Hello,

Does anyone have any information on applying turbulator tape to the wings of a PIK 20 B? Can any improvement in performance or handling be gained for this airfoil?

Thanks!

3Y
Formerly 9V

On Thursday, April 30, 2015 at 12:19:05 PM UTC-6, Blake Seese 9V wrote:
> Hello,
>
> Does anyone have any information on applying turbulator tape to the wings of a PIK 20 B? Can any improvement in performance or handling be gained for this airfoil?
>
> Thanks!
>
> 3Y
> Formerly 9V

All,

I found this on the web from Udo Rumpf:

The FX67 15%&17% was designed to be a naturally transitioning airfoil. In early wind tunnel test it looked to be a winner and was used on some of the first 15meter flapped gliders. As it turned out it was not as good as the designers hoped.

The FX67 has a steep pressure drop and a very pronounced pressure recovery, due to the high camber and the general layout of the airfoil. Also the separation bubble was not understood very well at that time. The leading edge is relatively sharp, which further makes the airfoil intolerant to gusty conditions, like very turbulent thermals. The back 45% of the chord is very sensitive for the turbulent flow to separate. That is why I think in smooth conditions that airfoil performance better.

The FX 67 15% Is used on the Mini Nimbus, Mosquito and our HP-16s, '18s and RS-15s.

The Pik20 and the LS3 use both the FX67-15%&17%

The Performance can be enhanced by first: making the airfoil accurate in both shape plus or minus 2.5% and waves within the .002"-.004" tolerance and second installing a turbulator on the top at about 52% chord. I would use 3/16" cylinder dots about .040" high and spaced 1.25" apart. Within 1.5" down stream due to the 35 deg. wake the "top" surface will be awash in turbulent attach flow, at higher speed the effect will take a little more distance..

Blake, Did you read the Johnson test report on the PIK-20?
I would follow that before you start throwing tape on it.
Doug


At 18:19 30 April 2015, Blake Seese 9V wrote:
>Hello,
>
>Does anyone have any information on applying turbulator tape to the
wings
>of a PIK 20 B? Can any improvement in performance or handling be
gained for
>this airfoil?
>
>Thanks!
>
>3Y
>Formerly 9V
>

Blake, I would read the Johnson report on the PIK and follow it
before I did any modifications to the wing of the PIK-20.
Doug

At 20:44 30 April 2015, Blake Seese 9V wrote:
>On Thursday, April 30, 2015 at 12:19:05 PM UTC-6, Blake Seese
9V wrote:
>> Hello,
>>=20
>> Does anyone have any information on applying turbulator tape
to the
>wings=
> of a PIK 20 B? Can any improvement in performance or handling
be gained
>fo=
>r this airfoil?
>>=20
>> Thanks!
>>=20
>> 3Y
>> Formerly 9V
>
>All,
>
>I found this on the web from Udo Rumpf:
>
>The FX67 15%&17% was designed to be a naturally transitioning
airfoil. In
>e=
>arly wind tunnel test it looked to be a winner and was used on
some of the
>=
>first 15meter flapped gliders. As it turned out it was not as good
as the
>d=
>esigners hoped.
>
>The FX67 has a steep pressure drop and a very pronounced
pressure
>recovery,=
> due to the high camber and the general layout of the airfoil. Also
the
>sep=
>aration bubble was not understood very well at that time. The
leading edge
>=
>is relatively sharp, which further makes the airfoil intolerant to
gusty
>co=
>nditions, like very turbulent thermals. The back 45% of the chord
is very
>s=
>ensitive for the turbulent flow to separate. That is why I think in
smooth
>=
>conditions that airfoil performance better.
>
>The FX 67 15% Is used on the Mini Nimbus, Mosquito and our HP-
16s, '18s
>and=
> RS-15s.
>
>The Pik20 and the LS3 use both the FX67-15%&17%
>
>The Performance can be enhanced by first: making the airfoil
accurate in
>bo=
>th shape plus or minus 2.5% and waves within the .002"-.004"
tolerance and
>=
>second installing a turbulator on the top at about 52% chord. I
would use
>3=
>/16" cylinder dots about .040" high and spaced 1.25" apart.
Within 1.5"
>dow=
>n stream due to the 35 deg. wake the "top" surface will be awash
in
>turbule=
>nt attach flow, at higher speed the effect will take a little more
>distance=
>..
>