Centering Rule of Reichmann

[danstrider]

Hello All,

I am working on an autonomous soaring algorithm in which a computer seeks thermals and max's out having found one and cored it. Question is how.

I heard wind of a "Centering Rule of Reichmann" and I am unfamiliar with this term. A while of searching Google turned up only parts and pieces and no clear definition/heuristic. Could someone take a few minutes to type a good explanation of Reichmann's centering technique or point me to a really detailed website definition?

Most appreciated gentlemen!
Dan Edwards
djedward@ncsu.edu

Dan:

My guess is that you are referring to Helmut Reichman, a
World Champion in 15m gliders and trainer of the German
national team for many years.

His book Cross-Country Soaring is a classic and he received
his Ph.d on the optimization of cross country flight. In it
he describes three methods for centering a thermal. No doubt
at least one of his methods could be modeled mathematically.

I am not aware of any algorithms for centering in his books
but you might find something in his Ph.d thesis.


His preferred method may be described as:

Imagine a sailplane gliding across the edge of a thermal and
the pilot initiates a turn to start centering.

As climb improves, flatten the circle ~15 to 20 degrees
(widens the circle, reducing the turn as the climb is still
increasing..it keeps you headed somewhat towards the core
you have yet to locate.)

As climb deteriorates, steepen the bank to ~ 50 degrees.
(Think of this as turning back towards the core.)

if climb remains constant, keep constant bank of 23-30 degrees.

The idea is to gradually displace the center of the turn of
the glider into the core of the thermal wher the lift is
strongest and then keep it there with a constant bank turn.

The reality is a bit more complex as thermals don't always
conform to our ideal of a nice round cross section whose
strength increases evenly towards the center but the
technique of varying the angle of bank will keep you headed
in the right direction as the thermal's shape changes.

Pete

danstrider wrote:
> Hello All,
>
> I am working on an autonomous soaring algorithm in which a computer
> seeks thermals and max's out having found one and cored it. Question
> is how.
>
> I heard wind of a "Centering Rule of Reichmann" and I am unfamiliar
> with this term. A while of searching Google turned up only parts and
> pieces and no clear definition/heuristic. Could someone take a few
> minutes to type a good explanation of Reichmann's centering technique
> or point me to a really detailed website definition?
>
> Most appreciated gentlemen!
> Dan Edwards
> djedward@ncsu.edu
>
>

--

Peter D. Brown
http://home.gci.net/~pdb/
http://groups.yahoo.com/group/akmtnsoaring/

Dan:

For a diagram, work through this powerpoint presentation
until you get to Technique #3. (Warning.. it makes it look a
bit more complicated then it is....getting out a pen and
paper might be a little easier, drawing a thermal with
concentric circles representing progressively stronger lift.)

www.sac.ca/cas/techniques/files/sacagm2000.ppt

Pete

danstrider wrote:

> Hello All,
>
> I am working on an autonomous soaring algorithm in which a computer
> seeks thermals and max's out having found one and cored it. Question
> is how.
>
> I heard wind of a "Centering Rule of Reichmann" and I am unfamiliar
> with this term. A while of searching Google turned up only parts and
> pieces and no clear definition/heuristic. Could someone take a few
> minutes to type a good explanation of Reichmann's centering technique
> or point me to a really detailed website definition?
>
> Most appreciated gentlemen!
> Dan Edwards
> djedward@ncsu.edu
>
>

--

Peter D. Brown
http://home.gci.net/~pdb/
http://groups.yahoo.com/group/akmtnsoaring/

"Pete Brown" <pdb@gci.net> wrote in message
news:10t4vd05ma0rrc1@corp.supernews.com...
> Dan:
>
> For a diagram, work through this powerpoint presentation until you get to
> Technique #3. (Warning.. it makes it look a bit more complicated then it
> is....getting out a pen and paper might be a little easier, drawing a
> thermal with concentric circles representing progressively stronger lift.)
>
> www.sac.ca/cas/techniques/files/sacagm2000.ppt
>
> Pete

Hi Pete,
That is an excellent presentation. Thanks for sharing. Kudos to the CAS
and in particular the author. Technique 3 is what I learned a few years ago
in a Blanik L3, thanks to an excellent instructor.
One comment, if I may. The pilot needs to remember that thermals don't
go straight up, they tilt downwind as the altitude increases. Small point,
but flying RC from the ground, it should be remembered.
Now, here's a challenge question. Sitting in the nest, we can rely, of
course on the vario. But how can Dan, and the rest of the folks, recognize
when it is time to decrease and increase the bank angles whilst watching the
model up there from down here? For the sake of this discussion, let's use
the diagram in the PPT presentation and all circles will be clockwise.

