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  #1  
Old 05-29-2017, 08:28 AM
gator gator is offline
 
Join Date: Feb 2009
Location: Naples, Fl
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Default Glide ratio

Does anyone have a good engine out glide ratio for a RV8?
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  #2  
Old 05-29-2017, 05:31 PM
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Bob Martin Bob Martin is offline
 
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Location: Richmond, Virginia
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Default RV-6

No sure it matter that much which RV.......
but I use 1 mile per 1000 foot AGL.
Just a rule of thumb.
FYI...if you are trying to squeak out every last foot, you might consider looking into a AOA.
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  #3  
Old 05-29-2017, 05:52 PM
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RVbySDI RVbySDI is offline
 
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Location: Tuttle, Oklahoma
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Quote:
Originally Posted by Bob Martin View Post
No sure it matter that much which RV.......
but I use 1 mile per 1000 foot AGL.
Just a rule of thumb.
FYI...if you are trying to squeak out every last foot, you might consider looking into a AOA.
Not sure if this is the intent for the OP question, but one of the potential reasons it would be good to know is due to Foreflight's latest update that uses the glide ratio along with best glide speed to display the glide range in the form of a ring around your location on the moving map display for your airplane. It graphically displays the glide range at all times should the need arise. It is a nice new feature but it requires knowing those two performance components of your airplane in order to configure it.
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  #4  
Old 05-29-2017, 06:46 PM
springer springer is offline
 
Join Date: May 2012
Location: AZ/MN
Posts: 261
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Quote:
Originally Posted by gator View Post
Does anyone have a good engine out glide ratio for a RV8?
2.3 miles/1000' in my FP -8 @ 85-90 mph.
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RV-4 '88-'09 Built & Sold
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  #5  
Old 05-30-2017, 05:48 PM
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chuckwn chuckwn is offline
 
Join Date: Jul 2007
Location: Petaluma, CA
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Default Glide Ratio

I plan 1.3NM/1000' at 86KIAS. O-360 with C/S prop
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  #6  
Old 05-30-2017, 06:11 PM
Robert Anglin Robert Anglin is offline
 
Join Date: Mar 2008
Location: houston, texas
Posts: 667
Default Garmin

The Garmin units take a little different data to program them.
The G3X touch we have asks for sink rate and speed. We are set up at 750'/ minute at 87 Kts. This was the mean average for Gross to as lite as we could fly. Keep in mind that they do fly 4-5 Knt. different on both ends of the weight range. Our system is all set up in Kts. not Sm./Hr. It is best to test your aircraft and get the numbers for that bird.
Hope this helps, Yours, R.E.A. III #80888
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  #7  
Old 05-30-2017, 06:38 PM
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snopercod snopercod is offline
 
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Location: Asheville, NC
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I think this is a situation where one should determine the numbers for oneself in one's own aircraft. Different props make a lot of difference.
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  #8  
Old 05-30-2017, 07:29 PM
brad walton brad walton is offline
 
Join Date: Jul 2007
Location: Cypress, TX
Posts: 460
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The only way to know what your glide ratio really is, is to turn off the fan. In a real engine out situation the prop will probably continue to turn unless the engine seizes up or you slow enough to stop the prop. Your glide ratio will be less with it turning and higher glide ratio with it stopped. So you really need two glide ratios. And don't forget the effects of wind.
Alternatively, choose a lower than real number for planning purposes. Remember that unless you are as cool as John Glenn, you really won't have a lot of time to be calculating whether you can make it to that airport at 10 to 1 from your present altitude.
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  #9  
Old 05-30-2017, 11:34 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 4,459
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The GRT EFIS units look at your real, current rate of descent and your actual ground speed (so wind is taken care of) and show how far you can go in your current direction. Tells you right away if you can make an airport or other landing site, or not.
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  #10  
Old 05-31-2017, 06:49 AM
Robert Anglin Robert Anglin is offline
 
Join Date: Mar 2008
Location: houston, texas
Posts: 667
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Quote:
Originally Posted by BobTurner View Post
The GRT EFIS units look at your real, current rate of descent and your actual ground speed (so wind is taken care of) and show how far you can go in your current direction. Tells you right away if you can make an airport or other landing site, or not.
Bob, has it here. Most of the units out there now do all the figuring for you and will adjust the glide ring for wind, best runway, into the wind, surface of the needed runway, length, they will even tell you if you mite want to pass on the closest runway in order to get to a better choice. As has been said above it is best to pick a number that is on the conservative side after you have tested your aircraft in order to get your program numbers. " Don't round up- round Down". Also try to get your numbers with the aircraft as close to gross as you can. This will give you a little extra bonus distance if you have to glide at a lower weight. And just what we have found is it is not a bad idea to test you glide ring by putting an airport on the edge of the ring and pull the power, then see if you can get there safely. If not adjust you figures. As always it is not a bad idea to stay current and practice your engine out simulations. Just 2 pennies for the pot. Yours, R.E.A. III 80888
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