BTW, two B-747s side-by-side at 35,000', one weighs 700,000#, the other,
500,000#.
If all engines are shut down, which one will glide the farthest distance?

If they are both flown at the best glide speed for their weight, they will go
the same distance, but the heavier one will get there first.

Bob Darrah

  HMMM??   Why wouldn't the heavier one need to fly at a slightly faster
speed (best glide speed) and therefore necessarily incur higher drag
since drag is a strong function of speed?  Further, it is necessary to produce
drag to produce lift, so more wt = more lift = more drag?

Please explain.  You may be right, but I don't instantly see why.

Bill
Long EZ builder & pilot
mechanical engineer

J believe that this answer can go slightly either way, depending on the lift drag
characteristics of the airfoil, and the resulting contour of the "drag bucket". At the
same glide slope, the heavier plane has more "power" (Weight times rate of sink)
allowing it to sustain that higher speed. Racing sailplanes use  water ballast to
exploit these characteristics at very small penalties in glide slope, - Vance

 
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