When are thermals not circular and do thermal helpers assume thatthey are?

Andrej, Tim Taylor accurately describes the conditions we have in the Western United States and why a good thermal assistant is an asset. I still soldier on with WinPilot because it's TA is simply the best. I have a copy of SYM but choose not to fly with it. I would dearly like to dump my PDA and fly with a more modern and supported system.

On Monday, 29 July 2013 17:00:11 UTC+1, son_of_flubber wrote:
I'm starting to think that the textbook circular thermal is primarily a flatland phenomena.

The thread title asks whether thermal assistants assume thermals are round. I would like to know whether thermal assistants assume you are flying a round circle - specifically, when I have made an adjustment to my circle, does the thermal assistant realise I have done so, or does making an adjustment completely invalidate the advice of the thermal assistant until I have completed the next round circle? Does anyone know?

Is there anyone who can give a specific explanation of what each thermal assistant does?

Currently, I am using an LX9000. I like that I get the benefit of a visual thermal assistant without losing the display of any other info, and I think the visual assistant does a good job - I generally find the best and worst lift just where the assistant shows them. I often also zoom the map right in to see my track line with lift colours. I cannot make sense of the audible bleeps. With the Winpilot assistant which I use in another glider, I do not like losing all other info while the assistant is active - whereas with SeeYou Mobile (not talking about the brand new version which obviously I have not yet seen in action) I like being able to retain my navboxes as well as the assistant. I find the Winpilot trend graph pretty but not useful - I decide when to leave a thermal based on the digital averager (and the picture ahead!).

Not since they came up with that new-fangled structured FORTRAN. Give me
spaghetti code any day!

But I *am* (was, since I'm retired) a Systems Engineer and I know how to
turn user requirements into a specification that the software engineers can
screw up. Herding cats is a full-time job.

You know, of course, that when the brakes on your car fail, you software
engineers will push the car back up the hill and try again to see if they
still fail. ;-P

"Eric Greenwell" wrote in message
...
Dan Marotta wrote, On 8/2/2013 6:55 AM:
An algorithm works for a single case and each thermal is different.

You aren't a programmer, are you? :^)


"jfitch" wrote in message
...

a lot of snipping Finding the lift is art. Centering it is science,
and science can be reduced to an algorithm. Computers, correctly
programmed, are very good at algorithms - without head down time or
otherwise adding to pilot workload.

But I will try the reworked Naviter version!


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email
me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

I agree with you on the rate of change aspect and, in that sense, I can see
where you could develop an algorithm that would command changes of turn
radius to maximize time in the strongest lift.

But I fly purely for fun, these days, except for when I'm towing, and I'd
happily wager a beer (or two!) with you that I can out climb you with
variometers and computers powered off. Heck, I'll even cover up the
mechanical vario. No fancy seals required as proof of compliance and I
don't even care if I lose the bet - I'll still get a beer!

"jfitch" wrote in message
...
On Friday, August 2, 2013 6:55:31 AM UTC-7, Dan Marotta wrote:
An algorithm works for a single case and each thermal is different.



"jfitch" wrote in message





a lot of snipping Finding the lift is art. Centering it is science, and

science can be reduced to an algorithm. Computers, correctly programmed,
are

very good at algorithms - without head down time or otherwise adding to

pilot workload.



But I will try the reworked Naviter version!

I disagree - using only the information from your variometer, the algorithm
is pretty consistent or almost any thermal you will encounter.

The explanations here seem incomplete. You should tighten or loosen your
turn (angle of bank) based on the *rate of change of lift*, not the
strength. If you loosen your turn at the peak of lift, you will be 90
degrees out of phase and will not center quickly, if at all. What you want
to do is loosen your turn at the peak rate of increase of lift.
Alternatively, loosen your turn at 90 degrees prior to the peak lift. When
you experience peak lift, you are already at 90 degrees to the desired
correction direction (mod vario lag). Human perception is not all that great
and estimating rate of change, and recording that rate of change around a
complete circle, and relating that to your angular position in that circle
accurately, all advanced by the time constant (lag) of the variometer. This
is however very easy for the computer.

