Wing root fairings

[D.A.L]

I have noticed that several articles on glider performance refer to
adding/modifying the wing root to get better performance. Can anyone
refer me to further info on wing root fairing design and or mods to
improve performance.

Cheers, Don

[Owain Walters]

What type of glider?


At 15:18 27 October 2003, D.A.L wrote:
>I have noticed that several articles on glider performance
>refer to
>adding/modifying the wing root to get better performance.
>Can anyone
>refer me to further info on wing root fairing design
>and or mods to
>improve performance.
>
>Cheers, Don
>

[Bob Kuykendall]

Earlier, D.A.L wrote:

> I have noticed that several articles
> on glider performance refer to
> adding/modifying the wing root to
> get better performance. Can anyone
> refer me to further info on wing root
> fairing design and or mods to
> improve performance.

Wing fuselage junction fillets are often a pretty troublesome
aspect of glider design. The way I understand it, they
are usually developed either empirically, using tuft
testing, or using lots of CFD computing horsepower.

On the other hand, it seems to be one of those aspects
where you get some points just for trying. Dick Schreder
developed the HP-18 side-of-body junction by eye, and
seemed to have gotten it pretty close on the first
try. The only thing I would have done differently would
be to adjust the fillet trailing edge slightly so that
it lines up at the -5 flap setting instead of 0.

There are some references in Thomas' _Fundamentals
of Sailplane Design_, but the book itself is pretty
skimpy regarding developing junction fillets for existing
sailplanes. Small radii near the leading edge, big
radius at the bac, that sort of thing.

One of the cites in Thomas is to a study by Mark Maughmer
at Penn State. If you can get in touch with him, he
might be able to give you some reasonable guidelines.
Another cite is to Dick Johnson's 1979 compendium of
flight test articles; you can get most of those off
of the SSA Web server.

Bob K.
http://www.hpaircraft.com/hp-24

[Slingsby]

Bob Kuykendall > wrote in message >...
> Earlier, D.A.L wrote:
>
> > I have noticed that several articles
> > on glider performance refer to
> > adding/modifying the wing root to
> > get better performance. Can anyone
> > refer me to further info on wing root
> > fairing design and or mods to
> > improve performance.
>
> Wing fuselage junction fillets are often a pretty troublesome
> aspect of glider design. The way I understand it, they
> are usually developed either empirically, using tuft
> testing, or using lots of CFD computing horsepower.
>
> On the other hand, it seems to be one of those aspects
> where you get some points just for trying. Dick Schreder
> developed the HP-18 side-of-body junction by eye, and
> seemed to have gotten it pretty close on the first
> try. The only thing I would have done differently would
> be to adjust the fillet trailing edge slightly so that
> it lines up at the -5 flap setting instead of 0.
>
> There are some references in Thomas' _Fundamentals
> of Sailplane Design_, but the book itself is pretty
> skimpy regarding developing junction fillets for existing
> sailplanes. Small radii near the leading edge, big
> radius at the bac, that sort of thing.
>
> One of the cites in Thomas is to a study by Mark Maughmer
> at Penn State. If you can get in touch with him, he
> might be able to give you some reasonable guidelines.
> Another cite is to Dick Johnson's 1979 compendium of
> flight test articles; you can get most of those off
> of the SSA Web server.
>
> Bob K.
> http://www.hpaircraft.com/hp-24

************************************************** ******************************
For the sake of the discussion, why have an upper wing root fillet at
all? The Caproni A 21 wing blends into the top of the fuselage. What
are the advantages/disadvantages to this type of design?

[Bert Willing]

The Calif A21 has a pretty elaborate wing root fairing (I own one, so I
should know).

--
Bert Willing

ASW20 "TW"


"Slingsby" > a écrit dans le message de
om...

> For the sake of the discussion, why have an upper wing root fillet at
> all? The Caproni A 21 wing blends into the top of the fuselage. What
> are the advantages/disadvantages to this type of design?

[D.A.L]

Bob Kuykendall > wrote in message >...
> Earlier, D.A.L wrote:
>
> > I have noticed that several articles
> > on glider performance refer to
> > adding/modifying the wing root to
> > get better performance. Can anyone
> > refer me to further info on wing root
> > fairing design and or mods to
> > improve performance.
>
> Wing fuselage junction fillets are often a pretty troublesome
> aspect of glider design. The way I understand it, they
> are usually developed either empirically, using tuft
> testing, or using lots of CFD computing horsepower.
>
> On the other hand, it seems to be one of those aspects
> where you get some points just for trying. Dick Schreder
> developed the HP-18 side-of-body junction by eye, and
> seemed to have gotten it pretty close on the first
> try. The only thing I would have done differently would
> be to adjust the fillet trailing edge slightly so that
> it lines up at the -5 flap setting instead of 0.
>
> There are some references in Thomas' _Fundamentals
> of Sailplane Design_, but the book itself is pretty
> skimpy regarding developing junction fillets for existing
> sailplanes. Small radii near the leading edge, big
> radius at the bac, that sort of thing.
>
> One of the cites in Thomas is to a study by Mark Maughmer
> at Penn State. If you can get in touch with him, he
> might be able to give you some reasonable guidelines.
> Another cite is to Dick Johnson's 1979 compendium of
> flight test articles; you can get most of those off
> of the SSA Web server.
>
> Bob K.
> http://www.hpaircraft.com/hp-24


Thanks for the info and references Bob!
Don.

