Gas Size		50cc		100cc		150cc
Total Watts		2KW +		4KW +		10KW +
Model Weight		12lbs. - 18lbs.		18lbs. - 25lbs.		25lbs. - 36lbs.

.40's are generally in the one horsepower range, . . . . . . . . . . give or take depending on make and model. .60's can vary from 1.2 to close to 2 horsepower depending on make and model.

What should I do if it lists horsepower rather than wattage? When a motor is rated in horsepower, convert horsepower to wattage. The wattage equivalent provided below considers starting load and motor inefficiency.

Horsepower v. eMotor Power (W) 1 horsepower = 746 Watts ... theory 1 horsepower = 1,000 Watts = 1KW ... reality

Calculating Power and Horsepower in Electrical Motors Electrical power is rated in Horsepower or Watts. Electrical power is in general rated in Watts or Horsepower. A horsepower is a unit of power equal to 746 watts or 33,0000 lb.ft per minute (or 550 lb.ft per second). A watt is a unit of measure equal to the power produced by a current of 1 amp across the potential difference of 1 volt. A watt is 1/746 of 1 horsepower. Even if the watt is the base unit of electrical power, its common to rate motor power is in either horsepower or watts. Power in Watts Electric power of a motor can be expressed as: . . . . . . . . . . Power in Horsepower Horespower of a motor can be expressed as: . . . . . . . . . . Example - The Horsepower of an Electrical Motor The horsepower of an 230 V electrical motor with 85% efficiency pulling 10 amps can be calculated as: . . . . . . . . . . Ohms Law The ohm is named for George Simon Ohm, a German scientist and early electrical pioneer, who discovered that there is a constant relationship between the electromotove force (E), the current (I), and the resistance (R) in any electrical circuit. This relationship is expressed in "Ohm's Law" as follows ... From the basic law it follow that ... Power is defined as "electrical work per unit of time." James Watt another early pioneer in the electrical field, discovered taht there is a constant relationship between the electromotove force (E), the current (I), and the power consumption (P) in a circuit. This relationship is expressed in the formula ... which it follows that ... Electric Motor Equivalents the Four Motor Constants ... 1. Speed Constant Kv = RPM/V 2. Torque Constant Kt = 1355/Kv = in-oz/A This constant for ALL motors. 3. Thermal Resistance Rm = Ohms 4. No Load Current Io = A = Amps Horse Power = HP = 550lbs./ft./sec. Foot Pounds per Second Torque = T = ft.*lbs./in. Force * Radius Torque = T = Kt*A Current Constant * Amps Torque = T = Kt*Inet RPM RPM = Kv*V Motor Resistance Vm = Vin - Im * Rm Stall Current Istall = Vin / Rm Restricting Motor Turn Heat @ Istall Histall = Vin * Istall = Vin/Rm Hysteresis Loss HL = Shunting Loss Inet = Iin - Io Friction Loss FL = HL Power IN Pin = Vin * Iin Watts = Volts * Amps Power OUT Pout = (Iin - Io) * (Vin -Iin * Rm) Torque * RPM = Kt * Kv Efficiency Eff = (Iin-Io)*(Vin-Iin*Rm)/Vin*Iin Eff is 0 @ No Load Stall Best Efficiency IMaxeff = Sqrt(Io*Istall) about 80% Efficiency Max% = ((Imaxeff-Io)/Imaxeff))^2 a little nfo borrowed from: Electric Motors: Introduction to Electric Motor Design Engineering Electric Motors - Power rating: Electric motors offer the horsepower required to drive a machine, which is typically referred to as electric motor load. The most common equation for power based electric motors on torque and rotational speed is: hp = (torque X rpm)/5,250. If the electric motor's load is not constant and follows a definite cycle, a horsepower versus time curve for the driven machine is helpful. From this curve both peak and rms the electric motor's horsepower can be determined. Rms load horsepower indicates the necessary continuous electric motor rating. Peak load horsepower is not necessarily an indication of the required electric motor rating. However, when a peak load is maintained for a period of time, electric motors feature a rating, which usually should not be less than peak load horsepower. Duty cycle - Electric Motors: Continuous steady-running loads over long periods are demonstrated by fans and blowers. On the other hand, electric motors installed in machines with flywheels may have wide variations in running loads. Often, electric motors use flywheels to supply the energy to do the work, and the electric motor does nothing but restore lost energy to the flywheel. Therefore, choosing the proper electric motor also depends on whether the load is steady, varies, follows a repetitive cycle of variation, or has pulsating torque or shocks. For example, electric motors that run continuously in fans and blowers for hours or days may be selected on the basis of continuous load. But electric motors located in devices like automatically controlled compressors and pumps start a number of times per hour. And electric motors in some machine tools start and stop many times per minute. Duty cycle is a fixed repetitive load pattern over a given period of time which is expressed as the ratio of on-time to cycle period. When operating cycle is such that electric motors operate at idle or a reduced load for more than 25% of the time, duty cycle becomes a factor in sizing electric motors. Also, energy required to start electric motors (that is, accelerating the inertia of the electric motor as well as the driven load) is much higher than for steady-state operation, so frequent starting could overheat the electric motor. For most electric motors (except squirrel-cage electric motors during acceleration and plugging) current is almost directly proportional to developed torque. At constant speed, torque is proportional to horsepower. For accelerating loads and overloads on electric motors that have considerable droop, equivalent horsepower is used as the load factor. The next step in sizing the electric motor is to examine the electric motor's performance curves to see if the electric motor has enough starting torque to overcome machine static friction, to accelerate the load to full running speed, and to handle maximum overload. Rules of Propellers … The thrust that the propeller producces decreases rather linearly with the vehicle speed until "pitch speed" is . . . . . . . . . . reached, after which the thrust drops off rather quickly with increasing vehicle speed. Electric Motors produce Torque & RPM … the Propeller produces Thrust 1HP = 55ft.lb/sec. Work … Hence Thrust = 550 * HP / Speed (ft./sec.) … or Thrust = 375 * HP / Speed (MPH) 1HP = 6lbs. Thrust @ 60MPH Because motors and Propellers are less than 100% efficient … figure 1KW of power = 1HP Two numbers of information for a propeller are … Diameter and Distance travelled during one rotation. Static Thrust = 2 * Design Pitch Speed … DPS is most efficient propeller speed. Very Low Pitch Props like a 9/3, 12/4, 18/6 or 24/8 won't fly but will mix paint nicely. Propellers w/a Pitch:Diameter Ratio of 0.7 to 1.0 are best for efficiency of flight. Power absorbed by the Propeller is controlled by RPM, Diameter and Pitch. Power = 1.31 * Dia.^4 * Pitch * RPM^3 … Watts = 1.31 * Dia^4 * Pitch * RPM^3 Low Pitch = Speed … High Pitch = Performance

the Results of Gearing ...

Ratio		RPM		Diameter		Thrust		Speed
1.00		100%		100%		100%		100%
1.40		71%		122%		114%		87.4%
1.60		63%		133%		121%		82.9%
2.00		50%		152%		132%		75.8%
2.50		40%		173%		144%		69.3%
3.00		33%		193%		155%		64.4%
4.00		25%		230%		174%		57.4%
5.00		20%		263%		190%		52.5%
10.0		10.0%		398%		251%		39.8%
100		1.00%		1600%		630%		16%
1000		0.10%		6400%		1580%		6.4%