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Vy versus best glide speed

AeroDog

Well Known Member
Friend
Looking at the latest POH, Vy is given as 75 kts and speed for best glide distance is given as 63 kts. I've never seen a spread this large between the two speeds in other aircraft I've flown. Does this square with what people with flying airplanes are seeing?

Jerre
 
On my RV?s, Vy and best glide was very nearly the same: 80-85 KIAS, depending on GW & air density. This should be approximately your best lift/drag speed which of course varies with density altitude. If you have an AOA, you can program this, but a target indicated airspeed is usually close enough.
 
In an ideal case they should be the same. Real world, most of the difference comes from prop efficiency - typically prop efficiency is a strongly increasing function of airspeed, in this speed range. Especially for fixed pitched props.
 
49clipper

In my flight testing of my RV-6, Vy came out about 95mph. Best glide was sort of hard to nail down, but I use Vy that also. Seems to work out well.
Jim
 
Those speeds are also dependent on weight. It might be worthwhile to investigate the effect weight makes in your initial test period(s)
 
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