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Old Feb 26, 2014, 01:53 AM
use the 4s luke, use the 4s...
scrub monkey's Avatar
Australia, QLD, Booyal
Joined Sep 2012
856 Posts
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aerofoil and foam core design

ok, does anybody have an aerofoil that would fit these requirements. if possible a profile that could be printed onto an a4 page for measuring.
-suitable for light lift
-suitable for aerobatics (semi/fully symetrical)
-foam core balsa sheeted wing
-about 1100mm wing span
-taperd LE and straight TE

the light lift is desirable but not essential. it is for a school project. ive got plenty of flying experience but nothing to do with slope soaring, i think i have a site or two i could use for slope flying. i plan to keep as light as possible with the ability to ballast if desired.

for lightening the foam core wing i am thinking after sheeting cut out circles along the length and gluing cross grain balsa to line the holes, the wing is going to have a 1/4 spruce spar top and bottom along with 2 6' sections top and bottom at the join between the two panels, the wing will be sheeted as one with the end grain joints between the sheets being staggered. it will have TE stock for the ailerons and flaps from the LHS and balsa strip for the LE sanded to shape. what would be an approximate auw to aim for and an approximate tail moment? it will have a conventional rudder elevator design and is a slab sided fuselage with cross grain sheeting top and bottom, still undecided as yet about triangle stock along the length of the fuselage or not yet, ill leave that till its closer to completion and i have a better idea about weight.


edit: i think i just found how the coordinates for the wing profile translate down on paper, i think. so a list of coordinates for the wing profile should work also. ill be drawing the wing in cad and cnc milling it in 4 parts (top right, bottom right, top left, bottom left) and the gluing together with 3m super 77 spray adhesive, same as the wing sheeting will be adhered with.
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Old Feb 26, 2014, 09:28 AM
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chip.greely's Avatar
Carlsbad, Ca
Joined Mar 2007
3,037 Posts
Check here:

http://aerospace.illinois.edu/m-seli..._database.html

Light lift: sd7037
Semi sym: RG14, RG15, s6062, s6063

Good luck
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Old Feb 26, 2014, 02:44 PM
Taranis Tyro...
MattyB's Avatar
United Kingdom, England, Hitchin
Joined Jan 2004
3,625 Posts
If this is a school project I'd add "easy to build accurately" to your list of criteria. For that reason I'd say E205 would be a good choice - it's of a reasonable thickness and is flat bottomed in the aft portion so easy to build flat on the board. Performance is reasonable if not earth shattering - it's the section used on the Phase 6 Sport, a bit of a classic in the UK.

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Old Feb 26, 2014, 03:59 PM
use the 4s luke, use the 4s...
scrub monkey's Avatar
Australia, QLD, Booyal
Joined Sep 2012
856 Posts
ive got a heap of cnc machines available for me use and i go no problem building and that. built plenty of them at home off plans etc. if it was a builtup wing i was doing id consider the building is straight but it will be foam core as i mentioned. the rg14 came up in the other thread i posted in the australia forum so im thinking of that. only problem is what they mean with like 7.9% thickness and 9% thickness etc
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Old Feb 26, 2014, 05:40 PM
Taranis Tyro...
MattyB's Avatar
United Kingdom, England, Hitchin
Joined Jan 2004
3,625 Posts
I guess school has moved on a bit since I went in the 80s and 90s - no CNC in those days, hence my suggestion for E205!

Thickness is expressed as a % of chord i.e an 8% wing of root chord 100mm will be 8mm thick at that point. Airfoil potting programmes will allow you to adjust this %, but bear in mind the designer usually chose that thickness to work with the overall shape of the airfoil to meet a specific goal.

Ps - More ideas here... http://www.slopeaerobatics.com/artic...glider-design/
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Old Feb 26, 2014, 08:34 PM
use the 4s luke, use the 4s...
scrub monkey's Avatar
Australia, QLD, Booyal
Joined Sep 2012
856 Posts
well ive been looking at the rg14 and have preety much settled on is this one. it looks to be about the middle of the range for that aerofoil
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Old Feb 26, 2014, 09:26 PM
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Mike Furcolow's Avatar
Paonia, Colorado
Joined Sep 2004
2,444 Posts
I just finished building a wing just like the one you described.

I wanted a light-weight wing that would be able to handle light lift well, but still be relatively fast, even in the light lift. I had built such a wing years ago, and finally beat it to death after much abuse and many repairs. The old wing performed amazingly well, was fast and very aerobatic. In decent lift, I could (occasionally) do some decent rolling circles with it. A great performing wing, that was lightweight, clean, and sleek. I just built a new replacement, but tried some newer techniques.

Here are the details and a few pictures;

The new wing has a span of 66" (1676mm), is foam core with thin obecchi sheeting and a leading edge of basswood. The airfoil is a thinned RG15-8.5% thickness. I've used this old-school airfoil for years (same as on a Blade, and many others) with great results. The leading edge is tapered, and trailing edge is straight, and I put in just 1/2 degree of dihedral, for just a little stability. I then covered the wing with 5mil NewStuff laminating film, to give it more toughness and rigidity, and it turned out great-really stiff, no twist. Part of the great performance of this plane in light lift is its overall light weight; the AUW is only 28oz for a plane with 66" span. And I can tell you, it works excellent for the purpose that I intended it for.


If you like it, I can print up some specs here, like cord measurements and tapers, etc.

Here's a couple of pictures during construction;
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Old Feb 26, 2014, 10:38 PM
use the 4s luke, use the 4s...
scrub monkey's Avatar
Australia, QLD, Booyal
Joined Sep 2012
856 Posts
Quote:
Originally Posted by Mike Furcolow View Post
I just finished building a wing just like the one you described.

I wanted a light-weight wing that would be able to handle light lift well, but still be relatively fast, even in the light lift. I had built such a wing years ago, and finally beat it to death after much abuse and many repairs. The old wing performed amazingly well, was fast and very aerobatic. In decent lift, I could (occasionally) do some decent rolling circles with it. A great performing wing, that was lightweight, clean, and sleek. I just built a new replacement, but tried some newer techniques.

Here are the details and a few pictures;

The new wing has a span of 66" (1676mm), is foam core with thin obecchi sheeting and a leading edge of basswood. The airfoil is a thinned RG15-8.5% thickness. I've used this old-school airfoil for years (same as on a Blade, and many others) with great results. The leading edge is tapered, and trailing edge is straight, and I put in just 1/2 degree of dihedral, for just a little stability. I then covered the wing with 5mil NewStuff laminating film, to give it more toughness and rigidity, and it turned out great-really stiff, no twist. Part of the great performance of this plane in light lift is its overall light weight; the AUW is only 28oz for a plane with 66" span. And I can tell you, it works excellent for the purpose that I intended it for.


If you like it, I can print up some specs here, like cord measurements and tapers, etc.

Here's a couple of pictures during construction;
actually that would be really useful thanks. im limited to the 1100mm ws but im sure just scaling it all down abit should work. using 9g servos for each aileron plus flaps, ill be mixing them in so it will be like having full length ailerons with two servos per wing.
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