Hovering thrust calulation

  • Thread starter reebrah
  • Start date
  • #1
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Main Question or Discussion Point

Basically I am doing work that requires me to calculate power for given thrust of a fan which is hovering.

Variables known:
diameter of fan: 0.8m, thrust output of fan: 250kg, rho=1.1455 kg/m^3 which is the density of air at 35Celcius , and eta which is the fan efficiency = 0.8



I tried this equation I found on wikipedia:

P^2 = (T^3) / ( (eta^2)(rho)A)

using this equation I got 7322w of power to attain a thrust of 250kg...This seems a little off. What is wrong here? does anyone know if this is even the correct value or even correct equation? thank you and appreciate it!
 

Answers and Replies

  • #3
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True but in this equation the eta^2 is replaced with a 4. This would then further decrease the power estimated from this relation. Anybody else know anything for hovering thrust?
 
  • #5
AlephZero
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Did you forget that thrust is in Newtons, not "kilograms"?
 
  • #6
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I think that might just solve my problem lolz
 
  • #7
AlephZero
Science Advisor
Homework Helper
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At least it will give you a bigger number. 7kW is obviously way too small for a quarter-tonne chopper with a teeny little 0.8m dia rotor :biggrin:
 

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