Ka-6 TE Probe

[vontresc]

My Ka-6 currently has no TE compensation for the Vario. At one time it
had a Scheumann compensator installed, but this nifty box didn't come
with the glider. So now I am looking to install a TE probe.

Does anyone have any recent experience in installing one?

I was initially thinking about the tail mounted type (probably the
ILEC with the socket), but the fuselage mount type would be a much
simpler install. Is the tail mounted probe worth the extra effort in
install over the fuselage type?

Does anyone have a Schuemann compensator gathering dust they want to
sell?

thanks

Pete

[Darryl Ramm]

On Aug 28, 9:24*am, vontresc > wrote:
> My Ka-6 currently has no TE compensation for the Vario. At one time it
> had a Scheumann compensator installed, but this nifty box didn't come
> with the glider. So now I am looking to install a TE probe.
>
> Does anyone have any recent experience in installing one?
>
> I was initially thinking about the tail mounted type (probably the
> ILEC with the socket), but the fuselage mount type would be a much
> simpler install. Is the tail mounted probe worth the extra effort in
> install over the fuselage type?
>
> Does anyone have a Schuemann compensator gathering dust they want to
> sell?
>
> thanks
>
> Pete

Dick Johnson would probably have told you the fin mount type are not
necessary. See his article on making simple but effective fueslage
mount TE probes in Soaring Magazine. Sorry I don't recall the issue,
think it was a in the last few years. I'd go the path of least work,
kind of hard to justify worrying about state of the art TE
compensation for a Ka-6.

Darryl

[Marc Ramsey[_2_]]

Darryl Ramm wrote:
> I'd go the path of least work,
> kind of hard to justify worrying about state of the art TE
> compensation for a Ka-6.

Last I looked, efficiently finding and centering thermals is even more
important in a Ka-6 than it might be in, say, an ASH-26E.

The Johnson article was in the June 2005 issue of Soaring...

Marc

[Darryl Ramm]

On Aug 28, 10:00*am, Marc Ramsey > wrote:
> Darryl Ramm wrote:
> > I'd go the path of least work,
> > kind of hard to justify worrying about state of the art TE
> > compensation for a Ka-6.
>
> Last I looked, efficiently finding and centering thermals is even more
> important in a Ka-6 than it might be in, say, an ASH-26E.
>
> The Johnson article was in the June 2005 issue of Soaring...
>
> Marc

Marc, that was not the point (and you know it :-)). having the T.E.
compensation work over a wide dynamic range makes T.E. compensation
less of a challenge given the performance of older gliders like this.
That is not a slight on the Ka-6. I'd put in an easier to install
fuselage mounted probe and spend that extra money you saved buying
beers/dinner for your tow pilot.

BTW I center iron thermals perfectly in the ASH-26E.


Darryl

[Eric Greenwell]

Marc Ramsey wrote:
> Darryl Ramm wrote:
>> I'd go the path of least work,
>> kind of hard to justify worrying about state of the art TE
>> compensation for a Ka-6.
>
> Last I looked, efficiently finding and centering thermals is even more
> important in a Ka-6 than it might be in, say, an ASH-26E.

My experience in both those gliders is the Ka-6e doesn't need as good a
TE as the 26E, because the cruise speed is much lower. Pulling up from
65 knots isn't as demanding as pulling up from 85 knots.

Once in the thermal, the variations in speed are small and don't affect
the vario reading enough to see the difference between a fin mount or a
fuselage mount. This is particularly true because a 2 or 3 knot
variation at the 50 knot thermalling speed of the 26E is over twice the
altitude change that 2 or 3 knots produces at the Ka-6's 33 knot
thermalling speed.

And finally, my distant recollection of flying the Ka-6e is it's 5 light
wing loading (lb/sqft vs 8.5 lb/sqft) and low thermalling speed made it
easier to find/feel/sense and center thermals.

So, I'd suggest trying the very easiest thing first: a TE probe mounted
on the removable turtledeck, probably towards the rear it. If it works,
great; if not, very little effort wasted.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[Eric Greenwell]

Eric Greenwell wrote:

>
> And finally, my distant recollection of flying the Ka-6e is it's 5 light
> wing loading (lb/sqft vs 8.5 lb/sqft)

Well, that went badly: it's 5 lb/sqft vs 8.5 lb/sqft!

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[Marc Ramsey[_2_]]

Darryl Ramm wrote:
> On Aug 28, 10:00 am, Marc Ramsey > wrote:
>> Darryl Ramm wrote:
>>> I'd go the path of least work,
>>> kind of hard to justify worrying about state of the art TE
>>> compensation for a Ka-6.
>> Last I looked, efficiently finding and centering thermals is even more
>> important in a Ka-6 than it might be in, say, an ASH-26E.
>>
>> The Johnson article was in the June 2005 issue of Soaring...
>>
>> Marc
>
> Marc, that was not the point (and you know it :-)). having the T.E.
> compensation work over a wide dynamic range makes T.E. compensation
> less of a challenge given the performance of older gliders like this.
> That is not a slight on the Ka-6. I'd put in an easier to install
> fuselage mounted probe and spend that extra money you saved buying
> beers/dinner for your tow pilot.
>
> BTW I center iron thermals perfectly in the ASH-26E.