Happy Soaring,

Casey Wilson
Freelance Writer and Photographer

Casey:

The RC pilot is at a disadvantage because he has to rely on
visual clues as to when the glider is in stronger lift. But,
that said, otherwise the technique is the same, shallow the
bank angle as lift is increasing, tighten up as it decreases.

In the olden days, Ace made a Thermic Sniffler which was
micro variometer carried by the glider which transmitted a
signal to an AM transistor radio on the ground. The pitch of
the signal gave the clues as to the strength of the lift,
just as an audio variometer does today to full scale glider
pilots.

The factor that makes rc sailplanes easy to fly is that the
speed at which they thermal is much slower than full scale
gliders, hence it is much easier for them to stay in the
very strongest part of the core of the thermal. The radius
of the turn is related to the square of the velocity so
slower flying aircraft have a real advantage in thermalling.

Unfortunately, this advantage is often given up once the
glider leaves the thermal. At this point, gliders with
higher speeds at max L/D sometimes beat out the better
thermalling gliders as they race to the next thermal.

Pete





> Hi Pete,
> That is an excellent presentation. Thanks for sharing. Kudos to the CAS
> and in particular the author. Technique 3 is what I learned a few years ago
> in a Blanik L3, thanks to an excellent instructor.
> One comment, if I may. The pilot needs to remember that thermals don't
> go straight up, they tilt downwind as the altitude increases. Small point,
> but flying RC from the ground, it should be remembered.
> Now, here's a challenge question. Sitting in the nest, we can rely, of
> course on the vario. But how can Dan, and the rest of the folks, recognize
> when it is time to decrease and increase the bank angles whilst watching the
> model up there from down here? For the sake of this discussion, let's use
> the diagram in the PPT presentation and all circles will be clockwise.
>
> Happy Soaring,
>
> Casey Wilson
> Freelance Writer and Photographer
>
>

--

Peter D. Brown
http://home.gci.net/~pdb/
http://groups.yahoo.com/group/akmtnsoaring/

[danstrider]

That was perfect! Exactly what I needed. I have searched around for Reichmann and I'm in the process of tracking down a copy of his book.

Thanks Pete for the verbal description of the method. That definitely corresponded with the powerpoint and helped me to grasp the concept quickly. And duly noted about thermals not being uniform all the time. The onboard computer will (hopefully) build a 3D model of the thermal as it flies through the air and I'll be able to assess how well it does in irregular thermals.

To address questions about wind, I assume this technique would allow re-centering a thermal as the wind blows it. Since it's a general technique, if the thermal moves, it should be able to re-center in the new core, yes? Is this a fair assumption?

To answer Casey's question, I will not be flying the airplane. An onboard computer will be evaluating the thermal, just as a human pilot would do in the air. So, the model can move with the wind with total disregard to my perception of it. Idealy, I could watch and evaluate the model doing its thing, but I likely will need telemetry to "see" the thermals as if I was sitting in the pilot's seat.

The computer will have access to a variometer with a TEK nozzle onboard. Similar to the audio signal a pilot hears, the computer will get an analog signal that represents a "tone." I will also transmit the vario signal to the ground, as a normal model vario would, for ground feedback of the success. If the tone signals lift and the glider circles by itself and the tone continues to signal lift, my mission is accomplished :-)

Information about model variometers can be found:
http://www.rcgroups.com/forums/showthread.php?t=307042

Gentlemen, thank you for the quick response to the perfect answer. In return, I will point you toward a small DIY project that does just what we're discussing (a little different system setup). I hope to improve the controller and add a 3D modelling package to allow a more optimum thermalling algorithm. Perhaps in a few years you'll see a commercial version of my ideas.
URL: http://hem.passagen.se/skj/engelska/rcel.htm

Are there any full-scale instruments that do autonomous thermalling?

