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HomeAircraftHelicopterComputer Flight SimulatorsOther › G3 and Altitude above Sea Level
05-07-2005 06:32 PM  13 years agoPost 1
pariah

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South Jordan, UT - United States of America

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This is more a question for Vitek than anyone else. (I could have PM'd him, but I figured the response may be generally useful).

The question is this: G3 has its altitude, which refers to altitude above sea level. Does this actually matter in terms of the flight model? ie. G3 actually simulates the differences due to air density changes caused by changes in altitude -- like how engines experience a drop in power output as the air gets thinner, prop efficiencies change with changes in air density, things like that.

Or is the altitude really just a number referring to how high the model is above a point called 'sea level', and the model's 'altitude' doesn't really have any bearing on the engine's power/prop efficiency, and there is no difference in other kinds of flight behavior due to thinner/thicker air.

I ask this because I live at a relatively high altitude, and often fly at even higher altitudes. And I wonder if G3 even attempts to account for the somewhat different flight characteristics I would see flying at a ground elevation of 10,000 feet versus if I were to fly the same model at sea level.

Of course, what would be a neat feature is if G3 could look up a pilot's local weather on the internet, and match the weather, cloud density, position of the sun, winds, etc. with what is actually outside...

Neat, but probably not practical... Besides, if it's raining outside, that would make it rain in the sim.

Hmmm... flying in a thunderstorm... or a hurricane. That cold be fun...


--
The last thing I want in a heli is a few loose screws.

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05-07-2005 09:11 PM  13 years agoPost 2
vitek

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Corvallis, OR

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G3 has its altitude... Does this actually matter in terms of the flight model?
I have seen chunks of code that look like this...
newtons lift_for_wing_section =
calculate_lift(
airspeed,
section->get_area(),
get_physics_object()->
get_air_density_percent() );
For those who don't read code, this would calculate the lift for a wing section based on airspeed, area, and air density.

Seeing that makes me feel all warm and fuzzy inside. Upon further inspection, I find a this...
percent
weather::calc_air_density_percent(
meters altitude,
celsius temperature,
bars pressure,
percent humidity )
{
static const override = true
if ( override )
return 1.f;

// calculate corrected air density
}
So apparently someone disabled the functionality and never re-enabled it. I will investigate turning it back on and file a bug to get it turned on.
Of course, what would be a neat feature is if G3 could look up a pilot's local weather on the internet, and match the weather, cloud density, position of the sun, winds, etc. with what is actually outside...
That is one thing that was originally intended to be part of G3. You can get current weather information from the internet pretty easily. Visibility, cloud levels, cloud types, wind direction, gust, variability, ...
Neat, but probably not practical... Besides, if it's raining outside, that would make it rain in the sim.
After a while, that is what we thought. It would be very cool, but not super useful.

Travis

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05-09-2005 01:51 AM  13 years agoPost 3
pariah

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South Jordan, UT - United States of America

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I sure like seeing how thorough the attention to detail is!

One thought to add, however: If this feature is turned on, how 'bout a setting on the flying fields where we can insert a 'fudge factor' for the altitude.

I say this because the Sierra Nevada terrain is awseome... if anyone takes the time to look, they can a spot in that terrain that matches their flying field fairly closely. (Well, as long as they live around mountains like me ). But the particular spot I found that is very much like my local field has the wrong altitude, by some-odd 2,000 feet. It would be nice to be able to input a correction for this.


--
The last thing I want in a heli is a few loose screws.

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05-09-2005 06:13 AM  13 years agoPost 4
vitek

rrKey Veteran

Corvallis, OR

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If the feature is added, I believe it would be entirely user specified. There would just be a air density percent option in the weather or airport settings.

Travis

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