lib/earth/air/aircraft_class.rb in earth-0.4.12 vs lib/earth/air/aircraft_class.rb in earth-0.5.0

@@ -1,8 +1,16 @@
 class AircraftClass < ActiveRecord::Base
   set_primary_key :code
   
-  # has_many :aircraft, :foreign_key => 'class_code', :primary_key => 'code'
+  has_many :aircraft, :foreign_key => 'class_code', :primary_key => 'code'
+  
+  def fuel_use_coefficients
+    [m3, m2, m1, b]
+  end
+  
+  def valid_fuel_use_equation?
+    fuel_use_coefficients.all?(&:present?) and fuel_use_coefficients.any?(&:nonzero?)
+  end
   
   data_miner do
     tap "Brighter Planet's aircraft class data", Earth.taps_server
   end
 end