Interested in determining how well your engine will run under certain meteorological and geological conditions?
This is the gem for you! (And I am sure there are a lot of you out there.)
EngineTune returns the following calculations when supplied with altitude, altimeter (barometric pressure), temperature and dew point:
AE Relative Horsepower
Dyno Correction Factor
ICAO Relative Air Density
Absolute Air Pressure
The calculations in this gem are modeled after Richard Shelquist's Engine Tuner's Calculator, but have been re-factored to be more ruby-like. I urge you to read his technical articles on Density Altitude and Corrected Horsepower for detailed explanations of these concepts.
Note that all observations must be supplied using the metric system of measurement.
observations = Hash.new observations[:temperature] = 32.0 # Celsius observations[:dew_point] = 22.0 # Celsius observations[:altitude] = 149.0 # Meters observations[:altimeter] = 1013.4 # Millibars calculations = EngineTune.calculate(observations) calculations.relative_horsepower #=> 96.2 (as percentage) calculations.density_altitude #=> 876 (as meters)
Calculations are returned in metric units, but if you prefer your calculations using the English system of measurement, do this:
calculations.metric = false calculations.density_altitude #=> 2874 (as feet)
And if you forget what system of measurement your calculations object is using, just ask it:
calculations.metric = false calculations.metric? #=> false calculations.english? #=> true
You can also bypass the calculations object and directly use the calculator:
temperature = 32.0 # Celsius dew_point = 22.0 # Celsius altitude = 149.0 # Meters altimeter = 1013.4 # Millibars EngineTune::Calculator.relative_horsepower(altimeter, altitude, dew_point, temperature) #=> 96.2 (as percentage)
Convenience methods to convert between metric and English units are provided as well:
EngineTune::Calculator.meters_to_feet 1054 #=> 3458.0052546 EngineTune::Calculator.inches_to_millibars 1223 #=> 41415.3694298
Copyright © 2012 twmills LLC. See LICENSE for details.