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Old Jan 17, 2013, 11:01 PM
Mark Harrison
USA, CA, Piedmont
Joined Jun 2010
2,197 Posts
Discussion
calculations

Given a prop length, prop pitch, and rotation speed (rpm), what are the formulas to calculate the theoretical

- airspeed
- volume of air
- thrust
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Old Jan 18, 2013, 02:42 AM
Registered User
Staffs, UK
Joined Nov 2003
10,345 Posts
http://www.mh-aerotools.de/airfoils/index.htm

Look under "Propellers".

Steve
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Old Jan 18, 2013, 06:00 AM
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Ken Myers's Avatar
Commerce Township, MI
Joined Aug 2001
4,376 Posts
Another good source here:

http://aircraft-world.com/prod_datas...p-proptalk.htm
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Old Jan 18, 2013, 12:54 PM
Jack
USA, ME, Ellsworth
Joined May 2008
16,804 Posts
The Powerplant calculators here will give most the useful info you're looking for:

http://2bfly.com/tools/

And if you are looking for info on specific motors with various props or specific props with various motors, the info at flybrushless.com is hard to beat:

http://www.flybrushless.com/

Jack
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Old Jan 19, 2013, 08:40 AM
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snoopy_schulz's Avatar
Germany, lake of constance
Joined Oct 2010
407 Posts
Another useful report (see attached file), but sorry in german language.
May use the google translater: http://translate.google.com/

I have written a propeller tcl script based on the document from Helmut Schenk.

Code:
# Michael Schulz 21.01.2012

proc calculate {} {
  global  Hz Dz np pin vp fp Prop N100
  
  set Kp 100.0
  set H [expr $Hz*2.54/100.0] 
  set D [expr $Dz*2.54/100.0] 
  
  if {($Prop == "APC")} {set Cp [expr 0.0856*($H/$D) - 0.0091]}
  if {($Prop == "AERONOUT-CAM")} {set Cp [expr 0.0833*($H/$D) - 0.0116]}
  if {($Prop == "Speed-Prop")} {set Cp [expr 0.116*pow(($H/$D),2)- 0.066*($H/$D) + 0.0467]}
  set n100 [expr 60*pow(($Kp/($Cp*pow($D,5)*1.225)),0.333)]
  set n100 [format %1.0f $n100]
  $N100 delete 0 100 ; # 
  $N100 insert 0 $n100 
  
  set Pin [expr pow(($np*1.0/$n100),3)*$Kp]
  set Pin [format %1.0f $Pin]
  $pin delete 0 100;  
  $pin insert 0 $Pin
  
  set Vp [expr $H*$np/60.0]
  set Vp [format %1.1f $Vp]
  $vp delete 0 100 ; # 
  $vp insert 0 $Vp 
  
  set F [expr 0.785 * pow($D,2)]
  set S1 [expr 0.55*$Pin]
  set S2 [expr pow($S1,2)]
  set S3 [expr (2 * 1.225 * $F * $S2)]
  set Fp [expr pow($S3,0.333)/9.81]
  set Fp [format %1.2f $Fp]
  $fp delete 0 100 ; # 
  $fp insert 0 $Fp 
  
  set SD [expr $H/$D]
  
  if {($SD >= 0.9) & ($Prop != "Speed-Prop")} {tk_messageBox -icon error -message "Use Prop Style -> Speed Prop !"}
  
}

proc gui {} {
      global Hz Dz np pin vp fp Prop N100
      wm minsize . 285 330
      wm title . "Propeller V1.0  M.Schulz"
           
      set a [labelframe .a -bd 3]
      
        set m1 [frame .a.m1]
        set f0 [frame $m1.f0]
          set lf0 [label $f0.lf0 -text "Prop Style: " -font {Arial 10 bold }]
          tk_optionMenu $f0.1 Prop AERONOUT-CAM APC Speed-Prop
          pack $lf0 -side left
          pack $f0.1 -side right
        pack $f0 
       pack $m1 -fill x -pady 6
      
        set a1 [frame $a.a1] 
          set al [label $a1.l -text {Prop Diameter ["] } -font {Arial 11 }] 
          set ae1 [entry $a1.e -width 6 -justify right -textvariable Dz  -font {Arial 11 }]
          pack $al -side left
          pack $ae1 -side right
        pack $a1  -fill x -pady 5
    
        set a2 [frame $a.a2]
           set al [label $a2.l -text {Prop Pitch ["] } -font {Arial 11 }] 
           set ae2 [entry $a2.e -width 6 -justify right -textvariable Hz -font {Arial 11 }]
           pack $al -side left
           pack $ae2 -side right
        pack $a2 -fill x -pady 5
      
        set a3 [frame $a.a3]
          set al [label $a3.l -text {Prop speed [rpm] } -font {Arial 11 }] 
          set ae3 [entry $a3.e -width 6 -justify right -textvariable np -font {Arial 11 }]
          pack $al -side left
          pack $ae3 -side right
        pack $a3 -fill x -pady 5
        
      pack $a -fill y -pady 12
   
      set b [labelframe .b -bd 3]      
      
        set b1 [frame $b.b1] 
          set bl [label $b1.l -text {n100 [rpm] } -font {Arial 11 }] 
          set N100 [entry $b1.e -width 6 -justify right -font {Arial 11 }]
          pack $bl -side left
          pack $N100 -side right
        pack $b1  -fill x -pady 5  
        
        set b2 [frame $b.b2] 
          set bl [label $b2.l -text {Prop Input Power [W] } -font {Arial 11 }] 
          set pin [entry $b2.e -width 6 -justify right -font {Arial 11 }]
          pack $bl -side left
          pack $pin -side right
        pack $b2  -fill x -pady 5
        
        set b3 [frame $b.b3] 
          set bl [label $b3.l -text {Static Prop Thrust [kg]} -font {Arial 11 }] 
          set fp [entry $b3.e -width 6 -justify right -font {Arial 11 }]
          pack $bl -side left
          pack $fp -side right
        pack $b3  -fill x -pady 5
        
        set b4 [frame $b.b4] 
          set bl [label $b4.l -text {Pitch Speed [m/s]} -font {Arial 11 }] 
          set vp [entry $b4.e -width 6 -justify right -font {Arial 11 }]
          pack $bl -side left
          pack $vp -side right
        pack $b4  -fill x -pady 5
         
                               
      pack $b -fill y -pady 20    
    
      set bu [labelframe .bu] 
        button $bu.1 -text "Calc" -command {calculate} -font {Arial 11 bold } -bd 3
        pack $bu.1 
      pack $bu
       
}      

########################## Main ###############################################  
set ignore [catch {eval {wm iconbitmap . -default [file join snoopy.ico]}}]
global Dz Hz np
set Dz 14; set Hz 8; set np 5500;
gui
Download of the Propeller program:
http://snoopy-schulz.square7.ch/Propeller.exe
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Last edited by snoopy_schulz; Jan 19, 2013 at 08:56 AM. Reason: typo
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Old Jan 22, 2013, 01:10 PM
Mark Harrison
USA, CA, Piedmont
Joined Jun 2010
2,197 Posts
These all look like great resources. Thanks guys!!
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