Now if a certain individual was to obtain a density altitude conversion chart to graph the loss in percentage of efficiency at altitudes above sea level he might learn something. Also needed is the ability to understand that a 55 degree day at 6,800 feet msl does not fall within the standard lapse rate and is therefore at a density altitude considerably higher than 6,800. A rather loose temperature lapse rate for a standard day is in the area of 3-1/2 degrees F. for every thousand foot gain in elevation above sea level. The base line at sea level is 59 degrees F.

But first he needs to understand that a constant gain in altitude causes a constant loss of available oxygen for "sea level" I.C. engines to mix with the fuel, thereby reducing the amount of available power without the addition of a super charger of one sort or another. You can only lean an engine so far.

Far too many flying r/c have little or no understanding of basic aerodynamics which seriously and adversly effects their ability to understand why their planes do what they do, and why those same planes can be utterly predictable to do certain things at certain speeds and attitudes. An understanding of weather and the atmosphere provides tremendous insights into engine performance.

Pat