Prop power and thrust calculation sheet at start: check setting of propellor constantLight green fields are for input, check setting of altitudesky fields are calculated output

New data calculator, takes prop disk load into accountCompare two engines or prop combos

power compared to engine 2:

engine 1 15820 %

Diameter inches 128 notesPitch inches 294Rpm 1480reduction efficiency 100%Motor power 1213244prop power [W] 1213244 HP: 1628.52Thrust kg 2145.52 lbs 4720.14lbs/hp 2.90prop noise rpm limit 1352 n-max (for noise requirements)pitch speed [ms] 184.2 km/h 663.12

Disk load 845.566 naut. Mph 358.1

Specific thrust lbs/hp 2.89842989

for model planes, look at disk loads 100 to 250

power ration engine1/engine2= 158.20

engine 2 power compared to engine 1:Diameter inches 30 0.6 %Pitch inches 12rpm 5500reduction efficiency 100%motor power [W] 7669

prop power [W] 7669 HP: 10.29

Thrust kg 27.882 lbs 61.34

lbs/hp 5.96 Some of the used basics for calculating the Dataprop noise rpm limit 5768 n-max (for noise requirements)pitch speed [ms] 27.9 km/h 100.6 standard method for correcting horsepowerDisk load 200.04 Dyno correction formula:Specific thrust lbs/hp 5.96 Cf=1.180[(990/Pd)((Tc+273)/298)^0.5]-0.18

Cf=Dyno correction factor

Pd=Dry air pressure (millibar)Tc=Temperature in Centigrade

Old sheet data, reasonable accurate:To Determine Required HP then use this Equation

engine 1Propeller Leng 5.0625 18.0 Inches barometric pressure reduction:Propeller Pitch 0.6666666667 8.0 Inches Noise limits for a prop start when tip speed exceeds 0.7 machEngine Speed 438.976 7,600 RPM This rpm for a prop will be inserted into the evaluationsRequired HP 2.347 <<HP/kW>> (not yet corrected for elevation, but use lower rpm if possible, because it gets worse up there)Thrust generated 14.08 <-Lbs/grams->

The sheet can be used for engines behind a prop drive reduction gear.

spitfire data: 990 hp at 12000 ft. prop 128" dia, 294" pitch, topspeed 350 miles (proto) at 12000 ft and 3000 rpm, relative pitch at that speed not known, but needed for proper power calculation. Gear ratio = 0.47: The spit nearly flew at pitch speed, despit very high disk load of 831

Below are some other useful calculations, by rearranging the data

To Determine Required RPM then use this Equation(how fast will my prop spin on that engine??)

Propeller Leng 9.37890625 21.0 InchesPropeller Pitch 1 12.0 InchesHP Produced 3788.1355932 6.0 HPRequired Engine Speed 7,377 RPM

To Determine Required Pitch then use this Equation(what pitch can I use with a certain dia prop??)

Propeller Leng 9.37890625 21.0 InchesEngine Speed 401.45729163 7,377 RPMHP Produced 3788.1355932 6.00 HPRequired Propeller Pitch 12.1 Inches

Pé Reivers Model Engines

Diameter inch 32Pitch inches 10Rpm 6500reduction effic 100%Motor power 13656prop power [W 13656 HP: 18.330Thrust kg 42.763 lbs 94.08lbs/hp 5.13prop noise rpm 5407 n-max (for noise requirements)pitch speed [m 27.5 km/h 99.06Disk load 269.653Specific thrust 5.1325548191

check setting of propellor constantcheck setting of altitude

Gentlemen, I am interested in prop rpm performance comparison, but only if

the data are from the same engine setup (damper system, fuel, altitude, weather)

Please report data to pe.reivers@mvvs-nl.com , so I can complete this sheet

Check altitude, BIG influence

Set prop constant value first! altitude: 0 meters,calculatedpropellor constant: 1.18 Calculated feet: 0 0 Feet, input(0 or none for meters input)

3W 1.3 0 meters, input is disregarded if feet value is greater than 04-blade 2.40 pressure 1000 mBarAPC 1.15 barometric pressure reduction:Bambula 1.44 10mb per 100m altitudeBME 1.40Bolly 1.1Dynaflite 1.05 SkorepaEngel 0.95

engel 3-bl 1.35 Temperature conversions (°C and °F)

Graupner 1.45 °C °F

JAS 1.22 38 100.4

MA 1.00 °F °CMejzlik 1.18 400 204.4

mejzlik 3-bl 1.80

Mejzlik-N 1.12MenzS 1.31MSC 1.4NX 1.27top flite 1.4Zinger 1.10

Some of the used basics for calculating the Data

standard method for correcting horsepowerDyno correction formula: (acc to SAE J1349)Cf=1.180[(990/Pd)((Tc+273)/298)^0.5]-0.18Cf=Dyno correction factor

Pd=Dry air pressure (millibar)Tc=Temperature in Centigrade

barometric pressure reduction: 10mb per 100m altitudeNoise limits for a prop start when tip speed exceeds 0.7 machThis rpm for a prop will be inserted into the evaluations(not yet corrected for elevation, but use lower rpm if possible, because it gets worse up there)

The sheet can be used for engines behind a prop drive reduction gear.

power ratio eng.2/eng.1

0.00

Feet, input(0 or none for meters input)meters, input is disregarded if feet value is greater than 0