Density Altitude / Speed

[tortoise]

I understand somewhat anerobics re- athlete performance, but think its more like stored energy (batteries) than "turbocharging".

Agreed. As I also pointed out, AGREEING with your point, even for one hour performances (primarily aerobic), human powered vehicles demonstrably run faster at altitude, at least up to 7500 feet.

Maybe it's the thinner air!

THAT'S THE POINT MY POSTS HAVE BEEN TRYING TO ESTABLISH!

Aerodynamic drag is lower at higher altitude. Nobody disagrees with you. What are you upset about? Normally aspirated gasoline motors make less power at altitude. Some vehicles run faster at Bonneville than they would at Maxton, some slower. As JackD has pointed out, there are a lot of variables beside altitude.

[sockjohn]

Some vehicles run faster at Bonneville than they would at Maxton, some slower. As JackD has pointed out, there are a lot of variables beside altitude.

I imagine all the pissing and moaning everyone does about tuning has something to do with it...

Say, what kind of name is tortoise in land racing?  What records do you hold or are trying to obtain?  Got to be a story there I suppose.

[tortoise]

Say, what kind of name is tortoise in land racing?  What records do you hold or are trying to obtain?  Got to be a story there I suppose.

Since you ask, I am (pardon the expression) an "interested bystander", with a great interest, respect, and love for the sport, and no credentials whatsoever. Not much of a story. The only landspeed racing I've excelled at is on foot. Don't feel shy about telling me to shut up if I'm being a pain in the ass.

[Flyboy]

We're probly getting way off the subject, or are we? (This horse could be dead).

My query a post or two back was intended to get some positive data -love yer tag, dynoroom- that density altitude is not the ONLY indicator to one's increased (or decreased) performance at differing altitudes.

I understand somewhat anerobics re- athlete performance, but think its more like stored energy (batteries) than "turbocharging".

And I KNOW that unlimited airplanes (worked on a couple) are supercharged at Reno- they were at Hamilton Field, also.DUH.

Death Valley was only in the 70's today.
Why do they hit lots of homers at Coors Field? Can it be the anerobic condition of the ballplayers. Doubtful, as all they do is stand around, spit and scratch like at every ballpark on the planet. Probably not the supercharging effect of Coors, either. 

Maybe it's the thinner air!

THAT'S THE POINT MY POSTS HAVE BEEN TRYING TO ESTABLISH!

With DATA, not BS, whoops, I meant opinions.ANYBODY?

Thank you for your insight. But engines are a fixed phenomena where as human bodies are in a constant state of movement. Did the ball player get laid before the big game and has weak legs? Was he smoking grass that morning and is 5% lacking in max power? I do agree with you that there is a better possibility of hitting a home run in thin air.

[Speed Limit 1000]

Tortoise, You hang in there, all are welcome in landspeed racing, some of us just like to get on other peoples nerves.

[JackD]

I have managed to set a few LSR records at El Mirage and Bonneville and all without refrence to a DA instrument.
Before I say I can , I watch others to see how they do first.
I do my homework at home and come to the races ready to race.
I adjust within the boundries of the equipment and conditions as the performance dictates.
All of that has served pretty well without all the automatic electronic FUFU that doesn't tell you much about reading a plug.   
 

[Flyboy]

"Some vehicles run faster at Bonneville than they would at Maxton, some slower. "



No naturally aspirated vehicle runs faster at Bonneville than Maxton. Just the opposite. That's the point of this discussion.

[John Nimphius]

"Some vehicles run faster at Bonneville than they would at Maxton, some slower. "



No naturally aspirated vehicle runs faster at Bonneville than Maxton. Just the opposite. That's the point of this discussion.

There are MANY naturally aspirated vehicle records at Bonneville culminating with Nish Motorsports AA/FS at 373.907 MPH.  As good as the Nish group is I doubt they could reach these speeds at Maxton.

[JackD]

"Some vehicles run faster at Bonneville than they would at Maxton, some slower. "



No naturally aspirated vehicle runs faster at Bonneville than Maxton. Just the opposite. That's the point of this discussion.

Mine seems to.
What am I doing wrong ?

[dwarner]

Good answer John. A flat statement without research proves something.

DW

[ack]

The answer is still the same a normally aspirated vehicle will always go fastest at sea level with standard meteorological conditions and variables i.e. temperature, humidity, pressure, length of track coefficient of friction.  Without a standard you can?t measure anything.  In a normally aspirated ICE vehicle operated at full power the ratio between available HP and drag goes down as you increase altitude.

[hitz]

The answer is still the same a normally aspirated vehicle will always go fastest at sea level with standard meteorological conditions and variables i.e. temperature, humidity, pressure, length of track coefficient of friction.  Without a standard you can?t measure anything.  In a normally aspirated ICE vehicle operated at full power the ratio between available HP and drag goes down as you increase altitude.

  Ack,

  Is the ratio HP to CD where the CD is the number?  Is the the HP falling behind as the altitude is going up? Not being smart just don't understand.

  Harvey

[tortoise]

Is the ratio HP to CD where the CD is the number?  Is the the HP falling behind as the altitude is going up? Not being smart just don't understand.

Aerodynamic drag at a given speed and horsepower in a normally aspirated engine are both directly proportional to air density. If aerodynamic drag were the only drag on the vehicle, it wouldn't slow down as air density decreases. But of course aerodynamic drag is not the only drag on the vehicle, and the other sources of drag do not decrease with lower air density. Thus, you go slower. (All other variables being equal, which they never are.)

[Flyboy]

The answer is still the same a normally aspirated vehicle will always go fastest at sea level with standard meteorological conditions and variables i.e. temperature, humidity, pressure, length of track coefficient of friction.  Without a standard you can?t measure anything.  In a normally aspirated ICE vehicle operated at full power the ratio between available HP and drag goes down as you increase altitude.

Ack,

Thanks again for the fuel you gave me at BUB. You're a real gentlemen--

[ack]

The answer is still the same a normally aspirated vehicle will always go fastest at sea level with standard meteorological conditions and variables i.e. temperature, humidity, pressure, length of track coefficient of friction.  Without a standard you can?t measure anything.  In a normally aspirated ICE vehicle operated at full power the ratio between available HP and drag goes down as you increase altitude.

  Ack,

  Is the ratio HP to CD where the CD is the number?  Is the the HP falling behind as the altitude is going up? Not being smart just don't understand.

  Harvey

More simply stated the total HP goes down faster than than the coefficient of drag as you increase altitude.