On Thursday, June 11, 2015 at 7:55:56 PM UTC-5, wrote:

* The "card" is in the form of a half-ring. It looks exactly like half a MacCready ring. It is taped around the lower half of the vario (sink portion only). To tell the best speed-to-fly through sink. It doesn't deal with what to do in lift. Think of it as MacCready ring set to zero, but with three added bands of numbers to deal with 10 mph 20mph and 30 mph headwinds, not just zero-wind conditions.

* I've also done this using a printed card that was separate from the vario but the ring mounted around the vario is much much easier to use.

* Yes absolutely there is some "chasing" involved. I mean, not chasing the airspeed up and down, but when you hit sink, you'll go through a gradual acceleration before the vario needle is finally pointing right at the airspeed number you are actually flying, and that's when you stop accelerating. You can't instantly know what speed you'll need to accelerate to, like you would if you were using netto. But this is nothing new, there's a long long history of pilots using MacCready speed-to-fly rings on non-netto variometers.

* If I were using a netto variometer it would be very easy to create the ring using a graphical printout of the polar curve, and a ruler. It would only take 10 minutes or 30 minutes at most to get data for a wide spread of sink rate points and 3 different wind conditions. It's using a non-netto vario, that makes the numbers more of a pain to come up with, especially if you to produce the appopriate airspeed to fly for nice ROUND numbers on the vario (100 fpm, 200 fpm, etc). If you are happy with a scattershot collection of numbers for the vario values on the ring, rather than round numbers, it's a little easier to make the ring, but a little less nice to use.

S

So, I guess the choice is yours. Quick, and "scattershot" numbers and be able to use it this weekend, or wait until you can resurrect the program and make it the way you like. If I were making one of these, I would color code, and put zero wind closest in, then 10 and 20 MPH headwinds and to heck with trying to put the speeds on a nice, round sink rate.

Steve Leonard