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-   -   Airfoil databases (https://ecomodder.com/forum/showthread.php/airfoil-databases-21245.html)

jeongyun 03-31-2012 07:15 PM

Airfoil databases
 
Airfoil Investigation Database - Search
You can sort the list by various parameters
For our interest, you'd want to sort the list by lift-to-drag, or lift coeff. Click column headings.

UIUC Airfoil Data Site

Frank Lee 03-31-2012 07:46 PM

Airfoils have somewhat limited utility for us landlubbers if one is thinking of basing an entire body on them- ground effect and all that. Still fun to play with though.

jeongyun 03-31-2012 09:54 PM

Another intersting one regarding airfoil and ground effect. Though paid membership's required to use this airfoil calculator.
Airfoil calculator

Aero template that's popular here seems great but if there's an alternative that has lower lift at the cost of slightly more drag, I'd like that over the aero template.

Frank Lee 03-31-2012 09:59 PM

I think the whole point of the template is to have neutral (no) lift. It is in ground effect and operates in the real world of approaches and departure angles and thus that is why it doesn't look like a true airfoil.

jeongyun 04-03-2012 08:59 AM

I found this simple tool can calculate and visualize ground effect of an airfoil. Though with some limitations.

JavaFoil
Quote:

Theoretical Background

JavaFoil is a relatively simple program, which uses several traditional methods for airfoil analysis. The following two methods build the backbone of the program:

The potential flow analysis is done with a higher order panel method (linear varying vorticity distribution). Taking a set of airfoil coordinates, it calculates the local, inviscid flow velocity along the surface of the airfoil for any desired angle of attack.
The boundary layer analysis module steps along the upper and the lower surfaces of the airfoil, starting at the stagnation point. It solves a set of differential equations to find the various boundary layer parameters. It is a so called integral method. The equations and criteria for transition and separation are based on the procedures described by Eppler [13, 14, 15]. Compared with CalcFoil, this module has been completely rewritten and cleaned up.
Quote:

Limitations

As said above, JavaFoil is a relatively simple program, with some limitations. As with all engineering computer codes, it is up to the user to judge and to decide how far he wants to trust a program. Because JavaFoil does not model laminar separation bubbles and flow separation, the results will be incorrect if either of these occur. Flow separation, as it occurs at stall, is modeled to some extent by empirical corrections, so that maximum lift can be predicted for "conventional" airfoils. If you analyze an airfoil beyond stall, the results will be quite inaccurate. It is questionable, whether a two dimensional analysis method can be used at all in this regime, as the flow field beyond stall is fully three dimensional with spanwise flow and strong vortices.
Wing in Ground Proximity

jeongyun 04-03-2012 10:36 AM

Quote:

Originally Posted by Frank Lee (Post 297333)
I think the whole point of the template is to have neutral (no) lift. It is in ground effect and operates in the real world of approaches and departure angles and thus that is why it doesn't look like a true airfoil.

It doesn't seem so. Rathe the opposite.

In fact, coefficient of lift was greater when the airfoil was closer to the ground.
In mid air CoL was 0.928.
In the picture below, CoL is 0.978.


http://pds24.egloos.com/pds/201204/0...b09a4d9801.png

With front air dam. there's net downforce
http://pds21.egloos.com/pds/201204/0...b11670a341.png

Frank Lee 04-03-2012 06:46 PM

Is that the template?

aerohead 04-04-2012 06:57 PM

lift
 
Quote:

Originally Posted by jeongyun (Post 297331)
Another intersting one regarding airfoil and ground effect. Though paid membership's required to use this airfoil calculator.
Airfoil calculator

Aero template that's popular here seems great but if there's an alternative that has lower lift at the cost of slightly more drag, I'd like that over the aero template.

Most automotive lift is a symptom of separated flow.The 'Tempate' is separation free at all points and by default produces minimum lift.Of course,at high speed,and crossed-up sideways,out of control,most automobiles will fly,as we witness in NASCAR.
It took 235 mph to get Racing Beat's Mazda RX7 in the air.


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