Thanks guys!
Dan Edwards
djedward@ncsu.edu

danstrider wrote:

> That was perfect! Exactly what I needed. I have searched around for
> Reichmann and I'm in the process of tracking down a copy of his book.

This is not the eassiets book to come acrosss. If you want
me to copy a few pages, email me.

> To address questions about wind, I assume this technique would allow
> re-centering a thermal as the wind blows it. Since it's a general
> technique, if the thermal moves, it should be able to re-center in the
> new core, yes? Is this a fair assumption?

Yes. The techniqques works as you climb. The thermal's shape
usually changes with altitude and the process is one of more
or less constant recentering.

> Are there any full-scale instruments that do autonomous thermalling?

See : http://www.themi.de/index.htm

Pete




--

Peter D. Brown
http://home.gci.net/~pdb/
http://groups.yahoo.com/group/akmtnsoaring/

There is one point you miss regarding RC flying. The pilot on the ground
has a large number of visual clues to help stay in a thermal and drift with
it as it moves. The visual references from the ground (buildings, trees,
etc.) provide immediate feedback on location. I am not a full scale pilot,
but I would think the vario is the only good clue as to location in a
thermal "up there".

The relative climb rate is also visible to the trained RC'ers eye, and a
good pilot knows when he/she has topped out (or gotten so high its time to
move on). Of particular interest to this discussion is RC XC flying. We
routinely stay above 2000' agl, and flights above 3000' are normal for more
experienced pilots. Consider that the current FAI free distance record for
an RC sailplane is 140 miles. The same pilot recently had a 125 mile flight
during a competition.

While ACE no longer makes the Thermal Sniffler, there are a number of modern
units that are much more efficient, smaller, and more user friendly. The
Skymelody, Piccolario are currently the top units, and the Multiplex Helios
is still very usable. These are all available with total energy
compensation, making the old stick thermal problem of the Ace era a thing of
the past.

Jim Thomas


"Pete Brown" <pdb@gci.net> wrote in message
news:10t7hvh6aqqu9c0@corp.supernews.com...
>
> Casey:
>
> The RC pilot is at a disadvantage because he has to rely on
> visual clues as to when the glider is in stronger lift. But,
> that said, otherwise the technique is the same, shallow the
> bank angle as lift is increasing, tighten up as it decreases.
>
> In the olden days, Ace made a Thermic Sniffler which was
> micro variometer carried by the glider which transmitted a
> signal to an AM transistor radio on the ground. The pitch of
> the signal gave the clues as to the strength of the lift,
> just as an audio variometer does today to full scale glider
> pilots.
>
> The factor that makes rc sailplanes easy to fly is that the
> speed at which they thermal is much slower than full scale
> gliders, hence it is much easier for them to stay in the
> very strongest part of the core of the thermal. The radius
> of the turn is related to the square of the velocity so
> slower flying aircraft have a real advantage in thermalling.
>
> Unfortunately, this advantage is often given up once the
> glider leaves the thermal. At this point, gliders with
> higher speeds at max L/D sometimes beat out the better
> thermalling gliders as they race to the next thermal.
>
> Pete
>
>
>
>
>
> > Hi Pete,
> > That is an excellent presentation. Thanks for sharing. Kudos to the
CAS
> > and in particular the author. Technique 3 is what I learned a few years
ago
> > in a Blanik L3, thanks to an excellent instructor.
> > One comment, if I may. The pilot needs to remember that thermals
don't
> > go straight up, they tilt downwind as the altitude increases. Small
point,
> > but flying RC from the ground, it should be remembered.
> > Now, here's a challenge question. Sitting in the nest, we can rely,
of
> > course on the vario. But how can Dan, and the rest of the folks,
recognize
> > when it is time to decrease and increase the bank angles whilst watching
the
> > model up there from down here? For the sake of this discussion, let's
use
> > the diagram in the PPT presentation and all circles will be clockwise.
> >
> > Happy Soaring,
> >
> > Casey Wilson
> > Freelance Writer and Photographer
> >
> >
>
> --
>
> Peter D. Brown
> http://home.gci.net/~pdb/
> http://groups.yahoo.com/group/akmtnsoaring/
>
>
>

[danstrider]

Pete:
I am indeed having trouble tracking down Reichmann. If you wouldn't mind scanning a few pages, I would greatly appreciate your time in doing so.

