Question for KnifeEdge

[dhk79]

As a modeler, I often find myself cycling through the available airfoils trying to find a match for one needed by my model. Since the airfoil list in RF is sorted by name, this can be a really long process.

So here's my question: Do you by chance have a list of the airfoils included in RealFlight that could be imported into a spreadsheet, such that it could then be sorted by thickness and camber values?

Thanks,
Doug

 

[crashed again]

As a modeler, I often find myself cycling through the available airfoils trying to find a match for one needed by my model. Since the airfoil list in RF is sorted by name, this can be a really long process.

So here's my question: Do you by chance have a list of the airfoils included in RealFlight that could be imported into a spreadsheet, such that it could then be sorted by thickness and camber values?

Thanks,
Doug

Hey Doug, been HERE ??
crashed

 

[dhk79]

Hey Doug, been HERE ??
crashed

Frequently... I'd like to be able to do the same with the ones in RealFlight, to find an included airfoil that meets my needs for a model (without paging through all of them).

 

[flexible]

Something like this

 

[dhk79]

Something like this

???

Something like what? Flex, that seems to be screenshots of the editor as it is now.

 

[flexible]

Is this not the list you are talking about?

 

[dhk79]

I want to be able to sort (and possibly search) the included airfoils by thickness and camber. Rather than paging through the whole alphabetized list to find all 12% thick airfoils, for example.

This is not a requested add-on feature for the software (while nice, it is not necessary). A stand-alone list included in the reference documentation would work just as well.

 

[flexible]

As long as you are wishing. This might be doable.

 

[mwilson914]

I would definately love some sort of list like this. Having a way to sort out symmetrical verses non-symmetrical would also be a BIG plus.

 

[willsonman]

I agree. Airfoil selection can be very tedious if you do not know the exact airfoil you would like to use. perhaps several methods of sorting would be useful? I'd like to see undercambered foils separate from the semi-symmetrical and so on. Laminar, I think should be more separate from the rest since it requires so real thought before use.

 

[crashed again]

I want to be able to sort (and possibly search) the included airfoils by thickness and camber. Rather than paging through the whole alphabetized list to find all 12% thick airfoils, for example.

This is not a requested add-on feature for the software (while nice, it is not necessary). A stand-alone list included in the reference documentation would work just as well.

Doug,
If you go to the link i provided, you can enter thickness and camber spec range, and it will sort for you.....
"print" that list and look in rf for the editor window.
Not the correct solution, but should get you much closer initially.
crashed

 

[dhk79]

Doug,
If you go to the link i provided, you can enter thickness and camber spec range, and it will sort for you.....

Thanks. DirtyHarry and I have copied that particular DB to a spreadsheet as a starting point, and will be manually editing it to conform solely to the list of airfoils in RealFlight (if KE cannot provide a supported list). If you would like to assist in the possible endeavor, let one of us know.

 

[inky00]

Thanks. DirtyHarry and I have copied that particular DB to a spreadsheet as a starting point, and will be manually editing it to conform solely to the list of airfoils in RealFlight (if KE cannot provide a supported list). If you would like to assist in the possible endeavor, let one of us know.

I decided that rather than wait for Knifeedge to answer i would just go ahead and start a spreadsheet.So far i have done about a 1/3rd of the list in RF,it only includes thickness and camber at present but i can easily add more columns for extra info such as aerofoil type etc.

 

[DirtyHarry3033]

Doug if we go that route I'm planning to take a # of screenshots of the RF airfoil list, to get the entire list into a single image file. I'm downloading a demo OCR package right now, if it can produce an accurate text file from the image then it should be a simple matter for me to create two text documents:

1) A list of airfoil names from the online database

2) A list of airfoil names from RF

If I can get that, I can run UltraCompare on the two lists and get an alpha listing of all RF airfoils missing from the database, and all database airfoils missing from RF.

That would greatly simplify "weeding out" what doesn't belong, and adding what's missing.

The font used in the RF editor windows may or may not be a prob. I've already tried this using a "freebie" OCR program called GOCR, with less-than-perfect results. It didn't like the RF font, and didn't like the small font size. I enlarged the image file and got better results but still nowhere near usable.

