Pirker Final Glide Theory

In short, the Pirker "theory" says that in a final glide to the determine
the best speed you do:
1) calculate the glide ratio needed to get over the final turnpoint
2) for that glide ratio you calculate the corrispondent MC value for your
polar
3) for that MC value you get the speed to fly

I did not know pirker wrote these things in 1999, for me they are just
obvious.

paolo


"Paul Remde" wrote in message ...

Hi,

I think we'd all love to have access to the document. I'd be glad to post
it on my web site if that would help.

Best Regards,

Paul Remde
Cumulus Soaring, Inc.
________________________

wrote in message
...

On Monday, January 14, 2013 10:19:27 AM UTC-5, wrote:
Does anyone have a link to, or a copy of, an English language paper or
explanation about Dr Herbert Pirker's final glide theory? I can't even
locate one in German via Google.



I can find snippets about it relating to implementation on StrePla in
2006vand I understand that a couple of the NavBoxes on LX 8000/9000 relate
to this.



http://www.strepla.de/StrePla4/engli...t_Winter05.htm



Thanks,



John Galloway

John: I've been looking through my stacks and finally found an english
translation as well as the artilcle from aerokurier. I'll get around to
scanning in PDF formats and email these articles to you.

Isn't this the principle behind the Stocker final glide
calculator, as described in Reichmann's
"Streckensegelflug", mid 1970s?


At 10:40 11 February 2013, pcool wrote:
In short, the Pirker "theory" says that in a final glide
to the determine
the best speed you do:
1) calculate the glide ratio needed to get over the
final turnpoint
2) for that glide ratio you calculate the
corrispondent MC value for your
polar
3) for that MC value you get the speed to fly

I did not know pirker wrote these things in 1999, for
me they are just
obvious.

paolo


"Paul Remde" wrote in message
...

Hi,

I think we'd all love to have access to the
document. I'd be glad to post
it on my web site if that would help.

Best Regards,

Paul Remde
Cumulus Soaring, Inc.
________________________

wrote in message
news:4b8c77f1-1a6e-489e-a98c-
...

On Monday, January 14, 2013 10:19:27 AM UTC-5,
wrote:
Does anyone have a link to, or a copy of, an
English language paper or
explanation about Dr Herbert Pirker's final glide
theory? I can't even
locate one in German via Google.



I can find snippets about it relating to
implementation on StrePla in
2006vand I understand that a couple of the
NavBoxes on LX 8000/9000
relate
to this.




http://www.strepla.de/StrePla4/english/News/News_in
_pocket_Winter05.htm



Thanks,



John Galloway

John: I've been looking through my stacks and
finally found an english
translation as well as the artilcle from aerokurier.
I'll get around to
scanning in PDF formats and email these articles to
you.

I remember I had implemente the Stocker final glide circles time ago in the
software, basically they represent glide ratio ranges.

Since these concept are just obvious nowadays, I assume that years ago -
before gps - everything had to be done using approximated distances and
airspeed only, so the final glide was relative to the airmass, in principle,
and not to the ground.
Apart from that, if I am not wrong the Pirker analysis does not consider the
wind in final glide according to the document I read.
Nor does it consider total energy, apparently.

paolo


"Richard Brisbourne" wrote in message
...

Isn't this the principle behind the Stocker final glide
calculator, as described in Reichmann's
"Streckensegelflug", mid 1970s?


At 10:40 11 February 2013, pcool wrote:
In short, the Pirker "theory" says that in a final glide
to the determine
the best speed you do:
1) calculate the glide ratio needed to get over the
final turnpoint
2) for that glide ratio you calculate the
corrispondent MC value for your
polar
3) for that MC value you get the speed to fly

I did not know pirker wrote these things in 1999, for
me they are just
obvious.

paolo


"Paul Remde" wrote in message
...

Hi,

I think we'd all love to have access to the
document. I'd be glad to post
it on my web site if that would help.

Best Regards,

Paul Remde
Cumulus Soaring, Inc.
________________________

wrote in message
news:4b8c77f1-1a6e-489e-a98c-
...

On Monday, January 14, 2013 10:19:27 AM UTC-5,
wrote:
Does anyone have a link to, or a copy of, an
English language paper or
explanation about Dr Herbert Pirker's final glide
theory? I can't even
locate one in German via Google.



