Jan 17, 2013, 11:01 PM Mark Harrison USA, CA, Piedmont Joined Jun 2010 2,208 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
 Jan 18, 2013, 02:42 AM Registered User Staffs, UK Joined Nov 2003 10,396 Posts http://www.mh-aerotools.de/airfoils/index.htm Look under "Propellers". Steve
 Jan 18, 2013, 06:00 AM Registered User Commerce Township, MI Joined Aug 2001 4,388 Posts Another good source here: http://aircraft-world.com/prod_datas...p-proptalk.htm
 Jan 18, 2013, 12:54 PM Jack USA, ME, Ellsworth Joined May 2008 16,857 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
Jan 19, 2013, 08:40 AM
Registered User
Germany, lake of constance
Joined Oct 2010
407 Posts
Another useful report (see attached file), but sorry in german language.

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```