Bill - The heading is not required. In the ILEC SN10 we do this
without heading, and it normally has the wind by the time you're
off tow. Pilot feedback and measurements indicate that we do
it quite accurately. We just use TAS and GPS ground track over
multiple observations (TAS requiring accurate IAS, press, temp).
Best Regards, Dave "YO"

"Bill Daniels" wrote in message news:gw%zc.59643$HG.25574@attbi_s53...
I've been analyzing the IGC files from my flights and comparing them to
others.

Generally, in good conditions, I'm circling less than 25% of the time.
Other, far better pilots than I, are circling less than 15% of the time.
This means that wind data that depends on the glider flying circles gets way
out of date during the long glides. OK, "S" turns can give the computer a
chance to compute wind if you remember to fly them but there are still a lot
of long, straight glides.

To compute real-time wind data we need Groundspeed, Ground Track (any GPS
gives these)True Airspeed (Some computers do this if they have OAT, Pressure
Altitude and IAS) and accurate heading data. Heading data it the tough nut
to crack.

So, how do we get Heading? One way might be to put a GPS antenna in each
wing and look at the carrier phase difference. If the computer saw a
constant track, it could assume the wings are level and determine a heading
value. This heading value might update an aerospace quality MEMS heading
gyro that would maintain a flow of heading data to the glide computer during
times when the wings were banked.

With good heading data we could get uninterrupted high quality wind data
regardless of the gliders' maneuvering or lack of it.

OK, RAS gageteers, how about it?

Bill Daniels