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Jul 14, 2012, 03:17 PM
If I build it, it will fly
Question

Wing taper: strait LE, strait TE, or dual taper?


I am working the bugs out of my foam cutter & have found a decent formula for wing & fuse dimensions. I have 90% of my electronics, i'm just trying to figure out a few design details that are bugging me.

What are the characteristics of the above mentioned wing tapers? I just don't like the look of a constant chord wing so I wanted to see what the differences are depending on which way I set the templates.

My electronics will weigh in at approx 400gr, yea it's hefty but it's what I've got to work with. I am going for a high wing 48" design with 750-900gr of thrust, depending on prop selection. Since I'll be soo heavy I figure every advantage would be worth the effort. I have decided on a flat or nearly flat bottomed airfoil with 10" root & 8" tip chords. This will give approx 430sq in. including the ailerons.

~psguardian
Last edited by psguardian; Jul 15, 2012 at 07:47 AM.
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Jul 14, 2012, 07:26 PM
Build straight - Fly twisty
Whiskers's Avatar
I'm also not too keen on the look of constant cord wings, but I love the way they fly.
Because of their lift distribution they are resistant to tip-stalling and are generally well behaved. I usually put on tapered full-span ailerons for 'looks.'
The most efficient lift distribution is obtained by using Spitfire type elliptical wings. However these tend to stall 'all over' whereas with the un-tapered wing the 'lazy area' at the tips stalls later than the in-board area.
Variations on the elliptical theme are often seen in high performance sailplanes that have an elliptical leading edge and a straight trailing edge.
Also used are multi-tapered wings, where the straight tapered sections approximate the elliptical plan-form.
Basically, go for a shape that pleases you.
Avoid wings with very pronounced taper and very small cord tips.
Do not have a wing section that becomes thicker, in percentage terms, nearer the tips.
Jul 15, 2012, 07:55 AM
If I build it, it will fly
Elliptical wings, I think, are beyond my cutting skills at present lol. I had seen a chart showing stall characteristics for different designs, on some website, but I can't find it now. Guess I'll take up the hunt again now that I've been away from it for a day.

I'm leaning towards strait LE with the tops of the templates even (since the tip will be thinner than the root this will put a few degrees dihedral into the underside, though I doubt it will be notable.

~psguardian
Jul 15, 2012, 08:33 AM
If I build it, it will fly
Found it! Just needed to take a break from the search I guess lol.

wing stall chart

As I read it (after elliptical), a gentle taper will have the best stall characteristics.

~psguardian
Jul 15, 2012, 10:43 AM
Registered User

psguardian


Personally, I have found that LE taper with a straight trailing edge is one of the most stable forgiving shapes. This also allows ailerons to be straight and untapered which improves control. Hope this helps
Jul 15, 2012, 11:11 AM
If I build it, it will fly
Good point, I suppose that's why most commercial air liners are set up with strait TE. That way ailerons & flaps are head on and square.

~psguardian


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