I can find snippets about it relating to
implementation on StrePla in
2006vand I understand that a couple of the
NavBoxes on LX 8000/9000
relate
to this.




http://www.strepla.de/StrePla4/english/News/News_in
_pocket_Winter05.htm



Thanks,



John Galloway

John: I've been looking through my stacks and
finally found an english
translation as well as the artilcle from aerokurier.
I'll get around to
scanning in PDF formats and email these articles to
you.

The Stocker calculator as described by Reichmann
(with instructions on how to make one) was
substantially more complex.

From memory you had a transparent disc with
altitude spirals in one hemisphere and in the other
hemisphere one set of curves corresponding to wind
components and an intersecting set of curves
corresponding to McReady readings. The latter set of
curves depended on the polar of the glider.

This disc was mounted on a map with the centre at
the goal point and it could be rotated about that point.
Above the disc was a linear cursor, also transparent
marked with distances, rotated about the disc centre.

To read the calculator, you rotated the disc so that
the spiral corresponding to your altitude lay over your
current position on the map. You then rotated the
cursor so that the line also lay over that point; the
other end of the cursor intersected the wind and
McReady spirals; the correct setting for the wind
could then be read off.



At 16:06 11 February 2013, pcool wrote:
I remember I had implemente the Stocker final
glide circles time ago in the

software, basically they represent glide ratio
ranges.

Since these concept are just obvious nowadays, I
assume that years ago -
before gps - everything had to be done using
approximated distances and
airspeed only, so the final glide was relative to the
airmass, in
principle,
and not to the ground.
Apart from that, if I am not wrong the Pirker
analysis does not consider
the
wind in final glide according to the document I read.
Nor does it consider total energy, apparently.

paolo


"Richard Brisbourne" wrote in message
...

Isn't this the principle behind the Stocker final glide
calculator, as described in Reichmann's
"Streckensegelflug", mid 1970s?


At 10:40 11 February 2013, pcool wrote:
In short, the Pirker "theory" says that in a final
glide
to the determine
the best speed you do:
1) calculate the glide ratio needed to get over the
final turnpoint
2) for that glide ratio you calculate the
corrispondent MC value for your
polar
3) for that MC value you get the speed to fly

I did not know pirker wrote these things in 1999,
for
me they are just
obvious.

paolo


"Paul Remde" wrote in message
...

Hi,

I think we'd all love to have access to the
document. I'd be glad to post
it on my web site if that would help.

Best Regards,

Paul Remde
Cumulus Soaring, Inc.
________________________

wrote in message
news:4b8c77f1-1a6e-489e-a98c-
...

On Monday, January 14, 2013 10:19:27 AM UTC-5,
wrote:
Does anyone have a link to, or a copy of, an
English language paper or
explanation about Dr Herbert Pirker's final glide
theory? I can't even
locate one in German via Google.



I can find snippets about it relating to
implementation on StrePla in
2006vand I understand that a couple of the
NavBoxes on LX 8000/9000
relate
to this.




http://www.strepla.de/StrePla4/english/News/News_
in
_pocket_Winter05.htm



Thanks,



John Galloway

John: I've been looking through my stacks and
finally found an english
translation as well as the artilcle from aerokurier.
I'll get around to
scanning in PDF formats and email these articles
to
you.

actually, as far as I remember, that is incomplete. it also said that once the calculated MC reaches the current average of your thermal it is time for starting the final glide. that way you will not waste time climbing any higher and you have the most efficient final glide compared to others who decided to stop climbing earlier but have to fly slower due to that.

this is pretty much also how the Final Glide AutoMC feature in XCSoar (and I think also LK8000?) works. I've used that feature for years now, and I think it is quite simple to use and understand, and also works quite well from my experience.

On Monday, February 11, 2013 12:56:53 PM UTC-5, Richard Brisbourne wrote:
The Stocker calculator as described by Reichmann
(with instructions on how to make one) was
substantially more complex.

From memory you had a transparent disc with
altitude spirals in one hemisphere and in the other
hemisphere one set of curves corresponding to wind
components and an intersecting set of curves
corresponding to McReady readings. The latter set of
curves depended on the polar of the glider.

This disc was mounted on a map with the centre at
the goal point and it could be rotated about that point.
Above the disc was a linear cursor, also transparent
marked with distances, rotated about the disc centre.

