iFly GPS Forum

Does anyone know of an app that provides active glide ratio. I had this feature on an early Garmin nav (Garmin Pilot) unit back 15 years ago, That unit finally died.

It took the GPS ground speed and descent rate and put the glide ratio i.e. 10:1, 7:1 etc, on the screen.

When I would practice engine off accuracy landings on one of our high desert dry lakes, I could just adjust pitch untill I got the best reading.

There is a school of thought that suggest adding extra speed in a headwind and less speed in a tailwind, but knowing the actual glide ration was very useful.

Maybe IFLY can add this while we're waiting for Vocal Traffic Alerts. This has got to be a no brainer since IFLY already presents GPS ground speed and altitude. Just program the algorithm below and there it is.

Ground speed times 88 gives speed in feet per minute divided by rate of descent in feet per minute equals glide ratio.

This could be an added selling point.

John M

This is actively being worked on!

I looked in the App Store for similar iOS apps and found several intended for Hike&Fly folks--wingsuits, BASE jumpers, et alia. My fav is "Glide Ratio," which is probably the simplest there is. It uses the camera: You just move the + sign to where you'd like to land and the app tells you the glide ratio needed to get there. It works in the other direction, too--from the landing point to find the takeoff point needed for your glide ratio.  I made a screenshot video, but the forum won't take attachments larger than 256 k, so here are four frames from the video showing straight down, 4:1, 9.1:1, and "flat." I'm not sure of the calibration, but it's reasonably close. The 9.1:1 spot is a floating dock at river level. The camera was about about 30 above the water, and the floating dock is about 320 feet horizontal from the camera, so that's roughly 320:30--close enough to the app's "9.1" for rough estimates.  So you'd need a 10:1 glide ratio to glide to the floating dock from the balcony.

I haven't tried the app in flight yet--and wouldn't want to have to use it in an emergency.  But it's lots of fun to play with. And ought to confirm what we already know about out airplane's engine-out performance.