L / D Max with Headwind / Tailwind...

[MauleSkinner]

May I suggest that you guys go spend a little time in a glider.
'Sled

That's how I came up with my answer

Fly safe!

David
CFI-G, among others

 

[100LL... Again!]

Go read aerodynamics for naval aviators.

Best range and best glide vary with wind speed.

Minimum sink and best endurance do not.

The Navy don't lie.

 

[Lead Sled]

That's how I came up with my answer

Fly safe!

David
CFI-G, among others

I thought so.

'Sled
CFI-G, among others as well.

 

[r1830]

Best range and best glide vary with wind speed.

Agreed. Your groundspeed has changed, it will affect how far you fly in a given time.

Minimum sink and best endurance do not.

Agreed. The wind won't help you stay aloft longer.

Descending at minumum sink airspeed will mean you will stay in the air for a longer period of time which gives you best endurance.

 

[NYCPilot]

At any given altitude, best glide speed must be increased for a headwind and decreased for a tailwind.

Best glide speed is normally based upon gross weight. Anything lighter will reduce this published speed.

 

[Lead Sled]

Best glide speed is normally based upon gross weight. Anything lighter will reduce this published speed.

Also, the glide ratio (L/D) doesn't change with weight, just the speed required to achieve it.

'Sled

 

[MauleSkinner]

At any given altitude, best glide speed must be increased for a headwind and decreased for a tailwind.

I tried to draw an airspeed vs sink rate polar for the Hawker one time, but it required such a LONG piece of paper to get to 500 ktas! (ok...450...but we ARE going downhill, so it's possible):0

 

[Lead Sled]

I tried to draw an airspeed vs sink rate polar for the Hawker one time, but it required such a LONG piece of paper to get to 500 ktas! (ok...450...but we ARE going downhill, so it's possible):0

Would it have helped if you dumped some ballast... er, fuel?

'Sled

 

[Thedude]

Lead Sled has the answer. The orginal question was L/D max. Wind has no bearing on L/D max and L/D max = best glide no wind. Too many people use L/D max and best glide interchangeably.

 

[Fedora]

When you read the initial question, regardless of how well intended, you have to realize it is an ill concieved question in the first place.
R1830 tried to answer with a proper response and got shot down for not answering the question.
The question is bogus to start with.
Putting the wind on your tail will always give you more choices of where to put it down.
The first poster had the most correct answer. Who cares? Find the best place and set her down, be it crosswind, upwind or downwind.
Brian, we don't get to pick what altitude our engine quits at, so R1830's answer about what to do "AT THAT MOMENT" is a logical one.
Unless there is more information about alternates, flying into a headwind is generally not ecouraged in these "hypothetical" situations. Why does the question state fly with a headwind at 15k? Can you not fly with the tailwind component for some reason? (say you are over the coast - the wind direction doesn't matter, don't fly out to sea!)
BTW, make sure your mask is on at 15000 feet!
The poster brought up a lot of good brain power trying to answer the question, which is always good discussion. But let's not lose site of the basics and get wrapped up in the math.
!. Don't panic.
2. Fly the plane.
3. Take the time to make a proper descision
4. Stick with that descision and don't change it unless it becomes obvious that it was the wrong one.

Let's hope it doesn't happen to you.
Flay safe, have fun, and think up more appropriate questions.