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Coordinates for NACA 23112

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Avion

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'MARSKE PIONEER IA AIRFOIL (NACA 23112/43012A HYBRID)"

Thanx George but that is the one i was referring to. A hybrid, not a straight 23112.
 

wsimpso1

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I am dying to know why you want to use that foil. 23000 series foils have a sharp stall break and a hysteresis loop to get it flying again. Not a terribly desireable set of features...

Billski
 

orion

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The interesting thing about the 23000 series of airfoils is that in spite of the section data, the family has been used on a whole range of different airplanes. The applications include Aero Commanders, several of the single engine Cessnas, the Cessna Citation family, virtually all the Beech aircraft, several of the Douglas airliners, and on our end, pretty much all the Van's aircraft, to name a few.

There are several reasons for its popularity. First, it has a very low pitching moment and as such, its use results in relatively low amounts of trim drag. This characteristic also allows for a more effective horizontal, resulting is a slightly larger allowable CG envelope for any given tail volume coefficient.

The section also has a fairly low drag count and the bottom of the drag curve extends over a fairly long range of lift coefficients. As such, the section performs relatively well not only in cruise but also in climb.

Also, the section's relatively large leading edge radius and thick nose allows it to achieve a fairly high aoa, making it quite effective with a variety of flap cofigurations.

Yes, the stall can be relatively sharp but with a conservative wing twist or light wing loading, most of the airplanes that used this section seemed to have avoided this characteritic.
 

Norman

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I don't wish to dredge up a zombie thread but in the interest of completeness and accuracy I'm adding this so that the next person to look for this obscure old airfoil section can find it and some of it's derivatives more easily. First the file in post #4 apparently is not the original 23112, it has a tiny bit more camber than what I now believe to be the real thing. Attached is the L/D & Cm part of a type 2 polar generated by Profili. Type 2 polars conform to the relationship Re x Cl^0.5 = constant which should more accurately reflect the speed vs AoA of an actual flight. I've included the NACA 23012 for reference and because the (1) in the third place in the 23()xx simply means it's a reflexed version.


The graphed sections are:
NACA 23012 for reference
the section from post #4 labeled “hba 23112”
the correct v labeled “Nacag 123 12.0 140 pts.”
and a more heavily reflexed v labeled “marske-23112-75”


I got the 23112-75 out of Jim Marske's book. This is what he said he used on the Pioneer I & II and it is not a hybrid with the 43012 as the UIUC database has it. He just added a little more reflex to the 23112 so that the mean line reverses direction at 75%c. The only original data on the 231xx that I know of is NACA-tr-537
 

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lr27

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If I recall correctly, Xfoil has a NACA foil coordinate generator. It's a free download. I know Profili does, although I don't know if that's in the free version or the licensed version. It's very inexpensive, however.

I'm sure Google can find either one.
 

Norman

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I tried it. If you type in "23112" it will creat simple (non-reflexed) airfoil with its maximum camber slightly farther AFT than a 23012. In other words it only generates the simple mean line as described inNACA-TR-537.
 

lr27

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There's another one here:
JavaFoil
However, you probably need to read the paper to put in the right inputs. It's possible to get at least two different airfoils designated 23112
 

Norman

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I'm using the registered version of Profili which I assume is using the Xfoil NACA section generator rather than writing a new one. When I first heard about "1" in the third place designating a reflexed mean line I thought it was a dumb idea because it would lead to this. Since the original description of the 5 digit naming convention clearly states that the second and third digits should describe twice the [chord-wise position ] of camber, and computers are dumb, what do you do, add "unless the third digit is a 1"? What if somebody wants a 23112 with a strait line on the aft part. Granted that would be 1/2% and the polars are so close it's probably within normal building tolerances for a homebuilder, but still it's a valid number in the sequence. Have you tried generating an NACA 6 digit section? Each 6 digit can be 4 different airfoils depending on whether the third place is occupied by an "A" or a "-" and mean line "1" or "0". Since Xfoil is no longer being developed and Profili is essentially a user friendly shell for modelers with some functionality for rib layout and foam CNC cutters I don't expect the NACA section generator to be a priority item.

BTW for anybody who doesn't have the correctly drawn, reflexed, NACA 23112 here it is. It's a DAT file with the extension changed to make it acceptable to the bulletin board.
 

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Lemans

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It's no secret that I I’m a fan of the control-wing concept, I should be the lightest 'wings and control surfaces' - set-up available
to build a part103/SSDR ultra light.

Is the concept free of use? In other words, can I use freely the NACA23112 air-foil in combination with – around the spar- pivoting wings?
 

Norman

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Sorry about bumping this zombie, again, but it's been brought to my attention that the Nacag 231 12 is also not quite the same shape as the original set of coordinates in NACA-TR-537. It appears that the splining algorithms of the various software out there alter these antique airfoils to some extent and the result is that an NACA-23112 from one database will be slightly different than an NACA-23112 from another database depending on the software that each administrator uses to proses the old crude coords into a modern data file that CAD systems and 2D analysis software expect. To check how close my software is to the crude shape I typed the coords from NACA-TR-537 and cloned it twice so I could check it against the two splines available to me in this software [Xfoil\Profili]. The file name is "NACA-23112_btb". "btb" stands for "by the book". The two splines in this program are "interpolate" and "smooth" and the splined clones are underlined. As you can see in this screen shot of part of my database sorted by similitude they both alter the airfoil significantly.


In fact they alter it more than the two sets of ordinates that I posted earlier in this thread. I have also included the leading edge template that Profili generated from the original coords. Obviously these coords need some sort of smoothing before a rib pattern can be created from them. At the time that they were made you would either use a set of ships curves (a giant french curve) or a flexible stick called a "spline" with weights called "ducks" to hold it in place while you traced the curve with a sharp pencil. These hand drafting techniques were only as accurate as the drafter's hand so different companies had slightly different versions of any given section. So from now on I'm going back to plotting old airfoils with polyarcs instead of splines. Unfortunately that's getting harder to do because CAD systems have all gon over to NURBS. The last program I know of that had polyarcs is Autocad R14 and even that had to be installed with certain "vintage" features turned on.

Here's the crude set of coords right out of NACA-TR-537. Well, hopefully, if the software didn't adjust something while writing the file:ermm:
 

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Retiree

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NACA Airfoil Coordinate Generator

This might be a good time to mention that NASA published a TM with a NACA airfoil coordinate generator, NASA TM X-3284. I do not know if it available online.
Hopefully this program will not disappear from the community memory.
Doug
 

Topaz

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Do these routines use the NACA method, or are they using the "corrected" method Riblett devised? Mostly applicable to the leading edge area, but if they're using the NACA method, they still have the problematic flattening of the effective mean line at the nose.
 

Retiree

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These routines predate Riblett's designs.
The reason I mentioned the NASA TM is as a source for the original coordinates.
I assume the only way to get info on Riblett's design is to buy his book. :silly:
 
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