[Marske Flying Wings]

The Root to fusleage junction is a source of separation in many gliders.

In our Marske Pioneer at extrmely slow speeds we discovered that a
separation seems to start at this wing root/ fuselage junction. And a fillet
may solve this.

Tuft the wing and record the result on film with voice commentary for the
differing speeds. When you have a newly constructed fillet record that too
on film to see if you have improved the airflow.

We will be adding a wingroot fillet on our Pioneer over the winter months.

-mat

Marske Flying Wings
http://www.continuo.com/marske

[Robert Ehrlich]

Bert Willing wrote:
>
> The Calif A21 has a pretty elaborate wing root fairing (I own one, so I
> should know).
>
> --
> Bert Willing
>
> ASW20 "TW"
>
> "Slingsby" > a écrit dans le message de
> om...
>
> > For the sake of the discussion, why have an upper wing root fillet at
> > all? The Caproni A 21 wing blends into the top of the fuselage. What
> > are the advantages/disadvantages to this type of design?

A better example of a wing root without fillet is the LS1f. But the manufacturer
added them to the LS4. Another example is the Janus B (just had a look on our
Janus now disassembeld in the workshop).

[JJ Sinclair]

Several of us have added Vortex Generators (VG's) to the upper wing / fuselage
juncture area on the Genesis 2 and found very good results. As I understand it,
the VG's, placed near the high camber location, cause the local flow to become
turbulent, but the "turbulent" flow reattaches and prevents complete
separation. Anyway, I am able to thermal 5 knots slower and no longer feel and
hear flow separation.

The VG's are 1" long X .25" high and .25" wide (base only) the vertical web is
about 1/16" wide. We place them in pairs that are angled in about 30 degrees to
each other. The hot set-up seems to be 3 sets on each side with 2 on the wing
and 1 on the fuselage. I have seen similar things on a Nimbus 3 and wondered if
they worked. I could play a tune on my Nimbus, by just moving the flaps up and
down, so something bad was going on back there.
The VG's work on the Genesis 2.
JJ Sinclair

[F.L. Whiteley]

"Robert Ehrlich" > wrote in message
...
> Bert Willing wrote:
> >
> > The Calif A21 has a pretty elaborate wing root fairing (I own one, so I
> > should know).
> >
> > --
> > Bert Willing
> >
> > ASW20 "TW"
> >
> > "Slingsby" > a écrit dans le message de
> > om...
> >
> > > For the sake of the discussion, why have an upper wing root fillet at
> > > all? The Caproni A 21 wing blends into the top of the fuselage. What
> > > are the advantages/disadvantages to this type of design?
>
> A better example of a wing root without fillet is the LS1f. But the
manufacturer
> added them to the LS4. Another example is the Janus B (just had a look on
our
> Janus now disassembeld in the workshop).

Most common Grob models have no fillet and fly like it.

Peter Masak had a small publication a few years ago on performance
enhancements, including photos of ASW-20 fillets and mods and tufts in
action. No clue if it's still available.

Frank Whiteley

[Doug Haluza]

Robert Ehrlich > wrote in message >...
> Bert Willing wrote:
> >
> > The Calif A21 has a pretty elaborate wing root fairing (I own one, so I
> > should know).
> >
> > --
> > Bert Willing
> >
> > ASW20 "TW"
> >
> > "Slingsby" > a écrit dans le message de
> > om...
> >
> > > For the sake of the discussion, why have an upper wing root fillet at
> > > all? The Caproni A 21 wing blends into the top of the fuselage. What
> > > are the advantages/disadvantages to this type of design?
>
> A better example of a wing root without fillet is the LS1f. But the manufacturer
> added them to the LS4. Another example is the Janus B (just had a look on our
> Janus now disassembeld in the workshop).

I have done extensive dye flow testing on the wing root area of my
Janus C. The Janus has no fairing--the wing just butts into the
fuselage. Where the leading edge of the wing meets the fuselage, the
fuselage boundary layer is rolled up by the wing boundary later,
forming a horshoe vortex that trails back over and under the wing
root. This is caused by the velocity gradient in the fuselage boundary
layer. The flow just above the surface overruns the flow below, but
when it runs into the stagnation at wing leading edge, it doubles back
along the surface.

At hight angles of attack, the dye tests show a clear stagnation point
on the fuselage in front of the leading edge (about 10cm), and
reversed flow from the leading edge forward to the stagnation point.
They also show the vortex is attached to the fuselage above the wing,
where any dye that enters the vortex is scrubbed out at an upward
tilted angle relative to the flow. A thick line of dye marks the upper
edge of the attached vortex. The vortex separates from the fuselage
near the point of maximum wing thickess (where the fuselage also
begins to taper sharply), briefly attaches to the wing upper surface,
and then trails off into the flow. If you imagine bending one of those
pool toy "noodles" in half over the leading edge of the wing root,
then straight back on both sides, you would get a pretty good picture
of what is going on.

BTW, the interesting finding from the Maughmer wing root study was
that a concave fairing was actually worse than no fairing at all. He
got the best results from a straight 45 degree angle fairing. Perhaps
the concave fairing supports the vortex while the 45 degree fairing
does not?