On Sunday, August 4, 2013 8:00:28 AM UTC-7, Dan Marotta wrote:
I agree with you on the rate of change aspect and, in that sense, I can see

where you could develop an algorithm that would command changes of turn

radius to maximize time in the strongest lift.



But I fly purely for fun, these days, except for when I'm towing, and I'd

happily wager a beer (or two!) with you that I can out climb you with

variometers and computers powered off. Heck, I'll even cover up the

mechanical vario. No fancy seals required as proof of compliance and I

don't even care if I lose the bet - I'll still get a beer!



"jfitch" wrote in message



On Friday, August 2, 2013 6:55:31 AM UTC-7, Dan Marotta wrote:

An algorithm works for a single case and each thermal is different.







"jfitch" wrote in message











a lot of snipping Finding the lift is art. Centering it is science, and



science can be reduced to an algorithm. Computers, correctly programmed,

are



very good at algorithms - without head down time or otherwise adding to



pilot workload.







But I will try the reworked Naviter version!



I disagree - using only the information from your variometer, the algorithm

is pretty consistent or almost any thermal you will encounter.



The explanations here seem incomplete. You should tighten or loosen your

turn (angle of bank) based on the *rate of change of lift*, not the

strength. If you loosen your turn at the peak of lift, you will be 90

degrees out of phase and will not center quickly, if at all. What you want

to do is loosen your turn at the peak rate of increase of lift.

Alternatively, loosen your turn at 90 degrees prior to the peak lift. When

you experience peak lift, you are already at 90 degrees to the desired

correction direction (mod vario lag). Human perception is not all that great

and estimating rate of change, and recording that rate of change around a

complete circle, and relating that to your angular position in that circle

accurately, all advanced by the time constant (lag) of the variometer. This

is however very easy for the computer.

Dan, you're on! Bring your glider out west (and bring lots of beer - you are going to need it).

Waremark,
From observation I believe all thermal assistants do the same thing: identify circling by rate of heading change, record variometer readings around the circle, integrate the readings over angular displacement to calculate a correction vector. There is no need to account for non-round circles or correction movements (other than to the extent that it affects angular displacement), as this information does not affect what you should do.

After all, this is exactly that a good pilot does. If you are high in a blue thermal that is all you can do: your only input is rate of climb and its derivatives. You integrate lift as a function of angular displacement, and reposition the circle the direction of the resultant vector. The computer simply does it in fine grained detail, without fatigue or distraction, and without the perception errors to which human senses are so susceptible. This is particularly true in rough/uneven/strong thermals. A pilot must determine and remember, "was that huge hole I just went through exactly equaled by the huge bump I just got? where they 80 or 110 degrees apart? how does that change the correction vector exactly?" Most humans aren't very good at this, and it requires a substantial amount of attention unless the thermals are well behaved. The less well behaved the thermal, the worse are your perception errors and the more the thermal assistant helps.

What separates the good, bad, and ugly thermal assistants is not the mechanics of recording vario readings or math to calculate the vector, all very straightforward I think. The devil is in the details:

-What algorithm is used to call up and dismiss the thermal assistant? Is it there when you want it and gone when you don't, without having to access menus and poke buttons?

-Is the data presented in a way that can be interpreted at a glance, and is associated data also available (such as average rate of climb, climb in thermal, better/worse than McReady expectation, better/worse than days average)?

-Is non associated but nevertheless important data also available (such as nearby Flarm targets) and easily interpreted with minimum attention?

-Does the algorithm account for data latency (such as varo lag) and reaction time in a useful way?

In my opinion Winpilot is better in each of the details than the others even in its earliest instance (but I haven't tried the latest SYM offering).