The Thermi instrument makes a very interesting read. It seems they are so close to having thermal flying "hands off." I suppose just integrate their LED indicators into control actuators and you're set. Needless to say, the link is a very good resource and is definitely helping me hash this out. Thanks!


Jim,
Thanks for your musing about RC vs full scale. I've been wondering something that is another rc vs full scale issue. Models fly in small thermals a couple meters across near the ground whereas full scale gliders fly in thermals tens or hundreds of meters across way up in the sky. Do all those thermals have the same shape (as in a core, sink around the thermal, etc)? Do model sized thermals eventually grow into full sized thermals, or how do the huge thermals form then?

Happy New Year!
Dan

"danstrider" <danstrider.1ibm8a@rcgroups.com> wrote in message
news:danstrider.1ibm8a@rcgroups.com...
> Jim,
> Thanks for your musing about RC vs full scale. I've been wondering
> something that is another rc vs full scale issue. Models fly in small
> thermals a couple meters across near the ground whereas full scale
> gliders fly in thermals tens or hundreds of meters across way up in the
> sky. Do all those thermals have the same shape (as in a core, sink
> around the thermal, etc)? Do model sized thermals eventually grow into
> full sized thermals, or how do the huge thermals form then?
>
> Happy New Year!
> Dan

I'm not Jim, but I'll throw a couple pennies worth into the pot. The
difference in temperature between two adjacent surfaces is a thermal engine.
The implication here is that very large thermals can exist very near the
surface. A good example of this is a paved parking area, or a tennis court,
in the middle of a park, surrounded by grass and trees. Another is a farm
acre or so of plowed ground surrounded by still growing vegetation.
The point is, thermals at the surface can be quite large.
Your intuition is correct that the span (I'm avoiding the word diameter
for a reason) increases with altitude -- and so does the vertical velocity.
A believable theory in the formation of a nascent thermal, is that the
warm surface area "burps" off a bubble of warm air. The burping is caused by
cool air being drawn in across the surface and pinching off the bubble.
Eventually, when the surface becomes warm enough to heat the incoming draft
fast enough to sustain the rising column, a stable thermal is created. The
theory is too logical to ignore, but I've never been able to prove it.
I have an experiment devised to try again in the spring when our
"boomers" start up here in the Mojave Desert. It involves a spot that I know
is a thermal generator; I've been flying it for years. I'm thinking about
hanging strands of light mylar ribbon at the top of ten-foot PVC poles and
see what happens. Don't laugh. I saw one flying field in California that had
five similar poles around a thermal area. It was interesting to see multiple
ribbons pointing in toward the center of the area from different directions
at the same time.
On more than one occasion, flying full-scale gliders, I've had to employ
maximum spoilers on final approach to counter act thermal lift created by
the runway when crossing over the approach threshold.

The use of mylar ribbons on poles has been around for years and years in RC,
and probably decades for free flight. In RC use, handlaunch tends to
benefit most from this method of thermal spotting. Consider that lauch
height for a handlaunch is 50-150 feet depending on the person/style/plane.
For 2-4 meter thermal duration planes, launches are 300-800 feet, again
depending on person/skill level/plane, so what is happening at 20' off the
ground is less help.

Regarding size, 20+ years of experience teaches me that at ground level
thermals are small, on the order of feet to a few yards across. They
increase in size as they rise, seeming to break up about where they coalesce
into full scale sized thermals around 2000' agl. Witness the many dust
devils on the ground. Even though these are typically small, they have the
same elements of a very active core and sink around. Same dynamics, just on
a smaller scale. The low level thermals tend to move around more randomly
than a well developed thermal does.

The phenomenon that Casey describes in full scales sounds more like a
combination of ground effect and hitting a bubble of hot air, either
breaking loose to generate a thermal, or just about to. The comment about
it happening at the runway threshold supports this, the glider is set up for
final to touchdown in one type of condition, which is upset when hitting
another type of condition. We experience the same thing with models, caused
by wind changes as thermals go by, small thermals at low level, etc.