I would assume so 8^)

[[email protected]]

On Aug 28, 12:24*pm, vontresc > wrote:
> My Ka-6 currently has no TE compensation for the Vario. At one time it
> had a Scheumann compensator installed, but this nifty box didn't come
> with the glider. So now I am looking to install a TE probe.
>
> Does anyone have any recent experience in installing one?
>
> I was initially thinking about the tail mounted type (probably the
> ILEC with the socket), but the fuselage mount type would be a much
> simpler install. Is the tail mounted probe worth the extra effort in
> install over the fuselage type?
>
> Does anyone have a Schuemann compensator gathering dust they want to
> sell?
>
> thanks
>
> Pete

Take the time to put it in the fin. This keeps it out of the wing
root wash and will make
the variometer reflect what the glider is doing instead of how it
responds to effect of gusts
on wing root.
It may be easier than trying to work as far behing wing root as it
should go.
Just put one in a K-21 fin and it is MUCH better than aft fuselage.
Good Luck
UH

[JJ Sinclair]

Eric wrote.......
> So, I'd suggest trying the very easiest thing first: a TE probe mounted
> on the removable turtledeck, probably towards the rear it. If it works,
> great; if not, very little effort wasted.

Yeah, what he said......................I used a vertical TE probe on
my Duster a hundred years ago and it worked as good as I did. If your
intimidated my the thought of drilling and stringing tubes, go the
easy way, it can be mounted forward of the canopy where there isn't
any interference with the wings. Wings & Wheels sells them and I
believe the top bent portion in set to be vertical with the ship set
in flying position (W&B level)
JJ

[Marc Ramsey[_2_]]

wrote:
> Take the time to put it in the fin. This keeps it out of the wing
> root wash and will make
> the variometer reflect what the glider is doing instead of how it
> responds to effect of gusts
> on wing root.
> It may be easier than trying to work as far behing wing root as it
> should go.
> Just put one in a K-21 fin and it is MUCH better than aft fuselage.

Johnson did do testing for both the 6/05 (and an earlier 4/98) article
to determine an appropriate location and height, and:

the author's flight testing indicated that its performance
was just as satisfactory as a tail fin mounted standard
factory built T.E. probe on a Ventus A

The probe was placed on top of the fuselage, just ahead of the aft drag
pin bulkhead, not the middle of the tail boom as is typical of K-21s.
Maybe it's as good, maybe it's not, but it sure beats cutting holes in
the fin...

Marc

[BB]

Or buy a vario with electronic compensation and forego the probe all
together.
John Cochrane
BBG

[Wayne Paul]

I had a nice vertical fin installation on my Ka-6E. Roger Frank did the
work. It was quite "spendy"; however, worked great.
(http://www.soaridaho.com/photogallery/valley/Ka-6E.jpg)

Wayne
HP-14 "6F"
http://'www.soaridaho.com/Schreder


> wrote in message
...
On Aug 28, 12:24 pm, vontresc > wrote:

Take the time to put it in the fin. This keeps it out of the wing
root wash and will make
the variometer reflect what the glider is doing instead of how it
responds to effect of gusts
on wing root.
It may be easier than trying to work as far behing wing root as it
should go.
Just put one in a K-21 fin and it is MUCH better than aft fuselage.
Good Luck
UH

[Neal Pfeiffer]

Like JJ said

If you want to do it easy and perfectly adequate as well, install a
nearly vertical tube ahead of the canopy near the bulkhead ahead of the
instrument panel (above the static buttons on the side of the fuselage).
I would suggest angling it slightly forward at the top so that the
tube is about perpendicular to the upwash induced by the wing. The top
of the tube could be about 6-8" outside the fuselage. Plug the top end
and put the hole or holes or slots in the back of the tube as drirected
from your favorite article by Oran Nicks' (Nicks tube) or Dick Johnson
or <insert other favorite name here>. The plumbing is short, easy to
do, and will give a reading that is well compensated. Our club Ka6CR
has one like this and it works well.

I would not suggest over the wing in the turtledeck, since it could
require uncoupling and coupling the pressure tube with some regularity
and it would be easy to damage when the turtledeck is off.

The position on top of the fuselage near the trailing edge of the wing,
however is not a bad one. The flow around the wing is nearly back to a
freestream static condition at the trailing edge and the flow had better
be attached while cruising or thermalling or there are other problems.
If one flys slow enough to separate the flow there, the inboard wing is
already stalled and that's flying too slow.

