**Horsepower Required Calculator wrote:**Horsepower & Aerodynamic Drag Calculator

By AssassinRacing.com

Calculate the theoretical Horsepower required to move a vehicle at a certain speed based on the Vehicle Drag Coefficient (Cd), Vehicle Frontal Area (sq. ft.), Vehicle Weight (in pounds), and desired Vehicle Speed (MPH).

Assumptions: The vehicle is a car driven on concrete with tire pressures set to 30 psi. Ambient temperature is around 25º Celsius (77º Fahrenheit), no wind.

Drag figures are usually calculated from wind tunnel models without side mirrors, gaps in the windows and body panels, and smooth wheel covers. These all contribute to Drag Coefficient (Cd) and can increase the vehicle's frontal area. Most of the drag on a car is aerodynamic drag rather than rolling resistance (from tires and vehicle weight).

Top speeds are either gear limited or drag limited. Use the Gear Ratio Speed Calculator to determine which is the case for your particular scenario.

Use the Drag Performance Calculator to calculate the theoretical 1/8 Mile ET, 1/4 Mile ET, 1/4 Mile Top End Speed, and Ideal 1/4 Mile Gear Ratio and the 0-60 MPH Time Calculator to calculate the theoretical 0-60 Time for a given application.

**Calculating HP wrote:**HORSEPOWER FORMULAS

For Rotating Objects

HP =

Where T = Torque (lbft)

N = Speed (rpm)

Objects in Linear Motion HP =

Where F = Force (lbs)

V = Velocity (ft/min)

For Pumps HP =

HP =

Where

GPM = Gallons per Minute

Head = Height of Water (ft)

Efficiency of Pump = %/100

PSI = Pounds per Inch

Specific Gravity of Water = 1.0

1 CuFt per Sec. = 448 GPM

1 PSI = A Head of 2.309 ft (water weight)

62.36 lbs per CuFt at 62°F

For Fans and Blowers HP =

HP =

HP =

Where CFM = Cubic Feet per Minute

PSF = Pounds per Square Foot

PIW = Inches of Water Gauge

PSI = Pounds per Square Inch

Efficiency of Fan = %/100

For Conveyors HP (verticle)

HP (horizontal)

Where

F = Force (lbs)

V = Velocity (ft/min)

Coef. of Friction

• Ball or Roller Slide = 0.02

• Dovetail Slide = 0.20

• Hydrostatic Ways = 0.01

• Rectangle Ways with Gib = 0.01 to 0.25

TORQUE FORMULAS

T = HP x 5252

N

Where T = Torque (LbFt)

HP = Horsepower

N = Speed (rpm)

T = F x R

Where T = Torque (LbFt)

F = Force (Lbs)

R = Radius (Ft)

Ta (accelerating) WK2 x Change in RPM

308 x t (Sec)

Where

Ta = Torque (LbFt)

WK2 = Inertia at Motor Shaft (LbFt)2

t = Time to Accelerate (Sec)

Note:

To change LbFt2 to InLbSec2, Divide by 2.68

To change InLbSec2 to LbFt2, Mult. by 2.68

AC MOTOR FORMULAS

Sync Speed = Freq x 120

Number of Poles

Where Sync Speed = Synchronous Speed (Rpm)

Freq = Frequency (Hz)

% Slip = (Sync Speed - FL Speed) x 100

Sync Speed

Where FL Speed = Full Load Speed (Rpm)

Sync Speed = Synchronous Speed (Rpm)

Reflected WK2 =

WK2 of Load

(Reduction Ratio)2