Lew Hartswick wrote:
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?

2) What do you use to determine if the thermal is on the left or the
right? This is the wing up or down when its near the thermal debate.

Thanks, John

Nothing new there, That system has been tried at least 25 years ago.
It intrigued me, as an electronics engineer just beginning to fly,
but the consensus of the "big boys" at the time was it wouldn't
be sufficiently accurate or too sensitive to random variations
or some other problems.
...lew...

This measurement technique has never been shown to even work, let alone
be supperior to existing variometers (which it would have to be by a
large margin to justify running wiring thru our wings, although that
might be done by the manufacturer; but they won't do it unless there is
a demand for the device). Personally, I think there are other methods
that will work significantly better than present technology that don't
require you to run wiring in your wings (which would have to be
connected and disconnected every time you assemble/disassemble, which,
in turn, requires an additional preflight inspection).

On the direction to turn: at the last convention I listened to Tom
Knauff declare that most glider pilots don't know which way to turn
into a thermal; the correct direction, according to Knauff, is towards
the down wing because sinking air surrounds a thermal. I am like Eric -
I turn towards the up wing. If Knauff is correct, I should be missing
the thermal (on the 1st turn) well over half of the time, and I am not.
Most of the time I do not immediately commit to the turn (of course,
there is occassionally those 10 kt monsters where there is question),
and actually like to turn slightly away from the direction that I think
the thermal is. The concept here is to find the boundary of the thermal
and to stay inside of it; if you search for the center of the thermal I
think you will end up flying thru it and turning too late, forcing the
glider into the sinking air around the thermal. Once I know where the
boundary is I turn into the thermal, gradually tightening the turn
until I am getting optimum climb. Ideally with this technique you will
seldom fly thru the center of the thermal, making it easier to center
the glider in the thermal. This is also helpful in identifying
streeting, since you turn only once you detect that the lift is
definitely falling off.

Tom Seim
Richland, WA