Hi,
When I looked at the history of flappers I found
that the earlier flapper designs like the Coot had the
wing glued at the center about 75% or 80% of the wing
chord, only about 20% flap. As the designs(later
years) progress(and new records were set), the number
became 50%. By the way I have tried only 40% back and
performance was down. I think if you glue the center
of the wing 100% it because a fixed wing with
underchamber.
Kurt
--- Bill Gowen <b.gowen_at_earthlink.net> wrote:
> Gary
> If you join the flaps at the center - assuming a
> wing with center dihedral - you will probably be
> locking the wing in the cambered configuration. I
> think it would be hard to generate enough bending
> force on the wing to make the flaps function. But I
> could for sure be wrong. As for thin wings I'm
> pushing that idea as hard as I can. One of my fairly
> large unlimiteds that I flew at Kent last year had a
> wing made from 1/16 sheet plus a lot of carbon. It
> flew pretty well but not long enough, which seems to
> be a common problem. I feel like getting a very
> light glider to high Cat 2 altitudes requires a thin
> wing to cut drag.
>
> Don
> My usual airfoil for low ceiling consists of a
> forward part of the wing as thin as I dare make it.
> The LE is shaped from both sides. I normally use a
> carbon rod either whole or split in half for the LE
> reinforcement. At the rear of the front part I sand
> only on the bottom and try to make an edge thickness
> that matches whatever I'm using for flaps. I join
> the front part to the flaps with the wing upside
> down to get a nice flush joint on the top of the
> wing. When the wing is close to being finished I
> bend the front part to give whatever camber I'm
> looking for and massage the flaps to form the rear
> of the airfoil. The finished airfoil looks somewhat
> similar to Kurt's Time Machine airfoil except that
> the step is smaller and farther back.
>
> I don't have any hard numbers for camber. I usually
> keep adding camber when I'm testing until I feel
> like the sink rate is the best I can get.
>
> ----- Original Message -----
> From: dgbj_at_aol.com
> To: Indoor_Construction_at_yahoogroups.com
> Sent: Sunday, February 11, 2007 9:03 PM
> Subject: Re: [Indoor_Construction] IHLG Flappers
>
>
> Bill,
>
> "Regardless of how hard the flap function is to
> analyze, they definitely do
> work."
>
> Yes, and Aki brings up an interesting point. Maybe
> the flattening of the
> whole wing is what does it, not just the flap.
> Maybe making the whole wing
> thinner and softer will work better. I have been
> wondering what would happen if
> there was no slot at the flap root.
>
> Gary
>
> [Non-text portions of this message have been
> removed]
>
>
>
>
>
> [Non-text portions of this message have been
> removed]
>
>
Kurt Krempetz
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Received on Sun Feb 11 2007 - 19:50:29 CET