To read the calculator, you rotated the disc so that
the spiral corresponding to your altitude lay over your
current position on the map. You then rotated the
cursor so that the line also lay over that point; the
other end of the cursor intersected the wind and
McReady spirals; the correct setting for the wind
could then be read off.

Yep - First commercial gliding product I did was a
version of this calculator, sold by Cambridge Aero
in the early 80s (maybe late 70s). Still have a few
in the basement I think ! Worked well but it was too
large for USA sectionals and LDs of modern gliders.
Anybody out there still have one ?
I think Chip Bearden needs one.

See ya, Dave "YO electric"

When you're doing Auto MC please mind the MC theory:

If you hit sink on the final glide the required MC value will go down. According to AutoMC you would be advised to fly slower. **Slower through sink**??

You should always fly your Speed to fly director from the Vario. Even if you fall below final that's the only way to get to the other side as high as possible. "Auto MC" is just a value which is "nice to know" but certainly not the optimal way to get home.

Having said that I too always make my final glides (since before GPS and SeeYou Mobile) comparing required L/D with Current L/D (which is just another way to represent the required MC value)

The original Pirker final glide calculator deals with wind and final glide around the corner iirc which is not as trivial as doing it in a straight line.

Regards,
Andrej Kolar
--
glider pilots use
http://www.Naviter.com

On Monday, February 11, 2013 11:57:49 PM UTC+1, Tobias Bieniek wrote:
actually, as far as I remember, that is incomplete. it also said that once the calculated MC reaches the current average of your thermal it is time for starting the final glide. that way you will not waste time climbing any higher and you have the most efficient final glide compared to others who decided to stop climbing earlier but have to fly slower due to that.



this is pretty much also how the Final Glide AutoMC feature in XCSoar (and I think also LK8000?) works. I've used that feature for years now, and I think it is quite simple to use and understand, and also works quite well from my experience.

At 10:14 12 February 2013, Naviter Info wrote:
When you're doing Auto MC please mind the MC
theory:

If you hit sink on the final glide the required MC
value will go down.
Acco=
rding to AutoMC you would be advised to fly slower.
**Slower through
sink**=
??

I don't quite follow this.

Surely the required McCready (McReady?) setting is a
function of height, wind and distance to run.

So if you hit sink and lose altitude of course your
required McCready setting will go down. But your
speed at that setting will still be what is appropriate
for that setting in that amount of sink.

You could of course keep your nerve and leave the
McCready setting where it is- if you expect to go
through lift later this is usually OK- it's a judgement
call. If you do this and don't go through any lift later
you're in a field.

The only way to avoid having to slow down at all is
not to fly through sink.

If you hit sink on the final glide the required MC value will go down. According to AutoMC you would be
advised to fly slower. **Slower through sink**??

Imagine flying "not slower" in the extreme case: flying at Vne through the sink.
The influence of the sink itself will be minimal, since the time you spend in the sink is minimal.
However, your glider's polar is also important, and it will probably not be enough to compensate. It is the sum
of these two that determines your total vertical speed (assuming linear flight).
Thus, you should minimize the sum of these two. You appear to want to minimize only the effect of the sink.

True. But while you're in sink you need to speed up. At least until you are flying the optimal speed for MC=0 for that sink. The AutoMC suggests you to slow down which is not ok any way you look at it.

Andrej Kolar
--
glider pilots use
http://www.Naviter.com

On Tuesday, February 12, 2013 11:29:03 AM UTC+1, Richard Brisbourne wrote:
At 10:14 12 February 2013, Naviter Info wrote:

When you're doing Auto MC please mind the MC

theory:



If you hit sink on the final glide the required MC

value will go down.

Acco=

rding to AutoMC you would be advised to fly slower.

**Slower through

sink**=

??



I don't quite follow this.



Surely the required McCready (McReady?) setting is a

function of height, wind and distance to run.



So if you hit sink and lose altitude of course your

required McCready setting will go down. But your

speed at that setting will still be what is appropriate

for that setting in that amount of sink.



You could of course keep your nerve and leave the

McCready setting where it is- if you expect to go

through lift later this is usually OK- it's a judgement

call. If you do this and don't go through any lift later

you're in a field.