If you fly in relatively cool, wet morning air, and then fly again in warmer, dryer afternoon air, which run is longer?  I can never remember this.  Asking in relation to fuel management at a contest.

Thanks,
Kim Mortimore

HI Kim

Typically  The runs are shorter in the cooler morning air and longer in the warmer air. Also normally if the morning air is  wet the afternoon air is also very humid, both heat and humidity will make for longer run times . as you need to lean the mixture in those conditions with all else being equal

Regards
Randy

Randy Now what Kim asked is  good  but what about the weather and and  % of Nitro / oils with temp?

I'm not Randy but Heat goes up use more nitro. The engine makes more power in cool air = less nitro. Same oil content. I use 20% oil for PA's

EDIT More nitro means you will have to open the needle valve up. So you will have to use more fule.

Randy Now what Kim asked is  good  but what about the weather and and  % of Nitro / oils with temp?

Hi Larry

There are dozens of differant setups, here is mine, When the weather is cool , or when I am in the cooler months my engines setups are normally running 5% nitro, as the heat or  hotter months come in I go up to 7.5%  or to 10% IF IT REALLY GETS HOT.
At the NATs this year I was running 7.5 % nitro and dropped to 5% when it got a little cooler.
This way for me I don't normally need to change anything but the fuel. I also have many people using my setups doing the same.  It works, and works very well.
Another example is when I went to places like  Lubbock  I had to go straight to 10% to get similar performance that I had in Atlanta with 5%.
I could very easily  setup for base 10 or 15% nitro but that would mean I would have to go to 20 or 25% in hotter months, or have to change prop/venturie/head shims much more than I would normally,That is not wanted or necessary.

I don't have to up oil percentages, I most always just use 21 % oil in the PA engines,  25% oil in STs 46,51,60,    26% in FOXs, and 23% in Aero Tigers and Magnums BB  engines. AS always you may have to adjust something for your conditions


Regards
Randy

Randy,

Do you count Aero One content as part of the oil percentage, or is it in addition to the oil % ?

Thanks,
Kim Mortimore

hi Kim

Yes I count the AERO-1 , example I use 20% in my PAs and add 1%  Aero-1

regards
Randy