All good points and certainly something we can consider and most importantly - test. Thanks.

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

On Sunday, August 4, 2013 12:50:57 AM UTC+2, wrote:
Andrej, Tim Taylor accurately describes the conditions we have in the Western United States and why a good thermal assistant is an asset. I still soldier on with WinPilot because it's TA is simply the best. I have a copy of SYM but choose not to fly with it. I would dearly like to dump my PDA and fly with a more modern and supported system.

I would like to know whether thermal assistants assume you are flying a round circle

I can obviously only speak for Naviter/SeeYou Mobile/Oudie. We do not assume that you are flying round circles. We remember the direction in which the thermal was strongest in your last turn and base our predictions on that.

I often also zoom the map right in to see my track line with lift colours..

The new Thermal Assistant in SeeYou Mobile will zoom in automatically, display the track of the last thermal with a thicker line and color-code it according to thermal strength. Even if you come to an area where you have circled before it will be very clear which is your last thermal's track.

I cannot make sense of the audible bleeps.

We also calculate your rate of turn. And we remember the direction in which the climb was strongest in your previous circle. 4 seconds before you will reach the direction of the peak of the previous circle (by default) we will give you a sound warning if the thresholds of how uneven the thermal may be are exceeded. If you are circling in a nicely centered thermal where the needle doesn't move much we will not bother to disturb you with the thermal assistant beeps.

All of the above only works well if you have at least pressure altitude input (vario input is even better).

Hope this explains how the TA works in SeeYou Mobile,
Andrej Kolar
--
glider pilots use
http://www.Naviter.com

On Sunday, August 4, 2013 12:52:26 AM UTC+2, waremark wrote:
On Monday, 29 July 2013 17:00:11 UTC+1, son_of_flubber wrote:

I'm starting to think that the textbook circular thermal is primarily a flatland phenomena.



The thread title asks whether thermal assistants assume thermals are round. I would like to know whether thermal assistants assume you are flying a round circle - specifically, when I have made an adjustment to my circle, does the thermal assistant realise I have done so, or does making an adjustment completely invalidate the advice of the thermal assistant until I have completed the next round circle? Does anyone know?



Is there anyone who can give a specific explanation of what each thermal assistant does?



Currently, I am using an LX9000. I like that I get the benefit of a visual thermal assistant without losing the display of any other info, and I think the visual assistant does a good job - I generally find the best and worst lift just where the assistant shows them. I often also zoom the map right in to see my track line with lift colours. I cannot make sense of the audible bleeps. With the Winpilot assistant which I use in another glider, I do not like losing all other info while the assistant is active - whereas with SeeYou Mobile (not talking about the brand new version which obviously I have not yet seen in action) I like being able to retain my navboxes as well as the assistant. I find the Winpilot trend graph pretty but not useful - I decide when to leave a thermal based on the digital averager (and the picture ahead!).

Gee, whiz, while that was a terrific explanation of a thermal assistant, for
me, at least, it removes all vestiges of fun from thermalling. Clearly
you're still employed as an engineer and enjoy your work, but I'm retired
and enjoy the freedom of plodding along without needing doodads to get that
last increment of performance.

I issued my beer challenge as a way of having a good time and demonstrating
that all those aids aren't necessary for a good time. I've no doubt that
given two equally talented pilots in identical ships, then the one with the
better instruments will probably do better. Does that mean he'll get all
the chicks, money, and endorsements?

BTW, I *am* out west - Moriarty. Where are you?


"jfitch" wrote in message
...
On Sunday, August 4, 2013 8:00:28 AM UTC-7, Dan Marotta wrote:
I agree with you on the rate of change aspect and, in that sense, I can
see

where you could develop an algorithm that would command changes of turn

radius to maximize time in the strongest lift.



