Hello, everyone,
I have a question-
Does air temperature and air humidity effect perfoemance of flight.
For example, is there a difference between flying at Mass and Florida???
Just wondering,
Thank you guys

Yup. Incresed temperature and humidity both decrease the density of the air, causing stall speed to go up, power available to drop, etc... It's like flying at a higher altitude.

Air temperature and humidity do have an effect on aircraft performance (models and full size). A term used in full-size flying that combines the affects of temperature, humidity, and pressure is called "density" altitude. On a hot, humid day the measured altitude might be 300 meters but the density altitude might be 1000 meters. The aircraft would perform as if it were flying at 1000 meters rather than 300. The engine would develop less power, the propellor less thrust, and the wings less lift at a given airspeed.

Now its clear,
Thank you guys!!!

CurtD;
so if an altimeter is available, you could set it at 29.91 and sort of read how much power your model engine is going to make...?

That would only give you "pressure" altitude (set the altimeter at 29.92 and read the apparent or pressure altitude). There's a calculator available that allows one to enter air temperature, ASL altitude, humidity, and current air pressure to get calculated density altitude.

There are also electronic altimeters that can automatically calculate and display density altitude. Impress your friends and add one of those to your flight box!!

Here's the link:

http://www.aircraftspruce.com/catalo...ges/taskem.php

From about March to November out here in the desert, the density altitude in the afternoon passes 5000 feet.... at 2400 feet ASL!
Power is seriously affected.
But the wind comes up also, making the runway longer.

hi,

you can get a decent approximation of your density altitude at your field by doing the following. it may seem a bit complicated at first, but its rather simple:

the conditions for this example are the following: 85ºF, true field elev. is 800 ft.

1. find the TRUE elevation above sea level at your field (800 ft in this case). if you cannot do this, use the closest airport field elevation near you.

2. get the current barometric pressure.

3. calculate the difference between the current barometric pressure (lets say it was 29.70) and the standard barometric pressure (which is always 29.92) (i.e., 29.92 - 29.70 = .22)

4. now add a zero and drop the decimal from the answer in step #3... .22 = 220.

5. now add or subtract this number to the airport elevation to find the current PRESSURE altitude. you add the number if the reported barometric pressure is below standard, and subtract it if it is above standard. in this case it's below, so you add 800 + 220 = 1020. 1000 ft pressure altitude is close enough.

6. now look at the temperature at the bottom of the chart available at http://bellinghamaero.com/densaltchrt.pdf which is 85ºF. be careful not to confuse it with the celcius scale. draw a line straight up until you reach the diaganol pressure altitude line of 1000 ft in this case. once there, go straight across to the left unril you hit the edge. you will see in this example i gave the density alt was between 2700 and 2800 ft.

7. you can see another example of this at
http://virtualskies.arc.nasa.gov/wea...tudeChart.html

One of the things I hate is to be flying in the morning and get great verticals and then fly around 3pm and watch your verticals loose their gusto!

Here's a density altitude chart...