Calculations

[Wayne Galligan]

Re: CalculationsI use a 20 lb fish scale with a length of thin rope attached to it and put a sleeve of pipe insulation over the rope.  I then run it around the stab and anchor the scale to solid spot.  Works quite well and is very portable.  Take it to the field or where ever.   Good enough for up to 1.70 size engines.

Wayne Galligan
  ----- Original Message ----- 
  From: Randall Bearden 
  To: discussion at nsrca.org 
  Sent: Monday, January 24, 2005 6:26 PM
  Subject: Re: Calculations


  On 1/23/05 11:31 AM, "Ron Van Putte" <vanputte at cox.net> wrote:



    On Jan 23, 2005, at 7:22 AM, Amram Privat wrote: 


      Does someone has an experience and can advise me on a good software for calculating thrust based on motor output (electric), prop size and pitch, speed weight etc etc.. 


    Go to; http://www.motocalc.com/.  They have a program which does everything you mentioned and more.  You can download  the program and use it free for 30 days.  If you decide it's what you want/need, you can pay them for it and use it from then on, after they give you an unlocking code. 

    Ron Van Putte 



  Thrust is measured in pounds, yes even thrust from a propeller driven aircraft.  The way full scale aircraft and engines measure thrust is on a test stand there the engine is mounted on a movable stand that is anchored with a force transducer calibrated in pounds.  The engine is ran up and the resultant trust is measured. 

  Apply the same principle to our smaller model engines.  You could make a stand on wheels (to minimize friction) and anchor it with a spring scale
  Mount the engine with a small tank on the stand and chose an appropriate size prop.  Run the engine up, record the RPM and the resultant trust from the scale.  Now you can see the effect of many different variables, fuel, prop size, mixture settings, even glow plug heat ranges.

  With all of the data you can collect you should be able to really fine tune your engines/fuel/props for maximum performance


  Randall Bearden 
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