1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Force of a propellor in fluid

  1. Mar 17, 2012 #1
    1. The problem statement, all variables and given/known data

    Dear physics forum users, I have a bit of a question about using a propellor to provide resistance. I am looking at designs for fall arrest devices and one idea I've looked at is using a propellor connected to a reel so that when the reel is unwound the propellor spins and is resisted by the fluid. The only thing is I'm not really sure on how to go about calculating the force exerted on the propellors. I know that we have a reel that is is spinning at roughly 60 RPM and the reel is connected to directly to the propeller so will spin at the same speed. However. what I need to do is work out how big my paddles on the propeller would need to be to provide a force equal to 981 N. Would it be best to use the force to work out the torque on the connecting shaft, and then work out the torque of the propeller? Im not really sure how to work out the second bit. lets assume the propellor has three paddles facing perpendicular to the fluid to give maximum surface area. How much force would each paddle exert on the fluid, if we had a fairly viscous fluid such as a motor oil with 0.3 Pa.s

    2. Relevant equations

    Not really sure what to use, obviously we have the basics of:


    3. The attempt at a solution

    Havn't got this far yet...
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted

Similar Threads - Force propellor fluid Date
Paint and Vertical Flow Wednesday at 6:29 PM
Resultant force and its point of action Feb 27, 2018
[First Year Statics] Replace Force System Feb 18, 2018
Mechanics of materials: Statically Indeterminate member Feb 17, 2018
Retarding Force Help Jan 4, 2018