This is my latest program. Still a bug in there somewhere.
The net thrust HP does not correlate with the calculated
HP given the torque and RPM. The thrust seems too high
for one blade at a lift coef. of only .5.
I am going to start with the spread sheet Bob White did and
convert it to spread sheet form. More people can deal with
spread sheets than they can deal with Quick BASIC.
Also QB is limited to 80 characters wide which is
a problem if you want a lot of debugging columns.
IMHO it is still faster than doing a spread sheet however.
I would love to have a version of QB (NOT VB!!!!) that
would handle 132 or more characters wide.
RPM = 2700 MPH = 200 Lift Coef. = .5 Drag Coef. = .01
Air density = .0026
Radius Tang Vel Angle Cord Vel Cord Seg Area Seg Thrust Seg Torq
Inch MPH Degree MPH Inch Sq. feet Pound Pound
3.00 48.2 76.5 206 7.20 0.15 8.5 0.04
6.00 96.3 64.3 222 6.60 0.14 9.8 0.09
9.00 144.5 54.1 247 6.00 0.13 12.2 0.15
12.00 192.7 46.1 278 5.40 0.11 15.7 0.23
15.00 240.9 39.7 313 4.80 0.10 19.9 0.32
18.00 289.0 34.7 351 4.20 0.09 24.7 0.42
21.00 337.2 30.7 392 3.60 0.08 29.4 0.52
24.00 385.4 27.4 434 3.00 0.06 33.3 0.61
27.00 433.5 24.8 477 2.40 0.05 35.4 0.67
30.00 481.7 22.5 522 2.40 0.05 46.1 0.88
33.00 529.9 20.7 566 1.80 0.04 44.3 0.86
36.00 578.0 19.1 612 1.20 0.03 37.2 0.73
Total Thrust Lb = 316 Thrust HP = 169 AvgCord Ft = 0.34
Induced Drag Lb = 4.24 Torque Due to Seg. Drag Ft/Lb = 5.52
Total Torque Ft/Lb = 18.3 Calculated HP = 9.4
'Pitch20D.BAS
OPEN "pitch200.dat" FOR OUTPUT AS #1
CLS
DIM Cord(25)
Thrust = 0: Torque = 0: TotArea = 0: TotCord = 0
AirDen = .0026: MPH = 200: CsubL = .5: CsubD = .01: RPM = 2700
PRINT #1, "RPM ="; RPM;
PRINT #1, " MPH ="; MPH;
PRINT #1, " Lift Coef. ="; CsubL;
PRINT #1, " Drag Coef. ="; CsubD
PRINT #1, "Air density ="; AirDen
PRINT #1,
PRINT #1, "Radius Tang Vel Angle Cord Vel Cord Seg Area Seg Thrust Seg Torq"
PRINT #1, "Inch MPH Degree MPH Inch Sq. feet Pound Pound"
FOR Radius = .25 TO 3 STEP .25 'in feet
RadiusInch = Radius * 12 'convert to inches
PRINT #1, USING "###.##"; RadiusInch;
TangVelFPS = (6.28 * Radius * RPM) / 60 'calc tang vel in FPS
TangVelMPH = (TangVelFPS * 60) / 88 'convert to MPH
PRINT #1, USING "#######.#"; TangVelMPH;
'Tan(a) = opp/adj
tan1 = MPH / TangVelMPH 'calc the ratio
angleRAD = ATN(tan1) 'calc the angle in radians
AngleDeg = (angleRAD * 57.295) 'convert to degrees
PRINT #1, USING "#######.#"; AngleDeg;
CordVel = (TangVelMPH ^ 2 + MPH ^ 2) ^ .5
PRINT #1, USING "#########"; CordVel;
READ Cord 'in feet
PRINT #1, USING "########.##"; Cord * 12; 'convert to inches
TotCord = TotCord + Cord 'add up all cords
SegArea = .25 * Cord '.25 feet or 3 inches times the cord in feet
PRINT #1, USING "#########.##"; SegArea;
TotArea = TotArea + SegArea
LiftInc = SegArea * (CordVel) ^ 2 * AirDen * CsubL
Angle2Deg = 90 - AngleDeg 'calc horz component
Angle2RAD = Angle2Deg / 57.295
'tan(a)=opp/adj adj = opp/tan(a)
'cos(a)=adj/hyp adj = cos(a)/hyp
ThrustInc = LiftInc / COS(Angle2RAD)
PRINT #1, USING "#######.#"; ThrustInc;
Thrust = Thrust + ThrustInc 'add them up
'drag = area times V^2 times Air density times Cd in pounds
DragInc = SegArea * (CordVel) ^ 2 * AirDen * CsubD
TorqueInc = DragInc * Radius 'Radius is in feet
PRINT #1, USING "######.##"; TorqueInc
Torque = Torque + TorqueInc 'add them up
NEXT
'arbritrary cord lengths in feet
DATA .6,.55,.5,.45,.4, .35, .3, .25, .2,.2,.15,.1
'from here on... done only one time
PRINT #1,
PRINT #1, "Total Thrust Lb =";
PRINT #1, USING "####"; Thrust;
'calculate the net thrust HP
FPS = MPH * 88 / 60
PRINT #1, " Thrust HP =";
PRINT #1, USING "####"; (Thrust * FPS) / 550;
'figure out the average cord
AvgCord = TotCord / 12 '12 steps AvgCord is in feet
PRINT #1, " AvgCord Ft =";
PRINT #1, USING "###.##"; AvgCord
AspectRat = 3 / AvgCord 'divide blade lenght by Avg cord
'InducedDrag = Cl^2/Pi*A
InducedDrag = (CsubL ^ 2 / (3.1416 * AspectRat)) / 2
PRINT #1, "Induced Drag Lb =";
PRINT #1, USING "###.##"; InducedDrag;
PRINT #1, " Torque Due to Seg. Drag Lb =";
PRINT #1, USING "###.##"; Torque
TotTorque = Torque + (InducedDrag * 3)
PRINT #1, "Total Torque Ft/Lb =";
PRINT #1, USING "###.#"; TotTorque;
CalcHP = TotTorque * 2700 / 5250
PRINT #1, " Calculated HP =";
PRINT #1, USING "###.#"; CalcHP
CLOSE
SHELL "more < pitch200.dat"
SYSTEM
Paul Lamar ...No rotor no motor.
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