Jim Thomas

"Casey Wilson" <N2310D @ gmail.com> wrote in message
news:1pCCd.25551$2X6.18731@trnddc07...
>
> "danstrider" <danstrider.1ibm8a@rcgroups.com> wrote in message
> news:danstrider.1ibm8a@rcgroups.com...
> > Jim,
> > Thanks for your musing about RC vs full scale. I've been wondering
> > something that is another rc vs full scale issue. Models fly in small
> > thermals a couple meters across near the ground whereas full scale
> > gliders fly in thermals tens or hundreds of meters across way up in the
> > sky. Do all those thermals have the same shape (as in a core, sink
> > around the thermal, etc)? Do model sized thermals eventually grow into
> > full sized thermals, or how do the huge thermals form then?
> >
> > Happy New Year!
> > Dan
>
> I'm not Jim, but I'll throw a couple pennies worth into the pot. The
> difference in temperature between two adjacent surfaces is a thermal
engine.
> The implication here is that very large thermals can exist very near the
> surface. A good example of this is a paved parking area, or a tennis
court,
> in the middle of a park, surrounded by grass and trees. Another is a farm
> acre or so of plowed ground surrounded by still growing vegetation.
> The point is, thermals at the surface can be quite large.
> Your intuition is correct that the span (I'm avoiding the word
diameter
> for a reason) increases with altitude -- and so does the vertical
velocity.
> A believable theory in the formation of a nascent thermal, is that the
> warm surface area "burps" off a bubble of warm air. The burping is caused
by
> cool air being drawn in across the surface and pinching off the bubble.
> Eventually, when the surface becomes warm enough to heat the incoming
draft
> fast enough to sustain the rising column, a stable thermal is created. The
> theory is too logical to ignore, but I've never been able to prove it.
> I have an experiment devised to try again in the spring when our
> "boomers" start up here in the Mojave Desert. It involves a spot that I
know
> is a thermal generator; I've been flying it for years. I'm thinking about
> hanging strands of light mylar ribbon at the top of ten-foot PVC poles and
> see what happens. Don't laugh. I saw one flying field in California that
had
> five similar poles around a thermal area. It was interesting to see
multiple
> ribbons pointing in toward the center of the area from different
directions
> at the same time.
> On more than one occasion, flying full-scale gliders, I've had to
employ
> maximum spoilers on final approach to counter act thermal lift created by
> the runway when crossing over the approach threshold.
>
>

Dan:

I can't scan but I can burn a xerox copy and email it if you
will send me your snail mail address via a seperate email.

Pete

danstrider wrote:
> Pete:
> I am indeed having trouble tracking down Reichmann. If you wouldn't
> mind scanning a few pages, I would greatly appreciate your time in
> doing so.
>
--

Peter D. Brown
http://home.gci.net/~pdb/
http://groups.yahoo.com/group/akmtnsoaring/

Hi all - I've enjoyed this thread, as micrometeorology has long been a
fascination. Sorry about the long post but it's winter here... This won't
be news to any of you (and it's just my experience/opinion), but perhaps it
will trigger more fun thoughts on your part. This applies to both RC and
full-size craft, as I participate in both. There are glaring oversights I
know about and surely some I don't, so I encourage you to dig in and point
them out for my benefit.

Yes, thermals used by full size sailplanes in their "working zone" do start
as the smaller thermals we utilize with RC craft.

Here are some concepts from atmospheric physics (ignoring many details) that
hold true on a nice summer day:

Earth's atmosphere decreases in pressure with increasing altitude, at a
known rate. Air decreases in temperature when pressure is decreased, at a
known rate. Together, these two give us the Dry Adiabatic Lapse Rate
(DALR); rising air cools at a rate of 3.5 degrees (F) per thousand feet.
In a model (average) atmosphere the still air above your flying field
decreases in temperature with height at exactly the DALR.

So - how/when does a thermal "start" and become useable, and how/when does
it cease to be useable?

Short answer - air begins rising when it is warmer than nearby air, and
ceases rising when it becomes the same temperature as nearby air.
The longer answer breaks down into initial heating, cooling mechanisms, and
the atmosphere's actual temperature lapse rate on a given day above your
field. I'll describe them in reverse order to set the stage.

