# What's the effect of air density and temperature in the range of aspirated reciprocating-engine airplanes?

Reciprocating engines give more power with less revs when the aspirated air has a higher density. Wings also give the same lift at less airspeed when the air has a higher density. Drag is higher, too... And for any thermal engine, efficiency is higher the colder is the 'cold reservoir' (for an internal combustion engine, the outside air). What's the combined effect of these variables (density and temperature) in the airplane range if the engine is an aspirated ICE?

• This seems a bit broad to me @xxavier. – GdD Nov 27 '17 at 15:30
• @GdD I believe that something like the 'Breguet equation' may be derived, containing the variables density and temperature... That's not so broad... – xxavier Nov 27 '17 at 16:01
• So you're asking for a mathematical formula? I have to admit I'm not sure what you're asking @xxavier. – GdD Nov 27 '17 at 16:02
• @GdD Of course, a mathematical formula would be the best answer to my question, that –put in another form– may be: ¿Do you have a better range flying in a cold day than flying in a hot day (same air density)...? And, having an answer to that, what would be the influence of a different air density...? – xxavier Nov 27 '17 at 16:10