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

On Friday, August 2, 2013 8:45:34 AM UTC-7, Tim Taylor wrote:
All I can say is try the Winpilot Pro version. There is very little head down time (a whole lot less than you spend on Flarm, as a comparison). There are rare instances when I think I can do better than the thermal assistants suggestion, but most of the time not. Of course it will not tell you where under the cloud to look, or that you may be precisely centering a small side tendril and the real core is over on the other side. 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!



Andrej, Thank you for working on the Thermal Assistant. I updated my Oudie yesterday and look forward to flying with it in a few days.



I encourage you to look at adding a thermal strength graph as well for the display. I concur with Jon that the WinPilot interface took almost no heads down time and as with SYM the beep was enough to adjust most of the time.



One comment on the difference in perceived benefit for a TA with any software. There may be a geographical bias for the preference for them. In the western US and I would guess similar location like Australia and South Africa we deal with very different thermals from the Eastern US and most of Central Europe. The thermals range from very small cores with 10 to 12 knot centers (5 to 6 m/s) to very large with two to three cores with a total range of 12 or more knots in lift and sink. It is literally like riding a bucking bronco. In addition there are often windy blue days where finding a small core off tow the direction of a TA is helpful. Most of us have found that we gain a slight advantage with a good Thermal Assistant like the one WinPilot implemented many years ago.

Good point about the difference in thermals.

As a data point, I fly an ASH26E. After launch and climb, the engine is shut down and folded back, but left a bit out with the engine bay doors open for a cooling period of several minutes. During that period the tail pneumatics are subject to turbulance from the prop and doors that results in rapid random +/- 3 or 4 m/s swings in the variometer. Only with extreme attention can you find your way towards the core in these circumstances, and then only if it is a fairly uniform core. Or you can simply do what the Winpilot thermal assistant tells you based on the same information. It is able to make at least as much sense of the trash as I can, and requires no attention at all. .

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!

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

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

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.

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).

On Thursday, August 1, 2013 3:20:49 PM UTC-7, Naviter Info wrote:

I dare to say that accurate thermal assistants are a myth and that head down time during circling is a waste unless you are consciously learning a particular technique. At the same time - I do keep the "ding ding" thermal assistant active most of the time. Mainly because at times I become useless when I am talking on the radio, looking at my landing options or become plain old tired. That's when the thermal assistant's "ding ding" is usually right and very useful.



Regards,

Andrej Kolar


Thanks for the reworked thermal assistant Andrej. I do like the zoom/tracking feature as it allows me to explore a spread out area of lift and still return to the hotspot(s) with some reliability. It also allows me to account for wind drift a bit better.

I do think the arrow and beep in the climb optimization is still a bit irregular as it is sometimes seems 180-degrees out of sync from where the stronger lift turns out to be. I'm not sure how you are integrating the climb rates around 360 degrees, but it feels as though the arrow points to the strongest single 20- or 30-degree sector of lift rather than the direction to move the circle to maximize the rate of climb around the entire circle. I realize that with a choppy thermal it is easy to confuse any estimation algorithm, but there is something my brain does (and WinPilot seems to do) that still nets this out a bit better. I wonder if there are more parameters you could expose to allow some tuning to individual preferences. Lastly, an average climb line graph over the past 5-7 circles would also be welcome - I make due today with the 20 second averager versus the climb for the thermal, but a trend line would be more intuitive.

Again, nice improvements - I agree it is very useful in those cases where I have gone brain dead for a moment, but I also use it to speed coring thermals any time when I am unable to core on the first turn and a half - which is most of the time.

9B