Inter-thermal Speed To Fly

On Jan 5, 11:31*am, Sandy Stevenson wrote:
On Jan 5, 11:08*am, Papa3 wrote:





On Jan 5, 8:51*am, "Ken Kochanski (KK)"
wrote:

Morning,

I'm reviewing some STF topics to correct some fallacies that seem to
have crept into my understanding of STF theory and application ... I
though I knew this stuff ... or maybe I forgot ... I am a senior now,
you know ... :-))

So, if I have MC set at 3 ... and I am crusing XC to the next three
knotter ... should I slow in lift and speed up in sink ... *or will I
have a faster average speed if I just hold speed steady ... i.e. at
the velocity appropriate for MC = 3 in still air. I see pilots doing
both ...

Also, do all flight computers compute inter-thermal STF with the
formula that does not include a wind component - as identified in
Reichmann's texts, for example.

Anybody have an excel program that will plot polars ... including the
tangent to the shifted origin you get when *when you change airmass
sink ... or tail/head winds ..

Gracias, Happy new Year ...
KK

Yo KK,

Is this all just theory for you or did you pick up a new chariot?

Anyway, *I did a lot of the number crunching and spreadsheet stuff
years ago when I was teaching a lot of XC groundschools. * Then, John
Cochrane came along and ruined everything - I mean I can't even spell
"sto-kas-tick"... *:-)

So, here's what I've been leaning toward lately. * *I've adopted a
"high gear", "low gear" approach. *For your standard east coast
conditions, I'll set and fly McCready up high (say above 4,000 feet),
which typically will mean cruising around 80kts dry on your 3-4kt day
in my LS8. * But, as soon as I get below that, I'll back off by at
least 10-15kts to make sure that I don't have to take a crappy thermal
just to survive.

I've also taken to the "whifferdill" approach when cruising - ie. if I
sense some lift I'll slow up and "explore" to see if I hit a good
pulse, but I'm really trying to avoid the 360 turn unless it really
feels solid. * *I've flown with CG a few times and watched how much of
the air he explores without doing a full turn - it's pretty amazing.

P3

As someone who is just starting to fly cross country, this is one of
the best discussions I've read here in the last few years.
Thanks for your posts, guys.- Hide quoted text -

- Show quoted text -

As someone who has been flailing around at XC for only a few
years..... Thanks!

On Jan 5, 10:08*am, Papa3 wrote:

I've also taken to the "whifferdill" approach when cruising - ie. if I
sense some lift I'll slow up and "explore" to see if I hit a good
pulse, but I'm really trying to avoid the 360 turn unless it really
feels solid. * *I've flown with CG a few times and watched how much of
the air he explores without doing a full turn - it's pretty amazing.

A lot of pilots do this - it serves two useful purposes: 1) it keeps
you in rising air longer without ever giving ground by doing a 360,
and 2) It allows you to search for the strong core.

I did some calculations on course deviations versus expected climb
rates - it's junior high school trigonometry. Conclusion: If you have
any good reason to believe that the lift will be stronger - course
deviations of 45 degrees and several miles make perfect sense.

The guys who are really fast on course are the ones who only settle
for the strongest lift along the way. The key skills are 1) being able
to use all available cues to go to where the lift is likely to be best
- in a micro and macro sense - clouds, terrain features, wind
direction and velocity, macro weather patterns, other gliders, etc, 2)
knowing how low to go before lowering you expectations for lift - or
being able to anticipate a change and adjust accordingly.

9B

Sandy,

If you are just starting, be sure to spend time at John Cochrane's web
page:

http://faculty.chicagobooth.edu/john...Papers/#corner

There you will find the "Just a Little Faster, Please" article that
Mike the Strike mentioned. The thing to take away from the article is
that small differences in your ability to pick the best lift have a
far greater impact on your x/c performance than what you do with your
STF decisions.

Or you can do what I do and follow 9B!

2NO

On Tue, 5 Jan 2010 05:51:14 -0800 (PST), "Ken Kochanski (KK)"
wrote:

Morning,

I'm reviewing some STF topics to correct some fallacies that seem to
have crept into my understanding..

