"Dave Nadler YO" wrote in message
om...
Bill, you're absolutely right, during a dead straight glide
with constant airspeed their isn't enough information to
compute the result. With an SN10 you need to make an S-turn
at least to get an update.

The heading sensor issue is a bit difficult. Certainly it can
be done with GPS using multiple antennas (I can't remember the
commercial products that do this off-hand). Google and you'll
find a few research projects using GPS for attitude as well
as heading. Cost is not on for gliders real soon. Compasses
are very cranky beasts, especially if they need to be glider-
pilot-proof (about which I could tell stories for hours).
Making something that is low-cost, self-calibrating, immune
to stupid installations - that's the hard bit.

Hope that all makes sense,
Best Regards, Dave

PS: Haven't seen anyone suggest a sun-tracker yet ?
Or vision-system with terrain matching ?


Bob Lepp e-mailed me info on a company called Aventech that makes wind
direction detection equipment for crop dusters. These folks need very
accurate winds aloft data to predict the drift of chemicals sprayed on
crops.

Their gadget works just like a glider computer with the addition of a
two-antenna GPS array that provides heading data accurate to .5 degree. To
cover any gaps in the GPS signal, they use a solid state inertial unit.

Sensors that detect the earth's magnetic field will always be tricky. GPS
heading sensing looks like a winner since we need the GPS receiver anyway.
Maybe a couple of self-contained Bluetooth GPS receivers attached to the
wingtips would work. An inertial measurement unit would be very useful for
applications other than wind data. These could determine true vertical
regardless of the glider's attitude and very accurately measure Z-axis
acceleration. What vario maker wouldn't love to have that data.

No doubt this will be expensive at first but then we couldn't afford GPS 20
years ago. Twenty years before that glider pilots couldn't afford radios.
Electronics always seems to follow a learning curve that exponentially
reduces cost.

Bill Daniels