Is the glide ring based on my inputed glide ratio or does it calculate my current rate of descent? I did a test where I flew power off with my airport on the edge of the ring, first at best glide then, with a slip and couldn’t see a difference in the ring, so just wondering.
What data is glide ring based on
- Thread starter yoda
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It's based on the glide ratio you set up for your aircraft. Otherwise, when you're flying straight-and-level or climbing, your glide ring would be infinite.
So, interpret the glide ring as "this is where you should be able to reach if your plane really has the glide ratio you input, AND you control it in a way to achieve that performance". It's what you *should* be capable of achieving. There is also a small margin built in, so there's a small chance you could do slightly better than what the ring shows if you fly everything perfectly.
iFly does also try to factor in winds, so you might see the ring bulge to one side or the other. But those are forecast/predicted winds, so YMMV.
So, interpret the glide ring as "this is where you should be able to reach if your plane really has the glide ratio you input, AND you control it in a way to achieve that performance". It's what you *should* be capable of achieving. There is also a small margin built in, so there's a small chance you could do slightly better than what the ring shows if you fly everything perfectly.
iFly does also try to factor in winds, so you might see the ring bulge to one side or the other. But those are forecast/predicted winds, so YMMV.
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Dave Hirschman reported on Garmin, Foreflight, and Dynon glide rings recently in an AOPA video: Glide Rings - Hirschman
Based on your response regarding the forecast/predicted winds, is that why my glide ring wouldn't predict me reaching the airport at my 3 o'clock in the attached screenshot? If so, what winds are being applied, data from current ADS-B or internet weather gathered before departure?
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Yes.
The most current wind data iFly has available. You can tell whether it was from the Internet or from ADSB by tapping the map near your plane to bring up a QuickView window, then: WX Tab -> Wx Info -> Winds, and look in the upper-right corner of the "Weather [Winds]" page. In blue text you'll see "(Downloaded xx minutes ago)" if the data came from the Internet, and (I think) "(Updated xx minutes ago)" if it came from ADSB.
I might be wrong about "Downloaded" vs "Updated". Regardless, there will be an indication of how old the data is, which I think is what you're really asking about.
Great info, thank you!
