Which Way is That Thermal?

wrote in message
oups.com...
ContestID67 wrote:
Look at the Themi:
http://www.themi.de/Themi%20Centering%20Device.htm



I do wish that someone who knows the theory behind this gadget would
speak about this, as it would help me understand how best to fly with
it.


I'm not a Themi expert either, though I've flown with one for 6 years or so.
I don't think the Themi uses accelerometers, as mounting the main box is not
position sensitive. It does have a flight logger, barometric pressure
sensor, gps engine, and computer. Thus it can determine wind when circling,
the best lift encountered during the circle, the direction of that lift from
current position, and which way to turn in order to center the lift. Also,
returning to a previous thermal, but at a different altitude, the Themi does
a credible job of determining where the thermal center is based on its
previous experience with that thermal.

The Themi isn't always right, but it's a useful tool nonetheless. Is it
worth the money? If you needed a logger anyway, maybe. Some soaring computer
interface software (Winpilot Pro w/ climb maximizer) already has most of the
Themi thermal centering features. Since I bought Winpilot Pro after the
Themi, I'm flying with both. The Themi has some features WP Pro doesn't
have, and Themi's display requires almost no head down time.. However, if I
already had WP Pro, I wouldn't buy the Themi.

bumper

In article .com,
writes
ContestID67 wrote:
I was sent a link to a gadget some college engineers-in-the-making
built. http://engenius.sece.rmit.edu.au/Abstracts/Page601.htm. It
tries to detect which way a thermal is based on temperature differences
between wing tips. Bright boys.

I have two questions;

1) Have there been other gadgets created to do the same thing? How
well did they work?

A long time ago, a Dr Brennig-Jones suggested that, because
thermals apparently produce sub-audible sound, you could use the
glider's wings as a directional microphone to "hear" where the thermal
is.

I don't think anyone took up this idea.

--
Mike Lindsay

Here is their patent.. http://tinyurl.com/hswdy



Larry Goddard

"01" USA






" wrote in message
oups.com:

ContestID67 wrote:
I was sent a link to a gadget some college engineers-in-the-making
built. http://engenius.sece.rmit.edu.au/Abstracts/Page601.htm. It
tries to detect which way a thermal is based on temperature differences
between wing tips. Bright boys.

I have two questions;

1) Have there been other gadgets created to do the same thing? How
well did they work?

Dear Sir:

Look at the Themi:
http://www.themi.de/Themi%20Centering%20Device.htm

And, I've been told that the Zander flight computer --
http://www.zander-variometer.de/ -- has similar capability, but don't
see evidence of this on their web site.

After hearing about the Themi, I *had* to buy one to see how it works.
Having said that, I have been using one for 2 years, and have some
experience with it -- it's a fun toy -- but I"ve been unable to find
any description of how it operates. Some things are obvious: It has a
GPS engine, and probably has a barometric sensor and/or accelerometers.

In any case, the maximum it coiuld do is to use 3-D GPS data to
calculate climb/descent; it could have accelerometers as well; and
sense pressure changes. It could calculate, therefore, the movement of
the glider, make some assumptions about flight, calculate wind, and on
this basis estimate where the best lift *was* so you can go back to it.

In my experience, if I fly in non-erratic circles, it does a pretty
good job of re-finding the last spots of lift after I've wandered away
fruitlessly looking for something better, and in doing this it seems to
compensate for wind.

Obviously, it can't predict the future, so I use my own judgment on
where lift is *going* to be.

It is useful? After 2 years with it, I do feel that I'm better than it
is. I look at the ground and the cloud (if any) and think about the
wind (my SN-10 is invaluable in this regard --
http://www.ilec-gmbh.com/sn10.htm ) and am reliably able to find lift.

But -- in weak or windy conditions, or when, as sometimes happens, I
lose my mental image of the thermal and where I've been, I will
somtimes turn my brain off for a couple of minutes and just "fly the
lights," and more often than not get back into lift.

I do wish that someone who knows the theory behind this gadget would
speak about this, as it would help me understand how best to fly with
it.