HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jun 15, 2014, 08:43 AM
Registered User
Joined Sep 2012
126 Posts
Discussion
Will this airfoil work?

Just made a wing, one of my first attempts using foamboard. So, I made the wing and it came out having this airfoil. What will happen if I try and fly it? I am worried it might not work that well,I guess I should have kept it flat on the bottom surface?
Uk flyer is offline Find More Posts by Uk flyer
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 15, 2014, 08:50 AM
yank and bank!!
Joined May 2013
1,622 Posts
You made a crude symmetrical airfoil.... speaking from experience, I'd imagine it will at least work somewhat and you'll have to find out how well.

I'd suggest setting the wing incidence based on a symmetrical airfoil btw...
failboat is online now Find More Posts by failboat
Reply With Quote
Old Jun 15, 2014, 10:56 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
11,190 Posts
Yes it will 'work' but if it is ideal for your needs depends on what your needs are. To make enough lift it will need to fly a little faster than a cambered (eg 'flat bottom') airfoil.
Symmetrical airfoils roughly like the one you made are found on many planes, especially aerobatic ones where inverted performance is important but efficiency is less important.
JetPlaneFlyer is offline Find More Posts by JetPlaneFlyer
Reply With Quote
Old Jun 15, 2014, 05:28 PM
Registered User
billisfree's Avatar
Joined Oct 2012
548 Posts
It WILL work. There's not a lot of difference between a crude airfoil and a precise one.
billisfree is offline Find More Posts by billisfree
Reply With Quote
Old Jun 15, 2014, 08:14 PM
Registered User
tacx's Avatar
United States, MI, Macomb
Joined Apr 2009
2,481 Posts
Yes it will work.
tacx is offline Find More Posts by tacx
Reply With Quote
Old Jun 15, 2014, 11:56 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
11,190 Posts
Quote:
Originally Posted by billisfree View Post
It WILL work. There's not a lot of difference between a crude airfoil and a precise one.
That depends on application. On a discuss launch sailplane i did some back to back testing of the standard drela airfoil vs. a home make 'KFm' type stepped airfoil. The Drela airfoil flew on average for 60% longer than the KFm one. Personally I'd call a 60% improvement in flight time a lot of difference.

You will also be noting a big difference between airfoils of different types, regardless of precision of build. For instance a symmetrical airfoil will tend to fly very differently to a heavily undercambered airfoil, or a very thin airfoil will fly quite differently to a very thick airfoil.

But of course they all 'work' insomuch as they all fly. You would have to come up with something really crazy to not be able to fly at all.
JetPlaneFlyer is offline Find More Posts by JetPlaneFlyer
Reply With Quote
Old Jun 16, 2014, 01:00 AM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
12,473 Posts
It'll work, but, as pointed out, you'll have to determine how well it will work by experimentation.

My first thought was that it looked just like the wings on the old Kyosho F-16, but that's just the colour, since the F-16 has a much more slender airfoil.
leccyflyer is offline Find More Posts by leccyflyer
Reply With Quote
Old Jun 16, 2014, 01:09 AM
Registered User
billisfree's Avatar
Joined Oct 2012
548 Posts
Quote:
Originally Posted by JetPlaneFlyer View Post
That depends on application. On a discuss launch sailplane i did some back to back testing of the standard drela airfoil vs. a home make 'KFm' type stepped airfoil. The Drela airfoil flew on average for 60% longer than the KFm one. Personally I'd call a 60% improvement in flight time a lot of difference.

But of course they all 'work' insomuch as they all fly. You would have to come up with something really crazy to not be able to fly at all.
I build a KFm airfoil for fun. It has been quite a durable airfoil with a carbon fiber rod. Two years later, I have yet to destroy it. I'm just surprised it lasted so long... through so many crashes.

