AG46ct-02F ?

[Chad Sullivan]

I noticed in my Profili airfoil library an AG46ct-02f section. Is anyone familiar with this? At first I thought...must be a typo and it should be r not f. I googled it. And have found some references to it. But nothing that is convincing me it's not a reference to the r version. I have done an overlay of the "f" and the "r" in both compufoil and profili. In compufoil there is not apparent difference. In profili the resolution is a bit crude and there may be a differance. Or it could just be the way profili draws the overlay, there is no obvious difference.
But in the polars there is. especially if you compute @ 70000. At 80000 things get a lot closer but there are some differences.
Wondering if I have some sort of Profili set up issue that is giving me these results on what appears to be identical sections. Or are the overlays I'm doing not showing the difference because of some setting there?

[kcaldwel]

My Profili catalog has the whole series of AG4*-0* airfoils as "f", not "r". I suspect it must be a typo. They do not exist on the Charles River site, as you probably know.

I'l try running Profili and take a look at the coordinates tonight.

Kevin

[kcaldwel]

I think I've found out where the "f" comes from! In the .dat files on Charles River, the files are all have an "r" in the file name, like AG46ct-02r. But, at the top of each .dat file, it says "AG46ct -02f rot." for example. I'm not sure if this is a typo, or if Mark means something not explained on the Charles River site.

When Profili imports a .dat file, it ignores the file name (with the "r"), and uses the first line of the .dat file to name the airfoil. So they all end up with an "f"!

I've checked 20 or so of the airfoil ordinates, and the airfoil file in Profili looks identical to the Charles River .dat file, except the Profili file has one less digit in all the ordinates.

Profili just calls Xfoil for the airfoil analysis.

I ran both the Profili Pro file of the AG46ct -02f, and the file I just downloaded from Charles River, at Re = 70,000 with both 0 and +2 degrees of flap deflection, and I get identical results. The airfoil ordinates are identical, except for the dropped digit, so I would be amazed if they were different. Are you sure you had identical parameters set for both airfoils when you saw a difference? Ncrit, flap deflection, Re, etc.?

I'm amazed I've never really thought about the "f" before!

Kevin

[Chad Sullivan]

Well that's why I asked. I probably need to sit down and figure out what I have going on. Because I do get different results. But now that I know this is happening I'm sure it's something simple. I will delete the files and get fresh ones. Perhaps I have messed with them and did not rename the file to show that. I'm not sure that I used the same file to overlay as I did to build the polars, ;0
Thanks for investigating this for me.

[Neil Stainton]

I think I've found out where the "f" comes from! In the .dat files on Charles River, the files are all have an "r" in the file name, like AG46ct-02r. But, at the top of each .dat file, it says "AG46ct -02f rot." for example. I'm not sure if this is a typo, or if Mark means something not explained on the Charles River site.

I don't use Profili, Xfoil, and haven't built an AG airfoil model, so I may well be totally out. But could "AG46ct -02f rot" be for Flap Rotated? I seem to remember that Mark plots the airfoil with the flap refelexed to the speed setting, to simplify construction.

Neil.

[kcaldwel]

Neil,

I'm not sure what the "f" means, probably only Mark does. It is strange the file name is not the same as the top of .dat file. If you use the .cor file, you never see this.

I'll PM Mark, and see if I get an answer.

Kevin

[kcaldwel]

I received this message from Mark:

"The "f" stands for "flap".
The "r" stands for "rotated" after the flap deflection so the TE is on the x axis.

MD"

The .cor file will not show the "f" if it is imported into Profili, it will have the "r". The .cor file and the .dat files on Charles River look identical, except for the title line with the "f" at the top of the .dat file.

Kevin