The boring physics background - feel free to jump ahead
------------------------------------------------------------------------------

ACTUAL ATMOSPHERIC LAPSE RATE:
Still air above you rarely matches the DALR. Macro-scale air movements
(high/low pressure systems and global jets) move warmer/colder air over your
field every few days. This changes the temperature of "still" air, and more
importantly it changes the temperature lapse rate with altitude.

A weather balloon rising from your field after a cold front passage or a
cloudless night will report temperatures that decrease with altitude at a
rate much faster than the DALR. After a warm front passage or a cloudy
night the rate is much less than the DALR and can even be negative (warmer
as you go up).

COOLING MECHANISMS:
You already know about the DALR; a steady 3.5 degrees F per thousand feet.

Conduction happens when molecules "bump" nearby molecules. Heat is the
measure of a molecule's random kinetic energy (how fast a molecule is
jumping around). When molecules collide, some kinetic energy (heat) is
transferred.

Convection requires two things; acceleration (gravity), and differing
densities in a fluid (liquid or gas) due to temperature, humidity, etc.
Dense (heavy) things have more weight than less dense things (rocks sink in
water, which we call 'kerplopp' instead of convection). In a fluid,
molecules are free to move about, and thus a region of more densely packed
molecules will be pulled more strongly than a region that is not so densely
packed. The colder molecules sink and the warmer ones rise.
Warm air is less dense than cool air because the frequent and energetic
collisions of "warm" molecules push them apart harder than milder collisions
between slower "cool" molecules.

Let's ignore emission and absorption of infra-red radiation due to the short
time scale and small temperature differences found in thermals.

INITIAL HEATING:
The initial size and vigor of a thermal depends on differential
heating/cooling (of meadow vs. forest, crop vs. no-crop field, land vs.
water/bog, paved car park, or just a shed roof), based on the albedo and
specific heats of different materials, and losses to photosynthesis or
evaporating the dew. Air in direct contact with the surface is warmed by
conduction. The energetic surface molecules bump neighboring air molecules,
transferring heat. The now-energetic air molecules can bump other air
molecules, transferring the heat further. Conducted heat decreases with
distance from the solid surface as a function of distance; the warmest air
molecules are right next to the surface.

The fun stuff - a thermal's birth and death
------------------------------------------------------------------------------

Air at the surface is warmed by conduction.
Convection begins immediately, but on scales too small to see. These "pico"
thermals (which cause the shimmer of heat rising) lose their heat by
conduction before they can rise a few yards, but by moving away from the
surface they warm the air within a few yards of the surface thus increasing
the volume of warmed air.

A thermal continues to rise as long as the temperature lapse rate of the
still air it is rising through is greater than the sum of the DALR plus the
rate it loses heat through conduction and mixing (boundary eddies).

Thermals of very small volume require a drastic lapse rate to continue. The
larger a thermal's volume, the less significant conduction becomes and the
less lapse rate it requires to continue rising.

The lower atmosphere has a typical temperature profile that is not a steady
decrease. It is warmest at the surface, cools quite rapidly for as much as
ten thousand feet, and then cools more slowly above that. When thermals
reach this change point ("thermal ceiling"), they weaken rapidly and come
to rest in a thousand feet or less.

Before reaching this thermal ceiling, thermals may cool to their dew point.
This is the base of a cumulus cloud and it's as high as we can thermal in
visual conditions. Cumulus looks so vigorous because when moisture
condenses out of the air, it imparts latent heat of vaporization back into
the air. A water molecule collides with an 'air' molecule, such that the
water molecule is slowed below the energy needed to remain vapor, adding
energy to the air. This causes air to cool at a pseudo-adiabatic rate
called the MOIST adiabatic lapse rate (MALR), which is only half the DALR.
We get thunderstorms when the thermal ceiling is well above the cloud base

In my RC flying, this thermal ceiling is zero feet in the early morning, may
rise to a few hundred feet by 10:00 AM, rises much faster once the dew burns
off, and becomes infinite for RC purposes by 2:00 PM.

The ebb and flow of warm/cool fronts may cause several changes in lapse rate
below the thermal ceiling. A thermal weakens when it encounters a layer
with a lower lapse rate, and (if it makes it through) will strengthen again
if it then enters a layer of greater lapse rate.