There's a lot of interesting thinking in Karel Termaat's soaring page
http://home.planet.nl/~kpt9/

in particular, on the topic of how to handle a positive air gust
during the glide: http://home.planet.nl/~kpt9/positive.htm

Aldo Cernezzi

On Jan 5, 2:19*pm, cernauta wrote:
On Tue, 5 Jan 2010 05:51:14 -0800 (PST), "Ken Kochanski (KK)"

wrote:
Morning,

I'm reviewing some STF topics to correct some fallacies that seem to
have crept into my understanding..

There's a lot of interesting thinking in Karel Termaat's soaring pagehttp://home.planet.nl/~kpt9/

in particular, on the topic of how *to handle a positive air gust
during the glide:http://home.planet.nl/~kpt9/positive.htm

Aldo Cernezzi

Another aspect of the best speed is the selection of the line to
follow. Like the comment above on course deviations. In one contest
I offset just 1/4 mile left of track into a real nice lift street
(blue day). The best pilots are integrating all the information from
terrain, clouds and previous climbs. Also looking in all directions to
select their course to fly. I know from previous experience in model
XC soaring that sometimes it all comes together. You look over that
direction and say "The thermal is right THERE!" and it is.

Phillip Wills also said something similar in his book (don't remember
which one). There are days that you fly that you just know where to
go for the lift.

I can't do it all the time but I'm getting better!

Mike

On Tue, 5 Jan 2010 11:31:38 -0800 (PST), Sandy Stevenson
wrote:


As someone who is just starting to fly cross country, this is one of
the best discussions I've read here in the last few years.
Thanks for your posts, guys.

Better stop reading now, Sandy.

Otherwise I guarantee that you'll be completely puzzled by the variety
of techniques and opinions you are going to read here over the next
week. vbg



Here's a method that is very simple yet makes champions. Invented by
Ingo Renner who became three time world gliding champion using it.

First, and most important, set the *correct* McCready setting.
A 3 kt thermal is usually only 2 kts if you count the time you need to
center it, therefore always use a lower McCready setting than the
average climb rate your variometer is showing you.

Between thermals fly a *constant speed* depending on the McCready
setting. Do not adjust speed to the current sink rate, only pull back
and climb into a thermal if it is really strong.
Keep the AoA constant - fly smooooooooth.

Set McCready to half your chosen value once you get below 50 percent
of the cloud base, and only fly with best glide speed if you really
desperately need a thermal in order to avoid an outlanding.


The same method is used by the pilots who have been dominating German
15m class for the last 6 years (... and by the guy writing this
posting). Works like a charm, and is very simple to use.

On Jan 5, 11:01*pm, Andreas Maurer wrote:
On Tue, 5 Jan 2010 11:31:38 -0800 (PST), Sandy Stevenson

wrote:
As someone who is just starting to fly cross country, this is one of
the best discussions I've read here in the last few years.
Thanks for your posts, guys.

Better stop reading now, Sandy.

Otherwise I guarantee that you'll be completely puzzled by the variety
of techniques and opinions you are going to read here over the next
week. vbg

Here's a method that is very simple yet makes champions. Invented by
Ingo Renner who became three time world gliding champion using it.

First, and most important, set the *correct* McCready setting.
A 3 kt thermal is usually only 2 kts if you count the time you need to
center it, therefore always use a lower McCready setting than the
average climb rate your variometer is showing you.

Between thermals fly a *constant speed* depending on the McCready
setting. Do not adjust speed to the current sink rate, only pull back
and climb into a thermal if it is really strong.
Keep the AoA constant - fly smooooooooth.

Set McCready to half your chosen value once you get below 50 percent
of the cloud base, and only fly with best glide speed if you really
desperately need a thermal in order to avoid an outlanding.

The same method is used by the pilots who have been dominating German
15m class for the last 6 years (... and by the guy writing this
posting). Works like a charm, and is very simple to use.

That sounds about right. The John Cochrane paper suggests a similar
technique. Since he's on the US international team now I guess it
works!