Now that you mentioned it, perhaps I ought to "time" my flights and see how long flights last with different airfoils.
billisfree is offline Find More Posts by billisfree
Reply With Quote
Old Jun 16, 2014, 03:49 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,321 Posts
Chris Foss in UK ... one the leading designers offered different wing aerofoils for various of his kits - particularly with slope soarers like Centi-Phase .. Phase 6 etc.

For competition work such as aerobatics - the Full Symet.

For cross-country, duration or sunday sport - Semi Symet

The flight difference was definitely obvious when flown.


Nigel
solentlife is offline Find More Posts by solentlife
Reply With Quote
Old Jun 16, 2014, 05:53 AM
Registered User
Joined Sep 2012
126 Posts
Thanks, I have put my building skills up a notch and managed to make one with a flat bottom.
Uk flyer is offline Find More Posts by Uk flyer
Reply With Quote
Old Jun 16, 2014, 06:10 AM
All under control, Grommit!
leccyflyer's Avatar
United Kingdom, Aberdeen
Joined Sep 2000
12,473 Posts
Quote:
Originally Posted by Uk flyer View Post
Thanks, I have put my building skills up a notch and managed to make one with a flat bottom.
I hadn't realised that aeromodelling was so slimming

It'll be interesting to see how your different wing sections perform - a nice little experiment.
leccyflyer is offline Find More Posts by leccyflyer
Reply With Quote
Old Jun 16, 2014, 08:59 AM
Electric Coolhunter
Thomas B's Avatar
United States, TX, Fort Worth
Joined Jun 2000
14,466 Posts
Quote:
Originally Posted by billisfree View Post
It WILL work. There's not a lot of difference between a crude airfoil and a precise one.
Not true as a general statement. There can be large differences between how a model flies with a crude airfoil vs. an accurate airfoil, depending on the model, size, planform wing loading, speed and many other factors. Yes, we operate at low Reynolds numbers, but it still makes a difference.

In particular, the cleanness and accuracy of the the wing leading edge has a significant effect on flight performance near the stall.

JetPlaneFlyers comments above are worth taking to heart. Mark Drela is considered to to be the best authority around for airfoils as applied to models and for applied aerodynamics at low Rn.

Using a well executed airfoil is not as critical on a lightly loaded parkflyer type model as it is on higher performance models, but using one can still yield useful improvements in flight performance and handling.
Thomas B is offline Find More Posts by Thomas B
RCG Plus Member
Last edited by Thomas B; Jun 16, 2014 at 09:04 AM.
Reply With Quote
Old Jun 16, 2014, 10:41 AM
What tree?
Rampage's Avatar
Yucca Valley, California
Joined Aug 2005
2,400 Posts
Put enough motor on the front and airfoil be damned.
Rampage is online now Find More Posts by Rampage
Reply With Quote
Old Jun 16, 2014, 10:51 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,321 Posts
Quote:
Originally Posted by Rampage View Post
Put enough motor on the front and airfoil be damned.
Given that various military fighters today have wing loadings higher than an iron manhole cover ............. that is certainly true.

Nigel
solentlife is offline Find More Posts by solentlife
Reply With Quote
Old Jun 16, 2014, 12:17 PM
yank and bank!!
Joined May 2013
1,622 Posts
I suspect the truth is somewhere between BIF and JPF's posts.... as evidenced by the nutball like planes I have witnessed which are just a flat circle of dtf and a "tunnel" for the electronics.... of course they drop like a rock once they lose airspeed.
failboat is online now Find More Posts by failboat
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Question How do you think this "airfoil" will perform? NineZeta Modeling Science 24 May 26, 2014 09:53 AM
Discussion will this combo work dalolyn Power Systems 10 Oct 17, 2013 05:59 AM
Discussion What kind of swash leveler will work for this heli? Domster_26 Electric Heli Talk 10 Oct 06, 2013 03:19 PM
Question will this electric motor work in my boat??? howdidjobdoit Racing Boats - Electric 3 Sep 22, 2013 08:15 AM
will this airfoil work? Teufel Hunden Modeling Science 4 Apr 27, 2003 12:55 AM