Hopefully this professional-grade demo (it runs for 15 days) will give better results. If it doesn't, I'll try another demo

DH

 

[opjose]

All too often I'll be looking for a suitable airfoil without any documentation or available info on what is used in a particular plane.

I end up doing this by sight and guesstimation, trying to match the shape I see on an actual RC aircraft with that in the database.

This is VERY tedious.

I would love some options that for instance groups all of the flat bottomed together, etc. to at the least eliminate non-suitable airfoil shapes from my search.

 

[DirtyHarry3033]

OK, just installed and tried that OCR software. MAJOR difference, the biggest problems were that it frequently replaces the number "0" with the letter "O", and also tends to throw in a space before the number "1".

For instance, the airfoil "AG03 (flat aft bottom)" comes out "AGO3 (flat aft bottom)" and airfoil "AG14" comes out "AG 14."

I only spent about 5 minutes messing with it, it is a high-dollar package and I'm sure there are all kinds of options that can be tweaked to improve accuracy. I'll have a look at that later tonight.

At any rate, it is a LOT better than the "freebie" I tried 1st, in that one the "AG03 (flat aft bottom)" came out as "AG03 (Aat afV bo_m)" - useless! With this one, I think I can tweak for MUCH better results and I can probably clean up any remaining errors with some regexp "search & replace" work. (Before I lost my job last year, I spent 23 years writing code on a unix system. I'm fairly handy with regular expressions )

With luck by tomorrow I should have a fairly complete list of differences between the RF database and the worldofkrauss database. That will simplify merging them together.

Also - if I can trouble myself to learn spreadsheet macros it should be possible to add a column for airfoil type, i.e. "flat-bottom," "symmetrical" and so on. I don't know enough about airfoils to do that for each one, but you guys do. Anyway I'm thinking (I may be wrong...) that you can set up a drop-down list in spreadsheet cells to choose a particular value. If so, then that feature is "doable" and would probably answer the needs of Opjose and willsonman (and many others)

DH

 

[dhk79]

Great Lee.

Just being able to sort by camber will be a big step towards that end, as fully symmetrical equates to zero camber while flat bottoms will tend towards a high camber.

 

[DirtyHarry3033]

OK, I just took 77 screenshots of the RF airfoil selection window. That was the easy part, took less than 20 seconds I've got every airfoil in RF listed in .bmp format now.

After I get something to eat, I'll stitch them together into a single file in Gimp (that will take a little longer...) and then run it thru that OCR program and see what happens. If I can do what I think I can, it should be fairly easy to get a comprehensive listing of the differences between the two databases.

Doug here is a question for you:

I notice in the worldofkrauss database that there are a number of almost "duplicate" entries. These seem mainly among the airfoils named "E***", for instance they list:

E212 (10.55%)

(and all the other "E***" airfoils) twice. The ONLY difference that I see in the displayed numbers is in the "TE Angle" (no idea what that means, guessing "Trailing Edge"?) where one is 9.9% and the other is 7.2% RF however, has only a single E212 airfoil.

So question is, does it MATTER which one I include in the spreadsheet? I don't see that value shown in RF's airfoil window, so I'm guessing that TE Angle value isn't reflected in RF?

Only reason I ask is, I like to be precise! And when you don't know something you ask the guys that do

Doug, that was a GREAT idea you had! I think we can get a good tool for the designers with this, sadly I don't have the brains to use it but maybe I can learn one day. After all a couple years ago I didn't have the brains to build an RF model

DH

 

[dhk79]

For our purposes, I think we really only need to have one included and which one is probably not important.

One of the earliest studies on drag reduction involved the modification of trailing edges on airfoils to change the wake area behind the wing. With the lower speeds that RC aircraft fly at and the increased relative air density, however, these sort of modifications should have very little effect on our models.

 

[flip3d]

The "Airfoil Selection" chart does need updated.

The update needs to go much further than you suggest. The correct aerodynamic properties need to be updated as well. While it is true that the "Aircraft Editor" allows a very wide range of adjustments in this area I find it interesting to note that the "2% Flat Plate" and the "NACA 0009" have identical graph properties. There are several other examples but this is the one that comes to mind.