TresCrows
Elite Member
Hello, seems the subject has been covered. I used to live in Phoenix and was there on the day that is referred to as "The Day Phoenix Stood Still". The temps were 130 ? degrees if I remember correct. In any case it was dang hot. The Sky Harbor Airport did not officially close (again I think this was the case) but the performance manuals for many of the airliners did not extend to that temp range therefore the pilots who are legally required to evaluate and calculate their take off performance via those charts could not do so. Therefore there were no takeoffs. This error has since been remedied. The company I work for now certainly has performance charts in the aircraft manuals for such conditions. Of course, payload is reduced and runway length and single engine performance factors must be considered by the pilot.
Yes, normal engines are affected by humidity. The water vapor displaces O2 and thus reduces horsepower. Mixtures have to be leaned and all that. Since we shoot for a stochiometric or close fuel/ air (O2) ratio if there is less O2 available then there must also be reduced fuel which means reduced power. Lift is affected as well by humidity. Thing is those unlimited racers are running such high boost and using injection etc it is hard to say exactly what REAL effect slightly cooler and more humid air might mean. I know one thing, if it is very humid and the temp falls then what you get is moisture condensation--rain, fog etc. Neither of those are good for airplane racing. /forums/images/graemlins/frown.gif. J
Yes, normal engines are affected by humidity. The water vapor displaces O2 and thus reduces horsepower. Mixtures have to be leaned and all that. Since we shoot for a stochiometric or close fuel/ air (O2) ratio if there is less O2 available then there must also be reduced fuel which means reduced power. Lift is affected as well by humidity. Thing is those unlimited racers are running such high boost and using injection etc it is hard to say exactly what REAL effect slightly cooler and more humid air might mean. I know one thing, if it is very humid and the temp falls then what you get is moisture condensation--rain, fog etc. Neither of those are good for airplane racing. /forums/images/graemlins/frown.gif. J