R., Donald F. Young, and Theodore H. Okiishi. Fundamentals of Fluid Mechanics. New York: John Wiley & Sons, Incorporated, 2005.

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