Final Glide Confidence

In previous articles, I talk about using an MC=6 for your final glide settings. Here are other considerations to make sure that you make it home using your flight computer.

At the 2018 WGC Mike and I flew our first flight together in the EB28 ASH25 with an electrical failure and we had to do our final glide by eyeball. So Day 1 was a ‘hope’ that this would all work. However, we slowly fell off on our conservative glide. The flight computer and reality separated the faster we flew.

Polar

We did not have the polar data for the EB 28, we had something close but not it. You need to make sure the data is correct for your sailplane. Your standard production glider is generally pretty easy to find if it is not already pre-loaded. But remember that saying ‘Garbage in Garbage out’.

Wind

Not having accurate wind is going to lead to a real problem. One issue we have here in Warner Springs during the summer is the sheerline will start to drift to the east. On the sheerline the wind will be light from the south, however, you could end up with a 20mph wind from the west, leading to a long glide into the wind. The altitude you are flying it might not be the same winds you are going to have on the final glide through lower altitudes.

Computers are different on how they calculate wind and final glides. However, they are all the same in the fact that they cannot predict what is happening ahead. However, you can. There are times when you have to manually enter the winds for your final glide.

Bugs

Why are we adjusting for bugs? Because the leading edge might actually be covered in them and you are not achieving the published performance. In general, you might not be achieving the published performance. This could vary from the rigging, sealing, tapes, mylar, etc. This is an easy adjustment to the polar to match your performance to what you are actually doing. You might notice that you always fall off of the glide, try adjusting the bug setting and see if the numbers begin to line up with reality.

Air

The last few articles I have been talking about how you might be doing better than the polar and are able to find good air. At the JWGC in Australia when I crewed and coached we would watch the other gliders on final glide and pass on that information to the pilots. Are others coming home high and fast or low and slow? With binoculars and different tracking, you could see how the air was on the final glide.

This information might help in your decision to leave the last thermal or stay a little longer. I have also passed on this information when on final glide to help out teammates that might be behind me somewhere.

If you have a Borgelt the Performance Index directly correlates the bug setting, so that is another way to make a quick adjustment on your final glide to make a more accurate guess on how fast to fly your final glide.

MC=6

Having that high McCready setting that I have talked about before gives you a safety margin for some errors that you might not have had perfectly calculated above.

 Banner Photo by Petr Kolmann

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 Garret Willat holds a flight instructor rating with over 8000 hours in sailplanes. His parents have owned Sky Sailing Inc. since 1979. He started instructing the day after his 18th birthday. Since then, Garret has represented the US Junior team in 2003 and 2005. He graduated from Embry-Riddle with a bachelor's degree in Professional Aeronautics. Garret represented the US Open Class team in 2008 and 2010 and the Club Class team in 2014. Garret has won 3 US National Championships.