Best Glide

[midlifeflyer]

20 hours ago, MB65E said:

Also remember best glide in a head wind isn’t best glide in a tail wind. 

-Matt

True, groundspeed counts in terms of the distance you will go at a given airspeed.

Tailwinds are great  they extend your distance without doing anything special. 

With headwinds, there is a point at which the increased ground speed from increasing airspeed will compensate for the decreased groundspeed produced by the headwind, giving you some extra distance.

But the gotcha is similar to the gross weigh differential. It changes during the flight. The wind at 4,000 AGL may be very different in direction or intensity from the winds at 3,000 AGL. So yo are left with working from guesstimates which may not be accurate.

Not something I want to play with during an emergency.

[flyingcheesehead]

On 6/22/2019 at 5:27 PM, MB65E said:

Also remember best glide in a head wind isn’t best glide in a tail wind. 

 

On 6/23/2019 at 2:34 PM, midlifeflyer said:

True, groundspeed counts in terms of the distance you will go at a given airspeed.

Tailwinds are great  they extend your distance without doing anything special. 

With headwinds, there is a point at which the increased ground speed from increasing airspeed will compensate for the decreased groundspeed produced by the headwind, giving you some extra distance.

There's more to it than that. With a tailwind, you'll likely get more glide distance if you use minimum sink instead of best glide. Minimum sink is going to give you an L/d ratio very close to that of Vg, but you will be exposed to the tailwind for a longer length of time and thus be able to extend the glide a little. It's unfortunate that most manufacturers never published a minimum sink speed for our birds, but that's something that's worth doing some of your own testing on. It'll be slower than Vg, and from what I've heard it's generally where you end up if you trim fully aft with power off.

In a headwind, of course, increasing speed will reduce your glide angle relative to the wind, but can increase it relative to the ground. It'll never be as good of an angle as Vg with no wind, though.