EngineTune
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
-
Air Density
-
Density Altitude
-
ICAO Relative Air Density
-
Virtual Temperature
-
Absolute Air Pressure
-
Vapor Pressure
-
Relative Humidity
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.
wahiduddin.net/calc/calc_hp_dp.htm
Standard Usage
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
The Calculator
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. 1223
#=> 41415.3694298
Copyright
Copyright © 2012 twmills LLC. See LICENSE for details.