"William W. Plummer" wrote in message news:26k6d.124957$MQ5.54256@attbi_s52...

I'm out of my league here, but intuitively it seems that flying at the
best glide speed is best for fuel consumption because that's where the
airframe is robbing the least kinetic energy and turning it into heat.
The fact that the aircraft is powered is irrelevant, you just want it to
be efficient. You can pick off the best glide speed graphically --
it's where a line from the origin is tangent to the polar. With sink
rate on the Y-axis and airspeed on the X-axis, you want to minimize the
slope of that line. The airframe must be somewhere on the polar with
speed determining exactly where.

Your intuition seems to work well. Basically pulling back the throttle
until you reach the speed of max L/D saves you fuel and pushing it
forward saves you time. But as the speed of max L/D is so slow and I
don't want to cruise at max allowed power setting, I am more
interested in the optimum altitude than power setting. Power settings
are normally between 55% and 75%.

Climbing higher burns more fuel, but depending on the distance you
might want to climb higher to get extra TAS and therefore save some
fuel. Certainly the wind is another factor. But anyway, the
mathematics behind all this is very simple.