...... Neal

JJ Sinclair wrote:
> Eric wrote.......
>
>>So, I'd suggest trying the very easiest thing first: a TE probe mounted
>>on the removable turtledeck, probably towards the rear it. If it works,
>>great; if not, very little effort wasted.
>
>
> Yeah, what he said......................I used a vertical TE probe on
> my Duster a hundred years ago and it worked as good as I did. If your
> intimidated my the thought of drilling and stringing tubes, go the
> easy way, it can be mounted forward of the canopy where there isn't
> any interference with the wings. Wings & Wheels sells them and I
> believe the top bent portion in set to be vertical with the ship set
> in flying position (W&B level)
> JJ

[[email protected]]

On Aug 28, 7:05*pm, Neal Pfeiffer > wrote:
> Like JJ said
>
> If you want to do it easy and perfectly adequate as well, install a
> nearly vertical tube ahead of the canopy near the bulkhead ahead of the
> instrument panel (above the static buttons on the side of the fuselage).
> * I would suggest angling it slightly forward at the top so that the
> tube is about perpendicular to the upwash induced by the wing. *The top
> of the tube could be about 6-8" outside the fuselage. *Plug the top end
> and put the hole or holes or slots in the back of the tube as drirected
> from your favorite article by Oran Nicks' (Nicks tube) or Dick Johnson
> or <insert other favorite name here>. *The plumbing is short, easy to
> do, and will give a reading that is well compensated. *Our club Ka6CR
> has one like this and it works well.
>
> I would not suggest over the wing in the turtledeck, since it could
> require uncoupling and coupling the pressure tube with some regularity
> and it would be easy to damage when the turtledeck is off.
>
> The position on top of the fuselage near the trailing edge of the wing,
> however is not a bad one. *The flow around the wing is nearly back to a
> freestream static condition at the trailing edge and the flow had better
> be attached while cruising or thermalling or there are other problems.
> If one flys slow enough to separate the flow there, the inboard wing is
> already stalled and that's flying too slow.
>
> ..... Neal
>
>
>
> JJ Sinclair wrote:
> > Eric wrote.......
>
> >>So, I'd suggest trying the very easiest thing first: a TE probe mounted
> >>on the removable turtledeck, probably towards the rear it. If it works,
> >>great; if not, very little effort wasted.
>
> > Yeah, what he said......................I used a vertical TE probe on
> > my Duster a hundred years ago and it worked as good as I did. If your
> > intimidated my the thought of drilling and stringing tubes, go the
> > easy way, it can be mounted forward of the canopy where there isn't
> > any interference with the wings. Wings & Wheels sells them and I
> > believe the top bent portion in set to be vertical with the ship set
> > in flying position (W&B level)
> > JJ- Hide quoted text -
>
> - Show quoted text -

If objective is just simple installation, do what JJ says and put it
on the nose.
Putting it anywhere close to the flow field of the wing- that is
anywhere near the top, means that the local pressure
changes every time you change angle of attack. This is the reason why
it is on the fin on essentially all modern gliders.
UH

[Neal Pfeiffer]

The fin is not the only location for good compensation.

A total energy probe works best when the flow passes by it at nearly the
same angle and at nearly freestream static pressure for the range of
speeds of interest.

Mounting in front of the fin puts the probe in a location that is close
to the freestream static pressure. The flow angularity may vary some
amount, but the combination of glider angle of attack and the downwash
field of the wing will tend to reduce the overall variation in flow
angle. Changing flap position will induce a step change in flow angle,
but again this is not too large.

Mounting the probe on the top of the fuselage a little aft of the wing
again puts the probe in a region that is close to freestream static
pressure and the straightening effect of the wing and fuselage produce
only a very small change in the flow angle at the probe.

Now, what about the forward fuselage? For a Ka6, the static buttons are
on the side of the fuselage at the bulkhead ahead of the instrument
panel, where they register near the freestream static value for the
thermaling and cruise conditions. On the top of the forward fuselage,
the canopy will slow the flow at its base, producing higher than
freestream static pressure, and then rapidly accelerate the flow as it
moves up and over the curved portion of the canopy, thus producing a
lower than freestream pressure. By placing the probe at the bulkhead
ahead of the panel, it is enough ahead of the canopy disturbance to have
a pressure value that is close to freestream, but possibly with more
variability than for the other two locations mentioned above. The pitch
flow angularity is pretty constant though. For the Ka6 with the speeds
mostly between 40 to 70 knots, the forward position is reasonable.

...... Neal


wrote:

>>
>>- Show quoted text -
>
>
> If objective is just simple installation, do what JJ says and put it
> on the nose.
> Putting it anywhere close to the flow field of the wing- that is
> anywhere near the top, means that the local pressure
> changes every time you change angle of attack. This is the reason why
> it is on the fin on essentially all modern gliders.
> UH