What would be a good airfoil to use
09-14-2011 | 02:06 PM
#1
Thread Starter
What would be a good airfoil to use
I'm rebuilding my Hangar 9 Cap 232 (60 inch wing span) after a... ahhhh.....hard landing
One wing panel was destroyed and the other is a mess with multiple cracks and splits. So I plan on a new wing. My first thought was to trace the root and tip ribs and cut a foam wing. I know this will be a bit heaver that the built up it had. Now I'm thinking of going with a built up wing but of course the ribs will be a bit more of a problem without plans. I could use the old trick of stacking the rib material between two templates and sanding away but with this tapered wing I don't know how accurate that method would be. Maybe I'm over thinking this[
] In any case the wing will be fully sheeted and glassed with 3/4 oz cloth for strength and durability.
In addition as long as I'm building a new wing I thought I might as well use a "better" airfoil than the one that's on it. The root rib is 13.125" long and 1.125" thick. The tip rib is 6.375" long by 1.0" thick. Is there a popular airfoil that might be better that this one? This wing seemed to be a bit "snappy" but then I guess it needs to be if it's on a aerobatic airplane LOL. It never seemed to have any bad landing habits though. It only flew about 10 flights before the horizontal stabilizer decided to part company with the rest of the airframe!
Thanks!
Ken
One wing panel was destroyed and the other is a mess with multiple cracks and splits. So I plan on a new wing. My first thought was to trace the root and tip ribs and cut a foam wing. I know this will be a bit heaver that the built up it had. Now I'm thinking of going with a built up wing but of course the ribs will be a bit more of a problem without plans. I could use the old trick of stacking the rib material between two templates and sanding away but with this tapered wing I don't know how accurate that method would be. Maybe I'm over thinking this[
] In any case the wing will be fully sheeted and glassed with 3/4 oz cloth for strength and durability.In addition as long as I'm building a new wing I thought I might as well use a "better" airfoil than the one that's on it. The root rib is 13.125" long and 1.125" thick. The tip rib is 6.375" long by 1.0" thick. Is there a popular airfoil that might be better that this one? This wing seemed to be a bit "snappy" but then I guess it needs to be if it's on a aerobatic airplane LOL. It never seemed to have any bad landing habits though. It only flew about 10 flights before the horizontal stabilizer decided to part company with the rest of the airframe!
Thanks!
Ken
09-16-2011 | 03:23 AM
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RE: What would be a good airfoil to use
Get Compufoil. This program will take the root, tip airfoils selected and produce all the airfoils in between. You specify spacing etc. At the size of our little airplanes, any symmetric airfoil will do just fine. Just stick with the chord and thickness of the original. In my design work I typically use NACA 00xx airfoils with about 12 to 13 Percent at the Root and 10% thick at the tip. Then, I set the max thickness to about 35% of the chord. All this can be done in Compufoil. [link=http://www.compufoil.com]Compufoil Web Site[/link]
Good Luck
Ken B
Good Luck
Ken B
09-16-2011 | 11:45 AM
#3
Thread Starter
RE: What would be a good airfoil to use
ORIGINAL: klblackw
Get Compufoil. This program will take the root, tip airfoils selected and produce all the airfoils in between. You specify spacing etc. At the size of our little airplanes, any symmetric airfoil will do just fine. Just stick with the chord and thickness of the original. In my design work I typically use NACA 00xx airfoils with about 12 to 13 Percent at the Root and 10% thick at the tip. Then, I set the max thickness to about 35% of the chord. All this can be done in Compufoil. [link=http://www.compufoil.com]Compufoil Web Site[/link]
Good Luck
Ken B
Get Compufoil. This program will take the root, tip airfoils selected and produce all the airfoils in between. You specify spacing etc. At the size of our little airplanes, any symmetric airfoil will do just fine. Just stick with the chord and thickness of the original. In my design work I typically use NACA 00xx airfoils with about 12 to 13 Percent at the Root and 10% thick at the tip. Then, I set the max thickness to about 35% of the chord. All this can be done in Compufoil. [link=http://www.compufoil.com]Compufoil Web Site[/link]
Good Luck
Ken B
I've looked at Compufoil and while it looks like a nice program I have to question just how much I would use it. I don't plan on scratch building that much but then at $40 it might be worth the investment to save on future frustration???? I'm on a pretty tight budget at the moment and any money I have needs to go towards building supplies. Thanks for the tip though.
Ken
09-16-2011 | 02:34 PM
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RE: What would be a good airfoil to use
I've downloded the demo of compufoil but never could justify spending the $$ on it. I'd rather buy plane parts.
I've used ... [link=http://tracfoil.free.fr/tracfoil/accueilE.htm]tracfoil[/link]
and ... [link=http://www.profili2.com/]Profili 2[/link]
and both of these programs work very well.
I've used ... [link=http://tracfoil.free.fr/tracfoil/accueilE.htm]tracfoil[/link]
and ... [link=http://www.profili2.com/]Profili 2[/link]
and both of these programs work very well.
09-16-2011 | 02:58 PM
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RE: What would be a good airfoil to use
I wouldn't be too concerned about what airfoil used as long as the percentage numbers are in the ball park. What I have done is played around with the tip airfoil having it's high point a few percent further forward then the root. Reason being is a more forgiving wing at low speeds. That part seems to be working but it ended up taking a little more effort to get clean breaks for snaps and spin entries. Properly done, a foam wing can be lighter then a built up one. The secret to that is careful wood selection. Use medium balsa on the high point, contest grade at leading edge and trailing edge, bond with epoxy and vacuum bag.
09-16-2011 | 06:56 PM
#6
Thread Starter
RE: What would be a good airfoil to use
I found a useful program (actually recommended by another RCU member) called AreoPlot http://www.cncplusplus.com/index.html Scroll down to Hobby software. If you go to the UIUC airfoil data site you can get all the info needed on hundreds of airfoils (link) http://www.ae.illinois.edu/m-selig/a...atabase.html#N. Oh, never mind the link is built right in to Aeroplot....
You can play with the airfoil in Areoplot and export it as a DFX file. These obviously can be imported into your cad program and manipulated from there. If only I could make Draft Sight make multiple ribs with the appropriate spacing, for a tapered wing panel, I'd be golden. I'm a newb with CAD so I know next to nothing
I played around with a low Reynolds number airfoil (Selig S8035 ). I made the root 10% thick and the tip 15%. The two following attachments are a PDF. I don't know how (yet) to get both images one sheet of paper.
Ken
You can play with the airfoil in Areoplot and export it as a DFX file. These obviously can be imported into your cad program and manipulated from there. If only I could make Draft Sight make multiple ribs with the appropriate spacing, for a tapered wing panel, I'd be golden. I'm a newb with CAD so I know next to nothing
I played around with a low Reynolds number airfoil (Selig S8035 ). I made the root 10% thick and the tip 15%. The two following attachments are a PDF. I don't know how (yet) to get both images one sheet of paper.
Ken
