Hi,
Yes I sand both the top and bottom of the wing to
get the airfoil and taper.
I might look at this wrong, but I feel the flaps
are really just changing the incidence of that
particular wing section. The cross-section of my
airfoil at the tips is basically a flat bottom airfoil
and at the root I basically lower the flap 1/4" for my
time machine and 1/2" for my Slow-Cat. I have
experimented alot with this and found this to be the
optimum numbers.
I hope this helps,
Kurt
--- Don DeLoach <ddeloach_at_comcast.net> wrote:
> Bill, well said. Anybody who has spent any time at
> all flying low ceiling
> gliders knows that flappers are a major performance
> improvement!
>
> Speaking of which, do you guys sand the top or the
> bottom of the wing on
> your cat I flappers? It looks like Kurt's plans
> indicate taper and airfoil
> shape sanded on both sides. Kurt?
>
> Also, how much mean camber do you think is optimum
> for a cat I glider? My
> best glider for our 36" site has only about 5/32" of
> undercamber, so mean
> camber is likely around 3/16".
>
> Thanks
> Don
>
>
>
> -----Original Message-----
> From: Indoor_Construction_at_yahoogroups.com
> [mailto:Indoor_Construction_at_yahoogroups.com] On
> Behalf Of Bill Gowen
> Sent: Sunday, February 11, 2007 5:23 PM
> To: Indoor_Construction_at_yahoogroups.com
> Subject: Re: [Indoor_Construction] IHLG Flappers
>
> Gary
> I tried for several years to equal the Cat 1 records
> with very light weight
> built up gliders. I never broke 40 seconds until I
> built my first Slow
> Poker. The Poker airfoil is very thin and has a lot
> of undercamber. My
> gliders with similar airfoils on fixed wings were a
> lot like trying to
> launch a parachute. With flatter airfoils altitude
> was not a problem but the
> sink rate was too much.
>
> A couple of years ago I had my best contest day with
> gliders by breaking 80
> seconds in Cat 1 in all 3 classes. The Slow Poker
> did it in HLG and UCLG and
> a similar shrunken version did it in Standard class.
>
> Regardless of how hard the flap function is to
> analyze, they definitely do
> work.
>
> ----- Original Message -----
> From: dgbj_at_aol.com
> To: Indoor_Construction_at_yahoogroups.com
> Sent: Sunday, February 11, 2007 6:37 PM
> Subject: Re: [Indoor_Construction] IHLG Flappers
>
>
> I've been wondering how those flaps worked ever
> since I first saw them.
> The
> theory is that under the increased flight loads of
> a fast launch, the
> flaps
> bend up, reducing the camber, the lift and the
> tendency to loop. But how
> much force really exists on the wing? With typical
> loadings, there is
> around
> 0.1-0.2 gram per square inch load, most
> concentrated in the forward half,
> less
> on the flap. How much force is required to move
> the flap? How much
> difference in lift does that flap change make? The
> lift is also not
> directly
> proportional to the square of the velocity. The
> excess lift will make the
> plane
> loop, yes, but in looping the circular airflow
> reduces both the attack
> angle and
> the decalage, both reducing lift and countering
> the tendency to loop.
> Somewhere the glider finds a balance, and it isn't
> at the same attack
> angle as in
> steady glide. What would that excess lift pull
> against? There is only 9
> grams of airplane and it only pulls back when it
> is accelerated. In a
> steep
> climb, most of the weight force is directed back
> toward the tail, not
> perpendicular to the wing chord. The balancing
> around the CG that
> establishes attack
> angle in steady glide is not at work here.
>
> [Non-text portions of this message have been
> removed]
>
>
>
>
>
> [Non-text portions of this message have been
> removed]
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
Kurt Krempetz
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Received on Sun Feb 11 2007 - 17:17:42 CET