In RL flying I have a PDA that measures the actual climb rate from
when you
start turning to when you leave, so I know my achieved climbs to base
my MC setting.
I set MC on my s2f vario independently from what my PDA suggests
(since my vario
doesn't listen to the PDA anyway) based on how aggressive I feel about
getting to
the next thermal. That feeling is based on the suggested speed to
fly, altitude,
time of day, look of the clouds ahead, whatever. I'll fiddle with it
as I get lower,
down to around MC=1 (Reichmann notes that your glide range at MC=0 and
MC=1
is really very similar, and MC=1 gets you to that thermal more
quickly). For that matter
I almost always fly dry so there's not a lot of difference in speed to
fly at different
settings anyway. I try to find lines of clouds more or less in the
direction of where
I'm going so I can try a bunch before settling on the right thermal.

It was interesting looking at one of my fastest days during contest
flying. I was flying
Sports class and found some amazing thermals that day. If I'd been
able to carry the 1
when adding the task time to my start time I would have flown nearly
60mph on course
(I came in about 10 minutes early so only got 54mph). However, I saw
a certain
standard class plane a couple of times up close. Out of curiosity I
pulled his trace
later on and compared it to my own. Mine had several really good
thermals that day,
but almost ALL of his thermals were really good! That alone is a good
reason he's
on the national team and I'm just cannon fodder.

-- Matt

On Jan 5, 4:48*pm, Andy wrote:
On Jan 5, 10:08*am, Papa3 wrote:

I did some calculations on course deviations versus expected climb
rates - it's junior high school trigonometry. Conclusion: If you have
any good reason to believe that the lift will be stronger - course
deviations of 45 degrees and several miles make perfect sense.



9B

Steve Sliwa wrote his thesis on this topic sometime back in the 1970s
IIRC. He used a bit more than junior high trig, but the conclusions
were similar. The secret was deciding sooner than later that "street
b" would work better than "street a", which is exactly what we see
qualitatively in contests.

On Jan 6, 12:26*pm, Papa3 wrote:
On Jan 5, 4:48*pm, Andy wrote:

On Jan 5, 10:08*am, Papa3 wrote:

I did some calculations on course deviations versus expected climb
rates - it's junior high school trigonometry. Conclusion: If you have
any good reason to believe that the lift will be stronger - course
deviations of 45 degrees and several miles make perfect sense.

9B

Steve Sliwa wrote his thesis on this topic sometime back in the 1970s
IIRC. * *He used a bit more than junior high trig, but the conclusions
were similar. * The secret was deciding sooner than later that "street
b" would work better than "street a", which is exactly what we see
qualitatively in contests.

Turns out the article was published in the April 1981 Soaring
magazine. I have a complete set of Soaring from late 1960s ... with
the exception of .... April 1981??!! Well, it's probably in one of
the "reading rooms" in the house, but don't have the energy to sort
through the stacks right now. If anyone has an electronic copy of
the article I'd love to re-read it; it's been years.

On Jan 5, 11:01*pm, Andreas Maurer wrote:
On Tue, 5 Jan 2010 11:31:38 -0800 (PST), Sandy Stevenson

wrote:
As someone who is just starting to fly cross country, this is one of
the best discussions I've read here in the last few years.
Thanks for your posts, guys.

Better stop reading now, Sandy.

Otherwise I guarantee that you'll be completely puzzled by the variety
of techniques and opinions you are going to read here over the next
week. vbg

Here's a method that is very simple yet makes champions. Invented by
Ingo Renner who became three time world gliding champion using it.

First, and most important, set the *correct* McCready setting.
A 3 kt thermal is usually only 2 kts if you count the time you need to
center it, therefore always use a lower McCready setting than the
average climb rate your variometer is showing you.

Between thermals fly a *constant speed* depending on the McCready
setting. Do not adjust speed to the current sink rate, only pull back
and climb into a thermal if it is really strong.
Keep the AoA constant - fly smooooooooth.

Set McCready to half your chosen value once you get below 50 percent
of the cloud base, and only fly with best glide speed if you really
desperately need a thermal in order to avoid an outlanding.

The same method is used by the pilots who have been dominating German
15m class for the last 6 years (... and by the guy writing this
posting). Works like a charm, and is very simple to use.

More Ingo: http://www.sac.ca/index2.php?option=...13 &Itemid=52
"Soaring with the Master"

-T8