Power-to-weight ratio

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Power-to-weight ratio (specific power) is a calculation commonly applied to engines and other mobile power plants to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power plant.

1 Power to weight (specific power)
- 1.1 Examples
  - 1.1.1 Turbocharged V-8 diesel engine
  - 1.1.2 Space shuttle
2 Weight to power (power loading)
- 2.1 Examples
  - 2.1.1 2007 Chevy Malibu Is, 5 seats
  - 2.1.2 Cessna 172 airplane, 4 seats
3 See also
4 External links

[edit] Power to weight (specific power)

The power-to-weight ratio (Specific Power) formula for an engine (power plant) is the power generated by the engine divided by weight of the engine as follows:

$\begin{matrix} \mbox{P-to-W}&= P/W \\ \end{matrix}$

English system units of measure are usually horsepower per pound (hp/lb)
Metric system units of measure are usually horsepower per kilogram (hp/kg)^{[citation needed]}
The use of watts, or kW (kilowatts), instead of horsepower is common (Conversion: 745.7 watts/hp).

[edit] Examples

Because this is a ratio, the denominator is always singular (1 lb or 1 kg) as in the following examples. Note: When looking at power to weight ratio (specific power), larger indicates greater power to weight.

[edit] Turbocharged V-8 diesel engine

250 hp (engine power)/1,000 lb (engine weight) = 0.25 hp/lb

[edit] Space shuttle

70,000 hp (turbine power)/700 lb (turbine weight) = 100 hp/lb

[edit] Weight to power (power loading)

It has been suggested that Weight ratio be merged into this article or section. (Discuss)

Weight-to-power ratio (power loading) is a calculation commonly applied to aircraft, cars, and vehicles in general, to enable the comparison of one vehicle performance to another. Weight-to-Power ratio is a measurement of the acceleration capability (potential) of any land vehicle or climb performance of any aircraft or space vehicle.

The Weight-to-Power ratio (power loading) formula for a vehicle is the weight of the vehicle divided by power generated by the engine as follows:

$\begin{matrix} \mbox{W-to-P}&= W/P \\ \end{matrix}$

English system units of measure are usually pounds per horsepower (lb/hp)
Metric system units of measure are usually kilograms per horsepower (kg/hp)
The use of watts, or kW (kilowatts), instead of horsepower is common (Conversion: 745.7 watts/hp).

[edit] Examples

Because this is a ratio, the denominator is always singular (1 hp or 1 kW) as in the following examples. Note: When looking at weight-to-power ratio (power loading), smaller is better.