Heat and qualifications

[Coyote Chris]

Looks like its going to be alittle warm when I arrive Saturday at Reno, and for the qualification days too. If you are qualifying, do you want a hot day or a cool day? Unencumbered by the thought process, I would say you would want a cool day.....

Chris who gets on his motorcycle and leaves in 58 hours, 48 minutes and ten seconds, but who is counting?

[shorebird]

Re: Heat and qualifications

Cool, dry,....smooth....air with no traffic to cause a wide, slow turn.

[Coyote Chris]

Re: Heat and qualifications

So, cool dry air makes more horsepower and makes better lift, while hot air can be more turbulent?

[Bigger Al]

Re: Heat and qualifications

Hey Chris,

You camping out at the Catholic church? My daughter and I will be there on my old BMW Airhead twin.
Whatcha riding?

[KAHNZILLA]

Re: Heat and qualifications

Have reserve seats and pit passes for two next Wednesday the 16th, first person to e-mail me with address can have them and I will put them in the mail. Thanks, KC

[Stevo]

Re: Heat and qualifications

Looks like its going to be alittle warm when I arrive Saturday at Reno, and for the qualification days too. If you are qualifying, do you want a hot day or a cool day? Unencumbered by the thought process, I would say you would want a cool day.....

The way I understand it... and I could be COMPLETELY wrong... on a cool day the engine performs better but on a warm day you get better speeds from the airframe.

[tow-3]

Re: Heat and qualifications

you are generally right, more dense air= better HP. less dense air= less airframe drag. what is the best combination? good question for juke and his slide rule, and a few others around here that have forgot more than i will ever know.........

[AirDOGGe]

Re: Heat and qualifications

For getting off the ground and landing....cooler denser air is premium. The prop and wings get a better bite, and the engine runs cooler and stronger for an equal throttle setting.

But aircraft DO go faster in thinner air due to decreased drag, so there's a trade-off.

For Stead's altitude (around 4500 ft?), I don't think the (sometimes very) hot desert air gets thin enough to reduce drag sufficently to compensate for the loss of power (thinner air means less oxygen to feed the engine too), and loss of lift.


So, for the Reno Races, I'd venture to say "cooler rules".

.

[Bob]

Re: Heat and qualifications

A motor with a super charger or turbo charger can always add more boost to make up for temp and altitude. A normally aspirated motor cant do this.
So, with this being said I believe that the smaller planes with carbs are looking for cooler temps and the big iron wants to see higher temps. Perhaps thats why the F-1 and the Bipes race in the cool early morning.

[Bigger Al]

Re: Heat and qualifications

A motor with a super charger or turbo charger can always add more boost to make up for temp and altitude. A normally aspirated motor cant do this.
So, with this being said I believe that the smaller planes with carbs are looking for cooler temps and the big iron wants to see higher temps. Perhaps thats why the F-1 and the Bipes race in the cool early morning.

The winds are lighter in the morning, too, which is a big part of why the smaller planes race at that time.

[Coyote Chris]

Re: Heat and qualifications

Hey Bigger Al, look for the red Kawasaki Concours in the 13 acre dirt lot the church runs....I camp back on the "hill". I like BMW twins...they remind me of aircraft engines....

Chris who doesn't want to see any Formula 1s go off into the dirt due to wind or any other reason....watching those guys land in a crosswind is not good for the heart....why, it takes a pilot with pretty big....ohhh...
never mind....

[AAFO_WSagar]

Re: Heat and qualifications

I think you guys are hitting it on the head (the nail).. The way it's been explained to me, is given sufficient cooling, a supercharged, or turbocharged engine doesn't care whether it's hot or cold, it can make the same levels of power either way.. .but the less dense the air, the faster a given groundspeed is for a given airspeed... less molecules, less drag, faster..

I think there were/are some caveats in there but that's pretty much how Lyle summed it up to me once when talking with him about a "500 MPH Lap" and how you'd best go about it.

[flyingjibus]

Re: Heat and qualifications

I drive a turbo charged car, the air temp and moisture content have a large effect on my horsepower levels

[Bigger Al]

Re: Heat and qualifications

Hey Bigger Al, look for the red Kawasaki Concours in the 13 acre dirt lot the church runs....I camp back on the "hill". I like BMW twins...they remind me of aircraft engines....

Will do! I love my Airhead for the same reason!

[AirDOGGe]

Re: Heat and qualifications

I would think that even a super/turbocharged engine would "feel the heat".

Compressing air generates more heat, and if you start with hotter air, then the compressed stuff will be hotter too, versus compressing cooler stuff.

Plus, your air-to-air intercooler has to remove that extra heat using hotter ambient air to do the cooling. If higher temperature outside air is flowing through it, then the thermal-transfer rate will be less efficent.