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#11
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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. |
#12
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Pirker Final Glide Theory
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. |
#13
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Pirker Final Glide Theory
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. |
#14
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Pirker Final Glide Theory
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. |
#15
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Pirker Final Glide Theory
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. |
#16
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Pirker Final Glide Theory
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" |
#17
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Pirker Final Glide Theory
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. |
#18
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Pirker Final Glide Theory
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. |
#19
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Pirker Final Glide 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**?? 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. |
#20
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Pirker Final Glide Theory
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. |
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