But I fly purely for fun, these days, except for when I'm towing, and I'd

happily wager a beer (or two!) with you that I can out climb you with

variometers and computers powered off. Heck, I'll even cover up the

mechanical vario. No fancy seals required as proof of compliance and I

don't even care if I lose the bet - I'll still get a beer!



"jfitch" wrote in message



On Friday, August 2, 2013 6:55:31 AM UTC-7, Dan Marotta wrote:

An algorithm works for a single case and each thermal is different.







"jfitch" wrote in message











a lot of snipping Finding the lift is art. Centering it is science,
and



science can be reduced to an algorithm. Computers, correctly programmed,

are



very good at algorithms - without head down time or otherwise adding to



pilot workload.







But I will try the reworked Naviter version!



I disagree - using only the information from your variometer, the
algorithm

is pretty consistent or almost any thermal you will encounter.



The explanations here seem incomplete. You should tighten or loosen your

turn (angle of bank) based on the *rate of change of lift*, not the

strength. If you loosen your turn at the peak of lift, you will be 90

degrees out of phase and will not center quickly, if at all. What you want

to do is loosen your turn at the peak rate of increase of lift.

Alternatively, loosen your turn at 90 degrees prior to the peak lift. When

you experience peak lift, you are already at 90 degrees to the desired

correction direction (mod vario lag). Human perception is not all that
great

and estimating rate of change, and recording that rate of change around a

complete circle, and relating that to your angular position in that circle

accurately, all advanced by the time constant (lag) of the variometer.
This

is however very easy for the computer.

Dan, you're on! Bring your glider out west (and bring lots of beer - you are
going to need it).

Waremark,
From observation I believe all thermal assistants do the same thing:
identify circling by rate of heading change, record variometer readings
around the circle, integrate the readings over angular displacement to
calculate a correction vector. There is no need to account for non-round
circles or correction movements (other than to the extent that it affects
angular displacement), as this information does not affect what you should
do.

After all, this is exactly that a good pilot does. If you are high in a blue
thermal that is all you can do: your only input is rate of climb and its
derivatives. You integrate lift as a function of angular displacement, and
reposition the circle the direction of the resultant vector. The computer
simply does it in fine grained detail, without fatigue or distraction, and
without the perception errors to which human senses are so susceptible.
This is particularly true in rough/uneven/strong thermals. A pilot must
determine and remember, "was that huge hole I just went through exactly
equaled by the huge bump I just got? where they 80 or 110 degrees apart? how
does that change the correction vector exactly?" Most humans aren't very
good at this, and it requires a substantial amount of attention unless the
thermals are well behaved. The less well behaved the thermal, the worse are
your perception errors and the more the thermal assistant helps.

What separates the good, bad, and ugly thermal assistants is not the
mechanics of recording vario readings or math to calculate the vector, all
very straightforward I think. The devil is in the details:

-What algorithm is used to call up and dismiss the thermal assistant? Is it
there when you want it and gone when you don't, without having to access
menus and poke buttons?

-Is the data presented in a way that can be interpreted at a glance, and is
associated data also available (such as average rate of climb, climb in
thermal, better/worse than McReady expectation, better/worse than days
average)?

-Is non associated but nevertheless important data also available (such as
nearby Flarm targets) and easily interpreted with minimum attention?

-Does the algorithm account for data latency (such as varo lag) and reaction
time in a useful way?

In my opinion Winpilot is better in each of the details than the others even
in its earliest instance (but I haven't tried the latest SYM offering).

On Sunday, August 4, 2013 7:37:20 PM UTC-4, Dan Marotta wrote:
Gee, whiz, while that was a terrific explanation of a thermal assistant, for
me, at least, it removes all vestiges of fun from thermalling.

Most of us got your point the third or fourth time that you made it in this thread about how thermals and thermal assistants work.

On Sunday, August 4, 2013 4:37:20 PM UTC-7, Dan Marotta wrote:


BTW, I *am* out west - Moriarty. Where are you?



There is still about 1/3 of the continent to the left of Moriarty.....