Yes, there are thermals in winter.
Yes, there are thermals at night, over water.
Yes, there are "negative thermals"; bubbles/columns of descending clear air.

Do any of you have information about "surface tension" existing between air
of differing temperatures or densities? It often comes up when describing a
"bubble" of air, especially one being held on the surface until it is warm
enough to overcome this effect. It would reduce mixing between air parcels.
I have used inertia and conductive losses instead of surface tension when
mentally modeling thermal formation, but I don't begin to think I've got the
whole answer.

Thanks for keeping me thinking, Marc
RC sailplanes: Airtronics Olympic-II, Airtronics Sagitta 900
Full-size (rent, not own): Schweitzer 2-33, Belanca Citabria, Mooney M20J
----------------------------------

You can buy a copy from a soaring dealer, Knauff & Grove Soaring Supplies.
Their web site is http://www.eglider.org/ . They are located in Penn. in
the USA. The book is a complete document on soaring and flying faster and
covering more distance. Reichmann was a professional instructor and
competition glider pilot.

Fred Blair

ps, copying books is illegal.

"danstrider" <danstrider.1i34ob@rcgroups.com> wrote in message
news:danstrider.1i34ob@rcgroups.com...
>
> That was perfect! Exactly what I needed. I have searched around for
> Reichmann and I'm in the process of tracking down a copy of his book.
>
>
> Thanks Pete for the verbal description of the method. That definitely
> corresponded with the powerpoint and helped me to grasp the concept
> quickly. And duly noted about thermals not being uniform all the time.
> The onboard computer will (hopefully) build a 3D model of the thermal
> as it flies through the air and I'll be able to assess how well it does
> in irregular thermals.
>
> To address questions about wind, I assume this technique would allow
> re-centering a thermal as the wind blows it. Since it's a general
> technique, if the thermal moves, it should be able to re-center in the
> new core, yes? Is this a fair assumption?
>
> To answer Casey's question, I will not be flying the airplane. An
> onboard computer will be evaluating the thermal, just as a human pilot
> would do in the air. So, the model can move with the wind with total
> disregard to my perception of it. Idealy, I could watch and evaluate
> the model doing its thing, but I likely will need telemetry to "see"
> the thermals as if I was sitting in the pilot's seat.
>
> The computer will have access to a variometer with a TEK nozzle
> onboard. Similar to the audio signal a pilot hears, the computer will
> get an analog signal that represents a "tone." I will also transmit
> the vario signal to the ground, as a normal model vario would, for
> ground feedback of the success. If the tone signals lift and the
> glider circles by itself and the tone continues to signal lift, my
> mission is accomplished :-)
>
> Information about model variometers can be found:
> http://www.rcgroups.com/forums/showthread.php?t=307042
>
> Gentlemen, thank you for the quick response to the perfect answer. In
> return, I will point you toward a small DIY project that does just what
> we're discussing (a little different system setup). I hope to improve
> the controller and add a 3D modelling package to allow a more optimum
> thermalling algorithm. Perhaps in a few years you'll see a commercial
> version of my ideas.
> URL: http://hem.passagen.se/skj/engelska/rcel.htm
>
> Are there any full-scale instruments that do autonomous thermalling?
>
> Thanks guys!
> Dan Edwards
> djedward@ncsu.edu
>
>
> --
> danstrider
>
>
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>

"f.blair" <fblair6@ev1.net> wrote in message
news:mXlEd.2981$Ii4.969@newsread3.news.pas.earthli nk.net...
> You can buy a copy from a soaring dealer, Knauff & Grove Soaring Supplies.
> Their web site is http://www.eglider.org/ . They are located in Penn. in
> the USA. The book is a complete document on soaring and flying faster and
> covering more distance. Reichmann was a professional instructor and
> competition glider pilot.
>
> Fred Blair
>
> ps, copying books is illegal.

Yep, especially without giving proper attribution to the source. The US
copyright laws, part of the US Title Code, available from the Library of
Congress and other sources, lay it out in pretty fine detail. But then, if
you have permission from the author, it's okay. Except for the footnoting
requirements.
It is something I'm acutely aware of as an author.
By the way, did you know the Department of Homeland Security, FBI, and
Secret Service actively monitor Usenet?

Go Fly!

Casey Wilson
Freelance Writer and Photographer